Hi,
here's an updated version of the patch, including a backport version. I
ended up making the code yet a bit closer to master by introducing
add_values_to_range(). The current pre-14 code has the loop adding data
to the BRIN tuple in two places, but with the "fixed" logic handling
NULLs and the empty_range flag the amount of duplicated code got too
high, so this seem reasonable.
Both cases have a patch extending pageinspect to show the new flag, but
obviously we should commit that only in master. In backbranches it's
meant only to make testing easier.
I plan to do a bit more testing, I'd welcome some feedback - it's a
long-standing bug, and it'd be good to finally get this fixed. I don't
think the patch can be made any simpler.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
From 42603e32bd0ad456a53a96ac2d05ce714f97e1ba Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.von...@postgresql.org>
Date: Sun, 23 Apr 2023 19:26:18 +0200
Subject: [PATCH 1/2] Fix handling of NULLs in BRIN indexes
BRIN indexes did not properly distinguish between summaries for empty
(no rows) and all-NULL ranges. All summaries were initialized with
allnulls=true, and the opclasses simply reset allnulls to false when
processing the first non-NULL value. This however fails if the range
starts with a NULL value (or a sequence of NULL values), in which case
we forget the range contains NULL values.
This happens because the allnulls flag is used for two separate
purposes - to mark empty ranges (not representing any rows yet) and
ranges containing only NULL values.
Opclasses don't know which of these cases it is, and so don't know
whether to set hasnulls=true. Setting hasnulls=true in both cases would
make it correct, but it would also make BRIN indexes useless for queries
with IS NULL clauses - all ranges start empty (and thus allnulls=true),
so all ranges would end up with either allnulls=true or hasnulls=true.
The severity of the issue is somewhat reduced by the fact that it only
happens when adding values to an existing summary with allnulls=true,
not when the summarization is processing values in bulk (e.g. during
CREATE INDEX or automatic summarization). In this case the flags were
updated in a slightly different way, not forgetting the NULL values.
The best solution would be to introduce a new flag marking index tuples
representing ranges with no rows, but that would break on-disk format
and/or ABI, depending on where we put the flag. Considering we need to
backpatch this, that's not acceptable.
So instead we use an "impossible" combination of both flags (allnulls
and hasnulls) set to true, to mark "empty" ranges with no rows. In
principle "empty" is a feature of the whole index tuple, which may
contain multiple summaries in a multi-column index, but this is where
the flags are, unfortunately.
We could also skip storing index tuples for empty summaries, but then
we'd have to always process such ranges - even if there are no rows in
large parts of the table (e.g. after a bulk DELETE), it would still
require reading the pages etc. So we store them, but ignore them when
building the bitmap.
Backpatch to 11. The issue exists since BRIN indexes were introduced in
9.5, but older releases are already EOL.
Backpatch-through: 11
Reviewed-by: Justin Pryzby, Matthias van de Meent
Discussion: https://postgr.es/m/402430e4-7d9d-6cf1-09ef-464d80aff...@enterprisedb.com
---
src/backend/access/brin/brin.c | 226 ++++++++++++++----
src/backend/access/brin/brin_tuple.c | 15 +-
src/include/access/brin_tuple.h | 6 +-
...summarization-and-inprogress-insertion.out | 8 +-
...ummarization-and-inprogress-insertion.spec | 1 +
5 files changed, 201 insertions(+), 55 deletions(-)
diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 0becfde1133..f99a9ba5cf9 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -35,6 +35,7 @@
#include "storage/freespace.h"
#include "utils/acl.h"
#include "utils/builtins.h"
+#include "utils/datum.h"
#include "utils/index_selfuncs.h"
#include "utils/memutils.h"
#include "utils/rel.h"
@@ -77,7 +78,8 @@ static void form_and_insert_tuple(BrinBuildState *state);
static void union_tuples(BrinDesc *bdesc, BrinMemTuple *a,
BrinTuple *b);
static void brin_vacuum_scan(Relation idxrel, BufferAccessStrategy strategy);
-
+static bool add_values_to_range(Relation idxRel, BrinDesc *bdesc,
+ BrinMemTuple *dtup, Datum *values, bool *nulls);
/*
* BRIN handler function: return IndexAmRoutine with access method parameters
@@ -173,11 +175,10 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
for (;;)
{
- bool need_insert = false;
+ bool need_insert;
OffsetNumber off;
BrinTuple *brtup;
BrinMemTuple *dtup;
- int keyno;
CHECK_FOR_INTERRUPTS();
@@ -241,31 +242,7 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
dtup = brin_deform_tuple(bdesc, brtup, NULL);
- /*
- * Compare the key values of the new tuple to the stored index values;
- * our deformed tuple will get updated if the new tuple doesn't fit
- * the original range (note this means we can't break out of the loop
- * early). Make a note of whether this happens, so that we know to
- * insert the modified tuple later.
- */
- for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
- {
- Datum result;
- BrinValues *bval;
- FmgrInfo *addValue;
-
- bval = &dtup->bt_columns[keyno];
- addValue = index_getprocinfo(idxRel, keyno + 1,
- BRIN_PROCNUM_ADDVALUE);
- result = FunctionCall4Coll(addValue,
- idxRel->rd_indcollation[keyno],
- PointerGetDatum(bdesc),
- PointerGetDatum(bval),
- values[keyno],
- nulls[keyno]);
- /* if that returned true, we need to insert the updated tuple */
- need_insert |= DatumGetBool(result);
- }
+ need_insert = add_values_to_range(idxRel, bdesc, dtup, values, nulls);
if (!need_insert)
{
@@ -508,6 +485,17 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
CurrentMemoryContext);
}
+ /*
+ * If the BRIN tuple indicates that this range is empty,
+ * we can skip it: there's nothing to match. We don't
+ * need to examine the next columns.
+ */
+ if (dtup->bt_empty_range)
+ {
+ addrange = false;
+ break;
+ }
+
/*
* Check whether the scan key is consistent with the page
* range values; if so, have the pages in the range added
@@ -611,7 +599,6 @@ brinbuildCallback(Relation index,
{
BrinBuildState *state = (BrinBuildState *) brstate;
BlockNumber thisblock;
- int i;
thisblock = ItemPointerGetBlockNumber(tid);
@@ -640,25 +627,8 @@ brinbuildCallback(Relation index,
}
/* Accumulate the current tuple into the running state */
- for (i = 0; i < state->bs_bdesc->bd_tupdesc->natts; i++)
- {
- FmgrInfo *addValue;
- BrinValues *col;
- Form_pg_attribute attr = TupleDescAttr(state->bs_bdesc->bd_tupdesc, i);
-
- col = &state->bs_dtuple->bt_columns[i];
- addValue = index_getprocinfo(index, i + 1,
- BRIN_PROCNUM_ADDVALUE);
-
- /*
- * Update dtuple state, if and as necessary.
- */
- FunctionCall4Coll(addValue,
- attr->attcollation,
- PointerGetDatum(state->bs_bdesc),
- PointerGetDatum(col),
- values[i], isnull[i]);
- }
+ (void) add_values_to_range(index, state->bs_bdesc, state->bs_dtuple,
+ values, isnull);
}
/*
@@ -1448,6 +1418,8 @@ form_and_insert_tuple(BrinBuildState *state)
/*
* Given two deformed tuples, adjust the first one so that it's consistent
* with the summary values in both.
+ *
+ * XXX I'm not sure we can actually get empty "b".
*/
static void
union_tuples(BrinDesc *bdesc, BrinMemTuple *a, BrinTuple *b)
@@ -1465,6 +1437,64 @@ union_tuples(BrinDesc *bdesc, BrinMemTuple *a, BrinTuple *b)
db = brin_deform_tuple(bdesc, b, NULL);
MemoryContextSwitchTo(oldcxt);
+ /*
+ * Check if the ranges are empty.
+ *
+ * If at least one of them is empty, we don't need to call per-key union
+ * functions at all. If "b" is empty, we just use "a" as the result (it
+ * might be empty fine, but that's fine). If "a" is empty but "b" is not,
+ * we use "b" as the result (but we have to copy the data into "a" first).
+ *
+ * Only when both ranges are non-empty, we actually do the per-key merge.
+ */
+
+ /* If "b" is empty - ignore it and just use "a" (even if it's empty etc.). */
+ if (db->bt_empty_range)
+ {
+ /* skip the per-key merge */
+ MemoryContextDelete(cxt);
+ return;
+ }
+
+ /*
+ * Now we know "b" is not empty. If "a" is empty, then "b" is the result.
+ * But we need to copy the data from "b" to "a" first, because that's how
+ * we pass result out.
+ *
+ * We have to copy all the global/per-key flags etc. too.
+ */
+ if (a->bt_empty_range)
+ {
+ for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
+ {
+ int i;
+ BrinValues *col_a = &a->bt_columns[keyno];
+ BrinValues *col_b = &db->bt_columns[keyno];
+ BrinOpcInfo *opcinfo = bdesc->bd_info[keyno];
+
+ col_a->bv_allnulls = col_b->bv_allnulls;
+ col_a->bv_hasnulls = col_b->bv_hasnulls;
+
+ /* If "b" has no data, we're done. */
+ if (col_b->bv_allnulls)
+ continue;
+
+ for (i = 0; i < opcinfo->oi_nstored; i++)
+ col_a->bv_values[i] =
+ datumCopy(col_b->bv_values[i],
+ opcinfo->oi_typcache[i]->typbyval,
+ opcinfo->oi_typcache[i]->typlen);
+ }
+
+ /* "a" started empty, but "b" was not empty, so remember that */
+ a->bt_empty_range = false;
+
+ /* skip the per-key merge */
+ MemoryContextDelete(cxt);
+ return;
+ }
+
+ /* Now we know neither range is empty. */
for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
{
FmgrInfo *unionFn;
@@ -1523,3 +1553,103 @@ brin_vacuum_scan(Relation idxrel, BufferAccessStrategy strategy)
*/
FreeSpaceMapVacuum(idxrel);
}
+
+static bool
+add_values_to_range(Relation idxRel, BrinDesc *bdesc, BrinMemTuple *dtup,
+ Datum *values, bool *nulls)
+{
+ int keyno;
+
+ /* If the range starts empty, we're certainly going to modify it. */
+ bool modified = dtup->bt_empty_range;
+
+ /*
+ * Compare the key values of the new tuple to the stored index values;
+ * our deformed tuple will get updated if the new tuple doesn't fit
+ * the original range (note this means we can't break out of the loop
+ * early). Make a note of whether this happens, so that we know to
+ * insert the modified tuple later.
+ */
+ for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
+ {
+ Datum result;
+ BrinValues *bval;
+ FmgrInfo *addValue;
+ bool has_nulls;
+
+ bval = &dtup->bt_columns[keyno];
+
+ /*
+ * Does the range have actual NULL values? Either of the flags can
+ * be set, but we ignore the state before adding first row.
+ *
+ * We have to remember this, because we'll modify the flags and we
+ * need to know if the range started as empty.
+ */
+ has_nulls = ((!dtup->bt_empty_range) &&
+ (bval->bv_hasnulls || bval->bv_allnulls));
+
+ /*
+ * If the value we're adding is NULL, handle it locally. Otherwise
+ * call the BRIN_PROCNUM_ADDVALUE procedure.
+ */
+ if (nulls[keyno])
+ {
+ /*
+ * We can't check "bv_hasnulls" because then we might end up with
+ * both flags set to true, which is interpreted as empty range.
+ * But that'd be wrong, because we've just added a value.
+ *
+ * So either the range has allnulls=true, or we have to set the
+ * hasnulls flag. Check if we're changing the value to determine
+ * if the index tuple was modified.
+ */
+ if (!bval->bv_allnulls)
+ {
+ /* Are we changing the tuple? */
+ modified |= (!bval->bv_hasnulls);
+ bval->bv_hasnulls = true;
+ }
+ }
+ else
+ {
+ addValue = index_getprocinfo(idxRel, keyno + 1,
+ BRIN_PROCNUM_ADDVALUE);
+ result = FunctionCall4Coll(addValue,
+ idxRel->rd_indcollation[keyno],
+ PointerGetDatum(bdesc),
+ PointerGetDatum(bval),
+ values[keyno],
+ nulls[keyno]);
+ /* if that returned true, we need to insert the updated tuple */
+ modified |= DatumGetBool(result);
+ }
+
+ /*
+ * If the range was had actual NULL values (i.e. did not start empty),
+ * make sure we don't forget about the NULL values. Either the allnulls
+ * flag is still set to true, or (if the opclass cleared it) we need to
+ * set hasnulls=true.
+ *
+ * XXX This can only happen when the opclass modified the tuple, so the
+ * modified flag should be set.
+ */
+ if (has_nulls && !(bval->bv_hasnulls || bval->bv_allnulls))
+ {
+ Assert(modified);
+ bval->bv_hasnulls = true;
+ }
+ }
+
+ /*
+ * After updating summaries for all the keys, mark it as not empty.
+ *
+ * If we're actually changing the flag value (i.e. tuple started as
+ * empty), we should have modified the tuple. So we should not see
+ * empty range that was not modified.
+ */
+ Assert(!dtup->bt_empty_range || modified);
+ dtup->bt_empty_range = false;
+
+ return modified;
+}
diff --git a/src/backend/access/brin/brin_tuple.c b/src/backend/access/brin/brin_tuple.c
index b3b453aed12..f9877980f4d 100644
--- a/src/backend/access/brin/brin_tuple.c
+++ b/src/backend/access/brin/brin_tuple.c
@@ -349,6 +349,9 @@ brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno, BrinMemTuple *tuple,
if (tuple->bt_placeholder)
rettuple->bt_info |= BRIN_PLACEHOLDER_MASK;
+ if (tuple->bt_empty_range)
+ rettuple->bt_info |= BRIN_EMPTY_RANGE_MASK;
+
*size = len;
return rettuple;
}
@@ -376,7 +379,7 @@ brin_form_placeholder_tuple(BrinDesc *brdesc, BlockNumber blkno, Size *size)
rettuple = palloc0(len);
rettuple->bt_blkno = blkno;
rettuple->bt_info = hoff;
- rettuple->bt_info |= BRIN_NULLS_MASK | BRIN_PLACEHOLDER_MASK;
+ rettuple->bt_info |= BRIN_NULLS_MASK | BRIN_PLACEHOLDER_MASK | BRIN_EMPTY_RANGE_MASK;
bitP = ((bits8 *) ((char *) rettuple + SizeOfBrinTuple)) - 1;
bitmask = HIGHBIT;
@@ -466,6 +469,8 @@ brin_new_memtuple(BrinDesc *brdesc)
dtup->bt_allnulls = palloc(sizeof(bool) * brdesc->bd_tupdesc->natts);
dtup->bt_hasnulls = palloc(sizeof(bool) * brdesc->bd_tupdesc->natts);
+ dtup->bt_empty_range = true;
+
dtup->bt_context = AllocSetContextCreate(CurrentMemoryContext,
"brin dtuple",
ALLOCSET_DEFAULT_SIZES);
@@ -499,6 +504,9 @@ brin_memtuple_initialize(BrinMemTuple *dtuple, BrinDesc *brdesc)
currdatum += sizeof(Datum) * brdesc->bd_info[i]->oi_nstored;
}
+ /* FIXME Shouldn't this reset bt_placeholder too? */
+ dtuple->bt_empty_range = true;
+
return dtuple;
}
@@ -532,6 +540,11 @@ brin_deform_tuple(BrinDesc *brdesc, BrinTuple *tuple, BrinMemTuple *dMemtuple)
if (BrinTupleIsPlaceholder(tuple))
dtup->bt_placeholder = true;
+
+ /* ranges start as empty, depends on the BrinTuple */
+ if (!BrinTupleIsEmptyRange(tuple))
+ dtup->bt_empty_range = false;
+
dtup->bt_blkno = tuple->bt_blkno;
values = dtup->bt_values;
diff --git a/src/include/access/brin_tuple.h b/src/include/access/brin_tuple.h
index a9ccc3995b4..5280872707a 100644
--- a/src/include/access/brin_tuple.h
+++ b/src/include/access/brin_tuple.h
@@ -36,6 +36,7 @@ typedef struct BrinValues
typedef struct BrinMemTuple
{
bool bt_placeholder; /* this is a placeholder tuple */
+ bool bt_empty_range; /* range represents no tuples */
BlockNumber bt_blkno; /* heap blkno that the tuple is for */
MemoryContext bt_context; /* memcxt holding the bt_columns values */
/* output arrays for brin_deform_tuple: */
@@ -61,7 +62,7 @@ typedef struct BrinTuple
*
* 7th (high) bit: has nulls
* 6th bit: is placeholder tuple
- * 5th bit: unused
+ * 5th bit: range is empty
* 4-0 bit: offset of data
* ---------------
*/
@@ -74,13 +75,14 @@ typedef struct BrinTuple
* bt_info manipulation macros
*/
#define BRIN_OFFSET_MASK 0x1F
-/* bit 0x20 is not used at present */
+#define BRIN_EMPTY_RANGE_MASK 0x20
#define BRIN_PLACEHOLDER_MASK 0x40
#define BRIN_NULLS_MASK 0x80
#define BrinTupleDataOffset(tup) ((Size) (((BrinTuple *) (tup))->bt_info & BRIN_OFFSET_MASK))
#define BrinTupleHasNulls(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_NULLS_MASK)) != 0)
#define BrinTupleIsPlaceholder(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_PLACEHOLDER_MASK)) != 0)
+#define BrinTupleIsEmptyRange(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_EMPTY_RANGE_MASK)) != 0)
extern BrinTuple *brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno,
diff --git a/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out b/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
index 2a4755d0998..584ac2602f7 100644
--- a/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
+++ b/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
@@ -4,7 +4,7 @@ starting permutation: s2check s1b s2b s1i s2summ s1c s2c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+--------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
(1 row)
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
@@ -26,7 +26,7 @@ step s2c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+-----------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
2| 1| 1|f |f |f |{1 .. 1000}
(2 rows)
@@ -35,7 +35,7 @@ starting permutation: s2check s1b s1i s2vacuum s1c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+--------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
(1 row)
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
@@ -45,7 +45,7 @@ step s1c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+-----------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
2| 1| 1|f |f |f |{1 .. 1000}
(2 rows)
diff --git a/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec b/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec
index 19ac18a2e88..18ba92b7ba1 100644
--- a/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec
+++ b/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec
@@ -9,6 +9,7 @@ setup
) WITH (fillfactor=10);
CREATE INDEX brinidx ON brin_iso USING brin (value) WITH (pages_per_range=1);
-- this fills the first page
+ INSERT INTO brin_iso VALUES (NULL);
DO $$
DECLARE curtid tid;
BEGIN
--
2.40.0
From 157923fb3d55095d8d45fb1e7fe56a992d667b32 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.von...@postgresql.org>
Date: Sun, 23 Apr 2023 22:19:05 +0200
Subject: [PATCH 2/2] pageinspect tweak
---
contrib/pageinspect/brinfuncs.c | 10 ++++++----
contrib/pageinspect/pageinspect--1.7--1.8.sql | 20 +++++++++++++++++++
2 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/contrib/pageinspect/brinfuncs.c b/contrib/pageinspect/brinfuncs.c
index 04a90c4782d..8db6f1bcc7d 100644
--- a/contrib/pageinspect/brinfuncs.c
+++ b/contrib/pageinspect/brinfuncs.c
@@ -227,8 +227,8 @@ brin_page_items(PG_FUNCTION_ARGS)
dtup = NULL;
for (;;)
{
- Datum values[7];
- bool nulls[7];
+ Datum values[8];
+ bool nulls[8];
/*
* This loop is called once for every attribute of every tuple in the
@@ -267,6 +267,7 @@ brin_page_items(PG_FUNCTION_ARGS)
nulls[4] = true;
nulls[5] = true;
nulls[6] = true;
+ nulls[7] = true;
}
else
{
@@ -278,6 +279,7 @@ brin_page_items(PG_FUNCTION_ARGS)
values[3] = BoolGetDatum(dtup->bt_columns[att].bv_allnulls);
values[4] = BoolGetDatum(dtup->bt_columns[att].bv_hasnulls);
values[5] = BoolGetDatum(dtup->bt_placeholder);
+ values[6] = BoolGetDatum(dtup->bt_empty_range);
if (!dtup->bt_columns[att].bv_allnulls)
{
BrinValues *bvalues = &dtup->bt_columns[att];
@@ -303,12 +305,12 @@ brin_page_items(PG_FUNCTION_ARGS)
}
appendStringInfoChar(&s, '}');
- values[6] = CStringGetTextDatum(s.data);
+ values[7] = CStringGetTextDatum(s.data);
pfree(s.data);
}
else
{
- nulls[6] = true;
+ nulls[7] = true;
}
}
diff --git a/contrib/pageinspect/pageinspect--1.7--1.8.sql b/contrib/pageinspect/pageinspect--1.7--1.8.sql
index 45031a026a6..edfb580a4ec 100644
--- a/contrib/pageinspect/pageinspect--1.7--1.8.sql
+++ b/contrib/pageinspect/pageinspect--1.7--1.8.sql
@@ -67,3 +67,23 @@ CREATE FUNCTION bt_page_items(IN page bytea,
RETURNS SETOF record
AS 'MODULE_PATHNAME', 'bt_page_items_bytea'
LANGUAGE C STRICT PARALLEL SAFE;
+
+--
+-- add information about BRIN empty ranges
+--
+DROP FUNCTION brin_page_items(IN page bytea, IN index_oid regclass);
+--
+-- brin_page_items()
+--
+CREATE FUNCTION brin_page_items(IN page bytea, IN index_oid regclass,
+ OUT itemoffset int,
+ OUT blknum int,
+ OUT attnum int,
+ OUT allnulls bool,
+ OUT hasnulls bool,
+ OUT placeholder bool,
+ OUT empty bool,
+ OUT value text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'brin_page_items'
+LANGUAGE C STRICT PARALLEL SAFE;
--
2.40.0
From 75ca742082cd50cef4609ecf0021e7bf69f34de6 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.von...@postgresql.org>
Date: Sun, 8 Jan 2023 16:43:06 +0100
Subject: [PATCH 1/2] Fix handling of NULLs in BRIN indexes
BRIN indexes did not properly distinguish between summaries for empty
(no rows) and all-NULL ranges. All summaries were initialized with
allnulls=true, and the opclasses simply reset allnulls to false when
processing the first non-NULL value. This however fails if the range
starts with a NULL value (or a sequence of NULL values), in which case
we forget the range contains NULL values.
This happens because the allnulls flag is used for two separate
purposes - to mark empty ranges (not representing any rows yet) and
ranges containing only NULL values.
Opclasses don't know which of these cases it is, and so don't know
whether to set hasnulls=true. Setting hasnulls=true in both cases would
make it correct, but it would also make BRIN indexes useless for queries
with IS NULL clauses - all ranges start empty (and thus allnulls=true),
so all ranges would end up with either allnulls=true or hasnulls=true.
The severity of the issue is somewhat reduced by the fact that it only
happens when adding values to an existing summary with allnulls=true,
not when the summarization is processing values in bulk (e.g. during
CREATE INDEX or automatic summarization). In this case the flags were
updated in a slightly different way, not forgetting the NULL values.
This introduces a new a new flag marking index tuples representing
ranges with no rows. Luckily we have an unused tuple in the BRIN tuple
header that we can use for this.
We still store index tuples for empty ranges, because otherwise we'd not
be able to say whether a range is empty or not yet summarized, and we'd
have to process them for any query.
Backpatch to 11. The issue exists since BRIN indexes were introduced in
9.5, but older releases are already EOL.
Backpatch-through: 11
Reviewed-by: Alvaro Herrera, Justin Pryzby, Matthias van de Meent
Discussion: https://postgr.es/m/402430e4-7d9d-6cf1-09ef-464d80aff...@enterprisedb.com
---
src/backend/access/brin/brin.c | 115 +++++++++++++++++-
src/backend/access/brin/brin_tuple.c | 15 ++-
src/include/access/brin_tuple.h | 6 +-
...summarization-and-inprogress-insertion.out | 8 +-
...ummarization-and-inprogress-insertion.spec | 1 +
5 files changed, 137 insertions(+), 8 deletions(-)
diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 41bf950a4af..2e20f318e95 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -592,6 +592,17 @@ bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm)
bval = &dtup->bt_columns[attno - 1];
+ /*
+ * If the BRIN tuple indicates that this range is empty,
+ * we can skip it: there's nothing to match. We don't
+ * need to examine the next columns.
+ */
+ if (dtup->bt_empty_range)
+ {
+ addrange = false;
+ break;
+ }
+
/*
* First check if there are any IS [NOT] NULL scan keys,
* and if we're violating them. In that case we can
@@ -1589,6 +1600,8 @@ form_and_insert_tuple(BrinBuildState *state)
/*
* Given two deformed tuples, adjust the first one so that it's consistent
* with the summary values in both.
+ *
+ * XXX I'm not sure we can actually get empty "b".
*/
static void
union_tuples(BrinDesc *bdesc, BrinMemTuple *a, BrinTuple *b)
@@ -1606,6 +1619,64 @@ union_tuples(BrinDesc *bdesc, BrinMemTuple *a, BrinTuple *b)
db = brin_deform_tuple(bdesc, b, NULL);
MemoryContextSwitchTo(oldcxt);
+ /*
+ * Check if the ranges are empty.
+ *
+ * If at least one of them is empty, we don't need to call per-key union
+ * functions at all. If "b" is empty, we just use "a" as the result (it
+ * might be empty fine, but that's fine). If "a" is empty but "b" is not,
+ * we use "b" as the result (but we have to copy the data into "a" first).
+ *
+ * Only when both ranges are non-empty, we actually do the per-key merge.
+ */
+
+ /* If "b" is empty - ignore it and just use "a" (even if it's empty etc.). */
+ if (db->bt_empty_range)
+ {
+ /* skip the per-key merge */
+ MemoryContextDelete(cxt);
+ return;
+ }
+
+ /*
+ * Now we know "b" is not empty. If "a" is empty, then "b" is the result.
+ * But we need to copy the data from "b" to "a" first, because that's how
+ * we pass result out.
+ *
+ * We have to copy all the global/per-key flags etc. too.
+ */
+ if (a->bt_empty_range)
+ {
+ for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
+ {
+ int i;
+ BrinValues *col_a = &a->bt_columns[keyno];
+ BrinValues *col_b = &db->bt_columns[keyno];
+ BrinOpcInfo *opcinfo = bdesc->bd_info[keyno];
+
+ col_a->bv_allnulls = col_b->bv_allnulls;
+ col_a->bv_hasnulls = col_b->bv_hasnulls;
+
+ /* If "b" has no data, we're done. */
+ if (col_b->bv_allnulls)
+ continue;
+
+ for (i = 0; i < opcinfo->oi_nstored; i++)
+ col_a->bv_values[i] =
+ datumCopy(col_b->bv_values[i],
+ opcinfo->oi_typcache[i]->typbyval,
+ opcinfo->oi_typcache[i]->typlen);
+ }
+
+ /* "a" started empty, but "b" was not empty, so remember that */
+ a->bt_empty_range = false;
+
+ /* skip the per-key merge */
+ MemoryContextDelete(cxt);
+ return;
+ }
+
+ /* Now we know neither range is empty. */
for (keyno = 0; keyno < bdesc->bd_tupdesc->natts; keyno++)
{
FmgrInfo *unionFn;
@@ -1703,7 +1774,9 @@ add_values_to_range(Relation idxRel, BrinDesc *bdesc, BrinMemTuple *dtup,
Datum *values, bool *nulls)
{
int keyno;
- bool modified = false;
+
+ /* If the range starts empty, we're certainly going to modify it. */
+ bool modified = dtup->bt_empty_range;
/*
* Compare the key values of the new tuple to the stored index values; our
@@ -1717,9 +1790,24 @@ add_values_to_range(Relation idxRel, BrinDesc *bdesc, BrinMemTuple *dtup,
Datum result;
BrinValues *bval;
FmgrInfo *addValue;
+ bool has_nulls;
bval = &dtup->bt_columns[keyno];
+ /*
+ * Does the range have actual NULL values? Either of the flags can
+ * be set, but we ignore the state before adding first row.
+ *
+ * We have to remember this, because we'll modify the flags and we
+ * need to know if the range started as empty.
+ */
+ has_nulls = ((!dtup->bt_empty_range) &&
+ (bval->bv_hasnulls || bval->bv_allnulls));
+
+ /*
+ * If the value we're adding is NULL, handle it locally. Otherwise
+ * call the BRIN_PROCNUM_ADDVALUE procedure.
+ */
if (bdesc->bd_info[keyno]->oi_regular_nulls && nulls[keyno])
{
/*
@@ -1745,8 +1833,33 @@ add_values_to_range(Relation idxRel, BrinDesc *bdesc, BrinMemTuple *dtup,
nulls[keyno]);
/* if that returned true, we need to insert the updated tuple */
modified |= DatumGetBool(result);
+
+ /*
+ * If the range was had actual NULL values (i.e. did not start empty),
+ * make sure we don't forget about the NULL values. Either the allnulls
+ * flag is still set to true, or (if the opclass cleared it) we need to
+ * set hasnulls=true.
+ *
+ * XXX This can only happen when the opclass modified the tuple, so the
+ * modified flag should be set.
+ */
+ if (has_nulls && !(bval->bv_hasnulls || bval->bv_allnulls))
+ {
+ Assert(modified);
+ bval->bv_hasnulls = true;
+ }
}
+ /*
+ * After updating summaries for all the keys, mark it as not empty.
+ *
+ * If we're actually changing the flag value (i.e. tuple started as empty),
+ * we should have modified the tuple. So we should not see empty range that
+ * was not modified.
+ */
+ Assert(!dtup->bt_empty_range || modified);
+ dtup->bt_empty_range = false;
+
return modified;
}
diff --git a/src/backend/access/brin/brin_tuple.c b/src/backend/access/brin/brin_tuple.c
index 84b79dbfc0d..b81247a262c 100644
--- a/src/backend/access/brin/brin_tuple.c
+++ b/src/backend/access/brin/brin_tuple.c
@@ -372,6 +372,9 @@ brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno, BrinMemTuple *tuple,
if (tuple->bt_placeholder)
rettuple->bt_info |= BRIN_PLACEHOLDER_MASK;
+ if (tuple->bt_empty_range)
+ rettuple->bt_info |= BRIN_EMPTY_RANGE_MASK;
+
*size = len;
return rettuple;
}
@@ -399,7 +402,7 @@ brin_form_placeholder_tuple(BrinDesc *brdesc, BlockNumber blkno, Size *size)
rettuple = palloc0(len);
rettuple->bt_blkno = blkno;
rettuple->bt_info = hoff;
- rettuple->bt_info |= BRIN_NULLS_MASK | BRIN_PLACEHOLDER_MASK;
+ rettuple->bt_info |= BRIN_NULLS_MASK | BRIN_PLACEHOLDER_MASK | BRIN_EMPTY_RANGE_MASK;
bitP = ((bits8 *) ((char *) rettuple + SizeOfBrinTuple)) - 1;
bitmask = HIGHBIT;
@@ -489,6 +492,8 @@ brin_new_memtuple(BrinDesc *brdesc)
dtup->bt_allnulls = palloc(sizeof(bool) * brdesc->bd_tupdesc->natts);
dtup->bt_hasnulls = palloc(sizeof(bool) * brdesc->bd_tupdesc->natts);
+ dtup->bt_empty_range = true;
+
dtup->bt_context = AllocSetContextCreate(CurrentMemoryContext,
"brin dtuple",
ALLOCSET_DEFAULT_SIZES);
@@ -527,6 +532,9 @@ brin_memtuple_initialize(BrinMemTuple *dtuple, BrinDesc *brdesc)
currdatum += sizeof(Datum) * brdesc->bd_info[i]->oi_nstored;
}
+ /* FIXME Shouldn't this reset bt_placeholder too? */
+ dtuple->bt_empty_range = true;
+
return dtuple;
}
@@ -560,6 +568,11 @@ brin_deform_tuple(BrinDesc *brdesc, BrinTuple *tuple, BrinMemTuple *dMemtuple)
if (BrinTupleIsPlaceholder(tuple))
dtup->bt_placeholder = true;
+
+ /* ranges start as empty, depends on the BrinTuple */
+ if (!BrinTupleIsEmptyRange(tuple))
+ dtup->bt_empty_range = false;
+
dtup->bt_blkno = tuple->bt_blkno;
values = dtup->bt_values;
diff --git a/src/include/access/brin_tuple.h b/src/include/access/brin_tuple.h
index 732f91edf11..c56747aca4a 100644
--- a/src/include/access/brin_tuple.h
+++ b/src/include/access/brin_tuple.h
@@ -44,6 +44,7 @@ typedef struct BrinValues
typedef struct BrinMemTuple
{
bool bt_placeholder; /* this is a placeholder tuple */
+ bool bt_empty_range; /* range represents no tuples */
BlockNumber bt_blkno; /* heap blkno that the tuple is for */
MemoryContext bt_context; /* memcxt holding the bt_columns values */
/* output arrays for brin_deform_tuple: */
@@ -69,7 +70,7 @@ typedef struct BrinTuple
*
* 7th (high) bit: has nulls
* 6th bit: is placeholder tuple
- * 5th bit: unused
+ * 5th bit: range is empty
* 4-0 bit: offset of data
* ---------------
*/
@@ -82,13 +83,14 @@ typedef struct BrinTuple
* bt_info manipulation macros
*/
#define BRIN_OFFSET_MASK 0x1F
-/* bit 0x20 is not used at present */
+#define BRIN_EMPTY_RANGE_MASK 0x20
#define BRIN_PLACEHOLDER_MASK 0x40
#define BRIN_NULLS_MASK 0x80
#define BrinTupleDataOffset(tup) ((Size) (((BrinTuple *) (tup))->bt_info & BRIN_OFFSET_MASK))
#define BrinTupleHasNulls(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_NULLS_MASK)) != 0)
#define BrinTupleIsPlaceholder(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_PLACEHOLDER_MASK)) != 0)
+#define BrinTupleIsEmptyRange(tup) (((((BrinTuple *) (tup))->bt_info & BRIN_EMPTY_RANGE_MASK)) != 0)
extern BrinTuple *brin_form_tuple(BrinDesc *brdesc, BlockNumber blkno,
diff --git a/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out b/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
index 2a4755d0998..584ac2602f7 100644
--- a/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
+++ b/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
@@ -4,7 +4,7 @@ starting permutation: s2check s1b s2b s1i s2summ s1c s2c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+--------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
(1 row)
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
@@ -26,7 +26,7 @@ step s2c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+-----------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
2| 1| 1|f |f |f |{1 .. 1000}
(2 rows)
@@ -35,7 +35,7 @@ starting permutation: s2check s1b s1i s2vacuum s1c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+--------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
(1 row)
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
@@ -45,7 +45,7 @@ step s1c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
----------+------+------+--------+--------+-----------+-----------
- 1| 0| 1|f |f |f |{1 .. 1}
+ 1| 0| 1|f |t |f |{1 .. 1}
2| 1| 1|f |f |f |{1 .. 1000}
(2 rows)
diff --git a/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec b/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec
index 19ac18a2e88..18ba92b7ba1 100644
--- a/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec
+++ b/src/test/modules/brin/specs/summarization-and-inprogress-insertion.spec
@@ -9,6 +9,7 @@ setup
) WITH (fillfactor=10);
CREATE INDEX brinidx ON brin_iso USING brin (value) WITH (pages_per_range=1);
-- this fills the first page
+ INSERT INTO brin_iso VALUES (NULL);
DO $$
DECLARE curtid tid;
BEGIN
--
2.40.0
From da108ee9bcfd4b8a4ac8b9fba2cc8b6ab4f757f7 Mon Sep 17 00:00:00 2001
From: Tomas Vondra <tomas.von...@postgresql.org>
Date: Mon, 27 Mar 2023 22:47:12 +0200
Subject: [PATCH 2/2] Show empty ranges in brin_page_items
Show which BRIN ranges are empty (no rows), as indicated by the newly
introduced flag.
---
contrib/pageinspect/brinfuncs.c | 10 ++++---
contrib/pageinspect/expected/brin.out | 6 ++--
.../pageinspect/pageinspect--1.11--1.12.sql | 17 +++++++++++
...summarization-and-inprogress-insertion.out | 28 +++++++++----------
4 files changed, 40 insertions(+), 21 deletions(-)
diff --git a/contrib/pageinspect/brinfuncs.c b/contrib/pageinspect/brinfuncs.c
index 000dcd8f5d8..a781f265514 100644
--- a/contrib/pageinspect/brinfuncs.c
+++ b/contrib/pageinspect/brinfuncs.c
@@ -201,8 +201,8 @@ brin_page_items(PG_FUNCTION_ARGS)
dtup = NULL;
for (;;)
{
- Datum values[7];
- bool nulls[7] = {0};
+ Datum values[8];
+ bool nulls[8] = {0};
/*
* This loop is called once for every attribute of every tuple in the
@@ -239,6 +239,7 @@ brin_page_items(PG_FUNCTION_ARGS)
nulls[4] = true;
nulls[5] = true;
nulls[6] = true;
+ nulls[7] = true;
}
else
{
@@ -261,6 +262,7 @@ brin_page_items(PG_FUNCTION_ARGS)
values[3] = BoolGetDatum(dtup->bt_columns[att].bv_allnulls);
values[4] = BoolGetDatum(dtup->bt_columns[att].bv_hasnulls);
values[5] = BoolGetDatum(dtup->bt_placeholder);
+ values[6] = BoolGetDatum(dtup->bt_empty_range);
if (!dtup->bt_columns[att].bv_allnulls)
{
BrinValues *bvalues = &dtup->bt_columns[att];
@@ -286,12 +288,12 @@ brin_page_items(PG_FUNCTION_ARGS)
}
appendStringInfoChar(&s, '}');
- values[6] = CStringGetTextDatum(s.data);
+ values[7] = CStringGetTextDatum(s.data);
pfree(s.data);
}
else
{
- nulls[6] = true;
+ nulls[7] = true;
}
}
diff --git a/contrib/pageinspect/expected/brin.out b/contrib/pageinspect/expected/brin.out
index e12fbeb4774..098ddc202f4 100644
--- a/contrib/pageinspect/expected/brin.out
+++ b/contrib/pageinspect/expected/brin.out
@@ -43,9 +43,9 @@ SELECT * FROM brin_revmap_data(get_raw_page('test1_a_idx', 1)) LIMIT 5;
SELECT * FROM brin_page_items(get_raw_page('test1_a_idx', 2), 'test1_a_idx')
ORDER BY blknum, attnum LIMIT 5;
- itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | value
-------------+--------+--------+----------+----------+-------------+----------
- 1 | 0 | 1 | f | f | f | {1 .. 1}
+ itemoffset | blknum | attnum | allnulls | hasnulls | placeholder | empty | value
+------------+--------+--------+----------+----------+-------------+-------+----------
+ 1 | 0 | 1 | f | f | f | f | {1 .. 1}
(1 row)
-- Mask DETAIL messages as these are not portable across architectures.
diff --git a/contrib/pageinspect/pageinspect--1.11--1.12.sql b/contrib/pageinspect/pageinspect--1.11--1.12.sql
index 70c3abccf57..a20d67a9e82 100644
--- a/contrib/pageinspect/pageinspect--1.11--1.12.sql
+++ b/contrib/pageinspect/pageinspect--1.11--1.12.sql
@@ -21,3 +21,20 @@ CREATE FUNCTION bt_multi_page_stats(IN relname text, IN blkno int8, IN blk_count
RETURNS SETOF record
AS 'MODULE_PATHNAME', 'bt_multi_page_stats'
LANGUAGE C STRICT PARALLEL RESTRICTED;
+
+--
+-- add information about BRIN empty ranges
+--
+DROP FUNCTION brin_page_items(IN page bytea, IN index_oid regclass);
+CREATE FUNCTION brin_page_items(IN page bytea, IN index_oid regclass,
+ OUT itemoffset int,
+ OUT blknum int8,
+ OUT attnum int,
+ OUT allnulls bool,
+ OUT hasnulls bool,
+ OUT placeholder bool,
+ OUT empty bool,
+ OUT value text)
+RETURNS SETOF record
+AS 'MODULE_PATHNAME', 'brin_page_items'
+LANGUAGE C STRICT PARALLEL RESTRICTED;
diff --git a/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out b/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
index 584ac2602f7..201786c82c0 100644
--- a/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
+++ b/src/test/modules/brin/expected/summarization-and-inprogress-insertion.out
@@ -2,9 +2,9 @@ Parsed test spec with 2 sessions
starting permutation: s2check s1b s2b s1i s2summ s1c s2c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
-itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
-----------+------+------+--------+--------+-----------+--------
- 1| 0| 1|f |t |f |{1 .. 1}
+itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|empty|value
+----------+------+------+--------+--------+-----------+-----+--------
+ 1| 0| 1|f |t |f |f |{1 .. 1}
(1 row)
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
@@ -24,18 +24,18 @@ brin_summarize_new_values
step s1c: COMMIT;
step s2c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
-itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
-----------+------+------+--------+--------+-----------+-----------
- 1| 0| 1|f |t |f |{1 .. 1}
- 2| 1| 1|f |f |f |{1 .. 1000}
+itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|empty|value
+----------+------+------+--------+--------+-----------+-----+-----------
+ 1| 0| 1|f |t |f |f |{1 .. 1}
+ 2| 1| 1|f |f |f |f |{1 .. 1000}
(2 rows)
starting permutation: s2check s1b s1i s2vacuum s1c s2check
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
-itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
-----------+------+------+--------+--------+-----------+--------
- 1| 0| 1|f |t |f |{1 .. 1}
+itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|empty|value
+----------+------+------+--------+--------+-----------+-----+--------
+ 1| 0| 1|f |t |f |f |{1 .. 1}
(1 row)
step s1b: BEGIN ISOLATION LEVEL REPEATABLE READ;
@@ -43,9 +43,9 @@ step s1i: INSERT INTO brin_iso VALUES (1000);
step s2vacuum: VACUUM brin_iso;
step s1c: COMMIT;
step s2check: SELECT * FROM brin_page_items(get_raw_page('brinidx', 2), 'brinidx'::regclass);
-itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|value
-----------+------+------+--------+--------+-----------+-----------
- 1| 0| 1|f |t |f |{1 .. 1}
- 2| 1| 1|f |f |f |{1 .. 1000}
+itemoffset|blknum|attnum|allnulls|hasnulls|placeholder|empty|value
+----------+------+------+--------+--------+-----------+-----+-----------
+ 1| 0| 1|f |t |f |f |{1 .. 1}
+ 2| 1| 1|f |f |f |f |{1 .. 1000}
(2 rows)
--
2.40.0
