On Tue, Nov 05, 2019 at 02:53:35PM -0800, Noah Misch wrote:
> I started pre-commit editing on 2019-10-28, and comment+README updates have
> been the largest part of that. I'll check my edits against the things you
> list here, and I'll share on-list before committing. I've now marked the CF
> entry Ready for Committer.
Having dedicated many days to that, I am attaching v24nm. I know of two
remaining defects:
=== Defect 1: gistGetFakeLSN()
When I modified pg_regress.c to use wal_level=minimal for all suites,
src/test/isolation/specs/predicate-gist.spec failed the assertion in
gistGetFakeLSN(). One could reproduce the problem just by running this
sequence in psql:
begin;
create table gist_point_tbl(id int4, p point);
create index gist_pointidx on gist_point_tbl using gist(p);
insert into gist_point_tbl (id, p)
select g, point(g*10, g*10) from generate_series(1, 1000) g;
I've included a wrong-in-general hack to make the test pass. I see two main
options for fixing this:
(a) Introduce an empty WAL record that reserves an LSN and has no other
effect. Make GiST use that for permanent relations that are skipping WAL.
Further optimizations are possible. For example, we could use a backend-local
counter (like the one gistGetFakeLSN() uses for temp relations) until the
counter is greater a recent real LSN. That optimization is probably too
clever, though it would make the new WAL record almost never appear.
(b) Exempt GiST from most WAL skipping. GiST index build could still skip
WAL, but it would do its own smgrimmedsync() in addition to the one done at
commit. Regular GiST mutations would test RELPERSISTENCE_PERMANENT instead of
RelationNeedsWal(), and we'd need some hack for index_copy_data() and possibly
other AM-independent code that skips WAL.
Overall, I like the cleanliness of (a). The main argument for (b) is that it
ensures we have all the features to opt-out of WAL skipping, which could be
useful for out-of-tree index access methods. (I think we currently have the
features for a tableam to do so, but not for an indexam to do so.) Overall, I
lean toward (a). Any other ideas or preferences?
=== Defect 2: repetitive work when syncing many relations
For deleting relfilenodes, smgrDoPendingDeletes() collects a list for
smgrdounlinkall() to pass to DropRelFileNodesAllBuffers(), which is
sophisticated about optimizing the shared buffers scan. Commit 279628a
introduced that, in 2013. I think smgrDoPendingSyncs() should do likewise, to
further reduce the chance of causing performance regressions. (One could,
however, work around the problem by raising wal_skip_threshold.) Kyotaro, if
you agree, could you modify v24nm to implement that?
Notable changes in v24nm:
- Wrote section "Skipping WAL for New RelFileNode" in
src/backend/access/transam/README to be the main source concerning the new
coding rules.
- Updated numerous comments and doc sections.
- Eliminated the pendingSyncs list in favor of a "sync" field in
pendingDeletes. I mostly did this to eliminate the possibility of the lists
getting out of sync. This removed considerable parallel code for managing a
second list at end-of-xact. We now call smgrDoPendingSyncs() only when
committing or preparing a top-level transaction.
- Whenever code sets an rd_*Subid field of a Relation, it must call
EOXactListAdd(). swap_relation_files() was not doing so, so the field
remained set during the next transaction. I introduced
RelationAssumeNewRelfilenode() to handle both tasks, and I located the call
so it also affects the mapped relation case.
- In ALTER TABLE cases where TryReuseIndex() avoided an index rebuild,
rd_createSubid remained set. (That happened before this patch, but it has
been harmless.) I fixed this in heap_create().
- Made smgrDoPendingSyncs() stop exempting FSM_FORKNUM. A sync is necessary
when checksums are enabled. Observe the precedent that
RelationCopyStorage() has not been exempting FSM_FORKNUM.
- Pass log_newpage_range() a "false" for page_std, for the same reason
RelationCopyStorage() does.
- log_newpage_range() ignored its forkNum and page_std arguments, so we logged
the wrong data for non-main forks. Before this patch, callers always passed
MAIN_FORKNUM and "true", hence the lack of complaints.
- Restored table_finish_bulk_insert(), though heapam no longer provides a
callback. The API is still well-defined, and other table AMs might have use
for it. Removing it feels like a separate proposal.
- Removed TABLE_INSERT_SKIP_WAL. Any out-of-tree code using it should revisit
itself in light of this patch.
- Fixed smgrDoPendingSyncs() to reinitialize total_blocks for each relation;
it was overcounting.
- Made us skip WAL after SET TABLESPACE, like we do after CLUSTER.
- Moved the wal_skip_threshold docs from "Resource Consumption" -> "Disk" to
"Write Ahead Log" -> "Settings", between similar settings
wal_writer_flush_after and commit_delay. The other place I considered was
"Resource Consumption" -> "Asynchronous Behavior", due to the similarity of
backend_flush_after.
- Gave each test a unique name. Changed test table names to be descriptive,
e.g. test7 became trunc_trig.
- Squashed all patches into one. Split patches are good when one could
reasonably choose to push a subset, but that didn't apply here. I wouldn't
push a GUC implementation without its documentation. Since the tests fail
without the main bug fix, I wouldn't push tests separately.
By the way, based on the comment at zheap_prepare_insert(), I expect zheap
will exempt itself from skipping WAL. It may stop calling RelationNeedsWAL()
and instead test for RELPERSISTENCE_PERMANENT.
nm
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f837703..f078775 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2462,21 +2462,14 @@ include_dir 'conf.d'
levels. This parameter can only be set at server start.
</para>
<para>
- In <literal>minimal</literal> level, WAL-logging of some bulk
- operations can be safely skipped, which can make those
- operations much faster (see <xref linkend="populate-pitr"/>).
- Operations in which this optimization can be applied include:
- <simplelist>
- <member><command>CREATE TABLE AS</command></member>
- <member><command>CREATE INDEX</command></member>
- <member><command>CLUSTER</command></member>
- <member><command>COPY</command> into tables that were created or
truncated in the same
- transaction</member>
- </simplelist>
- But minimal WAL does not contain enough information to reconstruct the
- data from a base backup and the WAL logs, so
<literal>replica</literal> or
- higher must be used to enable WAL archiving
- (<xref linkend="guc-archive-mode"/>) and streaming replication.
+ In <literal>minimal</literal> level, no information is logged for
+ tables or indexes for the remainder of a transaction that creates or
+ truncates them. This can make bulk operations much faster (see
+ <xref linkend="populate-pitr"/>). But minimal WAL does not contain
+ enough information to reconstruct the data from a base backup and the
+ WAL logs, so <literal>replica</literal> or higher must be used to
+ enable WAL archiving (<xref linkend="guc-archive-mode"/>) and
+ streaming replication.
</para>
<para>
In <literal>logical</literal> level, the same information is logged as
@@ -2868,6 +2861,26 @@ include_dir 'conf.d'
</listitem>
</varlistentry>
+ <varlistentry id="guc-wal-skip-threshold" xreflabel="wal_skip_threshold">
+ <term><varname>wal_skip_threshold</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>wal_skip_threshold</varname> configuration
parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ When <varname>wal_level</varname> is <literal>minimal</literal> and a
+ transaction commits after creating or rewriting a permanent table,
+ materialized view, or index, this setting determines how to persist
+ the new data. If the data is smaller than this setting, write it to
+ the WAL log; otherwise, use an fsync of the data file. Depending on
+ the properties of your storage, raising or lowering this value might
+ help if such commits are slowing concurrent transactions. The default
+ is 64 kilobytes (<literal>64kB</literal>).
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-commit-delay" xreflabel="commit_delay">
<term><varname>commit_delay</varname> (<type>integer</type>)
<indexterm>
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml
index 715aff6..fcc6017 100644
--- a/doc/src/sgml/perform.sgml
+++ b/doc/src/sgml/perform.sgml
@@ -1605,8 +1605,8 @@ SELECT * FROM x, y, a, b, c WHERE something AND
somethingelse;
needs to be written, because in case of an error, the files
containing the newly loaded data will be removed anyway.
However, this consideration only applies when
- <xref linkend="guc-wal-level"/> is <literal>minimal</literal> for
- non-partitioned tables as all commands must write WAL otherwise.
+ <xref linkend="guc-wal-level"/> is <literal>minimal</literal>
+ as all commands must write WAL otherwise.
</para>
</sect2>
@@ -1706,42 +1706,13 @@ SELECT * FROM x, y, a, b, c WHERE something AND
somethingelse;
</para>
<para>
- Aside from avoiding the time for the archiver or WAL sender to
- process the WAL data,
- doing this will actually make certain commands faster, because they
- are designed not to write WAL at all if <varname>wal_level</varname>
- is <literal>minimal</literal>. (They can guarantee crash safety more
cheaply
- by doing an <function>fsync</function> at the end than by writing WAL.)
- This applies to the following commands:
- <itemizedlist>
- <listitem>
- <para>
- <command>CREATE TABLE AS SELECT</command>
- </para>
- </listitem>
- <listitem>
- <para>
- <command>CREATE INDEX</command> (and variants such as
- <command>ALTER TABLE ADD PRIMARY KEY</command>)
- </para>
- </listitem>
- <listitem>
- <para>
- <command>ALTER TABLE SET TABLESPACE</command>
- </para>
- </listitem>
- <listitem>
- <para>
- <command>CLUSTER</command>
- </para>
- </listitem>
- <listitem>
- <para>
- <command>COPY FROM</command>, when the target table has been
- created or truncated earlier in the same transaction
- </para>
- </listitem>
- </itemizedlist>
+ Aside from avoiding the time for the archiver or WAL sender to process the
+ WAL data, doing this will actually make certain commands faster, because
+ they do not to write WAL at all if <varname>wal_level</varname>
+ is <literal>minimal</literal> and the current subtransaction (or top-level
+ transaction) created or truncated the table or index they change. (They
+ can guarantee crash safety more cheaply by doing
+ an <function>fsync</function> at the end than by writing WAL.)
</para>
</sect2>
diff --git a/src/backend/access/gist/gistutil.c
b/src/backend/access/gist/gistutil.c
index 553a6d6..66c52d6 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -1013,7 +1013,12 @@ gistGetFakeLSN(Relation rel)
{
static XLogRecPtr counter = FirstNormalUnloggedLSN;
- if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
+ /*
+ * XXX before commit fix this. This is not correct for
+ * RELPERSISTENCE_PERMANENT, but it suffices to make tests pass.
+ */
+ if (rel->rd_rel->relpersistence == RELPERSISTENCE_TEMP
+ || rel->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
{
/*
* Temporary relations are only accessible in our session, so a
simple
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 0128bb3..be19c34 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -21,7 +21,6 @@
* heap_multi_insert - insert multiple tuples into a relation
* heap_delete - delete a tuple from a relation
* heap_update - replace a tuple in a relation with
another tuple
- * heap_sync - sync heap, for when no WAL has been
written
*
* NOTES
* This file contains the heap_ routines which implement
@@ -1936,7 +1935,7 @@ heap_insert(Relation relation, HeapTuple tup, CommandId
cid,
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (!(options & HEAP_INSERT_SKIP_WAL) && RelationNeedsWAL(relation))
+ if (RelationNeedsWAL(relation))
{
xl_heap_insert xlrec;
xl_heap_header xlhdr;
@@ -2119,7 +2118,7 @@ heap_multi_insert(Relation relation, TupleTableSlot
**slots, int ntuples,
/* currently not needed (thus unsupported) for heap_multi_insert() */
AssertArg(!(options & HEAP_INSERT_NO_LOGICAL));
- needwal = !(options & HEAP_INSERT_SKIP_WAL) &&
RelationNeedsWAL(relation);
+ needwal = RelationNeedsWAL(relation);
saveFreeSpace = RelationGetTargetPageFreeSpace(relation,
HEAP_DEFAULT_FILLFACTOR);
@@ -8921,46 +8920,6 @@ heap2_redo(XLogReaderState *record)
}
/*
- * heap_sync - sync a heap, for use when no WAL has been
written
- *
- * This forces the heap contents (including TOAST heap if any) down to disk.
- * If we skipped using WAL, and WAL is otherwise needed, we must force the
- * relation down to disk before it's safe to commit the transaction. This
- * requires writing out any dirty buffers and then doing a forced fsync.
- *
- * Indexes are not touched. (Currently, index operations associated with
- * the commands that use this are WAL-logged and so do not need fsync.
- * That behavior might change someday, but in any case it's likely that
- * any fsync decisions required would be per-index and hence not appropriate
- * to be done here.)
- */
-void
-heap_sync(Relation rel)
-{
- /* non-WAL-logged tables never need fsync */
- if (!RelationNeedsWAL(rel))
- return;
-
- /* main heap */
- FlushRelationBuffers(rel);
- /* FlushRelationBuffers will have opened rd_smgr */
- smgrimmedsync(rel->rd_smgr, MAIN_FORKNUM);
-
- /* FSM is not critical, don't bother syncing it */
-
- /* toast heap, if any */
- if (OidIsValid(rel->rd_rel->reltoastrelid))
- {
- Relation toastrel;
-
- toastrel = table_open(rel->rd_rel->reltoastrelid,
AccessShareLock);
- FlushRelationBuffers(toastrel);
- smgrimmedsync(toastrel->rd_smgr, MAIN_FORKNUM);
- table_close(toastrel, AccessShareLock);
- }
-}
-
-/*
* Mask a heap page before performing consistency checks on it.
*/
void
diff --git a/src/backend/access/heap/heapam_handler.c
b/src/backend/access/heap/heapam_handler.c
index 92073fe..07fe717 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -555,17 +555,6 @@ tuple_lock_retry:
return result;
}
-static void
-heapam_finish_bulk_insert(Relation relation, int options)
-{
- /*
- * If we skipped writing WAL, then we need to sync the heap (but not
- * indexes since those use WAL anyway / don't go through tableam)
- */
- if (options & HEAP_INSERT_SKIP_WAL)
- heap_sync(relation);
-}
-
/* ------------------------------------------------------------------------
* DDL related callbacks for heap AM.
@@ -698,7 +687,6 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation
NewHeap,
IndexScanDesc indexScan;
TableScanDesc tableScan;
HeapScanDesc heapScan;
- bool use_wal;
bool is_system_catalog;
Tuplesortstate *tuplesort;
TupleDesc oldTupDesc = RelationGetDescr(OldHeap);
@@ -713,12 +701,9 @@ heapam_relation_copy_for_cluster(Relation OldHeap,
Relation NewHeap,
is_system_catalog = IsSystemRelation(OldHeap);
/*
- * We need to log the copied data in WAL iff WAL archiving/streaming is
- * enabled AND it's a WAL-logged rel.
+ * Valid smgr_targblock implies something already wrote to the relation.
+ * This may be harmless, but this function hasn't planned for it.
*/
- use_wal = XLogIsNeeded() && RelationNeedsWAL(NewHeap);
-
- /* use_wal off requires smgr_targblock be initially invalid */
Assert(RelationGetTargetBlock(NewHeap) == InvalidBlockNumber);
/* Preallocate values/isnull arrays */
@@ -728,7 +713,7 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation
NewHeap,
/* Initialize the rewrite operation */
rwstate = begin_heap_rewrite(OldHeap, NewHeap, OldestXmin, *xid_cutoff,
- *multi_cutoff,
use_wal);
+ *multi_cutoff);
/* Set up sorting if wanted */
@@ -2515,7 +2500,6 @@ static const TableAmRoutine heapam_methods = {
.tuple_delete = heapam_tuple_delete,
.tuple_update = heapam_tuple_update,
.tuple_lock = heapam_tuple_lock,
- .finish_bulk_insert = heapam_finish_bulk_insert,
.tuple_fetch_row_version = heapam_fetch_row_version,
.tuple_get_latest_tid = heap_get_latest_tid,
diff --git a/src/backend/access/heap/rewriteheap.c
b/src/backend/access/heap/rewriteheap.c
index d285b1f..3e56483 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -136,7 +136,6 @@ typedef struct RewriteStateData
Page rs_buffer; /* page currently being built */
BlockNumber rs_blockno; /* block where page will go */
bool rs_buffer_valid; /* T if any tuples in buffer */
- bool rs_use_wal; /* must we WAL-log inserts? */
bool rs_logical_rewrite; /* do we need to do logical
rewriting */
TransactionId rs_oldest_xmin; /* oldest xmin used by caller to
determine
*
tuple visibility */
@@ -230,15 +229,13 @@ static void logical_end_heap_rewrite(RewriteState state);
* oldest_xmin xid used by the caller to determine which tuples are dead
* freeze_xid xid before which tuples will be frozen
* cutoff_multi multixact before which multis will be removed
- * use_wal should the inserts to the new heap be WAL-logged?
*
* Returns an opaque RewriteState, allocated in current memory context,
* to be used in subsequent calls to the other functions.
*/
RewriteState
begin_heap_rewrite(Relation old_heap, Relation new_heap, TransactionId
oldest_xmin,
- TransactionId freeze_xid, MultiXactId
cutoff_multi,
- bool use_wal)
+ TransactionId freeze_xid, MultiXactId
cutoff_multi)
{
RewriteState state;
MemoryContext rw_cxt;
@@ -263,7 +260,6 @@ begin_heap_rewrite(Relation old_heap, Relation new_heap,
TransactionId oldest_xm
/* new_heap needn't be empty, just locked */
state->rs_blockno = RelationGetNumberOfBlocks(new_heap);
state->rs_buffer_valid = false;
- state->rs_use_wal = use_wal;
state->rs_oldest_xmin = oldest_xmin;
state->rs_freeze_xid = freeze_xid;
state->rs_cutoff_multi = cutoff_multi;
@@ -322,7 +318,7 @@ end_heap_rewrite(RewriteState state)
/* Write the last page, if any */
if (state->rs_buffer_valid)
{
- if (state->rs_use_wal)
+ if (RelationNeedsWAL(state->rs_new_rel))
log_newpage(&state->rs_new_rel->rd_node,
MAIN_FORKNUM,
state->rs_blockno,
@@ -337,18 +333,14 @@ end_heap_rewrite(RewriteState state)
}
/*
- * If the rel is WAL-logged, must fsync before commit. We use heap_sync
- * to ensure that the toast table gets fsync'd too.
- *
- * It's obvious that we must do this when not WAL-logging. It's less
- * obvious that we have to do it even if we did WAL-log the pages. The
+ * When we WAL-logged rel pages, we must nonetheless fsync them. The
* reason is the same as in storage.c's RelationCopyStorage(): we're
* writing data that's not in shared buffers, and so a CHECKPOINT
* occurring during the rewriteheap operation won't have fsync'd data we
* wrote before the checkpoint.
*/
if (RelationNeedsWAL(state->rs_new_rel))
- heap_sync(state->rs_new_rel);
+ smgrimmedsync(state->rs_new_rel->rd_smgr, MAIN_FORKNUM);
logical_end_heap_rewrite(state);
@@ -646,9 +638,6 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
{
int options = HEAP_INSERT_SKIP_FSM;
- if (!state->rs_use_wal)
- options |= HEAP_INSERT_SKIP_WAL;
-
/*
* While rewriting the heap for VACUUM FULL / CLUSTER, make
sure data
* for the TOAST table are not logically decoded. The main
heap is
@@ -687,7 +676,7 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
/* Doesn't fit, so write out the existing page */
/* XLOG stuff */
- if (state->rs_use_wal)
+ if (RelationNeedsWAL(state->rs_new_rel))
log_newpage(&state->rs_new_rel->rd_node,
MAIN_FORKNUM,
state->rs_blockno,
diff --git a/src/backend/access/nbtree/nbtsort.c
b/src/backend/access/nbtree/nbtsort.c
index c11a3fb..e9b8ba8 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -31,18 +31,6 @@
* them. They will need to be re-read into shared buffers on first use after
* the build finishes.
*
- * Since the index will never be used unless it is completely built,
- * from a crash-recovery point of view there is no need to WAL-log the
- * steps of the build. After completing the index build, we can just sync
- * the whole file to disk using smgrimmedsync() before exiting this module.
- * This can be seen to be sufficient for crash recovery by considering that
- * it's effectively equivalent to what would happen if a CHECKPOINT occurred
- * just after the index build. However, it is clearly not sufficient if the
- * DBA is using the WAL log for PITR or replication purposes, since another
- * machine would not be able to reconstruct the index from WAL. Therefore,
- * we log the completed index pages to WAL if and only if WAL archiving is
- * active.
- *
* This code isn't concerned about the FSM at all. The caller is responsible
* for initializing that.
*
@@ -563,12 +551,7 @@ _bt_leafbuild(BTSpool *btspool, BTSpool *btspool2)
wstate.heap = btspool->heap;
wstate.index = btspool->index;
wstate.inskey = _bt_mkscankey(wstate.index, NULL);
-
- /*
- * We need to log index creation in WAL iff WAL archiving/streaming is
- * enabled UNLESS the index isn't WAL-logged anyway.
- */
- wstate.btws_use_wal = XLogIsNeeded() && RelationNeedsWAL(wstate.index);
+ wstate.btws_use_wal = RelationNeedsWAL(wstate.index);
/* reserve the metapage */
wstate.btws_pages_alloced = BTREE_METAPAGE + 1;
@@ -1266,21 +1249,15 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool,
BTSpool *btspool2)
_bt_uppershutdown(wstate, state);
/*
- * If the index is WAL-logged, we must fsync it down to disk before it's
- * safe to commit the transaction. (For a non-WAL-logged index we don't
- * care since the index will be uninteresting after a crash anyway.)
- *
- * It's obvious that we must do this when not WAL-logging the build.
It's
- * less obvious that we have to do it even if we did WAL-log the index
- * pages. The reason is that since we're building outside shared
buffers,
- * a CHECKPOINT occurring during the build has no way to flush the
- * previously written data to disk (indeed it won't know the index even
- * exists). A crash later on would replay WAL from the checkpoint,
- * therefore it wouldn't replay our earlier WAL entries. If we do not
- * fsync those pages here, they might still not be on disk when the
crash
- * occurs.
+ * When we WAL-logged index pages, we must nonetheless fsync index
files.
+ * Since we're building outside shared buffers, a CHECKPOINT occurring
+ * during the build has no way to flush the previously written data to
+ * disk (indeed it won't know the index even exists). A crash later on
+ * would replay WAL from the checkpoint, therefore it wouldn't replay
our
+ * earlier WAL entries. If we do not fsync those pages here, they might
+ * still not be on disk when the crash occurs.
*/
- if (RelationNeedsWAL(wstate->index))
+ if (wstate->btws_use_wal)
{
RelationOpenSmgr(wstate->index);
smgrimmedsync(wstate->index->rd_smgr, MAIN_FORKNUM);
diff --git a/src/backend/access/transam/README
b/src/backend/access/transam/README
index b5a2cb2..641809c 100644
--- a/src/backend/access/transam/README
+++ b/src/backend/access/transam/README
@@ -717,6 +717,40 @@ then restart recovery. This is part of the reason for not
writing a WAL
entry until we've successfully done the original action.
+Skipping WAL for New RelFileNode
+--------------------------------
+
+Under wal_level=minimal, if a change modifies a relfilenode that
+RollbackAndReleaseCurrentSubTransaction() would unlink, in-tree access methods
+write no WAL for that change. For any access method, CommitTransaction()
+writes and fsyncs affected blocks before recording the commit. This skipping
+is mandatory; if a WAL-writing change preceded a WAL-skipping change for the
+same block, REDO could overwrite the WAL-skipping change. Code that writes
+WAL without calling RelationNeedsWAL() must check for this case.
+
+If skipping were not mandatory, a related problem would arise. Suppose, under
+full_page_writes=off, a WAL-writing change follows a WAL-skipping change.
+When a WAL record contains no full-page image, REDO expects the page to match
+its contents from just before record insertion. A WAL-skipping change may not
+reach disk at all, violating REDO's expectation.
+
+Prefer to do the same in future access methods. However, two other approaches
+can work. First, an access method can irreversibly transition a given fork
+from WAL-skipping to WAL-writing by calling FlushRelationBuffers() and
+smgrimmedsync(). Second, an access method can opt to write WAL
+unconditionally for permanent relations. When using the second method, do not
+call RelationCopyStorage(), which skips WAL.
+
+This applies only to WAL records whose replay would modify bytes stored in the
+new relfilenode. It does not apply to other records about the relfilenode,
+such as XLOG_SMGR_CREATE. Because it operates at the level of individual
+relfilenodes, RelationNeedsWAL() can differ for tightly-coupled relations.
+Consider "CREATE TABLE t (); BEGIN; ALTER TABLE t ADD c text; ..." in which
+ALTER TABLE adds a TOAST relation. The TOAST relation will skip WAL, while
+the table owning it will not. ALTER TABLE SET TABLESPACE will cause a table
+to skip WAL, but that won't affect its indexes.
+
+
Asynchronous Commit
-------------------
@@ -820,13 +854,12 @@ Changes to a temp table are not WAL-logged, hence could
reach disk in
advance of T1's commit, but we don't care since temp table contents don't
survive crashes anyway.
-Database writes made via any of the paths we have introduced to avoid WAL
-overhead for bulk updates are also safe. In these cases it's entirely
-possible for the data to reach disk before T1's commit, because T1 will
-fsync it down to disk without any sort of interlock, as soon as it finishes
-the bulk update. However, all these paths are designed to write data that
-no other transaction can see until after T1 commits. The situation is thus
-not different from ordinary WAL-logged updates.
+Database writes that skip WAL for new relfilenodes are also safe. In these
+cases it's entirely possible for the data to reach disk before T1's commit,
+because T1 will fsync it down to disk without any sort of interlock. However,
+all these paths are designed to write data that no other transaction can see
+until after T1 commits. The situation is thus not different from ordinary
+WAL-logged updates.
Transaction Emulation during Recovery
-------------------------------------
diff --git a/src/backend/access/transam/xact.c
b/src/backend/access/transam/xact.c
index 8fe38c3..a662ef9 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2109,6 +2109,13 @@ CommitTransaction(void)
*/
PreCommit_on_commit_actions();
+ /*
+ * Synchronize files that are created and not WAL-logged during this
+ * transaction. This must happen before AtEOXact_RelationMap(), so that
we
+ * don't see committed-but-broken files after a crash.
+ */
+ smgrDoPendingSyncs();
+
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
@@ -2341,6 +2348,13 @@ PrepareTransaction(void)
*/
PreCommit_on_commit_actions();
+ /*
+ * Synchronize files that are created and not WAL-logged during this
+ * transaction. This must happen before EndPrepare(), so that we don't
see
+ * committed-but-broken files after a crash and COMMIT PREPARED.
+ */
+ smgrDoPendingSyncs();
+
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
diff --git a/src/backend/access/transam/xloginsert.c
b/src/backend/access/transam/xloginsert.c
index aa9dca0..dda1dea 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -1043,8 +1043,13 @@ log_newpage_range(Relation rel, ForkNumber forkNum,
BlockNumber startblk, BlockNumber endblk,
bool page_std)
{
+ int flags;
BlockNumber blkno;
+ flags = REGBUF_FORCE_IMAGE;
+ if (page_std)
+ flags |= REGBUF_STANDARD;
+
/*
* Iterate over all the pages in the range. They are collected into
* batches of XLR_MAX_BLOCK_ID pages, and a single WAL-record is written
@@ -1066,7 +1071,8 @@ log_newpage_range(Relation rel, ForkNumber forkNum,
nbufs = 0;
while (nbufs < XLR_MAX_BLOCK_ID && blkno < endblk)
{
- Buffer buf = ReadBuffer(rel, blkno);
+ Buffer buf = ReadBufferExtended(rel, forkNum,
blkno,
+
RBM_NORMAL, NULL);
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
@@ -1088,7 +1094,7 @@ log_newpage_range(Relation rel, ForkNumber forkNum,
START_CRIT_SECTION();
for (i = 0; i < nbufs; i++)
{
- XLogRegisterBuffer(i, bufpack[i], REGBUF_FORCE_IMAGE |
REGBUF_STANDARD);
+ XLogRegisterBuffer(i, bufpack[i], flags);
MarkBufferDirty(bufpack[i]);
}
diff --git a/src/backend/access/transam/xlogutils.c
b/src/backend/access/transam/xlogutils.c
index 5f1e5ba..6d61f25 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -544,6 +544,8 @@ typedef FakeRelCacheEntryData *FakeRelCacheEntry;
* fields related to physical storage, like rd_rel, are initialized, so the
* fake entry is only usable in low-level operations like ReadBuffer().
*
+ * This is also used for syncing WAL-skipped files.
+ *
* Caller must free the returned entry with FreeFakeRelcacheEntry().
*/
Relation
@@ -552,18 +554,19 @@ CreateFakeRelcacheEntry(RelFileNode rnode)
FakeRelCacheEntry fakeentry;
Relation rel;
- Assert(InRecovery);
-
/* Allocate the Relation struct and all related space in one block. */
fakeentry = palloc0(sizeof(FakeRelCacheEntryData));
rel = (Relation) fakeentry;
rel->rd_rel = &fakeentry->pgc;
rel->rd_node = rnode;
- /* We will never be working with temp rels during recovery */
+ /*
+ * We will never be working with temp rels during recovery or while
+ * syncing WAL-skipped files.
+ */
rel->rd_backend = InvalidBackendId;
- /* It must be a permanent table if we're in recovery. */
+ /* It must be a permanent table here */
rel->rd_rel->relpersistence = RELPERSISTENCE_PERMANENT;
/* We don't know the name of the relation; use relfilenode instead */
@@ -572,9 +575,9 @@ CreateFakeRelcacheEntry(RelFileNode rnode)
/*
* We set up the lockRelId in case anything tries to lock the dummy
* relation. Note that this is fairly bogus since relNode may be
- * different from the relation's OID. It shouldn't really matter
though,
- * since we are presumably running by ourselves and can't have any lock
- * conflicts ...
+ * different from the relation's OID. It shouldn't really matter
though.
+ * In recovery, we are running by ourselves and can't have any lock
+ * conflicts. While syncing, we already hold AccessExclusiveLock.
*/
rel->rd_lockInfo.lockRelId.dbId = rnode.dbNode;
rel->rd_lockInfo.lockRelId.relId = rnode.relNode;
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index b7bcdd9..293ea9a 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -440,6 +440,10 @@ heap_create(const char *relname,
break;
}
}
+ else
+ {
+ rel->rd_createSubid = InvalidSubTransactionId;
+ }
return rel;
}
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index 056ea3d..51c233d 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -29,9 +29,13 @@
#include "miscadmin.h"
#include "storage/freespace.h"
#include "storage/smgr.h"
+#include "utils/hsearch.h"
#include "utils/memutils.h"
#include "utils/rel.h"
+/* GUC variables */
+int wal_skip_threshold = 64; /* in kilobytes */
+
/*
* We keep a list of all relations (represented as RelFileNode values)
* that have been created or deleted in the current transaction. When
@@ -58,6 +62,7 @@ typedef struct PendingRelDelete
BackendId backend; /* InvalidBackendId if not a
temp rel */
bool atCommit; /* T=delete at commit; F=delete
at abort */
int nestLevel; /* xact nesting level
of request */
+ bool sync; /* whether to fsync at commit */
struct PendingRelDelete *next; /* linked-list link */
} PendingRelDelete;
@@ -114,6 +119,8 @@ RelationCreateStorage(RelFileNode rnode, char
relpersistence)
pending->backend = backend;
pending->atCommit = false; /* delete if abort */
pending->nestLevel = GetCurrentTransactionNestLevel();
+ pending->sync =
+ relpersistence == RELPERSISTENCE_PERMANENT && !XLogIsNeeded();
pending->next = pendingDeletes;
pendingDeletes = pending;
@@ -155,6 +162,7 @@ RelationDropStorage(Relation rel)
pending->backend = rel->rd_backend;
pending->atCommit = true; /* delete if commit */
pending->nestLevel = GetCurrentTransactionNestLevel();
+ pending->sync = false;
pending->next = pendingDeletes;
pendingDeletes = pending;
@@ -355,7 +363,9 @@ RelationCopyStorage(SMgrRelation src, SMgrRelation dst,
/*
* We need to log the copied data in WAL iff WAL archiving/streaming is
- * enabled AND it's a permanent relation.
+ * enabled AND it's a permanent relation. This gives the same answer as
+ * "RelationNeedsWAL(rel) || copying_initfork", because we know the
+ * current operation created a new relfilenode.
*/
use_wal = XLogIsNeeded() &&
(relpersistence == RELPERSISTENCE_PERMANENT ||
copying_initfork);
@@ -397,25 +407,44 @@ RelationCopyStorage(SMgrRelation src, SMgrRelation dst,
}
/*
- * If the rel is WAL-logged, must fsync before commit. We use heap_sync
- * to ensure that the toast table gets fsync'd too. (For a temp or
- * unlogged rel we don't care since the data will be gone after a crash
- * anyway.)
- *
- * It's obvious that we must do this when not WAL-logging the copy. It's
- * less obvious that we have to do it even if we did WAL-log the copied
- * pages. The reason is that since we're copying outside shared
buffers, a
- * CHECKPOINT occurring during the copy has no way to flush the
previously
- * written data to disk (indeed it won't know the new rel even exists).
A
- * crash later on would replay WAL from the checkpoint, therefore it
- * wouldn't replay our earlier WAL entries. If we do not fsync those
pages
- * here, they might still not be on disk when the crash occurs.
+ * When we WAL-logged rel pages, we must nonetheless fsync them. The
+ * reason is that since we're copying outside shared buffers, a
CHECKPOINT
+ * occurring during the copy has no way to flush the previously written
+ * data to disk (indeed it won't know the new rel even exists). A crash
+ * later on would replay WAL from the checkpoint, therefore it wouldn't
+ * replay our earlier WAL entries. If we do not fsync those pages here,
+ * they might still not be on disk when the crash occurs.
*/
- if (relpersistence == RELPERSISTENCE_PERMANENT || copying_initfork)
+ if (use_wal || copying_initfork)
smgrimmedsync(dst, forkNum);
}
/*
+ * RelFileNodeSkippingWAL - check if a BM_PERMANENT relfilenode is using WAL
+ *
+ * Changes of certain relfilenodes must not write WAL; see "Skipping WAL for
+ * New RelFileNode" in src/backend/access/transam/README. Though it is
+ * known from Relation efficiently, this function is intended for the code
+ * paths not having access to Relation.
+ */
+bool
+RelFileNodeSkippingWAL(RelFileNode rnode)
+{
+ PendingRelDelete *pending;
+
+ if (XLogIsNeeded())
+ return false; /* no permanent relfilenode skips WAL */
+
+ for (pending = pendingDeletes; pending != NULL; pending = pending->next)
+ {
+ if (RelFileNodeEquals(pending->relnode, rnode) && pending->sync)
+ return true;
+ }
+
+ return false;
+}
+
+/*
* smgrDoPendingDeletes() -- Take care of relation deletes at end of xact.
*
* This also runs when aborting a subxact; we want to clean up a failed
@@ -493,6 +522,145 @@ smgrDoPendingDeletes(bool isCommit)
}
/*
+ * smgrDoPendingSyncs() -- Take care of relation syncs at commit.
+ *
+ * This should be called before smgrDoPendingDeletes() at every commit or
+ * prepare. Also this should be called before emitting WAL record so that sync
+ * failure prevents commit.
+ */
+void
+smgrDoPendingSyncs(void)
+{
+ PendingRelDelete *pending;
+ HTAB *delhash = NULL;
+
+ if (XLogIsNeeded())
+ return; /* no relation can use this */
+
+ Assert(GetCurrentTransactionNestLevel() == 1);
+ AssertPendingSyncs_RelationCache();
+
+ /*
+ * Pending syncs on the relation that are to be deleted in this
+ * transaction-end should be ignored. Collect pending deletes that will
+ * happen in the following call to smgrDoPendingDeletes().
+ */
+ for (pending = pendingDeletes; pending != NULL; pending = pending->next)
+ {
+ bool found PG_USED_FOR_ASSERTS_ONLY;
+
+ if (!pending->atCommit)
+ continue;
+
+ /* create the hash if not yet */
+ if (delhash == NULL)
+ {
+ HASHCTL hash_ctl;
+
+ memset(&hash_ctl, 0, sizeof(hash_ctl));
+ hash_ctl.keysize = sizeof(RelFileNode);
+ hash_ctl.entrysize = sizeof(RelFileNode);
+ hash_ctl.hcxt = CurrentMemoryContext;
+ delhash =
+ hash_create("pending del temporary hash", 8,
&hash_ctl,
+ HASH_ELEM | HASH_BLOBS
| HASH_CONTEXT);
+ }
+
+ (void) hash_search(delhash, (void *) &pending->relnode,
+ HASH_ENTER, &found);
+ Assert(!found);
+ }
+
+ for (pending = pendingDeletes; pending != NULL; pending = pending->next)
+ {
+ bool to_be_removed = false; /* don't sync if aborted */
+ ForkNumber fork;
+ BlockNumber nblocks[MAX_FORKNUM + 1];
+ BlockNumber total_blocks = 0;
+ SMgrRelation srel;
+
+ if (!pending->sync)
+ continue;
+ Assert(!pending->atCommit);
+
+ /* don't sync relnodes that is being deleted */
+ if (delhash)
+ hash_search(delhash, (void *) &pending->relnode,
+ HASH_FIND, &to_be_removed);
+ if (to_be_removed)
+ continue;
+
+ /* Now the time to sync the rnode */
+ srel = smgropen(pending->relnode, pending->backend);
+
+ /*
+ * We emit newpage WAL records for smaller relations.
+ *
+ * Small WAL records have a chance to be emitted along with
other
+ * backends' WAL records. We emit WAL records instead of
syncing for
+ * files that are smaller than a certain threshold, expecting
faster
+ * commit. The threshold is defined by the GUC
wal_skip_threshold.
+ */
+ for (fork = 0 ; fork <= MAX_FORKNUM ; fork++)
+ {
+ if (smgrexists(srel, fork))
+ {
+ BlockNumber n = smgrnblocks(srel, fork);
+
+ /* we shouldn't come here for unlogged
relations */
+ Assert(fork != INIT_FORKNUM);
+
+ nblocks[fork] = n;
+ total_blocks += n;
+ }
+ else
+ nblocks[fork] = InvalidBlockNumber;
+ }
+
+ /*
+ * Sync file or emit WAL record for the file according to the
total
+ * size.
+ */
+ if (total_blocks * BLCKSZ >= wal_skip_threshold * 1024)
+ {
+ /* Flush all buffers then sync the file */
+ FlushRelationBuffersWithoutRelcache(srel, false);
+
+ for (fork = 0; fork <= MAX_FORKNUM; fork++)
+ {
+ if (smgrexists(srel, fork))
+ smgrimmedsync(srel, fork);
+ }
+ }
+ else
+ {
+ /* Emit WAL records for all blocks. The file is small
enough. */
+ for (fork = 0 ; fork <= MAX_FORKNUM ; fork++)
+ {
+ int n = nblocks[fork];
+ Relation rel;
+
+ if (!BlockNumberIsValid(n))
+ continue;
+
+ /*
+ * Emit WAL for the whole file. Unfortunately
we don't know
+ * what kind of a page this is, so we have to
log the full
+ * page including any unused space.
ReadBufferExtended()
+ * counts some pgstat events; unfortunately, we
discard them.
+ */
+ rel =
CreateFakeRelcacheEntry(srel->smgr_rnode.node);
+ log_newpage_range(rel, fork, 0, n, false);
+ FreeFakeRelcacheEntry(rel);
+ }
+ }
+ }
+
+ if (delhash)
+ hash_destroy(delhash);
+}
+
+/*
* smgrGetPendingDeletes() -- Get a list of non-temp relations to be deleted.
*
* The return value is the number of relations scheduled for termination.
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index b8c349f..093fff8 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1014,6 +1014,7 @@ swap_relation_files(Oid r1, Oid r2, bool
target_is_pg_class,
relfilenode2;
Oid swaptemp;
char swptmpchr;
+ Relation rel1;
/* We need writable copies of both pg_class tuples. */
relRelation = table_open(RelationRelationId, RowExclusiveLock);
@@ -1039,6 +1040,7 @@ swap_relation_files(Oid r1, Oid r2, bool
target_is_pg_class,
*/
Assert(!target_is_pg_class);
+ /* swap relfilenodes, reltablespaces, relpersistence */
swaptemp = relform1->relfilenode;
relform1->relfilenode = relform2->relfilenode;
relform2->relfilenode = swaptemp;
@@ -1174,6 +1176,15 @@ swap_relation_files(Oid r1, Oid r2, bool
target_is_pg_class,
}
/*
+ * Recognize that rel1's relfilenode (swapped from rel2) is new in this
+ * subtransaction. Since the next step for rel2 is deletion, don't
bother
+ * recording the newness of its relfilenode.
+ */
+ rel1 = relation_open(r1, AccessExclusiveLock);
+ RelationAssumeNewRelfilenode(rel1);
+ relation_close(rel1, NoLock);
+
+ /*
* Post alter hook for modified relations. The change to r2 is always
* internal, but r1 depends on the invocation context.
*/
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 42a147b..607e255 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -2711,63 +2711,15 @@ CopyFrom(CopyState cstate)
RelationGetRelationName(cstate->rel))));
}
- /*----------
- * Check to see if we can avoid writing WAL
- *
- * If archive logging/streaming is not enabled *and* either
- * - table was created in same transaction as this COPY
- * - data is being written to relfilenode created in this
transaction
- * then we can skip writing WAL. It's safe because if the transaction
- * doesn't commit, we'll discard the table (or the new relfilenode
file).
- * If it does commit, we'll have done the table_finish_bulk_insert() at
- * the bottom of this routine first.
- *
- * As mentioned in comments in utils/rel.h, the in-same-transaction test
- * is not always set correctly, since in rare cases
rd_newRelfilenodeSubid
- * can be cleared before the end of the transaction. The exact case is
- * when a relation sets a new relfilenode twice in same transaction, yet
- * the second one fails in an aborted subtransaction, e.g.
- *
- * BEGIN;
- * TRUNCATE t;
- * SAVEPOINT save;
- * TRUNCATE t;
- * ROLLBACK TO save;
- * COPY ...
- *
- * Also, if the target file is new-in-transaction, we assume that
checking
- * FSM for free space is a waste of time, even if we must use WAL
because
- * of archiving. This could possibly be wrong, but it's unlikely.
- *
- * The comments for table_tuple_insert and RelationGetBufferForTuple
- * specify that skipping WAL logging is only safe if we ensure that our
- * tuples do not go into pages containing tuples from any other
- * transactions --- but this must be the case if we have a new table or
- * new relfilenode, so we need no additional work to enforce that.
- *
- * We currently don't support this optimization if the COPY target is a
- * partitioned table as we currently only lazily initialize partition
- * information when routing the first tuple to the partition. We cannot
- * know at this stage if we can perform this optimization. It should be
- * possible to improve on this, but it does mean maintaining heap insert
- * option flags per partition and setting them when we first open the
- * partition.
- *
- * This optimization is not supported for relation types which do not
- * have any physical storage, with foreign tables and views using
- * INSTEAD OF triggers entering in this category. Partitioned tables
- * are not supported as per the description above.
- *----------
+ /*
+ * If the target file is new-in-transaction, we assume that checking FSM
+ * for free space is a waste of time. This could possibly be wrong, but
+ * it's unlikely.
*/
- /* createSubid is creation check, newRelfilenodeSubid is truncation
check */
if (RELKIND_HAS_STORAGE(cstate->rel->rd_rel->relkind) &&
(cstate->rel->rd_createSubid != InvalidSubTransactionId ||
- cstate->rel->rd_newRelfilenodeSubid !=
InvalidSubTransactionId))
- {
+ cstate->rel->rd_firstRelfilenodeSubid !=
InvalidSubTransactionId))
ti_options |= TABLE_INSERT_SKIP_FSM;
- if (!XLogIsNeeded())
- ti_options |= TABLE_INSERT_SKIP_WAL;
- }
/*
* Optimize if new relfilenode was created in this subxact or one of its
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 2bf7083..20225dc 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -552,16 +552,13 @@ intorel_startup(DestReceiver *self, int operation,
TupleDesc typeinfo)
myState->rel = intoRelationDesc;
myState->reladdr = intoRelationAddr;
myState->output_cid = GetCurrentCommandId(true);
+ myState->ti_options = TABLE_INSERT_SKIP_FSM;
+ myState->bistate = GetBulkInsertState();
/*
- * We can skip WAL-logging the insertions, unless PITR or streaming
- * replication is in use. We can skip the FSM in any case.
+ * Valid smgr_targblock implies something already wrote to the relation.
+ * This may be harmless, but this function hasn't planned for it.
*/
- myState->ti_options = TABLE_INSERT_SKIP_FSM |
- (XLogIsNeeded() ? 0 : TABLE_INSERT_SKIP_WAL);
- myState->bistate = GetBulkInsertState();
-
- /* Not using WAL requires smgr_targblock be initially invalid */
Assert(RelationGetTargetBlock(intoRelationDesc) == InvalidBlockNumber);
}
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 537d0e8..ae809c9 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -457,17 +457,13 @@ transientrel_startup(DestReceiver *self, int operation,
TupleDesc typeinfo)
*/
myState->transientrel = transientrel;
myState->output_cid = GetCurrentCommandId(true);
-
- /*
- * We can skip WAL-logging the insertions, unless PITR or streaming
- * replication is in use. We can skip the FSM in any case.
- */
myState->ti_options = TABLE_INSERT_SKIP_FSM | TABLE_INSERT_FROZEN;
- if (!XLogIsNeeded())
- myState->ti_options |= TABLE_INSERT_SKIP_WAL;
myState->bistate = GetBulkInsertState();
- /* Not using WAL requires smgr_targblock be initially invalid */
+ /*
+ * Valid smgr_targblock implies something already wrote to the relation.
+ * This may be harmless, but this function hasn't planned for it.
+ */
Assert(RelationGetTargetBlock(transientrel) == InvalidBlockNumber);
}
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 45aae59..95721d7 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4768,19 +4768,14 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap,
LOCKMODE lockmode)
newrel = NULL;
/*
- * Prepare a BulkInsertState and options for table_tuple_insert. Because
- * we're building a new heap, we can skip WAL-logging and fsync it to
disk
- * at the end instead (unless WAL-logging is required for archiving or
- * streaming replication). The FSM is empty too, so don't bother using
it.
+ * Prepare a BulkInsertState and options for table_tuple_insert. The
FSM
+ * is empty, so don't bother using it.
*/
if (newrel)
{
mycid = GetCurrentCommandId(true);
bistate = GetBulkInsertState();
-
ti_options = TABLE_INSERT_SKIP_FSM;
- if (!XLogIsNeeded())
- ti_options |= TABLE_INSERT_SKIP_WAL;
}
else
{
@@ -12460,6 +12455,8 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace,
LOCKMODE lockmode)
table_close(pg_class, RowExclusiveLock);
+ RelationAssumeNewRelfilenode(rel);
+
relation_close(rel, NoLock);
/* Make sure the reltablespace change is visible */
diff --git a/src/backend/storage/buffer/bufmgr.c
b/src/backend/storage/buffer/bufmgr.c
index 7ad1073..746ce47 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -3203,20 +3203,27 @@ PrintPinnedBufs(void)
void
FlushRelationBuffers(Relation rel)
{
- int i;
- BufferDesc *bufHdr;
-
- /* Open rel at the smgr level if not already done */
RelationOpenSmgr(rel);
- if (RelationUsesLocalBuffers(rel))
+ FlushRelationBuffersWithoutRelcache(rel->rd_smgr,
+
RelationUsesLocalBuffers(rel));
+}
+
+void
+FlushRelationBuffersWithoutRelcache(SMgrRelation smgr, bool islocal)
+{
+ RelFileNode rnode = smgr->smgr_rnode.node;
+ int i;
+ BufferDesc *bufHdr;
+
+ if (islocal)
{
for (i = 0; i < NLocBuffer; i++)
{
uint32 buf_state;
bufHdr = GetLocalBufferDescriptor(i);
- if (RelFileNodeEquals(bufHdr->tag.rnode, rel->rd_node)
&&
+ if (RelFileNodeEquals(bufHdr->tag.rnode, rnode) &&
((buf_state =
pg_atomic_read_u32(&bufHdr->state)) &
(BM_VALID | BM_DIRTY)) == (BM_VALID |
BM_DIRTY))
{
@@ -3233,7 +3240,7 @@ FlushRelationBuffers(Relation rel)
PageSetChecksumInplace(localpage,
bufHdr->tag.blockNum);
- smgrwrite(rel->rd_smgr,
+ smgrwrite(smgr,
bufHdr->tag.forkNum,
bufHdr->tag.blockNum,
localpage,
@@ -3263,18 +3270,18 @@ FlushRelationBuffers(Relation rel)
* As in DropRelFileNodeBuffers, an unlocked precheck should be
safe
* and saves some cycles.
*/
- if (!RelFileNodeEquals(bufHdr->tag.rnode, rel->rd_node))
+ if (!RelFileNodeEquals(bufHdr->tag.rnode, rnode))
continue;
ReservePrivateRefCountEntry();
buf_state = LockBufHdr(bufHdr);
- if (RelFileNodeEquals(bufHdr->tag.rnode, rel->rd_node) &&
+ if (RelFileNodeEquals(bufHdr->tag.rnode, rnode) &&
(buf_state & (BM_VALID | BM_DIRTY)) == (BM_VALID |
BM_DIRTY))
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr),
LW_SHARED);
- FlushBuffer(bufHdr, rel->rd_smgr);
+ FlushBuffer(bufHdr, smgr);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
UnpinBuffer(bufHdr, true);
}
@@ -3484,13 +3491,15 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
(pg_atomic_read_u32(&bufHdr->state) & BM_PERMANENT))
{
/*
- * If we're in recovery we cannot dirty a page because
of a hint.
- * We can set the hint, just not dirty the page as a
result so the
- * hint is lost when we evict the page or shutdown.
+ * If we must not write WAL, due to a
relfilenode-specific
+ * condition or being in recovery, don't dirty the
page. We can
+ * set the hint, just not dirty the page as a result so
the hint
+ * is lost when we evict the page or shutdown.
*
* See src/backend/storage/page/README for longer
discussion.
*/
- if (RecoveryInProgress())
+ if (RecoveryInProgress() ||
+ RelFileNodeSkippingWAL(bufHdr->tag.rnode))
return;
/*
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 8a9eaf6..1d408c3 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -248,11 +248,10 @@ mdcreate(SMgrRelation reln, ForkNumber forkNum, bool
isRedo)
* During replay, we would delete the file and then recreate it, which is fine
* if the contents of the file were repopulated by subsequent WAL entries.
* But if we didn't WAL-log insertions, but instead relied on fsyncing the
- * file after populating it (as for instance CLUSTER and CREATE INDEX do),
- * the contents of the file would be lost forever. By leaving the empty file
- * until after the next checkpoint, we prevent reassignment of the relfilenode
- * number until it's safe, because relfilenode assignment skips over any
- * existing file.
+ * file after populating it (as we do at wal_level=minimal), the contents of
+ * the file would be lost forever. By leaving the empty file until after the
+ * next checkpoint, we prevent reassignment of the relfilenode number until
+ * it's safe, because relfilenode assignment skips over any existing file.
*
* We do not need to go through this dance for temp relations, though, because
* we never make WAL entries for temp rels, and so a temp rel poses no threat
diff --git a/src/backend/utils/cache/relcache.c
b/src/backend/utils/cache/relcache.c
index ad1ff01..f3831f0 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -262,6 +262,9 @@ static void RelationReloadIndexInfo(Relation relation);
static void RelationReloadNailed(Relation relation);
static void RelationFlushRelation(Relation relation);
static void RememberToFreeTupleDescAtEOX(TupleDesc td);
+#ifdef USE_ASSERT_CHECKING
+static void AssertPendingSyncConsistency(Relation relation);
+#endif
static void AtEOXact_cleanup(Relation relation, bool isCommit);
static void AtEOSubXact_cleanup(Relation relation, bool isCommit,
SubTransactionId mySubid, SubTransactionId parentSubid);
@@ -1095,6 +1098,7 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
relation->rd_isnailed = false;
relation->rd_createSubid = InvalidSubTransactionId;
relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
+ relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
switch (relation->rd_rel->relpersistence)
{
case RELPERSISTENCE_UNLOGGED:
@@ -1828,6 +1832,7 @@ formrdesc(const char *relationName, Oid relationReltype,
relation->rd_isnailed = true;
relation->rd_createSubid = InvalidSubTransactionId;
relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
+ relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
relation->rd_backend = InvalidBackendId;
relation->rd_islocaltemp = false;
@@ -2035,6 +2040,12 @@ RelationIdGetRelation(Oid relationId)
rd = RelationBuildDesc(relationId, true);
if (RelationIsValid(rd))
RelationIncrementReferenceCount(rd);
+
+#ifdef USE_ASSERT_CHECKING
+ if (!XLogIsNeeded() && RelationIsValid(rd))
+ AssertPendingSyncConsistency(rd);
+#endif
+
return rd;
}
@@ -2093,7 +2104,7 @@ RelationClose(Relation relation)
#ifdef RELCACHE_FORCE_RELEASE
if (RelationHasReferenceCountZero(relation) &&
relation->rd_createSubid == InvalidSubTransactionId &&
- relation->rd_newRelfilenodeSubid == InvalidSubTransactionId)
+ relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)
RelationClearRelation(relation, false);
#endif
}
@@ -2509,13 +2520,13 @@ RelationClearRelation(Relation relation, bool rebuild)
* problem.
*
* When rebuilding an open relcache entry, we must preserve ref
count,
- * rd_createSubid/rd_newRelfilenodeSubid, and rd_toastoid
state. Also
- * attempt to preserve the pg_class entry (rd_rel), tupledesc,
- * rewrite-rule, partition key, and partition descriptor
substructures
- * in place, because various places assume that these
structures won't
- * move while they are working with an open relcache entry.
(Note:
- * the refcount mechanism for tupledescs might someday allow us
to
- * remove this hack for the tupledesc.)
+ * rd_*Subid, and rd_toastoid state. Also attempt to preserve
the
+ * pg_class entry (rd_rel), tupledesc, rewrite-rule, partition
key,
+ * and partition descriptor substructures in place, because
various
+ * places assume that these structures won't move while they are
+ * working with an open relcache entry. (Note: the refcount
+ * mechanism for tupledescs might someday allow us to remove
this hack
+ * for the tupledesc.)
*
* Note that this process does not touch CurrentResourceOwner;
which
* is good because whatever ref counts the entry may have do not
@@ -2599,6 +2610,7 @@ RelationClearRelation(Relation relation, bool rebuild)
/* creation sub-XIDs must be preserved */
SWAPFIELD(SubTransactionId, rd_createSubid);
SWAPFIELD(SubTransactionId, rd_newRelfilenodeSubid);
+ SWAPFIELD(SubTransactionId, rd_firstRelfilenodeSubid);
/* un-swap rd_rel pointers, swap contents instead */
SWAPFIELD(Form_pg_class, rd_rel);
/* ... but actually, we don't have to update newrel->rd_rel */
@@ -2666,7 +2678,7 @@ static void
RelationFlushRelation(Relation relation)
{
if (relation->rd_createSubid != InvalidSubTransactionId ||
- relation->rd_newRelfilenodeSubid != InvalidSubTransactionId)
+ relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId)
{
/*
* New relcache entries are always rebuilt, not flushed; else
we'd
@@ -2751,11 +2763,10 @@ RelationCacheInvalidateEntry(Oid relationId)
* relation cache and re-read relation mapping data.
*
* This is currently used only to recover from SI message buffer overflow,
- * so we do not touch new-in-transaction relations; they cannot be targets
- * of cross-backend SI updates (and our own updates now go through a
- * separate linked list that isn't limited by the SI message buffer size).
- * Likewise, we need not discard new-relfilenode-in-transaction hints,
- * since any invalidation of those would be a local event.
+ * so we do not touch relations having new-in-transaction relfilenodes;
they
+ * cannot be targets of cross-backend SI updates (and our own updates now
go
+ * through a separate linked list that isn't limited by the SI message
+ * buffer size).
*
* We do this in two phases: the first pass deletes deletable items, and
* the second one rebuilds the rebuildable items. This is essential for
@@ -2806,7 +2817,7 @@ RelationCacheInvalidate(void)
* pending invalidations.
*/
if (relation->rd_createSubid != InvalidSubTransactionId ||
- relation->rd_newRelfilenodeSubid !=
InvalidSubTransactionId)
+ relation->rd_firstRelfilenodeSubid !=
InvalidSubTransactionId)
continue;
relcacheInvalsReceived++;
@@ -2918,6 +2929,40 @@ RememberToFreeTupleDescAtEOX(TupleDesc td)
EOXactTupleDescArray[NextEOXactTupleDescNum++] = td;
}
+#ifdef USE_ASSERT_CHECKING
+static void
+AssertPendingSyncConsistency(Relation relation)
+{
+ bool relcache_verdict =
+ relation->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT &&
+ ((relation->rd_createSubid != InvalidSubTransactionId &&
+ RELKIND_HAS_STORAGE(relation->rd_rel->relkind)) ||
+ relation->rd_firstRelfilenodeSubid != InvalidSubTransactionId);
+ Assert(relcache_verdict == RelFileNodeSkippingWAL(relation->rd_node));
+}
+
+/*
+ * AssertPendingSyncs_RelationCache
+ *
+ * Assert that relcache.c and storage.c agree on whether to skip WAL.
+ *
+ * This consistently detects relcache.c skipping WAL while storage.c is not
+ * skipping WAL. It often fails to detect the reverse error, because
+ * invalidation will have destroyed the relcache entry. It will detect the
+ * reverse error if something opens the relation after the DDL.
+ */
+void
+AssertPendingSyncs_RelationCache(void)
+{
+ HASH_SEQ_STATUS status;
+ RelIdCacheEnt *idhentry;
+
+ hash_seq_init(&status, RelationIdCache);
+ while ((idhentry = (RelIdCacheEnt *) hash_seq_search(&status)) != NULL)
+ AssertPendingSyncConsistency(idhentry->reldesc);
+}
+#endif
+
/*
* AtEOXact_RelationCache
*
@@ -3029,10 +3074,7 @@ AtEOXact_cleanup(Relation relation, bool isCommit)
*
* During commit, reset the flag to zero, since we are now out of the
* creating transaction. During abort, simply delete the relcache entry
- * --- it isn't interesting any longer. (NOTE: if we have forgotten the
- * new-ness of a new relation due to a forced cache flush, the entry
will
- * get deleted anyway by shared-cache-inval processing of the aborted
- * pg_class insertion.)
+ * --- it isn't interesting any longer.
*/
if (relation->rd_createSubid != InvalidSubTransactionId)
{
@@ -3060,9 +3102,10 @@ AtEOXact_cleanup(Relation relation, bool isCommit)
}
/*
- * Likewise, reset the hint about the relfilenode being new.
+ * Likewise, reset any record of the relfilenode being new.
*/
relation->rd_newRelfilenodeSubid = InvalidSubTransactionId;
+ relation->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
}
/*
@@ -3154,7 +3197,7 @@ AtEOSubXact_cleanup(Relation relation, bool isCommit,
}
/*
- * Likewise, update or drop any new-relfilenode-in-subtransaction hint.
+ * Likewise, update or drop any new-relfilenode-in-subtransaction.
*/
if (relation->rd_newRelfilenodeSubid == mySubid)
{
@@ -3163,6 +3206,14 @@ AtEOSubXact_cleanup(Relation relation, bool isCommit,
else
relation->rd_newRelfilenodeSubid =
InvalidSubTransactionId;
}
+
+ if (relation->rd_firstRelfilenodeSubid == mySubid)
+ {
+ if (isCommit)
+ relation->rd_firstRelfilenodeSubid = parentSubid;
+ else
+ relation->rd_firstRelfilenodeSubid =
InvalidSubTransactionId;
+ }
}
@@ -3252,6 +3303,7 @@ RelationBuildLocalRelation(const char *relname,
/* it's being created in this transaction */
rel->rd_createSubid = GetCurrentSubTransactionId();
rel->rd_newRelfilenodeSubid = InvalidSubTransactionId;
+ rel->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
/*
* create a new tuple descriptor from the one passed in. We do this
@@ -3549,14 +3601,29 @@ RelationSetNewRelfilenode(Relation relation, char
persistence)
*/
CommandCounterIncrement();
- /*
- * Mark the rel as having been given a new relfilenode in the current
- * (sub) transaction. This is a hint that can be used to optimize later
- * operations on the rel in the same transaction.
- */
+ RelationAssumeNewRelfilenode(relation);
+}
+
+/*
+ * RelationAssumeNewRelfilenode
+ *
+ * Code that modifies pg_class.reltablespace or pg_class.relfilenode must call
+ * this. The call shall precede any code that might insert WAL records whose
+ * replay would modify bytes in the new RelFileNode, and the call shall follow
+ * any WAL modifying bytes in the prior RelFileNode. See struct RelationData.
+ * Ideally, call this as near as possible to the CommandCounterIncrement()
+ * that makes the pg_class change visible (before it or after it); that
+ * minimizes the chance of future development adding a forbidden WAL insertion
+ * between RelationAssumeNewRelfilenode() and CommandCounterIncrement().
+ */
+void
+RelationAssumeNewRelfilenode(Relation relation)
+{
relation->rd_newRelfilenodeSubid = GetCurrentSubTransactionId();
+ if (relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)
+ relation->rd_firstRelfilenodeSubid =
relation->rd_newRelfilenodeSubid;
- /* Flag relation as needing eoxact cleanup (to remove the hint) */
+ /* Flag relation as needing eoxact cleanup (to clear these fields) */
EOXactListAdd(relation);
}
@@ -5591,6 +5658,7 @@ load_relcache_init_file(bool shared)
rel->rd_fkeylist = NIL;
rel->rd_createSubid = InvalidSubTransactionId;
rel->rd_newRelfilenodeSubid = InvalidSubTransactionId;
+ rel->rd_firstRelfilenodeSubid = InvalidSubTransactionId;
rel->rd_amcache = NULL;
MemSet(&rel->pgstat_info, 0, sizeof(rel->pgstat_info));
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 4b3769b..2348bef 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -36,6 +36,7 @@
#include "access/xlog_internal.h"
#include "catalog/namespace.h"
#include "catalog/pg_authid.h"
+#include "catalog/storage.h"
#include "commands/async.h"
#include "commands/prepare.h"
#include "commands/trigger.h"
@@ -2639,6 +2640,18 @@ static struct config_int ConfigureNamesInt[] =
},
{
+ {"wal_skip_threshold", PGC_USERSET, RESOURCES_DISK,
+ gettext_noop("Size of new file to fsync instead of
writing WAL."),
+ NULL,
+ GUC_UNIT_KB
+ },
+ &wal_skip_threshold,
+ 64,
+ 0, MAX_KILOBYTES,
+ NULL, NULL, NULL
+ },
+
+ {
{"max_wal_senders", PGC_POSTMASTER, REPLICATION_SENDING,
gettext_noop("Sets the maximum number of simultaneously
running WAL sender processes."),
NULL
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 858bcb6..22916e8 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -29,7 +29,6 @@
/* "options" flag bits for heap_insert */
-#define HEAP_INSERT_SKIP_WAL TABLE_INSERT_SKIP_WAL
#define HEAP_INSERT_SKIP_FSM TABLE_INSERT_SKIP_FSM
#define HEAP_INSERT_FROZEN TABLE_INSERT_FROZEN
#define HEAP_INSERT_NO_LOGICAL TABLE_INSERT_NO_LOGICAL
@@ -166,8 +165,6 @@ extern void simple_heap_delete(Relation relation,
ItemPointer tid);
extern void simple_heap_update(Relation relation, ItemPointer otid,
HeapTuple tup);
-extern void heap_sync(Relation relation);
-
extern TransactionId heap_compute_xid_horizon_for_tuples(Relation rel,
ItemPointerData *items,
int nitems);
diff --git a/src/include/access/rewriteheap.h b/src/include/access/rewriteheap.h
index 8056253..7f9736e 100644
--- a/src/include/access/rewriteheap.h
+++ b/src/include/access/rewriteheap.h
@@ -23,7 +23,7 @@ typedef struct RewriteStateData *RewriteState;
extern RewriteState begin_heap_rewrite(Relation OldHeap, Relation NewHeap,
TransactionId OldestXmin, TransactionId FreezeXid,
-
MultiXactId MultiXactCutoff, bool use_wal);
+
MultiXactId MultiXactCutoff);
extern void end_heap_rewrite(RewriteState state);
extern void rewrite_heap_tuple(RewriteState state, HeapTuple oldTuple,
HeapTuple newTuple);
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 6402291..aca88d0 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -127,7 +127,7 @@ typedef struct TM_FailureData
} TM_FailureData;
/* "options" flag bits for table_tuple_insert */
-#define TABLE_INSERT_SKIP_WAL 0x0001
+/* TABLE_INSERT_SKIP_WAL was 0x0001; RelationNeedsWAL() now governs */
#define TABLE_INSERT_SKIP_FSM 0x0002
#define TABLE_INSERT_FROZEN 0x0004
#define TABLE_INSERT_NO_LOGICAL 0x0008
@@ -409,9 +409,8 @@ typedef struct TableAmRoutine
/*
* Perform operations necessary to complete insertions made via
- * tuple_insert and multi_insert with a BulkInsertState specified. This
- * may for example be used to flush the relation, when the
- * TABLE_INSERT_SKIP_WAL option was used.
+ * tuple_insert and multi_insert with a BulkInsertState specified.
In-tree
+ * access methods ceased to use this.
*
* Typically callers of tuple_insert and multi_insert will just pass all
* the flags that apply to them, and each AM has to decide which of them
@@ -1087,10 +1086,6 @@ table_compute_xid_horizon_for_tuples(Relation rel,
* The options bitmask allows the caller to specify options that may change the
* behaviour of the AM. The AM will ignore options that it does not support.
*
- * If the TABLE_INSERT_SKIP_WAL option is specified, the new tuple doesn't
- * need to be logged to WAL, even for a non-temp relation. It is the AMs
- * choice whether this optimization is supported.
- *
* If the TABLE_INSERT_SKIP_FSM option is specified, AMs are free to not reuse
* free space in the relation. This can save some cycles when we know the
* relation is new and doesn't contain useful amounts of free space.
@@ -1309,10 +1304,9 @@ table_tuple_lock(Relation rel, ItemPointer tid, Snapshot
snapshot,
}
/*
- * Perform operations necessary to complete insertions made via
- * tuple_insert and multi_insert with a BulkInsertState specified. This
- * e.g. may e.g. used to flush the relation when inserting with
- * TABLE_INSERT_SKIP_WAL specified.
+ * Perform operations necessary to complete insertions made via tuple_insert
+ * and multi_insert with a BulkInsertState specified. In-tree access methods
+ * ceased to use this.
*/
static inline void
table_finish_bulk_insert(Relation rel, int options)
diff --git a/src/include/catalog/storage.h b/src/include/catalog/storage.h
index 3579d3f..108115a 100644
--- a/src/include/catalog/storage.h
+++ b/src/include/catalog/storage.h
@@ -19,18 +19,23 @@
#include "storage/smgr.h"
#include "utils/relcache.h"
+/* GUC variables */
+extern int wal_skip_threshold;
+
extern SMgrRelation RelationCreateStorage(RelFileNode rnode, char
relpersistence);
extern void RelationDropStorage(Relation rel);
extern void RelationPreserveStorage(RelFileNode rnode, bool atCommit);
extern void RelationTruncate(Relation rel, BlockNumber nblocks);
extern void RelationCopyStorage(SMgrRelation src, SMgrRelation dst,
ForkNumber
forkNum, char relpersistence);
+extern bool RelFileNodeSkippingWAL(RelFileNode rnode);
/*
* These functions used to be in storage/smgr/smgr.c, which explains the
* naming
*/
extern void smgrDoPendingDeletes(bool isCommit);
+extern void smgrDoPendingSyncs(void);
extern int smgrGetPendingDeletes(bool forCommit, RelFileNode **ptr);
extern void AtSubCommit_smgr(void);
extern void AtSubAbort_smgr(void);
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 17b97f7..8097d5a 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -49,6 +49,9 @@ typedef enum
/* forward declared, to avoid having to expose buf_internals.h here */
struct WritebackContext;
+/* forward declared, to avoid including smgr.h here */
+struct SMgrRelationData;
+
/* in globals.c ... this duplicates miscadmin.h */
extern PGDLLIMPORT int NBuffers;
@@ -189,6 +192,8 @@ extern BlockNumber RelationGetNumberOfBlocksInFork(Relation
relation,
ForkNumber forkNum);
extern void FlushOneBuffer(Buffer buffer);
extern void FlushRelationBuffers(Relation rel);
+extern void FlushRelationBuffersWithoutRelcache(struct SMgrRelationData *smgr,
+
bool islocal);
extern void FlushDatabaseBuffers(Oid dbid);
extern void DropRelFileNodeBuffers(RelFileNodeBackend rnode, ForkNumber
*forkNum,
int nforks,
BlockNumber *firstDelBlock);
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 8b8b237..d9abd61 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -63,22 +63,40 @@ typedef struct RelationData
*
rd_replidindex) */
bool rd_statvalid; /* is rd_statlist valid? */
- /*
+ /*----------
* rd_createSubid is the ID of the highest subtransaction the rel has
- * survived into; or zero if the rel was not created in the current top
- * transaction. This can be now be relied on, whereas previously it
could
- * be "forgotten" in earlier releases. Likewise, rd_newRelfilenodeSubid
is
- * the ID of the highest subtransaction the relfilenode change has
- * survived into, or zero if not changed in the current transaction (or
we
- * have forgotten changing it). rd_newRelfilenodeSubid can be forgotten
- * when a relation has multiple new relfilenodes within a single
- * transaction, with one of them occurring in a subsequently aborted
- * subtransaction, e.g. BEGIN; TRUNCATE t; SAVEPOINT save; TRUNCATE t;
- * ROLLBACK TO save; -- rd_newRelfilenodeSubid is now forgotten
+ * survived into or zero if the rel was not created in the current top
+ * transaction. rd_firstRelfilenodeSubid is the ID of the highest
+ * subtransaction an rd_node change has survived into or zero if rd_node
+ * matches the value it had at the start of the current top transaction.
+ * (Rolling back the subtransaction that rd_firstRelfilenodeSubid
denotes
+ * would restore rd_node to the value it had at the start of the current
+ * top transaction. Rolling back any lower subtransaction would not.)
+ * Their accuracy is critical to RelationNeedsWAL().
+ *
+ * rd_newRelfilenodeSubid is the ID of the highest subtransaction the
+ * most-recent relfilenode change has survived into or zero if not
changed
+ * in the current transaction (or we have forgotten changing it). This
+ * field is accurate when non-zero, but it can be zero when a relation
has
+ * multiple new relfilenodes within a single transaction, with one of
them
+ * occurring in a subsequently aborted subtransaction, e.g.
+ * BEGIN;
+ * TRUNCATE t;
+ * SAVEPOINT save;
+ * TRUNCATE t;
+ * ROLLBACK TO save;
+ * -- rd_newRelfilenodeSubid is now forgotten
+ *
+ * These fields are read-only outside relcache.c. Other files trigger
+ * rd_node changes by updating pg_class.reltablespace and/or
+ * pg_class.relfilenode. They must call RelationAssumeNewRelfilenode()
to
+ * update these fields.
*/
SubTransactionId rd_createSubid; /* rel was created in current
xact */
- SubTransactionId rd_newRelfilenodeSubid; /* new relfilenode
assigned in
-
* current xact */
+ SubTransactionId rd_newRelfilenodeSubid; /* highest subxact
changing
+
* rd_node to current value */
+ SubTransactionId rd_firstRelfilenodeSubid; /* highest subxact
changing
+
* rd_node to any value */
Form_pg_class rd_rel; /* RELATION tuple */
TupleDesc rd_att; /* tuple descriptor */
@@ -521,9 +539,16 @@ typedef struct ViewOptions
/*
* RelationNeedsWAL
* True if relation needs WAL.
- */
-#define RelationNeedsWAL(relation) \
- ((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
+ *
+ * Returns false if wal_level = minimal and this relation is created or
+ * truncated in the current transaction. See "Skipping WAL for New
+ * RelFileNode" in src/backend/access/transam/README.
+ */
+#define RelationNeedsWAL(relation)
\
+ ((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT &&
\
+ (XLogIsNeeded() ||
\
+ (relation->rd_createSubid == InvalidSubTransactionId &&
\
+ relation->rd_firstRelfilenodeSubid == InvalidSubTransactionId)))
/*
* RelationUsesLocalBuffers
diff --git a/src/include/utils/relcache.h b/src/include/utils/relcache.h
index 2f2ace3..d3e8348 100644
--- a/src/include/utils/relcache.h
+++ b/src/include/utils/relcache.h
@@ -105,9 +105,10 @@ extern Relation RelationBuildLocalRelation(const char
*relname,
char relkind);
/*
- * Routine to manage assignment of new relfilenode to a relation
+ * Routines to manage assignment of new relfilenode to a relation
*/
extern void RelationSetNewRelfilenode(Relation relation, char persistence);
+extern void RelationAssumeNewRelfilenode(Relation relation);
/*
* Routines for flushing/rebuilding relcache entries in various scenarios
@@ -120,6 +121,11 @@ extern void RelationCacheInvalidate(void);
extern void RelationCloseSmgrByOid(Oid relationId);
+#ifdef USE_ASSERT_CHECKING
+extern void AssertPendingSyncs_RelationCache(void);
+#else
+#define AssertPendingSyncs_RelationCache() do {} while (0)
+#endif
extern void AtEOXact_RelationCache(bool isCommit);
extern void AtEOSubXact_RelationCache(bool isCommit, SubTransactionId mySubid,
SubTransactionId parentSubid);
diff --git a/src/test/recovery/t/018_wal_optimize.pl
b/src/test/recovery/t/018_wal_optimize.pl
new file mode 100644
index 0000000..415d91c
--- /dev/null
+++ b/src/test/recovery/t/018_wal_optimize.pl
@@ -0,0 +1,353 @@
+# Test WAL replay when some operation has skipped WAL.
+#
+# These tests exercise code that once violated the mandate described in
+# src/backend/access/transam/README section "Skipping WAL for New
+# RelFileNode". The tests work by committing some transactions, initiating an
+# immediate shutdown, and confirming that the expected data survives recovery.
+# For many years, individual commands made the decision to skip WAL, hence the
+# frequent appearance of COPY in these tests.
+use strict;
+use warnings;
+
+use PostgresNode;
+use TestLib;
+use Test::More tests => 34;
+
+sub check_orphan_relfilenodes
+{
+ my($node, $test_name) = @_;
+
+ my $db_oid = $node->safe_psql('postgres',
+ "SELECT oid FROM pg_database WHERE datname = 'postgres'");
+ my $prefix = "base/$db_oid/";
+ my $filepaths_referenced = $node->safe_psql('postgres', "
+ SELECT pg_relation_filepath(oid) FROM pg_class
+ WHERE reltablespace = 0 AND relpersistence <> 't' AND
+ pg_relation_filepath(oid) IS NOT NULL;");
+ is_deeply([sort(map { "$prefix$_" }
+ grep(/^[0-9]+$/,
+ slurp_dir($node->data_dir .
"/$prefix")))],
+ [sort split /\n/, $filepaths_referenced],
+ $test_name);
+ return;
+}
+
+# We run this same test suite for both wal_level=minimal and replica.
+sub run_wal_optimize
+{
+ my $wal_level = shift;
+
+ my $node = get_new_node("node_$wal_level");
+ $node->init;
+ $node->append_conf('postgresql.conf', qq(
+wal_level = $wal_level
+max_prepared_transactions = 1
+wal_log_hints = on
+wal_skip_threshold = 0
+#wal_debug = on
+));
+ $node->start;
+
+ # Setup
+ my $tablespace_dir = $node->basedir . '/tablespace_other';
+ mkdir ($tablespace_dir);
+ $tablespace_dir = TestLib::perl2host($tablespace_dir);
+ $node->safe_psql('postgres',
+ "CREATE TABLESPACE other LOCATION '$tablespace_dir';");
+
+ # Test direct truncation optimization. No tuples
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE trunc (id serial PRIMARY KEY);
+ TRUNCATE trunc;
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ my $result = $node->safe_psql('postgres', "SELECT count(*) FROM
trunc;");
+ is($result, qq(0),
+ "wal_level = $wal_level, optimized truncation with empty table");
+
+ # Test truncation with inserted tuples within the same transaction.
+ # Tuples inserted after the truncation should be seen.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE trunc_ins (id serial PRIMARY KEY);
+ INSERT INTO trunc_ins VALUES (DEFAULT);
+ TRUNCATE trunc_ins;
+ INSERT INTO trunc_ins VALUES (DEFAULT);
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
trunc_ins;");
+ is($result, qq(1),
+ "wal_level = $wal_level, optimized truncation with inserted table");
+
+ # Same for prepared transaction
+ # Tuples inserted after the truncation should be seen.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE twophase (id serial PRIMARY KEY);
+ INSERT INTO twophase VALUES (DEFAULT);
+ TRUNCATE twophase;
+ INSERT INTO twophase VALUES (DEFAULT);
+ PREPARE TRANSACTION 't';
+ COMMIT PREPARED 't';");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
twophase;");
+ is($result, qq(1),
+ "wal_level = $wal_level, optimized truncation with prepared
transaction");
+
+ # Same with writing WAL at end of xact, instead of syncing
+ # Tuples inserted after the truncation should be seen.
+ $node->safe_psql('postgres', "
+ SET wal_skip_threshold = '1TB';
+ BEGIN;
+ CREATE TABLE noskip (id serial PRIMARY KEY);
+ INSERT INTO noskip VALUES (DEFAULT);
+ TRUNCATE noskip;
+ INSERT INTO noskip VALUES (DEFAULT);
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM noskip;");
+ is($result, qq(1),
+ "wal_level = $wal_level, optimized truncation with end-of-xact WAL");
+
+ # Data file for COPY query in subsequent tests.
+ my $basedir = $node->basedir;
+ my $copy_file = "$basedir/copy_data.txt";
+ TestLib::append_to_file($copy_file, qq(20000,30000
+20001,30001
+20002,30002));
+
+ # Test truncation with inserted tuples using COPY. Tuples copied after
+ # the truncation should be seen.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE trunc_copy (id serial PRIMARY KEY, id2 int);
+ INSERT INTO trunc_copy (id, id2) VALUES (DEFAULT,
generate_series(1,3000));
+ TRUNCATE trunc_copy;
+ COPY trunc_copy FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
trunc_copy;");
+ is($result, qq(3),
+ "wal_level = $wal_level, optimized truncation with copied table");
+
+ # Like previous test, but rollback SET TABLESPACE in a subtransaction.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE spc_abort (id serial PRIMARY KEY, id2 int);
+ INSERT INTO spc_abort (id, id2) VALUES (DEFAULT,
generate_series(1,3000));
+ TRUNCATE spc_abort;
+ SAVEPOINT s; ALTER TABLE spc_abort SET TABLESPACE other;
ROLLBACK TO s;
+ COPY spc_abort FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
spc_abort;");
+ is($result, qq(3),
+ "wal_level = $wal_level, SET TABLESPACE abort subtransaction");
+
+ # in different subtransaction patterns
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE spc_commit (id serial PRIMARY KEY, id2 int);
+ INSERT INTO spc_commit (id, id2) VALUES (DEFAULT,
generate_series(1,3000));
+ TRUNCATE spc_commit;
+ SAVEPOINT s; ALTER TABLE spc_commit SET TABLESPACE other;
RELEASE s;
+ COPY spc_commit FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
spc_commit;");
+ is($result, qq(3),
+ "wal_level = $wal_level, SET TABLESPACE commit subtransaction");
+
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE spc_nest (id serial PRIMARY KEY, id2 int);
+ INSERT INTO spc_nest (id, id2) VALUES (DEFAULT,
generate_series(1,3000));
+ TRUNCATE spc_nest;
+ SAVEPOINT s;
+ ALTER TABLE spc_nest SET TABLESPACE other;
+ SAVEPOINT s2;
+ ALTER TABLE spc_nest SET TABLESPACE pg_default;
+ ROLLBACK TO s2;
+ SAVEPOINT s2;
+ ALTER TABLE spc_nest SET TABLESPACE pg_default;
+ RELEASE s2;
+ ROLLBACK TO s;
+ COPY spc_nest FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
spc_nest;");
+ is($result, qq(3),
+ "wal_level = $wal_level, SET TABLESPACE nested subtransaction");
+
+ $node->safe_psql('postgres', "
+ CREATE TABLE spc_hint (id int);
+ INSERT INTO spc_hint VALUES (1);
+ BEGIN;
+ ALTER TABLE spc_hint SET TABLESPACE other;
+ CHECKPOINT;
+ SELECT * FROM spc_hint; -- set hint bit
+ INSERT INTO spc_hint VALUES (2);
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
spc_hint;");
+ is($result, qq(2),
+ "wal_level = $wal_level, SET TABLESPACE, hint bit");
+
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE idx_hint (c int PRIMARY KEY);
+ SAVEPOINT q; INSERT INTO idx_hint VALUES (1); ROLLBACK TO q;
+ CHECKPOINT;
+ INSERT INTO idx_hint VALUES (1); -- set index hint bit
+ INSERT INTO idx_hint VALUES (2);
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->psql('postgres', );
+ my($ret, $stdout, $stderr) = $node->psql(
+ 'postgres', "INSERT INTO idx_hint VALUES (2);");
+ is($ret, qq(3),
+ "wal_level = $wal_level, unique index LP_DEAD");
+ like($stderr, qr/violates unique/,
+ "wal_level = $wal_level, unique index LP_DEAD message");
+
+ # UPDATE touches two buffers for one row.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE upd (id serial PRIMARY KEY, id2 int);
+ INSERT INTO upd (id, id2) VALUES (DEFAULT,
generate_series(1,10000));
+ COPY upd FROM '$copy_file' DELIMITER ',';
+ UPDATE upd SET id2 = id2 + 1;
+ DELETE FROM upd;
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM upd;");
+ is($result, qq(0),
+ "wal_level = $wal_level, UPDATE touches two buffers for one row");
+
+ # Test truncation with inserted tuples using both INSERT and COPY.
Tuples
+ # inserted after the truncation should be seen.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE ins_trunc (id serial PRIMARY KEY, id2 int);
+ INSERT INTO ins_trunc (id, id2) VALUES (DEFAULT,
generate_series(1,10000));
+ TRUNCATE ins_trunc;
+ INSERT INTO ins_trunc (id, id2) VALUES (DEFAULT, 10000);
+ COPY ins_trunc FROM '$copy_file' DELIMITER ',';
+ INSERT INTO ins_trunc (id, id2) VALUES (DEFAULT, 10000);
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
ins_trunc;");
+ is($result, qq(5),
+ "wal_level = $wal_level, optimized truncation with inserted/copied
table");
+
+ # Test consistency of COPY with INSERT for table created in the same
+ # transaction.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE ins_copy (id serial PRIMARY KEY, id2 int);
+ INSERT INTO ins_copy VALUES (DEFAULT, 1);
+ COPY ins_copy FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
ins_copy;");
+ is($result, qq(4),
+ "wal_level = $wal_level, replay of optimized copy with inserted
table");
+
+ # Test consistency of COPY that inserts more to the same table using
+ # triggers. If the INSERTS from the trigger go to the same block data
+ # is copied to, and the INSERTs are WAL-logged, WAL replay will fail
when
+ # it tries to replay the WAL record but the "before" image doesn't
match,
+ # because not all changes were WAL-logged.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE ins_trig (id serial PRIMARY KEY, id2 text);
+ CREATE FUNCTION ins_trig_before_row_trig() RETURNS trigger
+ LANGUAGE plpgsql as \$\$
+ BEGIN
+ IF new.id2 NOT LIKE 'triggered%' THEN
+ INSERT INTO ins_trig VALUES (DEFAULT, 'triggered row
before' || NEW.id2);
+ END IF;
+ RETURN NEW;
+ END; \$\$;
+ CREATE FUNCTION ins_trig_after_row_trig() RETURNS trigger
+ LANGUAGE plpgsql as \$\$
+ BEGIN
+ IF new.id2 NOT LIKE 'triggered%' THEN
+ INSERT INTO ins_trig VALUES (DEFAULT, 'triggered row
after' || OLD.id2);
+ END IF;
+ RETURN NEW;
+ END; \$\$;
+ CREATE TRIGGER ins_trig_before_row_insert
+ BEFORE INSERT ON ins_trig
+ FOR EACH ROW EXECUTE PROCEDURE ins_trig_before_row_trig();
+ CREATE TRIGGER ins_trig_after_row_insert
+ AFTER INSERT ON ins_trig
+ FOR EACH ROW EXECUTE PROCEDURE ins_trig_after_row_trig();
+ COPY ins_trig FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
ins_trig;");
+ is($result, qq(9),
+ "wal_level = $wal_level, replay of optimized copy with INSERT
trigger");
+
+ # Test consistency of INSERT, COPY and TRUNCATE in same transaction
block
+ # with TRUNCATE triggers.
+ $node->safe_psql('postgres', "
+ BEGIN;
+ CREATE TABLE trunc_trig (id serial PRIMARY KEY, id2 text);
+ CREATE FUNCTION trunc_trig_before_stat_trig() RETURNS trigger
+ LANGUAGE plpgsql as \$\$
+ BEGIN
+ INSERT INTO trunc_trig VALUES (DEFAULT, 'triggered stat
before');
+ RETURN NULL;
+ END; \$\$;
+ CREATE FUNCTION trunc_trig_after_stat_trig() RETURNS trigger
+ LANGUAGE plpgsql as \$\$
+ BEGIN
+ INSERT INTO trunc_trig VALUES (DEFAULT, 'triggered stat
before');
+ RETURN NULL;
+ END; \$\$;
+ CREATE TRIGGER trunc_trig_before_stat_truncate
+ BEFORE TRUNCATE ON trunc_trig
+ FOR EACH STATEMENT EXECUTE PROCEDURE
trunc_trig_before_stat_trig();
+ CREATE TRIGGER trunc_trig_after_stat_truncate
+ AFTER TRUNCATE ON trunc_trig
+ FOR EACH STATEMENT EXECUTE PROCEDURE
trunc_trig_after_stat_trig();
+ INSERT INTO trunc_trig VALUES (DEFAULT, 1);
+ TRUNCATE trunc_trig;
+ COPY trunc_trig FROM '$copy_file' DELIMITER ',';
+ COMMIT;");
+ $node->stop('immediate');
+ $node->start;
+ $result = $node->safe_psql('postgres', "SELECT count(*) FROM
trunc_trig;");
+ is($result, qq(4),
+ "wal_level = $wal_level, replay of optimized copy with TRUNCATE
trigger");
+
+ # Test redo of temp table creation.
+ $node->safe_psql('postgres', "
+ CREATE TEMP TABLE temp (id serial PRIMARY KEY, id2 text);");
+ $node->stop('immediate');
+ $node->start;
+ check_orphan_relfilenodes($node, "wal_level = $wal_level, no orphan
relfilenode remains");
+
+ return;
+}
+
+# Run same test suite for multiple wal_level values.
+run_wal_optimize("minimal");
+run_wal_optimize("replica");
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
index 297b8fb..1ddde3e 100644
--- a/src/test/regress/pg_regress.c
+++ b/src/test/regress/pg_regress.c
@@ -2354,6 +2354,8 @@ regression_main(int argc, char *argv[], init_function
ifunc, test_function tfunc
fputs("log_lock_waits = on\n", pg_conf);
fputs("log_temp_files = 128kB\n", pg_conf);
fputs("max_prepared_transactions = 2\n", pg_conf);
+ fputs("wal_level = minimal\n", pg_conf); /* XXX before commit
remove */
+ fputs("max_wal_senders = 0\n", pg_conf);
for (sl = temp_configs; sl != NULL; sl = sl->next)
{
