commit 6428245702a40b3e3fa11bb64b7611cdd33a0778
Author: Alexander Korotkov <a.korot...@postgrespro.ru>
Date: Sat Apr 7 18:51:20 2018 +0300
Implement incremental sort
Incremental sort is an optimized variant of multikey sort for cases when the
input is already sorted by a prefix of the sort keys. For example when a
sort
by (key1, key2 ... keyN) is requested, and the input is already sorted by
(key1, key2 ... keyM), M < N, we can divide the input into groups where keys
(key1, ... keyM) are equal, and only sort on the remaining columns.
Incremental sort can give a huge benefit when LIMIT clause is specified,
then it wouldn't even have to read the whole input. Another huge benefit
of incremental sort is that sorting data in small groups may help to evade
using disk during sort. However, on small datasets which fit into memory
incremental sort may be slightly slower than full sort. That was reflected
in costing.
This patch implements very basic usage of incremental sort: it gets used
only in create_ordered_paths(), while it sort can help in much more use
cases,
for instance in merge join. But latter would require much more changes in
optimizer and postponed for further releases.
diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out
b/contrib/postgres_fdw/expected/postgres_fdw.out
index e4d9469fdd..61775e6726 100644
--- a/contrib/postgres_fdw/expected/postgres_fdw.out
+++ b/contrib/postgres_fdw/expected/postgres_fdw.out
@@ -1999,28 +1999,62 @@ SELECT t1.c1 FROM ft1 t1 WHERE NOT EXISTS (SELECT 1
FROM ft2 t2 WHERE t1.c1 = t2
119
(10 rows)
--- CROSS JOIN, not pushed down
+-- CROSS JOIN, not pushed down. For this query, essential optimization is
top-N
+-- sort. But it can't be processed at remote side, because we never do LIMIT
+-- push down. Assuming that sorting is not worth it to push down, CROSS JOIN
+-- is also not pushed down in order to transfer less tuples over network.
EXPLAIN (VERBOSE, COSTS OFF)
-SELECT t1.c1, t2.c1 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c1, t2.c1 OFFSET
100 LIMIT 10;
- QUERY PLAN
----------------------------------------------------------------------
+SELECT t1.c3, t2.c3 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c3, t2.c3 OFFSET
100 LIMIT 10;
+ QUERY PLAN
+------------------------------------------------------------------
Limit
- Output: t1.c1, t2.c1
+ Output: t1.c3, t2.c3
-> Sort
- Output: t1.c1, t2.c1
- Sort Key: t1.c1, t2.c1
+ Output: t1.c3, t2.c3
+ Sort Key: t1.c3, t2.c3
-> Nested Loop
- Output: t1.c1, t2.c1
+ Output: t1.c3, t2.c3
-> Foreign Scan on public.ft1 t1
- Output: t1.c1
- Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+ Output: t1.c3
+ Remote SQL: SELECT c3 FROM "S 1"."T 1"
-> Materialize
- Output: t2.c1
+ Output: t2.c3
-> Foreign Scan on public.ft2 t2
- Output: t2.c1
- Remote SQL: SELECT "C 1" FROM "S 1"."T 1"
+ Output: t2.c3
+ Remote SQL: SELECT c3 FROM "S 1"."T 1"
(15 rows)
+SELECT t1.c3, t2.c3 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c3, t2.c3 OFFSET
100 LIMIT 10;
+ c3 | c3
+-------+-------
+ 00001 | 00101
+ 00001 | 00102
+ 00001 | 00103
+ 00001 | 00104
+ 00001 | 00105
+ 00001 | 00106
+ 00001 | 00107
+ 00001 | 00108
+ 00001 | 00109
+ 00001 | 00110
+(10 rows)
+
+-- CROSS JOIN, pushed down. Unlike previous query, remote side is able to
+-- return tuples in given order without full sort, but using index scan and
+-- incremental sort. This is much cheaper than full sort on local side, even
+-- despite we don't know LIMIT on remote side.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c1, t2.c1 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c1, t2.c1 OFFSET
100 LIMIT 10;
+
QUERY PLAN
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Limit
+ Output: t1.c1, t2.c1
+ -> Foreign Scan
+ Output: t1.c1, t2.c1
+ Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
+ Remote SQL: SELECT r1."C 1", r2."C 1" FROM ("S 1"."T 1" r1 INNER JOIN
"S 1"."T 1" r2 ON (TRUE)) ORDER BY r1."C 1" ASC NULLS LAST, r2."C 1" ASC NULLS
LAST
+(6 rows)
+
SELECT t1.c1, t2.c1 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c1, t2.c1 OFFSET
100 LIMIT 10;
c1 | c1
----+-----
diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql
b/contrib/postgres_fdw/sql/postgres_fdw.sql
index e1df952e7a..05c8df8da9 100644
--- a/contrib/postgres_fdw/sql/postgres_fdw.sql
+++ b/contrib/postgres_fdw/sql/postgres_fdw.sql
@@ -514,7 +514,17 @@ SELECT t1.c1 FROM ft1 t1 WHERE EXISTS (SELECT 1 FROM ft2
t2 WHERE t1.c1 = t2.c1)
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1 FROM ft1 t1 WHERE NOT EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 =
t2.c2) ORDER BY t1.c1 OFFSET 100 LIMIT 10;
SELECT t1.c1 FROM ft1 t1 WHERE NOT EXISTS (SELECT 1 FROM ft2 t2 WHERE t1.c1 =
t2.c2) ORDER BY t1.c1 OFFSET 100 LIMIT 10;
--- CROSS JOIN, not pushed down
+-- CROSS JOIN, not pushed down. For this query, essential optimization is
top-N
+-- sort. But it can't be processed at remote side, because we never do LIMIT
+-- push down. Assuming that sorting is not worth it to push down, CROSS JOIN
+-- is also not pushed down in order to transfer less tuples over network.
+EXPLAIN (VERBOSE, COSTS OFF)
+SELECT t1.c3, t2.c3 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c3, t2.c3 OFFSET
100 LIMIT 10;
+SELECT t1.c3, t2.c3 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c3, t2.c3 OFFSET
100 LIMIT 10;
+-- CROSS JOIN, pushed down. Unlike previous query, remote side is able to
+-- return tuples in given order without full sort, but using index scan and
+-- incremental sort. This is much cheaper than full sort on local side, even
+-- despite we don't know LIMIT on remote side.
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c1 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c1, t2.c1 OFFSET
100 LIMIT 10;
SELECT t1.c1, t2.c1 FROM ft1 t1 CROSS JOIN ft2 t2 ORDER BY t1.c1, t2.c1 OFFSET
100 LIMIT 10;
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index a189a8efc3..1145a9bdda 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3717,6 +3717,20 @@ ANY <replaceable
class="parameter">num_sync</replaceable> ( <replaceable class="
</listitem>
</varlistentry>
+ <varlistentry id="guc-enable-incrementalsort"
xreflabel="enable_incrementalsort">
+ <term><varname>enable_incrementalsort</varname> (<type>boolean</type>)
+ <indexterm>
+ <primary><varname>enable_incrementalsort</varname> configuration
parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Enables or disables the query planner's use of incremental sort
+ steps. The default is <literal>on</literal>.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-enable-indexscan" xreflabel="enable_indexscan">
<term><varname>enable_indexscan</varname> (<type>boolean</type>)
<indexterm>
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 79f639d5e2..da9b030670 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -81,6 +81,8 @@ static void show_upper_qual(List *qual, const char *qlabel,
ExplainState *es);
static void show_sort_keys(SortState *sortstate, List *ancestors,
ExplainState *es);
+static void show_incremental_sort_keys(IncrementalSortState *incrsortstate,
+ List *ancestors, ExplainState *es);
static void show_merge_append_keys(MergeAppendState *mstate, List *ancestors,
ExplainState *es);
static void show_agg_keys(AggState *astate, List *ancestors,
@@ -94,7 +96,7 @@ static void show_grouping_set_keys(PlanState *planstate,
static void show_group_keys(GroupState *gstate, List *ancestors,
ExplainState *es);
static void show_sort_group_keys(PlanState *planstate, const char *qlabel,
- int nkeys, AttrNumber *keycols,
+ int nkeys, int nPresortedKeys,
AttrNumber *keycols,
Oid *sortOperators, Oid *collations,
bool *nullsFirst,
List *ancestors, ExplainState *es);
static void show_sortorder_options(StringInfo buf, Node *sortexpr,
@@ -102,6 +104,8 @@ static void show_sortorder_options(StringInfo buf, Node
*sortexpr,
static void show_tablesample(TableSampleClause *tsc, PlanState *planstate,
List *ancestors, ExplainState *es);
static void show_sort_info(SortState *sortstate, ExplainState *es);
+static void show_incremental_sort_info(IncrementalSortState *incrsortstate,
+
ExplainState *es);
static void show_hash_info(HashState *hashstate, ExplainState *es);
static void show_tidbitmap_info(BitmapHeapScanState *planstate,
ExplainState *es);
@@ -1067,6 +1071,9 @@ ExplainNode(PlanState *planstate, List *ancestors,
case T_Sort:
pname = sname = "Sort";
break;
+ case T_IncrementalSort:
+ pname = sname = "Incremental Sort";
+ break;
case T_Group:
pname = sname = "Group";
break;
@@ -1677,6 +1684,12 @@ ExplainNode(PlanState *planstate, List *ancestors,
show_sort_keys(castNode(SortState, planstate),
ancestors, es);
show_sort_info(castNode(SortState, planstate), es);
break;
+ case T_IncrementalSort:
+
show_incremental_sort_keys(castNode(IncrementalSortState, planstate),
+
ancestors, es);
+
show_incremental_sort_info(castNode(IncrementalSortState, planstate),
+ es);
+ break;
case T_MergeAppend:
show_merge_append_keys(castNode(MergeAppendState,
planstate),
ancestors,
es);
@@ -2006,12 +2019,29 @@ show_sort_keys(SortState *sortstate, List *ancestors,
ExplainState *es)
Sort *plan = (Sort *) sortstate->ss.ps.plan;
show_sort_group_keys((PlanState *) sortstate, "Sort Key",
- plan->numCols,
plan->sortColIdx,
+ plan->numCols, 0,
plan->sortColIdx,
plan->sortOperators,
plan->collations,
plan->nullsFirst,
ancestors, es);
}
+/*
+ * Show the sort keys for a IncrementalSort node.
+ */
+static void
+show_incremental_sort_keys(IncrementalSortState *incrsortstate,
+ List *ancestors,
ExplainState *es)
+{
+ IncrementalSort *plan = (IncrementalSort *) incrsortstate->ss.ps.plan;
+
+ show_sort_group_keys((PlanState *) incrsortstate, "Sort Key",
+ plan->sort.numCols,
plan->presortedCols,
+ plan->sort.sortColIdx,
+ plan->sort.sortOperators,
plan->sort.collations,
+ plan->sort.nullsFirst,
+ ancestors, es);
+}
+
/*
* Likewise, for a MergeAppend node.
*/
@@ -2022,7 +2052,7 @@ show_merge_append_keys(MergeAppendState *mstate, List
*ancestors,
MergeAppend *plan = (MergeAppend *) mstate->ps.plan;
show_sort_group_keys((PlanState *) mstate, "Sort Key",
- plan->numCols,
plan->sortColIdx,
+ plan->numCols, 0,
plan->sortColIdx,
plan->sortOperators,
plan->collations,
plan->nullsFirst,
ancestors, es);
@@ -2046,7 +2076,7 @@ show_agg_keys(AggState *astate, List *ancestors,
show_grouping_sets(outerPlanState(astate), plan,
ancestors, es);
else
show_sort_group_keys(outerPlanState(astate), "Group
Key",
- plan->numCols,
plan->grpColIdx,
+ plan->numCols,
0, plan->grpColIdx,
NULL, NULL,
NULL,
ancestors, es);
@@ -2115,7 +2145,7 @@ show_grouping_set_keys(PlanState *planstate,
if (sortnode)
{
show_sort_group_keys(planstate, "Sort Key",
- sortnode->numCols,
sortnode->sortColIdx,
+ sortnode->numCols, 0,
sortnode->sortColIdx,
sortnode->sortOperators, sortnode->collations,
sortnode->nullsFirst,
ancestors, es);
@@ -2172,7 +2202,7 @@ show_group_keys(GroupState *gstate, List *ancestors,
/* The key columns refer to the tlist of the child plan */
ancestors = lcons(gstate, ancestors);
show_sort_group_keys(outerPlanState(gstate), "Group Key",
- plan->numCols, plan->grpColIdx,
+ plan->numCols, 0,
plan->grpColIdx,
NULL, NULL, NULL,
ancestors, es);
ancestors = list_delete_first(ancestors);
@@ -2185,13 +2215,14 @@ show_group_keys(GroupState *gstate, List *ancestors,
*/
static void
show_sort_group_keys(PlanState *planstate, const char *qlabel,
- int nkeys, AttrNumber *keycols,
+ int nkeys, int nPresortedKeys,
AttrNumber *keycols,
Oid *sortOperators, Oid *collations,
bool *nullsFirst,
List *ancestors, ExplainState *es)
{
Plan *plan = planstate->plan;
List *context;
List *result = NIL;
+ List *resultPresorted = NIL;
StringInfoData sortkeybuf;
bool useprefix;
int keyno;
@@ -2231,9 +2262,13 @@ show_sort_group_keys(PlanState *planstate, const char
*qlabel,
nullsFirst[keyno]);
/* Emit one property-list item per sort key */
result = lappend(result, pstrdup(sortkeybuf.data));
+ if (keyno < nPresortedKeys)
+ resultPresorted = lappend(resultPresorted, exprstr);
}
ExplainPropertyList(qlabel, result, es);
+ if (nPresortedKeys > 0)
+ ExplainPropertyList("Presorted Key", resultPresorted, es);
}
/*
@@ -2441,6 +2476,95 @@ show_sort_info(SortState *sortstate, ExplainState *es)
}
}
+/*
+ * If it's EXPLAIN ANALYZE, show tuplesort stats for a incremental sort node
+ */
+static void
+show_incremental_sort_info(IncrementalSortState *incrsortstate,
+ ExplainState *es)
+{
+ if (es->analyze && incrsortstate->sort_Done &&
+ incrsortstate->tuplesortstate != NULL)
+ {
+ Tuplesortstate *state = (Tuplesortstate *)
incrsortstate->tuplesortstate;
+ TuplesortInstrumentation stats;
+ const char *sortMethod;
+ const char *spaceType;
+ long spaceUsed;
+
+ tuplesort_get_stats(state, &stats);
+ sortMethod = tuplesort_method_name(stats.sortMethod);
+ spaceType = tuplesort_space_type_name(stats.spaceType);
+ spaceUsed = stats.spaceUsed;
+
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ appendStringInfoSpaces(es->str, es->indent * 2);
+ appendStringInfo(es->str, "Sort Method: %s %s:
%ldkB\n",
+ sortMethod, spaceType,
spaceUsed);
+ appendStringInfoSpaces(es->str, es->indent * 2);
+ appendStringInfo(es->str, "Sort Groups: %ld\n",
+
incrsortstate->group_count);
+ }
+ else
+ {
+ ExplainPropertyText("Sort Method", sortMethod, es);
+ ExplainPropertyInteger("Sort Space Used", "kB",
spaceUsed, es);
+ ExplainPropertyText("Sort Space Type", spaceType, es);
+ ExplainPropertyInteger("Sort Groups:", NULL,
+
incrsortstate->group_count, es);
+ }
+ }
+
+ if (incrsortstate->shared_info != NULL)
+ {
+ int n;
+ bool opened_group = false;
+
+ for (n = 0; n < incrsortstate->shared_info->num_workers; n++)
+ {
+ TuplesortInstrumentation *sinstrument;
+ const char *sortMethod;
+ const char *spaceType;
+ long spaceUsed;
+ int64 group_count;
+
+ sinstrument =
&incrsortstate->shared_info->sinfo[n].sinstrument;
+ group_count =
incrsortstate->shared_info->sinfo[n].group_count;
+ if (sinstrument->sortMethod ==
SORT_TYPE_STILL_IN_PROGRESS)
+ continue; /* ignore any unfilled
slots */
+ sortMethod =
tuplesort_method_name(sinstrument->sortMethod);
+ spaceType =
tuplesort_space_type_name(sinstrument->spaceType);
+ spaceUsed = sinstrument->spaceUsed;
+
+ if (es->format == EXPLAIN_FORMAT_TEXT)
+ {
+ appendStringInfoSpaces(es->str, es->indent * 2);
+ appendStringInfo(es->str,
+ "Worker %d:
Sort Method: %s %s: %ldkB Groups: %ld\n",
+ n, sortMethod,
spaceType, spaceUsed, group_count);
+ }
+ else
+ {
+ if (!opened_group)
+ {
+ ExplainOpenGroup("Workers", "Workers",
false, es);
+ opened_group = true;
+ }
+ ExplainOpenGroup("Worker", NULL, true, es);
+ ExplainPropertyInteger("Worker Number", NULL,
n, es);
+ ExplainPropertyText("Sort Method", sortMethod,
es);
+ ExplainPropertyInteger("Sort Space Used", "kB",
spaceUsed, es);
+ ExplainPropertyText("Sort Space Type",
spaceType, es);
+ ExplainPropertyInteger("Sort Groups", NULL,
group_count, es);
+ ExplainCloseGroup("Worker", NULL, true, es);
+ }
+ }
+ if (opened_group)
+ ExplainCloseGroup("Workers", "Workers", false, es);
+ }
+}
+
/*
* Show information on hash buckets/batches.
*/
diff --git a/src/backend/executor/Makefile b/src/backend/executor/Makefile
index 76d87eea49..c2f06da4e5 100644
--- a/src/backend/executor/Makefile
+++ b/src/backend/executor/Makefile
@@ -24,8 +24,8 @@ OBJS = execAmi.o execCurrent.o execExpr.o execExprInterp.o \
nodeLimit.o nodeLockRows.o nodeGatherMerge.o \
nodeMaterial.o nodeMergeAppend.o nodeMergejoin.o nodeModifyTable.o \
nodeNestloop.o nodeProjectSet.o nodeRecursiveunion.o nodeResult.o \
- nodeSamplescan.o nodeSeqscan.o nodeSetOp.o nodeSort.o nodeUnique.o \
- nodeValuesscan.o \
+ nodeSamplescan.o nodeSeqscan.o nodeSetOp.o \
+ nodeSort.o nodeIncrementalSort.o nodeUnique.o nodeValuesscan.o \
nodeCtescan.o nodeNamedtuplestorescan.o nodeWorktablescan.o \
nodeGroup.o nodeSubplan.o nodeSubqueryscan.o nodeTidscan.o \
nodeForeignscan.o nodeWindowAgg.o tstoreReceiver.o tqueue.o spi.o \
diff --git a/src/backend/executor/execAmi.c b/src/backend/executor/execAmi.c
index 9e78421978..520aeefd83 100644
--- a/src/backend/executor/execAmi.c
+++ b/src/backend/executor/execAmi.c
@@ -31,6 +31,7 @@
#include "executor/nodeGroup.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
+#include "executor/nodeIncrementalSort.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeLimit.h"
@@ -253,6 +254,10 @@ ExecReScan(PlanState *node)
ExecReScanSort((SortState *) node);
break;
+ case T_IncrementalSortState:
+ ExecReScanIncrementalSort((IncrementalSortState *)
node);
+ break;
+
case T_GroupState:
ExecReScanGroup((GroupState *) node);
break;
@@ -525,8 +530,16 @@ ExecSupportsBackwardScan(Plan *node)
case T_CteScan:
case T_Material:
case T_Sort:
+ /* these don't evaluate tlist */
return true;
+ case T_IncrementalSort:
+ /*
+ * Unlike full sort, incremental sort keeps only a
single group
+ * of tuples in memory, so it can't scan backwards.
+ */
+ return false;
+
case T_LockRows:
case T_Limit:
return ExecSupportsBackwardScan(outerPlan(node));
diff --git a/src/backend/executor/execParallel.c
b/src/backend/executor/execParallel.c
index 52f1a96db5..fc3910502b 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -32,6 +32,7 @@
#include "executor/nodeForeignscan.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
+#include "executor/nodeIncrementalSort.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeSeqscan.h"
@@ -281,6 +282,10 @@ ExecParallelEstimate(PlanState *planstate,
ExecParallelEstimateContext *e)
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortEstimate((SortState *) planstate, e->pcxt);
break;
+ case T_IncrementalSortState:
+ /* even when not parallel-aware, for EXPLAIN ANALYZE */
+ ExecIncrementalSortEstimate((IncrementalSortState *)
planstate, e->pcxt);
+ break;
default:
break;
@@ -494,6 +499,10 @@ ExecParallelInitializeDSM(PlanState *planstate,
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortInitializeDSM((SortState *) planstate, d->pcxt);
break;
+ case T_IncrementalSortState:
+ /* even when not parallel-aware, for EXPLAIN ANALYZE */
+ ExecIncrementalSortInitializeDSM((IncrementalSortState
*) planstate, d->pcxt);
+ break;
default:
break;
@@ -918,6 +927,7 @@ ExecParallelReInitializeDSM(PlanState *planstate,
break;
case T_HashState:
case T_SortState:
+ case T_IncrementalSortState:
/* these nodes have DSM state, but no reinitialization
is required */
break;
@@ -978,6 +988,9 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate,
case T_SortState:
ExecSortRetrieveInstrumentation((SortState *)
planstate);
break;
+ case T_IncrementalSortState:
+
ExecIncrementalSortRetrieveInstrumentation((IncrementalSortState *) planstate);
+ break;
case T_HashState:
ExecHashRetrieveInstrumentation((HashState *)
planstate);
break;
@@ -1227,6 +1240,11 @@ ExecParallelInitializeWorker(PlanState *planstate,
ParallelWorkerContext *pwcxt)
/* even when not parallel-aware, for EXPLAIN ANALYZE */
ExecSortInitializeWorker((SortState *) planstate,
pwcxt);
break;
+ case T_IncrementalSortState:
+ /* even when not parallel-aware, for EXPLAIN ANALYZE */
+
ExecIncrementalSortInitializeWorker((IncrementalSortState *) planstate,
+
pwcxt);
+ break;
default:
break;
diff --git a/src/backend/executor/execProcnode.c
b/src/backend/executor/execProcnode.c
index a3fb4495d2..943ca65372 100644
--- a/src/backend/executor/execProcnode.c
+++ b/src/backend/executor/execProcnode.c
@@ -88,6 +88,7 @@
#include "executor/nodeGroup.h"
#include "executor/nodeHash.h"
#include "executor/nodeHashjoin.h"
+#include "executor/nodeIncrementalSort.h"
#include "executor/nodeIndexonlyscan.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeLimit.h"
@@ -314,6 +315,11 @@ ExecInitNode(Plan *node, EState *estate, int eflags)
estate, eflags);
break;
+ case T_IncrementalSort:
+ result = (PlanState *)
ExecInitIncrementalSort((IncrementalSort *) node,
+
estate, eflags);
+ break;
+
case T_Group:
result = (PlanState *) ExecInitGroup((Group *) node,
estate, eflags);
@@ -695,6 +701,10 @@ ExecEndNode(PlanState *node)
ExecEndSort((SortState *) node);
break;
+ case T_IncrementalSortState:
+ ExecEndIncrementalSort((IncrementalSortState *) node);
+ break;
+
case T_GroupState:
ExecEndGroup((GroupState *) node);
break;
diff --git a/src/backend/executor/nodeIncrementalSort.c
b/src/backend/executor/nodeIncrementalSort.c
new file mode 100644
index 0000000000..0fbb63d4b2
--- /dev/null
+++ b/src/backend/executor/nodeIncrementalSort.c
@@ -0,0 +1,681 @@
+/*-------------------------------------------------------------------------
+ *
+ * nodeIncremenalSort.c
+ * Routines to handle incremental sorting of relations.
+ *
+ * DESCRIPTION
+ *
+ * Incremental sort is an optimized variant of multikey sort for
cases
+ * when the input is already sorted by a prefix of the sort keys.
For
+ * example when a sort by (key1, key2 ... keyN) is requested, and
the
+ * input is already sorted by (key1, key2 ... keyM), M < N, we can
+ * divide the input into groups where keys (key1, ... keyM) are
equal,
+ * and only sort on the remaining columns.
+ *
+ * Consider the following example. We have input tuples
consisting of
+ * two integers (X, Y) already presorted by X, while it's required
to
+ * sort them by both X and Y. Let input tuples be following.
+ *
+ * (1, 5)
+ * (1, 2)
+ * (2, 9)
+ * (2, 1)
+ * (2, 5)
+ * (3, 3)
+ * (3, 7)
+ *
+ * Incremental sort algorithm would split the input into the
following
+ * groups, which have equal X, and then sort them by Y
individually:
+ *
+ * (1, 5) (1, 2)
+ * (2, 9) (2, 1) (2, 5)
+ * (3, 3) (3, 7)
+ *
+ * After sorting these groups and putting them altogether, we
would get
+ * the following result which is sorted by X and Y, as requested:
+ *
+ * (1, 2)
+ * (1, 5)
+ * (2, 1)
+ * (2, 5)
+ * (2, 9)
+ * (3, 3)
+ * (3, 7)
+ *
+ * Incremental sort may be more efficient than plain sort,
parcitularly
+ * on large datasets, as it reduces the amount of data to sort at
once,
+ * making it more likely it fits into work_mem (eliminating the
need to
+ * spill to disk). But the main advantage of incremental sort is
that
+ * it can start producing rows early, before sorting the whole
dataset,
+ * which is a significant benefit especially for queries with
LIMIT.
+ *
+ * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ * src/backend/executor/nodeIncremenalSort.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/htup_details.h"
+#include "executor/execdebug.h"
+#include "executor/nodeIncrementalSort.h"
+#include "miscadmin.h"
+#include "utils/lsyscache.h"
+#include "utils/tuplesort.h"
+
+/*
+ * Prepare information for presorted_keys comparison.
+ */
+static void
+preparePresortedCols(IncrementalSortState *node)
+{
+ IncrementalSort *plannode = (IncrementalSort *) node->ss.ps.plan;
+ int presortedCols,
+ i;
+
+ Assert(IsA(plannode, IncrementalSort));
+ presortedCols = plannode->presortedCols;
+
+ node->presorted_keys = (PresortedKeyData *) palloc(presortedCols *
+
sizeof(PresortedKeyData));
+
+ for (i = 0; i < presortedCols; i++)
+ {
+ Oid equalityOp,
+ equalityFunc;
+ PresortedKeyData *key;
+
+ key = &node->presorted_keys[i];
+ key->attno = plannode->sort.sortColIdx[i];
+
+ equalityOp = get_equality_op_for_ordering_op(
+
plannode->sort.sortOperators[i], NULL);
+ if (!OidIsValid(equalityOp))
+ elog(ERROR, "missing equality operator for ordering
operator %u",
+ plannode->sort.sortOperators[i]);
+
+ equalityFunc = get_opcode(equalityOp);
+ if (!OidIsValid(equalityFunc))
+ elog(ERROR, "missing function for operator %u",
equalityOp);
+
+ /* Lookup the comparison function */
+ fmgr_info_cxt(equalityFunc, &key->flinfo, CurrentMemoryContext);
+
+ /* We can initialize the callinfo just once and re-use it */
+ InitFunctionCallInfoData(key->fcinfo, &key->flinfo, 2,
+
plannode->sort.collations[i], NULL, NULL);
+ key->fcinfo.argnull[0] = false;
+ key->fcinfo.argnull[1] = false;
+ }
+}
+
+/*
+ * Check whether a given tuple belongs to the current sort group.
+ *
+ * We do this by comparing its first 'presortedCols' column values to
+ * the pivot tuple of the current group.
+ *
+ */
+static bool
+isCurrentGroup(IncrementalSortState *node, TupleTableSlot *tupleSlot)
+{
+ int presortedCols, i;
+ TupleTableSlot *group_pivot = node->group_pivot;
+
+ Assert(IsA(node->ss.ps.plan, IncrementalSort));
+
+ presortedCols = ((IncrementalSort *) node->ss.ps.plan)->presortedCols;
+
+ /*
+ * We do assume the input is sorted by keys (0, ... n), which means
+ * the tail keys are more likely to change. So we do the comparison
+ * from the end, to minimize the number of function calls.
+ */
+ for (i = presortedCols - 1; i >= 0; i--)
+ {
+ Datum datumA,
+ datumB,
+ result;
+ bool isnullA,
+ isnullB;
+ AttrNumber attno =
node->presorted_keys[i].attno;
+ PresortedKeyData *key;
+
+ datumA = slot_getattr(group_pivot, attno, &isnullA);
+ datumB = slot_getattr(tupleSlot, attno, &isnullB);
+
+ /* Special case for NULL-vs-NULL, else use standard comparison
*/
+ if (isnullA || isnullB)
+ {
+ if (isnullA == isnullB)
+ continue;
+ else
+ return false;
+ }
+
+ key = &node->presorted_keys[i];
+
+ key->fcinfo.arg[0] = datumA;
+ key->fcinfo.arg[1] = datumB;
+
+ /* just for paranoia's sake, we reset isnull each time */
+ key->fcinfo.isnull = false;
+
+ result = FunctionCallInvoke(&key->fcinfo);
+
+ /* Check for null result, since caller is clearly not expecting
one */
+ if (key->fcinfo.isnull)
+ elog(ERROR, "function %u returned NULL",
key->flinfo.fn_oid);
+
+ if (!DatumGetBool(result))
+ return false;
+ }
+ return true;
+}
+
+/*
+ * Sorting many small groups with tuplesort is inefficient. In order to
+ * cope with this problem we don't start a new group until the current one
+ * contains at least DEFAULT_MIN_GROUP_SIZE tuples. However, in the case
+ * of bounded sort where bound is less than DEFAULT_MIN_GROUP_SIZE we start
+ * looking for the new group when bound is done.
+ */
+#define DEFAULT_MIN_GROUP_SIZE 32
+
+/* ----------------------------------------------------------------
+ * ExecIncrementalSort
+ *
+ * Assuming that outer subtree returns tuple presorted by some
prefix
+ * of target sort columns, performs incremental sort. It fetches
+ * groups of tuples where prefix sort columns are equal and sorts
them
+ * using tuplesort. This approach allows to evade sorting of whole
+ * dataset. Besides taking less memory and being faster, it
allows to
+ * start returning tuples before fetching full dataset from outer
+ * subtree.
+ *
+ * Conditions:
+ * -- none.
+ *
+ * Initial States:
+ * -- the outer child is prepared to return the first tuple.
+ * ----------------------------------------------------------------
+ */
+static TupleTableSlot *
+ExecIncrementalSort(PlanState *pstate)
+{
+ IncrementalSortState *node = castNode(IncrementalSortState, pstate);
+ EState *estate;
+ ScanDirection dir;
+ Tuplesortstate *tuplesortstate;
+ TupleTableSlot *slot;
+ IncrementalSort *plannode = (IncrementalSort *) node->ss.ps.plan;
+ PlanState *outerNode;
+ TupleDesc tupDesc;
+ int64 nTuples = 0;
+ int64 minGroupSize;
+
+ CHECK_FOR_INTERRUPTS();
+
+ /*
+ * get state info from node
+ */
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "entering routine");
+
+ estate = node->ss.ps.state;
+ dir = estate->es_direction;
+ tuplesortstate = (Tuplesortstate *) node->tuplesortstate;
+
+ /*
+ * Return next tuple from the current sorted group set if available.
+ * If there are no more tuples in the current group, we need to try
+ * to fetch more tuples from the input and build another group.
+ */
+ if (node->sort_Done)
+ {
+ slot = node->ss.ps.ps_ResultTupleSlot;
+ if (tuplesort_gettupleslot(tuplesortstate,
+
ScanDirectionIsForward(dir),
+
false, slot, NULL) || node->finished)
+ return slot;
+ }
+
+ /*
+ * First time through or no tuples in the current group. Read next
+ * batch of tuples from the outer plan and pass them to tuplesort.c.
+ * Subsequent calls just fetch tuples from tuplesort, until the group
+ * is exhausted, at which point we build the next group.
+ */
+
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "sorting subplan");
+
+ /*
+ * Want to scan subplan in the forward direction while creating the
+ * sorted data.
+ */
+ estate->es_direction = ForwardScanDirection;
+
+ outerNode = outerPlanState(node);
+ tupDesc = ExecGetResultType(outerNode);
+
+ /*
+ * Initialize tuplesort module (needed only before the first group).
+ */
+ if (node->tuplesortstate == NULL)
+ {
+ /*
+ * We are going to process the first group of presorted data.
+ * Initialize support structures for cmpSortPresortedCols -
already
+ * sorted columns.
+ */
+ preparePresortedCols(node);
+
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "calling tuplesort_begin_heap");
+
+ /*
+ * Pass all the columns to tuplesort. We pass to tuple sort
groups
+ * of at least minGroupSize size. Thus, these groups doesn't
+ * necessary have equal value of the first column.
+ */
+ tuplesortstate = tuplesort_begin_heap(
+ tupDesc,
+
plannode->sort.numCols,
+
plannode->sort.sortColIdx,
+
plannode->sort.sortOperators,
+
plannode->sort.collations,
+
plannode->sort.nullsFirst,
+
work_mem,
+ NULL,
+ false);
+ node->tuplesortstate = (void *) tuplesortstate;
+ }
+ else
+ {
+ /* Next group of presorted data */
+ tuplesort_reset((Tuplesortstate *) node->tuplesortstate);
+ }
+ node->group_count++;
+
+ /*
+ * Calculate remaining bound for bounded sort and minimal group size
+ * accordingly.
+ */
+ if (node->bounded)
+ {
+ tuplesort_set_bound(tuplesortstate, node->bound -
node->bound_Done);
+ minGroupSize = Min(DEFAULT_MIN_GROUP_SIZE, node->bound -
node->bound_Done);
+ }
+ else
+ {
+ minGroupSize = DEFAULT_MIN_GROUP_SIZE;
+ }
+
+ /* If we got a leftover tuple from the last group, pass it to
tuplesort. */
+ if (!TupIsNull(node->group_pivot))
+ {
+ tuplesort_puttupleslot(tuplesortstate, node->group_pivot);
+ ExecClearTuple(node->group_pivot);
+ nTuples++;
+ }
+
+ /*
+ * Put next group of tuples where presortedCols sort values are equal to
+ * tuplesort.
+ */
+ for (;;)
+ {
+ slot = ExecProcNode(outerNode);
+
+ if (TupIsNull(slot))
+ {
+ node->finished = true;
+ break;
+ }
+
+ /*
+ * Accumulate the next group of presorted tuples for tuplesort.
+ * We always accumulate at least minGroupSize tuples, and only
+ * then we start to compare the prefix keys.
+ *
+ * The last tuple is kept as a pivot, so that we can determine
if
+ * the subsequent tuples have the same prefix key (same group).
+ */
+ if (nTuples < minGroupSize)
+ {
+ tuplesort_puttupleslot(tuplesortstate, slot);
+
+ /* Keep the last tuple in minimal group as a pivot. */
+ if (nTuples == minGroupSize - 1)
+ ExecCopySlot(node->group_pivot, slot);
+ nTuples++;
+ }
+ else
+ {
+ /*
+ * Iterate while presorted cols are the same as in the
pivot
+ * tuple.
+ *
+ * After accumulating at least minGroupSize tuples (we
don't
+ * know how many groups are there in that set), we need
to keep
+ * accumulating until we reach the end of the group.
Only then
+ * we can do the sort and output all the tuples.
+ *
+ * We compare the prefix keys to the pivot - if the
prefix keys
+ * are the same the tuple belongs to the same group, so
we pass
+ * it to the tuplesort.
+ *
+ * If the prefix differs, we've reached the end of the
group. We
+ * need to keep the last tuple, so we copy it into the
pivot slot
+ * (it does not serve as pivot, though).
+ */
+ if (isCurrentGroup(node, slot))
+ {
+ tuplesort_puttupleslot(tuplesortstate, slot);
+ nTuples++;
+ }
+ else
+ {
+ ExecCopySlot(node->group_pivot, slot);
+ break;
+ }
+ }
+ }
+
+ /*
+ * Complete the sort.
+ */
+ tuplesort_performsort(tuplesortstate);
+
+ /*
+ * restore to user specified direction
+ */
+ estate->es_direction = dir;
+
+ /*
+ * finally set the sorted flag to true
+ */
+ node->sort_Done = true;
+ node->bounded_Done = node->bounded;
+ if (node->shared_info && node->am_worker)
+ {
+ TuplesortInstrumentation *si;
+
+ Assert(IsParallelWorker());
+ Assert(ParallelWorkerNumber <= node->shared_info->num_workers);
+ si =
&node->shared_info->sinfo[ParallelWorkerNumber].sinstrument;
+ tuplesort_get_stats(tuplesortstate, si);
+ node->shared_info->sinfo[ParallelWorkerNumber].group_count =
+
node->group_count;
+ }
+
+ /*
+ * Adjust bound_Done with number of tuples we've actually sorted.
+ */
+ if (node->bounded)
+ {
+ if (node->finished)
+ node->bound_Done = node->bound;
+ else
+ node->bound_Done = Min(node->bound, node->bound_Done +
nTuples);
+ }
+
+ SO1_printf("ExecIncrementalSort: %s\n", "sorting done");
+
+ SO1_printf("ExecIncrementalSort: %s\n",
+ "retrieving tuple from tuplesort");
+
+ /*
+ * Get the first or next tuple from tuplesort. Returns NULL if no more
+ * tuples.
+ */
+ slot = node->ss.ps.ps_ResultTupleSlot;
+ (void) tuplesort_gettupleslot(tuplesortstate,
+
ScanDirectionIsForward(dir),
+ false, slot,
NULL);
+ return slot;
+}
+
+/* ----------------------------------------------------------------
+ * ExecInitIncrementalSort
+ *
+ * Creates the run-time state information for the sort node
+ * produced by the planner and initializes its outer subtree.
+ * ----------------------------------------------------------------
+ */
+IncrementalSortState *
+ExecInitIncrementalSort(IncrementalSort *node, EState *estate, int eflags)
+{
+ IncrementalSortState *incrsortstate;
+
+ SO1_printf("ExecInitIncrementalSort: %s\n",
+ "initializing sort node");
+
+ /*
+ * Incremental sort can't be used with either EXEC_FLAG_REWIND,
+ * EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK, because we hold only current
+ * bucket in tuplesortstate.
+ */
+ Assert((eflags & (EXEC_FLAG_REWIND |
+ EXEC_FLAG_BACKWARD |
+ EXEC_FLAG_MARK)) == 0);
+
+ /*
+ * create state structure
+ */
+ incrsortstate = makeNode(IncrementalSortState);
+ incrsortstate->ss.ps.plan = (Plan *) node;
+ incrsortstate->ss.ps.state = estate;
+ incrsortstate->ss.ps.ExecProcNode = ExecIncrementalSort;
+
+ incrsortstate->bounded = false;
+ incrsortstate->sort_Done = false;
+ incrsortstate->finished = false;
+ incrsortstate->tuplesortstate = NULL;
+ incrsortstate->group_pivot = NULL;
+ incrsortstate->bound_Done = 0;
+ incrsortstate->group_count = 0;
+ incrsortstate->presorted_keys = NULL;
+
+ /*
+ * Miscellaneous initialization
+ *
+ * Sort nodes don't initialize their ExprContexts because they never
call
+ * ExecQual or ExecProject.
+ */
+
+ /*
+ * initialize child nodes
+ *
+ * We shield the child node from the need to support REWIND, BACKWARD,
or
+ * MARK/RESTORE.
+ */
+ eflags &= ~(EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK);
+
+ outerPlanState(incrsortstate) = ExecInitNode(outerPlan(node), estate,
eflags);
+
+ /*
+ * Initialize scan slot and type.
+ */
+ ExecCreateScanSlotFromOuterPlan(estate, &incrsortstate->ss);
+
+ /*
+ * Initialize return slot and type. No need to initialize projection
info because
+ * this node doesn't do projections.
+ */
+ ExecInitResultTupleSlotTL(estate, &incrsortstate->ss.ps);
+ incrsortstate->ss.ps.ps_ProjInfo = NULL;
+
+ /* make standalone slot to store previous tuple from outer node */
+ incrsortstate->group_pivot = MakeSingleTupleTableSlot(
+
ExecGetResultType(outerPlanState(incrsortstate)));
+
+ SO1_printf("ExecInitIncrementalSort: %s\n",
+ "sort node initialized");
+
+ return incrsortstate;
+}
+
+/* ----------------------------------------------------------------
+ * ExecEndIncrementalSort(node)
+ * ----------------------------------------------------------------
+ */
+void
+ExecEndIncrementalSort(IncrementalSortState *node)
+{
+ SO1_printf("ExecEndIncrementalSort: %s\n",
+ "shutting down sort node");
+
+ /*
+ * clean out the tuple table
+ */
+ ExecClearTuple(node->ss.ss_ScanTupleSlot);
+ /* must drop pointer to sort result tuple */
+ ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
+ /* must drop stanalone tuple slot from outer node */
+ ExecDropSingleTupleTableSlot(node->group_pivot);
+
+ /*
+ * Release tuplesort resources
+ */
+ if (node->tuplesortstate != NULL)
+ tuplesort_end((Tuplesortstate *) node->tuplesortstate);
+ node->tuplesortstate = NULL;
+
+ /*
+ * shut down the subplan
+ */
+ ExecEndNode(outerPlanState(node));
+
+ SO1_printf("ExecEndIncrementalSort: %s\n",
+ "sort node shutdown");
+}
+
+void
+ExecReScanIncrementalSort(IncrementalSortState *node)
+{
+ PlanState *outerPlan = outerPlanState(node);
+
+ /*
+ * If we haven't sorted yet, just return. If outerplan's chgParam is not
+ * NULL then it will be re-scanned by ExecProcNode, else no reason to
+ * re-scan it at all.
+ */
+ if (!node->sort_Done)
+ return;
+
+ /* must drop pointer to sort result tuple */
+ ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
+
+ /*
+ * If subnode is to be rescanned then we forget previous sort results;
we
+ * have to re-read the subplan and re-sort. Also must re-sort if the
+ * bounded-sort parameters changed or we didn't select randomAccess.
+ *
+ * Otherwise we can just rewind and rescan the sorted output.
+ */
+ node->sort_Done = false;
+ tuplesort_end((Tuplesortstate *) node->tuplesortstate);
+ node->tuplesortstate = NULL;
+ node->bound_Done = 0;
+
+ /*
+ * if chgParam of subnode is not null then plan will be re-scanned by
+ * first ExecProcNode.
+ */
+ if (outerPlan->chgParam == NULL)
+ ExecReScan(outerPlan);
+}
+
+/* ----------------------------------------------------------------
+ * Parallel Query Support
+ * ----------------------------------------------------------------
+ */
+
+/* ----------------------------------------------------------------
+ * ExecSortEstimate
+ *
+ * Estimate space required to propagate sort statistics.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortEstimate(IncrementalSortState *node, ParallelContext *pcxt)
+{
+ Size size;
+
+ /* don't need this if not instrumenting or no workers */
+ if (!node->ss.ps.instrument || pcxt->nworkers == 0)
+ return;
+
+ size = mul_size(pcxt->nworkers, sizeof(IncrementalSortInfo));
+ size = add_size(size, offsetof(SharedIncrementalSortInfo, sinfo));
+ shm_toc_estimate_chunk(&pcxt->estimator, size);
+ shm_toc_estimate_keys(&pcxt->estimator, 1);
+}
+
+/* ----------------------------------------------------------------
+ * ExecSortInitializeDSM
+ *
+ * Initialize DSM space for sort statistics.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortInitializeDSM(IncrementalSortState *node, ParallelContext
*pcxt)
+{
+ Size size;
+
+ /* don't need this if not instrumenting or no workers */
+ if (!node->ss.ps.instrument || pcxt->nworkers == 0)
+ return;
+
+ size = offsetof(SharedIncrementalSortInfo, sinfo)
+ + pcxt->nworkers * sizeof(IncrementalSortInfo);
+ node->shared_info = shm_toc_allocate(pcxt->toc, size);
+ /* ensure any unfilled slots will contain zeroes */
+ memset(node->shared_info, 0, size);
+ node->shared_info->num_workers = pcxt->nworkers;
+ shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id,
+ node->shared_info);
+}
+
+/* ----------------------------------------------------------------
+ * ExecSortInitializeWorker
+ *
+ * Attach worker to DSM space for sort statistics.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortInitializeWorker(IncrementalSortState *node,
ParallelWorkerContext *pwcxt)
+{
+ node->shared_info =
+ shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id,
true);
+ node->am_worker = true;
+}
+
+/* ----------------------------------------------------------------
+ * ExecSortRetrieveInstrumentation
+ *
+ * Transfer sort statistics from DSM to private memory.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIncrementalSortRetrieveInstrumentation(IncrementalSortState *node)
+{
+ Size size;
+ SharedIncrementalSortInfo *si;
+
+ if (node->shared_info == NULL)
+ return;
+
+ size = offsetof(SharedIncrementalSortInfo, sinfo)
+ + node->shared_info->num_workers * sizeof(IncrementalSortInfo);
+ si = palloc(size);
+ memcpy(si, node->shared_info, size);
+ node->shared_info = si;
+}
diff --git a/src/backend/executor/nodeSort.c b/src/backend/executor/nodeSort.c
index 73f16c9aba..bdab33f5c4 100644
--- a/src/backend/executor/nodeSort.c
+++ b/src/backend/executor/nodeSort.c
@@ -93,7 +93,8 @@ ExecSort(PlanState *pstate)
plannode->collations,
plannode->nullsFirst,
work_mem,
-
NULL, node->randomAccess);
+
NULL,
+
node->randomAccess);
if (node->bounded)
tuplesort_set_bound(tuplesortstate, node->bound);
node->tuplesortstate = (void *) tuplesortstate;
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 9287baaedc..9b117f7f05 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -924,6 +924,24 @@ _copyMaterial(const Material *from)
}
+/*
+ * CopySortFields
+ *
+ * This function copies the fields of the Sort node. It is used by
+ * all the copy functions for classes which inherit from Sort.
+ */
+static void
+CopySortFields(const Sort *from, Sort *newnode)
+{
+ CopyPlanFields((const Plan *) from, (Plan *) newnode);
+
+ COPY_SCALAR_FIELD(numCols);
+ COPY_POINTER_FIELD(sortColIdx, from->numCols * sizeof(AttrNumber));
+ COPY_POINTER_FIELD(sortOperators, from->numCols * sizeof(Oid));
+ COPY_POINTER_FIELD(collations, from->numCols * sizeof(Oid));
+ COPY_POINTER_FIELD(nullsFirst, from->numCols * sizeof(bool));
+}
+
/*
* _copySort
*/
@@ -935,13 +953,29 @@ _copySort(const Sort *from)
/*
* copy node superclass fields
*/
- CopyPlanFields((const Plan *) from, (Plan *) newnode);
+ CopySortFields(from, newnode);
- COPY_SCALAR_FIELD(numCols);
- COPY_POINTER_FIELD(sortColIdx, from->numCols * sizeof(AttrNumber));
- COPY_POINTER_FIELD(sortOperators, from->numCols * sizeof(Oid));
- COPY_POINTER_FIELD(collations, from->numCols * sizeof(Oid));
- COPY_POINTER_FIELD(nullsFirst, from->numCols * sizeof(bool));
+ return newnode;
+}
+
+
+/*
+ * _copyIncrementalSort
+ */
+static IncrementalSort *
+_copyIncrementalSort(const IncrementalSort *from)
+{
+ IncrementalSort *newnode = makeNode(IncrementalSort);
+
+ /*
+ * copy node superclass fields
+ */
+ CopySortFields((const Sort *) from, (Sort *) newnode);
+
+ /*
+ * copy remainder of node
+ */
+ COPY_SCALAR_FIELD(presortedCols);
return newnode;
}
@@ -4900,6 +4934,9 @@ copyObjectImpl(const void *from)
case T_Sort:
retval = _copySort(from);
break;
+ case T_IncrementalSort:
+ retval = _copyIncrementalSort(from);
+ break;
case T_Group:
retval = _copyGroup(from);
break;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 03a91c3352..51d0e3008c 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -894,12 +894,10 @@ _outMaterial(StringInfo str, const Material *node)
}
static void
-_outSort(StringInfo str, const Sort *node)
+_outSortInfo(StringInfo str, const Sort *node)
{
int i;
- WRITE_NODE_TYPE("SORT");
-
_outPlanInfo(str, (const Plan *) node);
WRITE_INT_FIELD(numCols);
@@ -921,6 +919,24 @@ _outSort(StringInfo str, const Sort *node)
appendStringInfo(str, " %s", booltostr(node->nullsFirst[i]));
}
+static void
+_outSort(StringInfo str, const Sort *node)
+{
+ WRITE_NODE_TYPE("SORT");
+
+ _outSortInfo(str, node);
+}
+
+static void
+_outIncrementalSort(StringInfo str, const IncrementalSort *node)
+{
+ WRITE_NODE_TYPE("INCREMENTALSORT");
+
+ _outSortInfo(str, (const Sort *) node);
+
+ WRITE_INT_FIELD(presortedCols);
+}
+
static void
_outUnique(StringInfo str, const Unique *node)
{
@@ -3806,6 +3822,9 @@ outNode(StringInfo str, const void *obj)
case T_Sort:
_outSort(str, obj);
break;
+ case T_IncrementalSort:
+ _outIncrementalSort(str, obj);
+ break;
case T_Unique:
_outUnique(str, obj);
break;
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 2812dc9646..ee730bd52d 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -2134,12 +2134,13 @@ _readMaterial(void)
}
/*
- * _readSort
+ * ReadCommonSort
+ * Assign the basic stuff of all nodes that inherit from Sort
*/
-static Sort *
-_readSort(void)
+static void
+ReadCommonSort(Sort *local_node)
{
- READ_LOCALS(Sort);
+ READ_TEMP_LOCALS();
ReadCommonPlan(&local_node->plan);
@@ -2148,6 +2149,32 @@ _readSort(void)
READ_OID_ARRAY(sortOperators, local_node->numCols);
READ_OID_ARRAY(collations, local_node->numCols);
READ_BOOL_ARRAY(nullsFirst, local_node->numCols);
+}
+
+/*
+ * _readSort
+ */
+static Sort *
+_readSort(void)
+{
+ READ_LOCALS_NO_FIELDS(Sort);
+
+ ReadCommonSort(local_node);
+
+ READ_DONE();
+}
+
+/*
+ * _readIncrementalSort
+ */
+static IncrementalSort *
+_readIncrementalSort(void)
+{
+ READ_LOCALS(IncrementalSort);
+
+ ReadCommonSort(&local_node->sort);
+
+ READ_INT_FIELD(presortedCols);
READ_DONE();
}
@@ -2723,6 +2750,8 @@ parseNodeString(void)
return_value = _readMaterial();
else if (MATCH("SORT", 4))
return_value = _readSort();
+ else if (MATCH("INCREMENTALSORT", 15))
+ return_value = _readIncrementalSort();
else if (MATCH("GROUP", 5))
return_value = _readGroup();
else if (MATCH("AGG", 3))
diff --git a/src/backend/optimizer/path/allpaths.c
b/src/backend/optimizer/path/allpaths.c
index 65a34a255d..b13f7a68ba 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -3713,6 +3713,10 @@ print_path(PlannerInfo *root, Path *path, int indent)
ptype = "Sort";
subpath = ((SortPath *) path)->subpath;
break;
+ case T_IncrementalSortPath:
+ ptype = "IncrementalSort";
+ subpath = ((SortPath *) path)->subpath;
+ break;
case T_GroupPath:
ptype = "Group";
subpath = ((GroupPath *) path)->subpath;
diff --git a/src/backend/optimizer/path/costsize.c
b/src/backend/optimizer/path/costsize.c
index 47729de896..f6d4bec556 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -128,6 +128,7 @@ bool enable_indexonlyscan = true;
bool enable_bitmapscan = true;
bool enable_tidscan = true;
bool enable_sort = true;
+bool enable_incrementalsort = true;
bool enable_hashagg = true;
bool enable_nestloop = true;
bool enable_material = true;
@@ -1611,9 +1612,9 @@ cost_recursive_union(Path *runion, Path *nrterm, Path
*rterm)
}
/*
- * cost_sort
- * Determines and returns the cost of sorting a relation, including
- * the cost of reading the input data.
+ * cost_tuplesort
+ * Determines and returns the cost of sorting a relation using tuplesort,
+ * not including the cost of reading the input data.
*
* If the total volume of data to sort is less than sort_mem, we will do
* an in-memory sort, which requires no I/O and about t*log2(t) tuple
@@ -1640,39 +1641,23 @@ cost_recursive_union(Path *runion, Path *nrterm, Path
*rterm)
* specifying nonzero comparison_cost; typically that's used for any extra
* work that has to be done to prepare the inputs to the comparison operators.
*
- * 'pathkeys' is a list of sort keys
- * 'input_cost' is the total cost for reading the input data
* 'tuples' is the number of tuples in the relation
* 'width' is the average tuple width in bytes
* 'comparison_cost' is the extra cost per comparison, if any
* 'sort_mem' is the number of kilobytes of work memory allowed for the sort
* 'limit_tuples' is the bound on the number of output tuples; -1 if no bound
- *
- * NOTE: some callers currently pass NIL for pathkeys because they
- * can't conveniently supply the sort keys. Since this routine doesn't
- * currently do anything with pathkeys anyway, that doesn't matter...
- * but if it ever does, it should react gracefully to lack of key data.
- * (Actually, the thing we'd most likely be interested in is just the number
- * of sort keys, which all callers *could* supply.)
*/
-void
-cost_sort(Path *path, PlannerInfo *root,
- List *pathkeys, Cost input_cost, double tuples, int width,
+static void
+cost_tuplesort(Cost *startup_cost, Cost *run_cost,
+ double tuples, int width,
Cost comparison_cost, int sort_mem,
double limit_tuples)
{
- Cost startup_cost = input_cost;
- Cost run_cost = 0;
double input_bytes = relation_byte_size(tuples, width);
double output_bytes;
double output_tuples;
long sort_mem_bytes = sort_mem * 1024L;
- if (!enable_sort)
- startup_cost += disable_cost;
-
- path->rows = tuples;
-
/*
* We want to be sure the cost of a sort is never estimated as zero,
even
* if passed-in tuple count is zero. Besides, mustn't do log(0)...
@@ -1711,7 +1696,7 @@ cost_sort(Path *path, PlannerInfo *root,
*
* Assume about N log2 N comparisons
*/
- startup_cost += comparison_cost * tuples * LOG2(tuples);
+ *startup_cost = comparison_cost * tuples * LOG2(tuples);
/* Disk costs */
@@ -1722,7 +1707,7 @@ cost_sort(Path *path, PlannerInfo *root,
log_runs = 1.0;
npageaccesses = 2.0 * npages * log_runs;
/* Assume 3/4ths of accesses are sequential, 1/4th are not */
- startup_cost += npageaccesses *
+ *startup_cost += npageaccesses *
(seq_page_cost * 0.75 + random_page_cost * 0.25);
}
else if (tuples > 2 * output_tuples || input_bytes > sort_mem_bytes)
@@ -1733,12 +1718,12 @@ cost_sort(Path *path, PlannerInfo *root,
* factor is a bit higher than for quicksort. Tweak it so that
the
* cost curve is continuous at the crossover point.
*/
- startup_cost += comparison_cost * tuples * LOG2(2.0 *
output_tuples);
+ *startup_cost = comparison_cost * tuples * LOG2(2.0 *
output_tuples);
}
else
{
/* We'll use plain quicksort on all the input tuples */
- startup_cost += comparison_cost * tuples * LOG2(tuples);
+ *startup_cost = comparison_cost * tuples * LOG2(tuples);
}
/*
@@ -1749,8 +1734,183 @@ cost_sort(Path *path, PlannerInfo *root,
* here --- the upper LIMIT will pro-rate the run cost so we'd be double
* counting the LIMIT otherwise.
*/
- run_cost += cpu_operator_cost * tuples;
+ *run_cost = cpu_operator_cost * tuples;
+}
+/*
+ * cost_full_sort
+ * Determines and returns the cost of sorting a relation, including the
+ * cost of reading the input data.
+ *
+ * For the precise description of how the cost is calculated, see the comment
+ * for cost_tuplesort().
+ */
+void
+cost_full_sort(Cost *startup_cost, Cost *run_cost,
+ Cost input_total_cost, double tuples, int width,
+ Cost comparison_cost, int sort_mem,
+ double limit_tuples)
+{
+ cost_tuplesort(startup_cost, run_cost,
+ tuples, width,
+ comparison_cost, sort_mem,
+ limit_tuples);
+
+ if (!enable_sort)
+ *startup_cost += disable_cost;
+
+ *startup_cost += input_total_cost;
+}
+
+/*
+ * cost_incremental_sort
+ * Determines and returns the cost of sorting a relation incrementally,
when
+ * the input path is already sorted by some of the pathkeys.
+ *
+ * 'presorted_keys' is the number of leading pathkeys by which the input path
+ * is sorted.
+ *
+ * We estimate the number of groups into which the relation is divided by the
+ * leading pathkeys, and then calculate the cost of sorting a single group
+ * with tuplesort using cost_tuplesort().
+ */
+void
+cost_incremental_sort(Path *path,
+ PlannerInfo *root, List *pathkeys, int presorted_keys,
+ Cost input_startup_cost, Cost input_total_cost,
+ double input_tuples, int width, Cost comparison_cost, int
sort_mem,
+ double limit_tuples)
+{
+ Cost startup_cost = 0,
+ run_cost = 0,
+ input_run_cost = input_total_cost -
input_startup_cost;
+ double output_tuples,
+ output_groups,
+ group_tuples,
+ input_groups;
+ Cost group_startup_cost,
+ group_run_cost,
+ group_input_run_cost;
+ List *presortedExprs = NIL;
+ ListCell *l;
+ int i = 0;
+
+ Assert(presorted_keys != 0);
+
+ if (!enable_sort)
+ startup_cost += disable_cost;
+
+ if (!enable_incrementalsort)
+ startup_cost += disable_cost;
+
+ /*
+ * We want to be sure the cost of a sort is never estimated as zero,
even
+ * if passed-in tuple count is zero. Besides, mustn't do log(0)...
+ */
+ if (input_tuples < 2.0)
+ input_tuples = 2.0;
+
+ /* Extract presorted keys as list of expressions */
+ foreach(l, pathkeys)
+ {
+ PathKey *key = (PathKey *)lfirst(l);
+ EquivalenceMember *member = (EquivalenceMember *)
+
linitial(key->pk_eclass->ec_members);
+
+ presortedExprs = lappend(presortedExprs, member->em_expr);
+
+ i++;
+ if (i >= presorted_keys)
+ break;
+ }
+
+ /* Estimate number of groups with equal presorted keys */
+ input_groups = estimate_num_groups(root, presortedExprs, input_tuples,
NULL);
+ group_tuples = input_tuples / input_groups;
+ group_input_run_cost = input_run_cost / input_groups;
+
+ /*
+ * Estimate average cost of sorting of one group where presorted keys
+ * are equal. Incremental sort is sensitive to distribution of tuples
+ * to the groups, where we're relying on quite rough assumptions. Thus,
+ * we're pessimistic about incremental sort performance and increase
+ * its average group size by half.
+ */
+ cost_tuplesort(&group_startup_cost, &group_run_cost,
+ 1.5 * group_tuples, width, comparison_cost,
sort_mem,
+ limit_tuples);
+
+ /* If we have a LIMIT, adjust the number of groups we'll have to
return. */
+ if (limit_tuples > 0 && limit_tuples < input_tuples)
+ {
+ output_tuples = limit_tuples;
+ output_groups = floor(output_tuples / group_tuples) + 1;
+ }
+ else
+ {
+ output_tuples = input_tuples;
+ output_groups = input_groups;
+ }
+
+ /*
+ * Startup cost of incremental sort is the startup cost of its first
group
+ * plus the cost of its input.
+ */
+ startup_cost += group_startup_cost
+ + input_startup_cost + group_input_run_cost;
+
+ /*
+ * After we started producing tuples from the first group, the cost of
+ * producing all the tuples is given by the cost to finish processing
+ * this group, plus the total cost to process the remaining groups,
+ * plus the remaining cost of input.
+ */
+ run_cost += group_run_cost
+ + (group_run_cost + group_startup_cost) * (output_groups - 1)
+ + group_input_run_cost * (output_groups - 1);
+
+ /*
+ * Incremental sort adds some overhead by itself. Firstly, it has to
+ * detect the sort groups. This is roughly equal to one extra copy and
+ * comparison per tuple. Secondly, it has to reset the tuplesort context
+ * for every group.
+ */
+ run_cost += (cpu_tuple_cost + comparison_cost) * output_tuples;
+ run_cost += 2.0 * cpu_tuple_cost * output_groups;
+
+ path->rows = input_tuples;
+ path->startup_cost = startup_cost;
+ path->total_cost = startup_cost + run_cost;
+}
+
+/*
+ * cost_sort
+ * Determines and returns the cost of sorting a relation, including
+ * the cost of reading the input data.
+ *
+ * NOTE: some callers currently pass NIL for pathkeys because they
+ * can't conveniently supply the sort keys. Since this routine doesn't
+ * currently do anything with pathkeys anyway, that doesn't matter...
+ * but if it ever does, it should react gracefully to lack of key data.
+ * (Actually, the thing we'd most likely be interested in is just the number
+ * of sort keys, which all callers *could* supply.)
+ */
+void
+cost_sort(Path *path, PlannerInfo *root,
+ List *pathkeys, Cost input_cost, double tuples, int width,
+ Cost comparison_cost, int sort_mem,
+ double limit_tuples)
+
+{
+ Cost startup_cost;
+ Cost run_cost;
+
+ cost_full_sort(&startup_cost, &run_cost,
+ input_cost,
+ tuples, width, comparison_cost, sort_mem,
+ limit_tuples);
+
+ path->rows = tuples;
path->startup_cost = startup_cost;
path->total_cost = startup_cost + run_cost;
}
diff --git a/src/backend/optimizer/path/pathkeys.c
b/src/backend/optimizer/path/pathkeys.c
index 6d1cc3b8a0..3a3b2b6b14 100644
--- a/src/backend/optimizer/path/pathkeys.c
+++ b/src/backend/optimizer/path/pathkeys.c
@@ -327,6 +327,51 @@ pathkeys_contained_in(List *keys1, List *keys2)
return false;
}
+
+/*
+ * pathkeys_common_contained_in
+ * Same as pathkeys_contained_in, but also sets length of longest
+ * common prefix of keys1 and keys2.
+ */
+bool
+pathkeys_common_contained_in(List *keys1, List *keys2, int *n_common)
+{
+ int n = 0;
+ ListCell *key1,
+ *key2;
+
+ forboth(key1, keys1, key2, keys2)
+ {
+ PathKey *pathkey1 = (PathKey *) lfirst(key1);
+ PathKey *pathkey2 = (PathKey *) lfirst(key2);
+
+ if (pathkey1 != pathkey2)
+ {
+ *n_common = n;
+ return false;
+ }
+ n++;
+ }
+
+ *n_common = n;
+ return (key1 == NULL);
+}
+
+
+/*
+ * pathkeys_common
+ * Returns length of longest common prefix of keys1 and keys2.
+ */
+int
+pathkeys_common(List *keys1, List *keys2)
+{
+ int n;
+
+ (void) pathkeys_common_contained_in(keys1, keys2, &n);
+ return n;
+}
+
+
/*
* get_cheapest_path_for_pathkeys
* Find the cheapest path (according to the specified criterion) that
@@ -1587,19 +1632,23 @@ right_merge_direction(PlannerInfo *root, PathKey
*pathkey)
static int
pathkeys_useful_for_ordering(PlannerInfo *root, List *pathkeys)
{
+ int n_common_pathkeys;
+
if (root->query_pathkeys == NIL)
return 0; /* no special ordering
requested */
if (pathkeys == NIL)
return 0; /* unordered path */
- if (pathkeys_contained_in(root->query_pathkeys, pathkeys))
- {
- /* It's useful ... or at least the first N keys are */
- return list_length(root->query_pathkeys);
- }
+ (void) pathkeys_common_contained_in(root->query_pathkeys, pathkeys,
+
&n_common_pathkeys);
- return 0; /* path ordering not
useful */
+ /*
+ * Return the number of path keys in common, or 0 if there are none.
+ * Any leading common pathkeys could be useful for ordering because
+ * we can use the incremental sort.
+ */
+ return n_common_pathkeys;
}
/*
diff --git a/src/backend/optimizer/plan/createplan.c
b/src/backend/optimizer/plan/createplan.c
index 99d0736029..34b2417c4c 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -96,6 +96,8 @@ static Plan *create_projection_plan(PlannerInfo *root,
int flags);
static Plan *inject_projection_plan(Plan *subplan, List *tlist, bool
parallel_safe);
static Sort *create_sort_plan(PlannerInfo *root, SortPath *best_path, int
flags);
+static IncrementalSort *create_incrementalsort_plan(PlannerInfo *root,
+
IncrementalSortPath *best_path, int flags);
static Group *create_group_plan(PlannerInfo *root, GroupPath *best_path);
static Unique *create_upper_unique_plan(PlannerInfo *root, UpperUniquePath
*best_path,
int flags);
@@ -245,6 +247,10 @@ static MergeJoin *make_mergejoin(List *tlist,
static Sort *make_sort(Plan *lefttree, int numCols,
AttrNumber *sortColIdx, Oid *sortOperators,
Oid *collations, bool *nullsFirst);
+static IncrementalSort *make_incrementalsort(Plan *lefttree,
+ int numCols, int presortedCols,
+ AttrNumber *sortColIdx, Oid *sortOperators,
+ Oid *collations, bool *nullsFirst);
static Plan *prepare_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
Relids relids,
const AttrNumber *reqColIdx,
@@ -259,6 +265,8 @@ static EquivalenceMember
*find_ec_member_for_tle(EquivalenceClass *ec,
Relids relids);
static Sort *make_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
Relids relids);
+static IncrementalSort *make_incrementalsort_from_pathkeys(Plan *lefttree,
+ List *pathkeys, Relids relids,
int presortedCols);
static Sort *make_sort_from_groupcols(List *groupcls,
AttrNumber *grpColIdx,
Plan *lefttree);
@@ -458,6 +466,11 @@ create_plan_recurse(PlannerInfo *root, Path *best_path,
int flags)
(SortPath *) best_path,
flags);
break;
+ case T_IncrementalSort:
+ plan = (Plan *) create_incrementalsort_plan(root,
+
(IncrementalSortPath *) best_path,
+
flags);
+ break;
case T_Group:
plan = (Plan *) create_group_plan(root,
(GroupPath *) best_path);
@@ -1741,6 +1754,32 @@ create_sort_plan(PlannerInfo *root, SortPath *best_path,
int flags)
return plan;
}
+/*
+ * create_incrementalsort_plan
+ *
+ * Do the same as create_sort_plan, but create IncrementalSort plan.
+ */
+static IncrementalSort *
+create_incrementalsort_plan(PlannerInfo *root, IncrementalSortPath *best_path,
+ int flags)
+{
+ IncrementalSort *plan;
+ Plan *subplan;
+
+ /* See comments in create_sort_plan() above */
+ subplan = create_plan_recurse(root, best_path->spath.subpath,
+ flags |
CP_SMALL_TLIST);
+ plan = make_incrementalsort_from_pathkeys(subplan,
+
best_path->spath.path.pathkeys,
+
IS_OTHER_REL(best_path->spath.subpath->parent) ?
+
best_path->spath.path.parent->relids : NULL,
+
best_path->presortedCols);
+
+ copy_generic_path_info(&plan->sort.plan, (Path *) best_path);
+
+ return plan;
+}
+
/*
* create_group_plan
*
@@ -5000,17 +5039,24 @@ static void
label_sort_with_costsize(PlannerInfo *root, Sort *plan, double limit_tuples)
{
Plan *lefttree = plan->plan.lefttree;
- Path sort_path; /* dummy for result of
cost_sort */
+ Cost startup_cost,
+ run_cost;
+
+ /*
+ * This function shouldn't have to deal with IncrementalSort plans
+ * because they are only created from corresponding Path nodes.
+ */
+ Assert(IsA(plan, Sort));
- cost_sort(&sort_path, root, NIL,
+ cost_full_sort(&startup_cost, &run_cost,
lefttree->total_cost,
lefttree->plan_rows,
lefttree->plan_width,
0.0,
work_mem,
limit_tuples);
- plan->plan.startup_cost = sort_path.startup_cost;
- plan->plan.total_cost = sort_path.total_cost;
+ plan->plan.startup_cost = startup_cost;
+ plan->plan.total_cost = startup_cost + run_cost;
plan->plan.plan_rows = lefttree->plan_rows;
plan->plan.plan_width = lefttree->plan_width;
plan->plan.parallel_aware = false;
@@ -5597,9 +5643,12 @@ make_sort(Plan *lefttree, int numCols,
AttrNumber *sortColIdx, Oid *sortOperators,
Oid *collations, bool *nullsFirst)
{
- Sort *node = makeNode(Sort);
- Plan *plan = &node->plan;
+ Sort *node;
+ Plan *plan;
+ node = makeNode(Sort);
+
+ plan = &node->plan;
plan->targetlist = lefttree->targetlist;
plan->qual = NIL;
plan->lefttree = lefttree;
@@ -5613,6 +5662,37 @@ make_sort(Plan *lefttree, int numCols,
return node;
}
+/*
+ * make_incrementalsort --- basic routine to build a IncrementalSort plan node
+ *
+ * Caller must have built the sortColIdx, sortOperators, collations, and
+ * nullsFirst arrays already.
+ */
+static IncrementalSort *
+make_incrementalsort(Plan *lefttree, int numCols, int presortedCols,
+ AttrNumber *sortColIdx, Oid *sortOperators,
+ Oid *collations, bool *nullsFirst)
+{
+ IncrementalSort *node;
+ Plan *plan;
+
+ node = makeNode(IncrementalSort);
+
+ plan = &node->sort.plan;
+ plan->targetlist = lefttree->targetlist;
+ plan->qual = NIL;
+ plan->lefttree = lefttree;
+ plan->righttree = NULL;
+ node->presortedCols = presortedCols;
+ node->sort.numCols = numCols;
+ node->sort.sortColIdx = sortColIdx;
+ node->sort.sortOperators = sortOperators;
+ node->sort.collations = collations;
+ node->sort.nullsFirst = nullsFirst;
+
+ return node;
+}
+
/*
* prepare_sort_from_pathkeys
* Prepare to sort according to given pathkeys
@@ -5959,6 +6039,42 @@ make_sort_from_pathkeys(Plan *lefttree, List *pathkeys,
Relids relids)
collations, nullsFirst);
}
+/*
+ * make_incrementalsort_from_pathkeys
+ * Create sort plan to sort according to given pathkeys
+ *
+ * 'lefttree' is the node which yields input tuples
+ * 'pathkeys' is the list of pathkeys by which the result is to be sorted
+ * 'relids' is the set of relations required by
prepare_sort_from_pathkeys()
+ * 'presortedCols' is the number of presorted columns in input tuples
+ */
+static IncrementalSort *
+make_incrementalsort_from_pathkeys(Plan *lefttree, List *pathkeys,
+ Relids relids, int
presortedCols)
+{
+ int numsortkeys;
+ AttrNumber *sortColIdx;
+ Oid *sortOperators;
+ Oid *collations;
+ bool *nullsFirst;
+
+ /* Compute sort column info, and adjust lefttree as needed */
+ lefttree = prepare_sort_from_pathkeys(lefttree, pathkeys,
+
relids,
+
NULL,
+
false,
+
&numsortkeys,
+
&sortColIdx,
+
&sortOperators,
+
&collations,
+
&nullsFirst);
+
+ /* Now build the Sort node */
+ return make_incrementalsort(lefttree, numsortkeys, presortedCols,
+ sortColIdx,
sortOperators,
+ collations,
nullsFirst);
+}
+
/*
* make_sort_from_sortclauses
* Create sort plan to sort according to given sortclauses
@@ -6723,6 +6839,7 @@ is_projection_capable_plan(Plan *plan)
case T_Hash:
case T_Material:
case T_Sort:
+ case T_IncrementalSort:
case T_Unique:
case T_SetOp:
case T_LockRows:
diff --git a/src/backend/optimizer/plan/planner.c
b/src/backend/optimizer/plan/planner.c
index 008492bad5..aa3d97b77d 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -4840,8 +4840,8 @@ create_distinct_paths(PlannerInfo *root,
* Build a new upperrel containing Paths for ORDER BY evaluation.
*
* All paths in the result must satisfy the ORDER BY ordering.
- * The only new path we need consider is an explicit sort on the
- * cheapest-total existing path.
+ * The only new paths we need consider is an explicit full or
+ * incremental sort on the cheapest-total existing path.
*
* input_rel: contains the source-data Paths
* target: the output tlist the result Paths must emit
@@ -4880,29 +4880,60 @@ create_ordered_paths(PlannerInfo *root,
foreach(lc, input_rel->pathlist)
{
- Path *path = (Path *) lfirst(lc);
+ Path *input_path = (Path *) lfirst(lc);
+ Path *sorted_path = input_path;
bool is_sorted;
+ int presorted_keys;
+
+ is_sorted = pathkeys_common_contained_in(root->sort_pathkeys,
+
input_path->pathkeys, &presorted_keys);
- is_sorted = pathkeys_contained_in(root->sort_pathkeys,
-
path->pathkeys);
- if (path == cheapest_input_path || is_sorted)
+ if (is_sorted)
{
- if (!is_sorted)
+ /* Use the input path as is, but add a projection step
if needed */
+ if (sorted_path->pathtarget != target)
+ sorted_path = apply_projection_to_path(root,
ordered_rel,
+
sorted_path, target);
+
+ add_path(ordered_rel, sorted_path);
+ }
+ else
+ {
+ if (input_path == cheapest_input_path)
{
- /* An explicit sort here can take advantage of
LIMIT */
- path = (Path *) create_sort_path(root,
-
ordered_rel,
-
path,
-
root->sort_pathkeys,
-
limit_tuples);
+ /*
+ * Sort the cheapest input path. An explicit
sort here can take
+ * advantage of LIMIT.
+ */
+ sorted_path = (Path *) create_sort_path(root,
+
ordered_rel,
+
input_path,
+
root->sort_pathkeys,
+
limit_tuples);
+ /* Add projection step if needed */
+ if (sorted_path->pathtarget != target)
+ sorted_path =
apply_projection_to_path(root, ordered_rel,
+
sorted_path, target);
+
+ add_path(ordered_rel, sorted_path);
+ }
+ if (presorted_keys > 0)
+ {
+ /* Also consider incremental sort. */
+ sorted_path = (Path *)
create_incremental_sort_path(root,
+
ordered_rel,
+
input_path,
+
root->sort_pathkeys,
+
presorted_keys,
+
limit_tuples);
+
+ /* Add projection step if needed */
+ if (sorted_path->pathtarget != target)
+ sorted_path =
apply_projection_to_path(root, ordered_rel,
+
sorted_path, target);
+
+ add_path(ordered_rel, sorted_path);
}
-
- /* Add projection step if needed */
- if (path->pathtarget != target)
- path = apply_projection_to_path(root,
ordered_rel,
-
path, target);
-
- add_path(ordered_rel, path);
}
}
diff --git a/src/backend/optimizer/plan/setrefs.c
b/src/backend/optimizer/plan/setrefs.c
index 833a92f538..af0b720067 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -642,6 +642,7 @@ set_plan_refs(PlannerInfo *root, Plan *plan, int rtoffset)
case T_Hash:
case T_Material:
case T_Sort:
+ case T_IncrementalSort:
case T_Unique:
case T_SetOp:
diff --git a/src/backend/optimizer/plan/subselect.c
b/src/backend/optimizer/plan/subselect.c
index 83008d7661..313cad266f 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -2795,6 +2795,7 @@ finalize_plan(PlannerInfo *root, Plan *plan,
case T_Hash:
case T_Material:
case T_Sort:
+ case T_IncrementalSort:
case T_Unique:
case T_SetOp:
case T_Group:
diff --git a/src/backend/optimizer/util/pathnode.c
b/src/backend/optimizer/util/pathnode.c
index 416b3f9578..dfee78c43e 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -2593,6 +2593,57 @@ create_set_projection_path(PlannerInfo *root,
return pathnode;
}
+/*
+ * create_incremental_sort_path
+ * Creates a pathnode that represents performing an incremental sort.
+ *
+ * 'rel' is the parent relation associated with the result
+ * 'subpath' is the path representing the source of data
+ * 'pathkeys' represents the desired sort order
+ * 'presorted_keys' is the number of keys by which the input path is
+ * already sorted
+ * 'limit_tuples' is the estimated bound on the number of output tuples,
+ * or -1 if no LIMIT or couldn't estimate
+ */
+SortPath *
+create_incremental_sort_path(PlannerInfo *root,
+ RelOptInfo *rel,
+ Path *subpath,
+ List *pathkeys,
+ int presorted_keys,
+ double limit_tuples)
+{
+ IncrementalSortPath *sort = makeNode(IncrementalSortPath);
+ SortPath *pathnode = &sort->spath;
+
+ pathnode->path.pathtype = T_IncrementalSort;
+ pathnode->path.parent = rel;
+ /* Sort doesn't project, so use source path's pathtarget */
+ pathnode->path.pathtarget = subpath->pathtarget;
+ /* For now, assume we are above any joins, so no parameterization */
+ pathnode->path.param_info = NULL;
+ pathnode->path.parallel_aware = false;
+ pathnode->path.parallel_safe = rel->consider_parallel &&
+ subpath->parallel_safe;
+ pathnode->path.parallel_workers = subpath->parallel_workers;
+ pathnode->path.pathkeys = pathkeys;
+
+ pathnode->subpath = subpath;
+
+ cost_incremental_sort(&pathnode->path,
+ root, pathkeys, presorted_keys,
+ subpath->startup_cost,
+ subpath->total_cost,
+ subpath->rows,
+ subpath->pathtarget->width,
+ 0.0, /* XXX comparison_cost
shouldn't be 0? */
+ work_mem, limit_tuples);
+
+ sort->presortedCols = presorted_keys;
+
+ return pathnode;
+}
+
/*
* create_sort_path
* Creates a pathnode that represents performing an explicit sort.
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 71c2b4eff1..060790198a 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -873,6 +873,15 @@ static struct config_bool ConfigureNamesBool[] =
true,
NULL, NULL, NULL
},
+ {
+ {"enable_incrementalsort", PGC_USERSET, QUERY_TUNING_METHOD,
+ gettext_noop("Enables the planner's use of incremental
sort steps."),
+ NULL
+ },
+ &enable_incrementalsort,
+ true,
+ NULL, NULL, NULL
+ },
{
{"enable_hashagg", PGC_USERSET, QUERY_TUNING_METHOD,
gettext_noop("Enables the planner's use of hashed
aggregation plans."),
diff --git a/src/backend/utils/sort/tuplesort.c
b/src/backend/utils/sort/tuplesort.c
index e433faad86..029c43b1d5 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -125,6 +125,15 @@
#define PARALLEL_SORT(state) ((state)->shared == NULL ? 0 : \
(state)->worker >= 0 ? 1 : 2)
+/*
+ * Initial size of memtuples array. We're trying to select this size so that
+ * array don't exceed ALLOCSET_SEPARATE_THRESHOLD and overhead of allocation
+ * be possible less. However, we don't cosider array sizes less than 1024
+ *
+ */
+#define INITIAL_MEMTUPSIZE Max(1024, \
+ ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1)
+
/* GUC variables */
#ifdef TRACE_SORT
bool trace_sort = false;
@@ -243,6 +252,14 @@ struct Tuplesortstate
int64 allowedMem; /* total memory allowed, in
bytes */
int maxTapes; /* number of tapes
(Knuth's T) */
int tapeRange; /* maxTapes-1 (Knuth's
P) */
+ int64 maxSpace; /* maximum amount of space
occupied among sort
+ of groups,
either in-memory or on-disk */
+ bool maxSpaceOnDisk; /* true when maxSpace is value for
on-disk
+ space, false
when it's value for in-memory
+ space */
+ TupSortStatus maxSpaceStatus; /* sort status when maxSpace was reached
*/
+ MemoryContext maincontext; /* memory context for tuple sort
metadata
+ that persist
across multiple batches */
MemoryContext sortcontext; /* memory context holding most sort
data */
MemoryContext tuplecontext; /* sub-context of sortcontext for tuple
data */
LogicalTapeSet *tapeset; /* logtape.c object for tapes in a temp
file */
@@ -647,6 +664,8 @@ static void worker_freeze_result_tape(Tuplesortstate
*state);
static void worker_nomergeruns(Tuplesortstate *state);
static void leader_takeover_tapes(Tuplesortstate *state);
static void free_sort_tuple(Tuplesortstate *state, SortTuple *stup);
+static void tuplesort_free(Tuplesortstate *state);
+static void tuplesort_updatemax(Tuplesortstate *state);
/*
* Special versions of qsort just for SortTuple objects. qsort_tuple() sorts
@@ -682,6 +701,7 @@ tuplesort_begin_common(int workMem, SortCoordinate
coordinate,
bool randomAccess)
{
Tuplesortstate *state;
+ MemoryContext maincontext;
MemoryContext sortcontext;
MemoryContext tuplecontext;
MemoryContext oldcontext;
@@ -691,13 +711,21 @@ tuplesort_begin_common(int workMem, SortCoordinate
coordinate,
elog(ERROR, "random access disallowed under parallel sort");
/*
- * Create a working memory context for this sort operation. All data
- * needed by the sort will live inside this context.
+ * Memory context surviving tuplesort_reset. This memory context holds
+ * data which is useful to keep while sorting multiple similar batches.
*/
- sortcontext = AllocSetContextCreate(CurrentMemoryContext,
+ maincontext = AllocSetContextCreate(CurrentMemoryContext,
"TupleSort main",
ALLOCSET_DEFAULT_SIZES);
+ /*
+ * Create a working memory context for one sort operation. The content
of
+ * this context is deleted by tuplesort_reset.
+ */
+ sortcontext = AllocSetContextCreate(maincontext,
+
"TupleSort sort",
+
ALLOCSET_DEFAULT_SIZES);
+
/*
* Caller tuple (e.g. IndexTuple) memory context.
*
@@ -715,7 +743,7 @@ tuplesort_begin_common(int workMem, SortCoordinate
coordinate,
* Make the Tuplesortstate within the per-sort context. This way, we
* don't need a separate pfree() operation for it at shutdown.
*/
- oldcontext = MemoryContextSwitchTo(sortcontext);
+ oldcontext = MemoryContextSwitchTo(maincontext);
state = (Tuplesortstate *) palloc0(sizeof(Tuplesortstate));
@@ -740,6 +768,7 @@ tuplesort_begin_common(int workMem, SortCoordinate
coordinate,
state->availMem = state->allowedMem;
state->sortcontext = sortcontext;
state->tuplecontext = tuplecontext;
+ state->maincontext = maincontext;
state->tapeset = NULL;
state->memtupcount = 0;
@@ -748,9 +777,7 @@ tuplesort_begin_common(int workMem, SortCoordinate
coordinate,
* Initial size of array must be more than ALLOCSET_SEPARATE_THRESHOLD;
* see comments in grow_memtuples().
*/
- state->memtupsize = Max(1024,
-
ALLOCSET_SEPARATE_THRESHOLD / sizeof(SortTuple) + 1);
-
+ state->memtupsize = INITIAL_MEMTUPSIZE;
state->growmemtuples = true;
state->slabAllocatorUsed = false;
state->memtuples = (SortTuple *) palloc(state->memtupsize *
sizeof(SortTuple));
@@ -814,7 +841,7 @@ tuplesort_begin_heap(TupleDesc tupDesc,
MemoryContext oldcontext;
int i;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
AssertArg(nkeys > 0);
@@ -890,7 +917,7 @@ tuplesort_begin_cluster(TupleDesc tupDesc,
Assert(indexRel->rd_rel->relam == BTREE_AM_OID);
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -985,7 +1012,7 @@ tuplesort_begin_index_btree(Relation heapRel,
MemoryContext oldcontext;
int i;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -1064,7 +1091,7 @@ tuplesort_begin_index_hash(Relation heapRel,
randomAccess);
MemoryContext oldcontext;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -1107,7 +1134,7 @@ tuplesort_begin_datum(Oid datumType, Oid sortOperator,
Oid sortCollation,
int16 typlen;
bool typbyval;
- oldcontext = MemoryContextSwitchTo(state->sortcontext);
+ oldcontext = MemoryContextSwitchTo(state->maincontext);
#ifdef TRACE_SORT
if (trace_sort)
@@ -1224,16 +1251,12 @@ tuplesort_set_bound(Tuplesortstate *state, int64 bound)
}
/*
- * tuplesort_end
- *
- * Release resources and clean up.
+ * tuplesort_free
*
- * NOTE: after calling this, any pointers returned by tuplesort_getXXX are
- * pointing to garbage. Be careful not to attempt to use or free such
- * pointers afterwards!
+ * Internal routine for freeing resources of tuplesort.
*/
-void
-tuplesort_end(Tuplesortstate *state)
+static void
+tuplesort_free(Tuplesortstate *state)
{
/* context swap probably not needed, but let's be safe */
MemoryContext oldcontext = MemoryContextSwitchTo(state->sortcontext);
@@ -1294,7 +1317,111 @@ tuplesort_end(Tuplesortstate *state)
* Free the per-sort memory context, thereby releasing all working
memory,
* including the Tuplesortstate struct itself.
*/
- MemoryContextDelete(state->sortcontext);
+ MemoryContextReset(state->sortcontext);
+}
+
+/*
+ * tuplesort_end
+ *
+ * Release resources and clean up.
+ *
+ * NOTE: after calling this, any pointers returned by tuplesort_getXXX are
+ * pointing to garbage. Be careful not to attempt to use or free such
+ * pointers afterwards!
+ */
+void
+tuplesort_end(Tuplesortstate *state)
+{
+ tuplesort_free(state);
+ MemoryContextDelete(state->maincontext);
+}
+
+/*
+ * tuplesort_updatemax
+ *
+ * Update maximum resource usage statistics.
+ */
+static void
+tuplesort_updatemax(Tuplesortstate *state)
+{
+ int64 spaceUsed;
+ bool spaceUsedOnDisk;
+
+ /*
+ * Note: it might seem we should provide both memory and disk usage for
a
+ * disk-based sort. However, the current code doesn't track memory
space
+ * accurately once we have begun to return tuples to the caller (since
we
+ * don't account for pfree's the caller is expected to do), so we cannot
+ * rely on availMem in a disk sort. This does not seem worth the
overhead
+ * to fix. Is it worth creating an API for the memory context code to
+ * tell us how much is actually used in sortcontext?
+ */
+ if (state->tapeset)
+ {
+ spaceUsedOnDisk = true;
+ spaceUsed = LogicalTapeSetBlocks(state->tapeset) * BLCKSZ;
+ }
+ else
+ {
+ spaceUsedOnDisk = false;
+ spaceUsed = state->allowedMem - state->availMem;
+ }
+
+ /*
+ * Sort evicts data to the disk when it didn't manage to fit those data
+ * to the main memory. This is why we assume space used on the disk to
+ * be more important for tracking resource usage than space used in
memory.
+ * Note that amount of space occupied by some tuple set on the disk
might
+ * be less than amount of space occupied by the same tuple set in the
+ * memory due to more compact representation.
+ */
+ if ((spaceUsedOnDisk && !state->maxSpaceOnDisk) ||
+ (spaceUsedOnDisk == state->maxSpaceOnDisk && spaceUsed >
state->maxSpace))
+ {
+ state->maxSpace = spaceUsed;
+ state->maxSpaceOnDisk = spaceUsedOnDisk;
+ state->maxSpaceStatus = state->status;
+ }
+}
+
+/*
+ * tuplesort_reset
+ *
+ * Reset the tuplesort. Reset all the data in the tuplesort, but leave the
+ * meta-information in. After tuplesort_reset, tuplesort is ready to start
+ * a new sort. It allows evade recreation of tuple sort (and save
resources)
+ * when sorting multiple small batches.
+ */
+void
+tuplesort_reset(Tuplesortstate *state)
+{
+ tuplesort_updatemax(state);
+ tuplesort_free(state);
+
+ state->status = TSS_INITIAL;
+ state->memtupcount = 0;
+ state->boundUsed = false;
+ state->tapeset = NULL;
+ state->currentRun = 0;
+ state->result_tape = -1;
+ state->bounded = false;
+ state->availMem = state->allowedMem;
+ state->lastReturnedTuple = NULL;
+ state->slabAllocatorUsed = false;
+ state->slabMemoryBegin = NULL;
+ state->slabMemoryEnd = NULL;
+ state->slabFreeHead = NULL;
+ state->growmemtuples = true;
+
+ if (state->memtupsize < INITIAL_MEMTUPSIZE)
+ {
+ if (state->memtuples)
+ pfree(state->memtuples);
+ state->memtuples = (SortTuple *) palloc(INITIAL_MEMTUPSIZE *
sizeof(SortTuple));
+ state->memtupsize = INITIAL_MEMTUPSIZE;
+ }
+
+ USEMEM(state, GetMemoryChunkSpace(state->memtuples));
}
/*
@@ -2591,8 +2718,7 @@ mergeruns(Tuplesortstate *state)
* Reset tuple memory. We've freed all the tuples that we previously
* allocated. We will use the slab allocator from now on.
*/
- MemoryContextDelete(state->tuplecontext);
- state->tuplecontext = NULL;
+ MemoryContextResetOnly(state->tuplecontext);
/*
* We no longer need a large memtuples array. (We will allocate a
smaller
@@ -2642,7 +2768,8 @@ mergeruns(Tuplesortstate *state)
* from each input tape.
*/
state->memtupsize = numInputTapes;
- state->memtuples = (SortTuple *) palloc(numInputTapes *
sizeof(SortTuple));
+ state->memtuples = (SortTuple *) MemoryContextAlloc(state->maincontext,
+
numInputTapes * sizeof(SortTuple));
USEMEM(state, GetMemoryChunkSpace(state->memtuples));
/*
@@ -3139,18 +3266,15 @@ tuplesort_get_stats(Tuplesortstate *state,
* to fix. Is it worth creating an API for the memory context code to
* tell us how much is actually used in sortcontext?
*/
- if (state->tapeset)
- {
+ tuplesort_updatemax(state);
+
+ if (state->maxSpaceOnDisk)
stats->spaceType = SORT_SPACE_TYPE_DISK;
- stats->spaceUsed = LogicalTapeSetBlocks(state->tapeset) *
(BLCKSZ / 1024);
- }
else
- {
stats->spaceType = SORT_SPACE_TYPE_MEMORY;
- stats->spaceUsed = (state->allowedMem - state->availMem + 1023)
/ 1024;
- }
+ stats->spaceUsed = (state->maxSpace + 1023) / 1024;
- switch (state->status)
+ switch (state->maxSpaceStatus)
{
case TSS_SORTEDINMEM:
if (state->boundUsed)
diff --git a/src/include/executor/nodeIncrementalSort.h
b/src/include/executor/nodeIncrementalSort.h
new file mode 100644
index 0000000000..90d7a81711
--- /dev/null
+++ b/src/include/executor/nodeIncrementalSort.h
@@ -0,0 +1,30 @@
+/*-------------------------------------------------------------------------
+ *
+ * nodeIncrementalSort.h
+ *
+ *
+ *
+ * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/executor/nodeIncrementalSort.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef NODEINCREMENTALSORT_H
+#define NODEINCREMENTALSORT_H
+
+#include "access/parallel.h"
+#include "nodes/execnodes.h"
+
+extern IncrementalSortState *ExecInitIncrementalSort(IncrementalSort *node,
EState *estate, int eflags);
+extern void ExecEndIncrementalSort(IncrementalSortState *node);
+extern void ExecReScanIncrementalSort(IncrementalSortState *node);
+
+/* parallel instrumentation support */
+extern void ExecIncrementalSortEstimate(IncrementalSortState *node,
ParallelContext *pcxt);
+extern void ExecIncrementalSortInitializeDSM(IncrementalSortState *node,
ParallelContext *pcxt);
+extern void ExecIncrementalSortInitializeWorker(IncrementalSortState *node,
ParallelWorkerContext *pcxt);
+extern void ExecIncrementalSortRetrieveInstrumentation(IncrementalSortState
*node);
+
+#endif /* NODEINCREMENTALSORT_H */
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 538e679cdf..88f18e3701 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1876,6 +1876,20 @@ typedef struct MaterialState
Tuplestorestate *tuplestorestate;
} MaterialState;
+
+/* ----------------
+ * When performing sorting by multiple keys input dataset could be already
+ * presorted by some prefix of these keys. We call them "presorted keys".
+ * PresortedKeyData represents information about one such key.
+ * ----------------
+ */
+typedef struct PresortedKeyData
+{
+ FmgrInfo flinfo; /* comparison function
info */
+ FunctionCallInfoData fcinfo; /* comparison function call info */
+ OffsetNumber attno; /* attribute number in tuple */
+} PresortedKeyData;
+
/* ----------------
* Shared memory container for per-worker sort information
* ----------------
@@ -1904,6 +1918,46 @@ typedef struct SortState
SharedSortInfo *shared_info; /* one entry per worker */
} SortState;
+/* ----------------
+ * Shared memory container for per-worker incremental sort information
+ * ----------------
+ */
+typedef struct IncrementalSortInfo
+{
+ TuplesortInstrumentation sinstrument;
+ int64 group_count;
+} IncrementalSortInfo;
+
+typedef struct SharedIncrementalSortInfo
+{
+ int num_workers;
+ IncrementalSortInfo sinfo[FLEXIBLE_ARRAY_MEMBER];
+} SharedIncrementalSortInfo;
+
+/* ----------------
+ * IncrementalSortState information
+ * ----------------
+ */
+typedef struct IncrementalSortState
+{
+ ScanState ss; /* its first field is
NodeTag */
+ bool bounded; /* is the result set bounded? */
+ int64 bound; /* if bounded, how many tuples
are needed */
+ bool sort_Done; /* sort completed yet? */
+ bool finished; /* fetching tuples from outer
node
+ is finished
? */
+ bool bounded_Done; /* value of bounded we did the sort
with */
+ int64 bound_Done; /* value of bound we did the
sort with */
+ void *tuplesortstate; /* private state of tuplesort.c */
+ /* the keys by which the input path is already sorted */
+ PresortedKeyData *presorted_keys;
+ int64 group_count; /* number of groups with equal
presorted keys */
+ /* slot for pivot tuple defining values of presorted keys within group
*/
+ TupleTableSlot *group_pivot;
+ bool am_worker; /* are we a worker? */
+ SharedIncrementalSortInfo *shared_info; /* one entry per worker */
+} IncrementalSortState;
+
/* ---------------------
* GroupState information
* ---------------------
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 4fc2de7184..cf9e2e64f9 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -74,6 +74,7 @@ typedef enum NodeTag
T_HashJoin,
T_Material,
T_Sort,
+ T_IncrementalSort,
T_Group,
T_Agg,
T_WindowAgg,
@@ -127,6 +128,7 @@ typedef enum NodeTag
T_HashJoinState,
T_MaterialState,
T_SortState,
+ T_IncrementalSortState,
T_GroupState,
T_AggState,
T_WindowAggState,
@@ -245,6 +247,7 @@ typedef enum NodeTag
T_ProjectionPath,
T_ProjectSetPath,
T_SortPath,
+ T_IncrementalSortPath,
T_GroupPath,
T_UpperUniquePath,
T_AggPath,
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 0a797f0a05..81f1844574 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -757,6 +757,17 @@ typedef struct Sort
bool *nullsFirst; /* NULLS FIRST/LAST directions */
} Sort;
+
+/* ----------------
+ * incremental sort node
+ * ----------------
+ */
+typedef struct IncrementalSort
+{
+ Sort sort;
+ int presortedCols; /* number of presorted columns
*/
+} IncrementalSort;
+
/* ---------------
* group node -
* Used for queries with GROUP BY (but no aggregates) specified.
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index acb8814924..75569203f3 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -1534,6 +1534,15 @@ typedef struct SortPath
Path *subpath; /* path representing input source */
} SortPath;
+/*
+ * IncrementalSortPath
+ */
+typedef struct IncrementalSortPath
+{
+ SortPath spath;
+ int presortedCols; /* number of presorted columns
*/
+} IncrementalSortPath;
+
/*
* GroupPath represents grouping (of presorted input)
*
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index d3269eae71..13b1c80632 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -61,6 +61,7 @@ extern PGDLLIMPORT bool enable_indexonlyscan;
extern PGDLLIMPORT bool enable_bitmapscan;
extern PGDLLIMPORT bool enable_tidscan;
extern PGDLLIMPORT bool enable_sort;
+extern PGDLLIMPORT bool enable_incrementalsort;
extern PGDLLIMPORT bool enable_hashagg;
extern PGDLLIMPORT bool enable_nestloop;
extern PGDLLIMPORT bool enable_material;
@@ -109,6 +110,15 @@ extern void cost_sort(Path *path, PlannerInfo *root,
List *pathkeys, Cost input_cost, double tuples, int width,
Cost comparison_cost, int sort_mem,
double limit_tuples);
+extern void cost_full_sort(Cost *startup_cost, Cost *run_cost,
+ Cost input_total_cost, double tuples, int width,
+ Cost comparison_cost, int sort_mem,
+ double limit_tuples);
+extern void cost_incremental_sort(Path *path,
+ PlannerInfo *root, List *pathkeys, int presorted_keys,
+ Cost input_startup_cost, Cost input_total_cost,
+ double input_tuples, int width, Cost comparison_cost, int
sort_mem,
+ double limit_tuples);
extern void cost_append(AppendPath *path);
extern void cost_merge_append(Path *path, PlannerInfo *root,
List *pathkeys, int n_streams,
diff --git a/src/include/optimizer/pathnode.h b/src/include/optimizer/pathnode.h
index 895bf6959d..72da4cec08 100644
--- a/src/include/optimizer/pathnode.h
+++ b/src/include/optimizer/pathnode.h
@@ -170,6 +170,12 @@ extern ProjectSetPath
*create_set_projection_path(PlannerInfo *root,
RelOptInfo *rel,
Path *subpath,
PathTarget *target);
+extern SortPath *create_incremental_sort_path(PlannerInfo *root,
+ RelOptInfo *rel,
+ Path *subpath,
+ List *pathkeys,
+ int presorted_keys,
+ double limit_tuples);
extern SortPath *create_sort_path(PlannerInfo *root,
RelOptInfo *rel,
Path *subpath,
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index 50e180c554..3285a8055b 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -189,6 +189,8 @@ typedef enum
extern PathKeysComparison compare_pathkeys(List *keys1, List *keys2);
extern bool pathkeys_contained_in(List *keys1, List *keys2);
+extern bool pathkeys_common_contained_in(List *keys1, List *keys2, int
*n_common);
+extern int pathkeys_common(List *keys1, List *keys2);
extern Path *get_cheapest_path_for_pathkeys(List *paths, List *pathkeys,
Relids
required_outer,
CostSelector
cost_criterion,
diff --git a/src/include/utils/tuplesort.h b/src/include/utils/tuplesort.h
index d2e6754f04..4cad0d4fc2 100644
--- a/src/include/utils/tuplesort.h
+++ b/src/include/utils/tuplesort.h
@@ -192,8 +192,7 @@ extern Tuplesortstate *tuplesort_begin_heap(TupleDesc
tupDesc,
int nkeys, AttrNumber *attNums,
Oid *sortOperators, Oid
*sortCollations,
bool *nullsFirstFlags,
- int workMem, SortCoordinate coordinate,
- bool randomAccess);
+ int workMem, SortCoordinate
coordinate, bool randomAccess);
extern Tuplesortstate *tuplesort_begin_cluster(TupleDesc tupDesc,
Relation indexRel, int workMem,
SortCoordinate coordinate, bool
randomAccess);
@@ -240,6 +239,8 @@ extern bool tuplesort_skiptuples(Tuplesortstate *state,
int64 ntuples,
extern void tuplesort_end(Tuplesortstate *state);
+extern void tuplesort_reset(Tuplesortstate *state);
+
extern void tuplesort_get_stats(Tuplesortstate *state,
TuplesortInstrumentation *stats);
extern const char *tuplesort_method_name(TuplesortMethod m);
diff --git a/src/test/isolation/expected/drop-index-concurrently-1.out
b/src/test/isolation/expected/drop-index-concurrently-1.out
index 75dff56bc4..e11fb617b5 100644
--- a/src/test/isolation/expected/drop-index-concurrently-1.out
+++ b/src/test/isolation/expected/drop-index-concurrently-1.out
@@ -19,9 +19,10 @@ Sort
step explains: EXPLAIN (COSTS OFF) EXECUTE getrow_seq;
QUERY PLAN
-Sort
+Incremental Sort
Sort Key: id, data
- -> Seq Scan on test_dc
+ Presorted Key: id
+ -> Index Scan using test_dc_pkey on test_dc
Filter: ((data)::text = '34'::text)
step select2: SELECT * FROM test_dc WHERE data=34 ORDER BY id,data;
id data
diff --git a/src/test/regress/expected/incremental_sort.out
b/src/test/regress/expected/incremental_sort.out
new file mode 100644
index 0000000000..fa7fb23319
--- /dev/null
+++ b/src/test/regress/expected/incremental_sort.out
@@ -0,0 +1,45 @@
+-- When we have to sort the entire table, incremental sort will
+-- be slower than plain sort, so it should not be used.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+ QUERY PLAN
+-----------------------------------
+ Sort
+ Sort Key: tenk1.four, tenk1.ten
+ -> Sort
+ Sort Key: tenk1.four
+ -> Seq Scan on tenk1
+(5 rows)
+
+-- When there is a LIMIT clause, incremental sort is beneficial because
+-- it only has to sort some of the groups, and not the entire table.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten
+limit 1;
+ QUERY PLAN
+-----------------------------------------
+ Limit
+ -> Incremental Sort
+ Sort Key: tenk1.four, tenk1.ten
+ Presorted Key: tenk1.four
+ -> Sort
+ Sort Key: tenk1.four
+ -> Seq Scan on tenk1
+(7 rows)
+
+-- When work_mem is not enough to sort the entire table, incremental sort
+-- may be faster if individual groups still fit into work_mem.
+set work_mem to '2MB';
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+ QUERY PLAN
+-----------------------------------
+ Incremental Sort
+ Sort Key: tenk1.four, tenk1.ten
+ Presorted Key: tenk1.four
+ -> Sort
+ Sort Key: tenk1.four
+ -> Seq Scan on tenk1
+(6 rows)
+
+reset work_mem;
diff --git a/src/test/regress/expected/partition_aggregate.out
b/src/test/regress/expected/partition_aggregate.out
index 76a8209ec2..b7b65fc62d 100644
--- a/src/test/regress/expected/partition_aggregate.out
+++ b/src/test/regress/expected/partition_aggregate.out
@@ -8,6 +8,8 @@ SET enable_partitionwise_aggregate TO true;
SET enable_partitionwise_join TO true;
-- Disable parallel plans.
SET max_parallel_workers_per_gather TO 0;
+-- Disable incremental sort, which can influence selected plans due to fuzz
factor.
+SET enable_incrementalsort TO off;
--
-- Tests for list partitioned tables.
--
diff --git a/src/test/regress/expected/sysviews.out
b/src/test/regress/expected/sysviews.out
index a19ee08749..9dec75060d 100644
--- a/src/test/regress/expected/sysviews.out
+++ b/src/test/regress/expected/sysviews.out
@@ -76,6 +76,7 @@ select name, setting from pg_settings where name like
'enable%';
enable_gathermerge | on
enable_hashagg | on
enable_hashjoin | on
+ enable_incrementalsort | on
enable_indexonlyscan | on
enable_indexscan | on
enable_material | on
@@ -89,7 +90,7 @@ select name, setting from pg_settings where name like
'enable%';
enable_seqscan | on
enable_sort | on
enable_tidscan | on
-(17 rows)
+(18 rows)
-- Test that the pg_timezone_names and pg_timezone_abbrevs views are
-- more-or-less working. We can't test their contents in any great detail
diff --git a/src/test/regress/parallel_schedule
b/src/test/regress/parallel_schedule
index 00c324dd44..1e0d6f4b62 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -84,7 +84,7 @@ test: select_into select_distinct select_distinct_on
select_implicit select_havi
# ----------
# Another group of parallel tests
# ----------
-test: brin gin gist spgist privileges init_privs security_label collate
matview lock replica_identity rowsecurity object_address tablesample
groupingsets drop_operator password func_index
+test: brin gin gist spgist privileges init_privs security_label collate
matview lock replica_identity rowsecurity object_address tablesample
groupingsets drop_operator password func_index incremental_sort
# ----------
# Another group of parallel tests
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 39c3fa9c85..c43abdf1fc 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -90,6 +90,7 @@ test: select_distinct_on
test: select_implicit
test: select_having
test: subselect
+test: incremental_sort
test: union
test: case
test: join
diff --git a/src/test/regress/sql/incremental_sort.sql
b/src/test/regress/sql/incremental_sort.sql
new file mode 100644
index 0000000000..bd66228ada
--- /dev/null
+++ b/src/test/regress/sql/incremental_sort.sql
@@ -0,0 +1,17 @@
+-- When we have to sort the entire table, incremental sort will
+-- be slower than plain sort, so it should not be used.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+
+-- When there is a LIMIT clause, incremental sort is beneficial because
+-- it only has to sort some of the groups, and not the entire table.
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten
+limit 1;
+
+-- When work_mem is not enough to sort the entire table, incremental sort
+-- may be faster if individual groups still fit into work_mem.
+set work_mem to '2MB';
+explain (costs off)
+select * from (select * from tenk1 order by four) t order by four, ten;
+reset work_mem;
diff --git a/src/test/regress/sql/partition_aggregate.sql
b/src/test/regress/sql/partition_aggregate.sql
index c60d7d2342..1b05456316 100644
--- a/src/test/regress/sql/partition_aggregate.sql
+++ b/src/test/regress/sql/partition_aggregate.sql
@@ -9,6 +9,8 @@ SET enable_partitionwise_aggregate TO true;
SET enable_partitionwise_join TO true;
-- Disable parallel plans.
SET max_parallel_workers_per_gather TO 0;
+-- Disable incremental sort, which can influence selected plans due to fuzz
factor.
+SET enable_incrementalsort TO off;
--
-- Tests for list partitioned tables.
I've attached an updated copy of the patch that applies cleanly to
current master.
- Re: Re: [HACKERS] [PATCH] Incremental sort James Coleman
- Re: Re: [HACKERS] [PATCH] Incremental sort Alexander Korotkov
