Re: [HACKERS] WAL logging problem in 9.4.3?
| От | Kyotaro HORIGUCHI |
|---|---|
| Тема | Re: [HACKERS] WAL logging problem in 9.4.3? |
| Дата | |
| Msg-id | 20171211.175424.09346818.horiguchi.kyotaro@lab.ntt.co.jp обсуждение исходный текст |
| Ответ на | Re: [HACKERS] WAL logging problem in 9.4.3? (Michael Paquier <michael.paquier@gmail.com>) |
| Ответы |
Re: [HACKERS] WAL logging problem in 9.4.3?
|
| Список | pgsql-hackers |
At Tue, 28 Nov 2017 10:36:39 +0900, Michael Paquier <michael.paquier@gmail.com> wrote in
<CAB7nPqSqukqS5Xx6_6KEk53eRy5ObdvaNG-5aN_4cE8=gTeOdg@mail.gmail.com>
> On Thu, Sep 14, 2017 at 3:34 PM, Kyotaro HORIGUCHI
> <horiguchi.kyotaro@lab.ntt.co.jp> wrote:
> > At Wed, 13 Sep 2017 17:42:39 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> wrote
in<20170913.174239.25978735.horiguchi.kyotaro@lab.ntt.co.jp>
> >> filterdiff seems to did something wrong..
> >
> > # to did...
It's horrid to see that:p
> > The patch is broken by filterdiff so I send a new patch made
> > directly by git format-patch. I confirmed that a build completes
> > with applying this.
>
> To my surprise this patch still applies but fails recovery tests. I am
> bumping it to next CF, for what will be its 8th registration as it is
> for a bug fix, switching the status to "waiting on author".
Thank you for checking that. I saw maybe the same failure. It
occurred when visibilitymap_set() is called with heapBuf =
InvalidBuffer during recovery. Checking pendingSyncs and
no_pending_sync before the elog fixes it. Anyway the DEBUG2 elogs
are to removed before committing. They are just to look how it
works.
The attached patch applies on the current HEAD and passes all
recovery tests.
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center
From af24850bf8ec5ea082d3affce9d0754daf1862ea Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horiguchi.kyotaro@lab.ntt.co.jp>
Date: Tue, 12 Sep 2017 13:01:33 +0900
Subject: [PATCH] Fix WAL logging problem
---
src/backend/access/heap/heapam.c | 113 ++++++++---
src/backend/access/heap/pruneheap.c | 3 +-
src/backend/access/heap/rewriteheap.c | 4 +-
src/backend/access/heap/visibilitymap.c | 3 +-
src/backend/access/transam/xact.c | 7 +
src/backend/catalog/storage.c | 324 +++++++++++++++++++++++++++++---
src/backend/commands/copy.c | 13 +-
src/backend/commands/createas.c | 9 +-
src/backend/commands/matview.c | 6 +-
src/backend/commands/tablecmds.c | 8 +-
src/backend/commands/vacuumlazy.c | 6 +-
src/backend/storage/buffer/bufmgr.c | 40 +++-
src/backend/utils/cache/relcache.c | 13 ++
src/include/access/heapam.h | 8 +-
src/include/catalog/storage.h | 5 +-
src/include/storage/bufmgr.h | 2 +
src/include/utils/rel.h | 8 +
17 files changed, 482 insertions(+), 90 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 3acef27..ecb9ad8 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -34,6 +34,28 @@
* the POSTGRES heap access method used for all POSTGRES
* relations.
*
+ * WAL CONSIDERATIONS
+ * All heap operations are normally WAL-logged. but there are a few
+ * exceptions. Temporary and unlogged relations never need to be
+ * WAL-logged, but we can also skip WAL-logging for a table that was
+ * created in the same transaction, if we don't need WAL for PITR or
+ * WAL archival purposes (i.e. if wal_level=minimal), and we fsync()
+ * the file to disk at COMMIT instead.
+ *
+ * The same-relation optimization is not employed automatically on all
+ * updates to a table that was created in the same transacton, because
+ * for a small number of changes, it's cheaper to just create the WAL
+ * records than fsyncing() the whole relation at COMMIT. It is only
+ * worthwhile for (presumably) large operations like COPY, CLUSTER,
+ * or VACUUM FULL. Use heap_register_sync() to initiate such an
+ * operation; it will cause any subsequent updates to the table to skip
+ * WAL-logging, if possible, and cause the heap to be synced to disk at
+ * COMMIT.
+ *
+ * To make that work, all modifications to heap must use
+ * HeapNeedsWAL() to check if WAL-logging is needed in this transaction
+ * for the given block.
+ *
*-------------------------------------------------------------------------
*/
#include "postgres.h"
@@ -56,6 +78,7 @@
#include "access/xlogutils.h"
#include "catalog/catalog.h"
#include "catalog/namespace.h"
+#include "catalog/storage.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "port/atomics.h"
@@ -2373,12 +2396,6 @@ ReleaseBulkInsertStatePin(BulkInsertState bistate)
* The new tuple is stamped with current transaction ID and the specified
* command ID.
*
- * If the HEAP_INSERT_SKIP_WAL option is specified, the new tuple is not
- * logged in WAL, even for a non-temp relation. Safe usage of this behavior
- * requires that we arrange that all new tuples go into new pages not
- * containing any tuples from other transactions, and that the relation gets
- * fsync'd before commit. (See also heap_sync() comments)
- *
* The HEAP_INSERT_SKIP_FSM option is passed directly to
* RelationGetBufferForTuple, which see for more info.
*
@@ -2409,6 +2426,7 @@ ReleaseBulkInsertStatePin(BulkInsertState bistate)
* TID where the tuple was stored. But note that any toasting of fields
* within the tuple data is NOT reflected into *tup.
*/
+extern HTAB *pendingSyncs;
Oid
heap_insert(Relation relation, HeapTuple tup, CommandId cid,
int options, BulkInsertState bistate)
@@ -2482,7 +2500,7 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (!(options & HEAP_INSERT_SKIP_WAL) && RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
xl_heap_insert xlrec;
xl_heap_header xlhdr;
@@ -2683,12 +2701,10 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
int ndone;
char *scratch = NULL;
Page page;
- bool needwal;
Size saveFreeSpace;
bool need_tuple_data = RelationIsLogicallyLogged(relation);
bool need_cids = RelationIsAccessibleInLogicalDecoding(relation);
- needwal = !(options & HEAP_INSERT_SKIP_WAL) && RelationNeedsWAL(relation);
saveFreeSpace = RelationGetTargetPageFreeSpace(relation,
HEAP_DEFAULT_FILLFACTOR);
@@ -2703,7 +2719,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
* palloc() within a critical section is not safe, so we allocate this
* beforehand.
*/
- if (needwal)
+ if (RelationNeedsWAL(relation))
scratch = palloc(BLCKSZ);
/*
@@ -2738,6 +2754,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
Buffer vmbuffer = InvalidBuffer;
bool all_visible_cleared = false;
int nthispage;
+ bool needwal;
CHECK_FOR_INTERRUPTS();
@@ -2749,6 +2766,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
InvalidBuffer, options, bistate,
&vmbuffer, NULL);
page = BufferGetPage(buffer);
+ needwal = BufferNeedsWAL(relation, buffer);
/* NO EREPORT(ERROR) from here till changes are logged */
START_CRIT_SECTION();
@@ -3305,7 +3323,7 @@ l1:
* NB: heap_abort_speculative() uses the same xlog record and replay
* routines.
*/
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
xl_heap_delete xlrec;
XLogRecPtr recptr;
@@ -4271,7 +4289,8 @@ l2:
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer) ||
+ BufferNeedsWAL(relation, newbuf))
{
XLogRecPtr recptr;
@@ -5162,7 +5181,7 @@ failed:
* (Also, in a PITR log-shipping or 2PC environment, we have to have XLOG
* entries for everything anyway.)
*/
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, *buffer))
{
xl_heap_lock xlrec;
XLogRecPtr recptr;
@@ -5896,7 +5915,7 @@ l4:
MarkBufferDirty(buf);
/* XLOG stuff */
- if (RelationNeedsWAL(rel))
+ if (BufferNeedsWAL(rel, buf))
{
xl_heap_lock_updated xlrec;
XLogRecPtr recptr;
@@ -6052,7 +6071,7 @@ heap_finish_speculative(Relation relation, HeapTuple tuple)
htup->t_ctid = tuple->t_self;
/* XLOG stuff */
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
xl_heap_confirm xlrec;
XLogRecPtr recptr;
@@ -6185,7 +6204,7 @@ heap_abort_speculative(Relation relation, HeapTuple tuple)
* The WAL records generated here match heap_delete(). The same recovery
* routines are used.
*/
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
xl_heap_delete xlrec;
XLogRecPtr recptr;
@@ -6294,7 +6313,7 @@ heap_inplace_update(Relation relation, HeapTuple tuple)
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
xl_heap_inplace xlrec;
XLogRecPtr recptr;
@@ -7408,7 +7427,7 @@ log_heap_clean(Relation reln, Buffer buffer,
XLogRecPtr recptr;
/* Caller should not call me on a non-WAL-logged relation */
- Assert(RelationNeedsWAL(reln));
+ Assert(BufferNeedsWAL(reln, buffer));
xlrec.latestRemovedXid = latestRemovedXid;
xlrec.nredirected = nredirected;
@@ -7456,7 +7475,7 @@ log_heap_freeze(Relation reln, Buffer buffer, TransactionId cutoff_xid,
XLogRecPtr recptr;
/* Caller should not call me on a non-WAL-logged relation */
- Assert(RelationNeedsWAL(reln));
+ Assert(BufferNeedsWAL(reln, buffer));
/* nor when there are no tuples to freeze */
Assert(ntuples > 0);
@@ -7541,7 +7560,7 @@ log_heap_update(Relation reln, Buffer oldbuf,
int bufflags;
/* Caller should not call me on a non-WAL-logged relation */
- Assert(RelationNeedsWAL(reln));
+ Assert(BufferNeedsWAL(reln, newbuf) || BufferNeedsWAL(reln, oldbuf));
XLogBeginInsert();
@@ -8632,8 +8651,13 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
*/
/* Deal with old tuple version */
- oldaction = XLogReadBufferForRedo(record, (oldblk == newblk) ? 0 : 1,
- &obuffer);
+ if (oldblk == newblk)
+ oldaction = XLogReadBufferForRedo(record, 0, &obuffer);
+ else if (XLogRecHasBlockRef(record, 1))
+ oldaction = XLogReadBufferForRedo(record, 1, &obuffer);
+ else
+ oldaction = BLK_DONE;
+
if (oldaction == BLK_NEEDS_REDO)
{
page = BufferGetPage(obuffer);
@@ -8687,6 +8711,8 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
PageInit(page, BufferGetPageSize(nbuffer), 0);
newaction = BLK_NEEDS_REDO;
}
+ else if (!XLogRecHasBlockRef(record, 0))
+ newaction = BLK_DONE;
else
newaction = XLogReadBufferForRedo(record, 0, &nbuffer);
@@ -9123,9 +9149,16 @@ 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.
+ * If we did any changes to the heap bypassing the buffer manager, we must
+ * force the relation down to disk before it's safe to commit the
+ * transaction, because the direct modifications will not be flushed by
+ * the next checkpoint.
+ *
+ * We used to also use this after batch operations like COPY and CLUSTER,
+ * if we skipped using WAL and WAL is otherwise needed, but there were
+ * corner-cases involving other WAL-logged operations to the same
+ * relation, where that was not enough. heap_register_sync() should be
+ * used for that purpose instead.
*
* Indexes are not touched. (Currently, index operations associated with
* the commands that use this are WAL-logged and so do not need fsync.
@@ -9235,3 +9268,33 @@ heap_mask(char *pagedata, BlockNumber blkno)
}
}
}
+
+/*
+ * heap_register_sync - register a heap to be synced to disk at commit
+ *
+ * This can be used to skip WAL-logging changes on a relation file that has
+ * been created in the same transaction. This makes note of the current size of
+ * the relation, and ensures that when the relation is extended, any changes
+ * to the new blocks in the heap, in the same transaction, will not be
+ * WAL-logged. Instead, the heap contents are flushed to disk at commit,
+ * like heap_sync() does.
+ *
+ * This does the same for the TOAST heap, if any. Indexes are not affected.
+ */
+void
+heap_register_sync(Relation rel)
+{
+ /* non-WAL-logged tables never need fsync */
+ if (!RelationNeedsWAL(rel))
+ return;
+
+ RecordPendingSync(rel);
+ if (OidIsValid(rel->rd_rel->reltoastrelid))
+ {
+ Relation toastrel;
+
+ toastrel = heap_open(rel->rd_rel->reltoastrelid, AccessShareLock);
+ RecordPendingSync(toastrel);
+ heap_close(toastrel, AccessShareLock);
+ }
+}
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 9f33e0c..1f184c9 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -20,6 +20,7 @@
#include "access/htup_details.h"
#include "access/xlog.h"
#include "catalog/catalog.h"
+#include "catalog/storage.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
@@ -259,7 +260,7 @@ heap_page_prune(Relation relation, Buffer buffer, TransactionId OldestXmin,
/*
* Emit a WAL HEAP_CLEAN record showing what we did
*/
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
XLogRecPtr recptr;
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index f93c194..899d7a5 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -649,9 +649,7 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
}
else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD)
heaptup = toast_insert_or_update(state->rs_new_rel, tup, NULL,
- HEAP_INSERT_SKIP_FSM |
- (state->rs_use_wal ?
- 0 : HEAP_INSERT_SKIP_WAL));
+ HEAP_INSERT_SKIP_FSM);
else
heaptup = tup;
diff --git a/src/backend/access/heap/visibilitymap.c b/src/backend/access/heap/visibilitymap.c
index 4c2a13a..971d469 100644
--- a/src/backend/access/heap/visibilitymap.c
+++ b/src/backend/access/heap/visibilitymap.c
@@ -88,6 +88,7 @@
#include "access/heapam_xlog.h"
#include "access/visibilitymap.h"
#include "access/xlog.h"
+#include "catalog/storage.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
@@ -307,7 +308,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
map[mapByte] |= (flags << mapOffset);
MarkBufferDirty(vmBuf);
- if (RelationNeedsWAL(rel))
+ if (BufferNeedsWAL(rel, heapBuf))
{
if (XLogRecPtrIsInvalid(recptr))
{
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 046898c..24400e7 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2000,6 +2000,9 @@ CommitTransaction(void)
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
+ /* Flush updates to relations that we didn't WAL-logged */
+ smgrDoPendingSyncs(true);
+
/*
* Mark serializable transaction as complete for predicate locking
* purposes. This should be done as late as we can put it and still allow
@@ -2228,6 +2231,9 @@ PrepareTransaction(void)
/* close large objects before lower-level cleanup */
AtEOXact_LargeObject(true);
+ /* Flush updates to relations that we didn't WAL-logged */
+ smgrDoPendingSyncs(true);
+
/*
* Mark serializable transaction as complete for predicate locking
* purposes. This should be done as late as we can put it and still allow
@@ -2541,6 +2547,7 @@ AbortTransaction(void)
AtAbort_Notify();
AtEOXact_RelationMap(false);
AtAbort_Twophase();
+ smgrDoPendingSyncs(false); /* abandone pending syncs */
/*
* Advertise the fact that we aborted in pg_xact (assuming that we got as
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index 9a5fde0..722f740 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -29,6 +29,7 @@
#include "catalog/storage_xlog.h"
#include "storage/freespace.h"
#include "storage/smgr.h"
+#include "utils/hsearch.h"
#include "utils/memutils.h"
#include "utils/rel.h"
@@ -64,6 +65,49 @@ typedef struct PendingRelDelete
static PendingRelDelete *pendingDeletes = NULL; /* head of linked list */
/*
+ * We also track relation files (RelFileNode values) that have been created
+ * in the same transaction, and that have been modified without WAL-logging
+ * the action (an optimization possible with wal_level=minimal). When we are
+ * about to skip WAL-logging, a PendingRelSync entry is created, and
+ * 'sync_above' is set to the current size of the relation. Any operations
+ * on blocks < sync_above need to be WAL-logged as usual, but for operations
+ * on higher blocks, WAL-logging is skipped.
+ *
+ * NB: after WAL-logging has been skipped for a block, we must not WAL-log
+ * any subsequent actions on the same block either. Replaying the WAL record
+ * of the subsequent action might fail otherwise, as the "before" state of
+ * the block might not match, as the earlier actions were not WAL-logged.
+ * Likewise, after we have WAL-logged an operation for a block, we must
+ * WAL-log any subsequent operations on the same page as well. Replaying
+ * a possible full-page-image from the earlier WAL record would otherwise
+ * revert the page to the old state, even if we sync the relation at end
+ * of transaction.
+ *
+ * If a relation is truncated (without creating a new relfilenode), and we
+ * emit a WAL record of the truncation, we can't skip WAL-logging for any
+ * of the truncated blocks anymore, as replaying the truncation record will
+ * destroy all the data inserted after that. But if we have already decided
+ * to skip WAL-logging changes to a relation, and the relation is truncated,
+ * we don't need to WAL-log the truncation either.
+ *
+ * This mechanism is currently only used by heaps. Indexes are always
+ * WAL-logged. Also, this only applies for wal_level=minimal; with higher
+ * WAL levels we need the WAL for PITR/replication anyway.
+ */
+typedef struct PendingRelSync
+{
+ RelFileNode relnode; /* relation created in same xact */
+ BlockNumber sync_above; /* WAL-logging skipped for blocks >=
+ * sync_above */
+ BlockNumber truncated_to; /* truncation WAL record was written */
+} PendingRelSync;
+
+/* Relations that need to be fsync'd at commit */
+static HTAB *pendingSyncs = NULL;
+
+static void createPendingSyncsHash(void);
+
+/*
* RelationCreateStorage
* Create physical storage for a relation.
*
@@ -226,6 +270,8 @@ RelationPreserveStorage(RelFileNode rnode, bool atCommit)
void
RelationTruncate(Relation rel, BlockNumber nblocks)
{
+ PendingRelSync *pending = NULL;
+ bool found;
bool fsm;
bool vm;
@@ -260,37 +306,81 @@ RelationTruncate(Relation rel, BlockNumber nblocks)
*/
if (RelationNeedsWAL(rel))
{
- /*
- * Make an XLOG entry reporting the file truncation.
- */
- XLogRecPtr lsn;
- xl_smgr_truncate xlrec;
-
- xlrec.blkno = nblocks;
- xlrec.rnode = rel->rd_node;
- xlrec.flags = SMGR_TRUNCATE_ALL;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, sizeof(xlrec));
+ /* no_pending_sync is ignored since new entry is created here */
+ if (!rel->pending_sync)
+ {
+ if (!pendingSyncs)
+ createPendingSyncsHash();
+ elog(DEBUG2, "RelationTruncate: accessing hash");
+ pending = (PendingRelSync *) hash_search(pendingSyncs,
+ (void *) &rel->rd_node,
+ HASH_ENTER, &found);
+ if (!found)
+ {
+ pending->sync_above = InvalidBlockNumber;
+ pending->truncated_to = InvalidBlockNumber;
+ }
- lsn = XLogInsert(RM_SMGR_ID,
- XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE);
+ rel->no_pending_sync= false;
+ rel->pending_sync = pending;
+ }
- /*
- * Flush, because otherwise the truncation of the main relation might
- * hit the disk before the WAL record, and the truncation of the FSM
- * or visibility map. If we crashed during that window, we'd be left
- * with a truncated heap, but the FSM or visibility map would still
- * contain entries for the non-existent heap pages.
- */
- if (fsm || vm)
- XLogFlush(lsn);
+ if (rel->pending_sync->sync_above == InvalidBlockNumber ||
+ rel->pending_sync->sync_above < nblocks)
+ {
+ /*
+ * Make an XLOG entry reporting the file truncation.
+ */
+ XLogRecPtr lsn;
+ xl_smgr_truncate xlrec;
+
+ xlrec.blkno = nblocks;
+ xlrec.rnode = rel->rd_node;
+
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, sizeof(xlrec));
+
+ lsn = XLogInsert(RM_SMGR_ID,
+ XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE);
+
+ elog(DEBUG2, "WAL-logged truncation of rel %u/%u/%u to %u blocks",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ nblocks);
+
+ /*
+ * Flush, because otherwise the truncation of the main relation
+ * might hit the disk before the WAL record, and the truncation of
+ * the FSM or visibility map. If we crashed during that window,
+ * we'd be left with a truncated heap, but the FSM or visibility
+ * map would still contain entries for the non-existent heap
+ * pages.
+ */
+ if (fsm || vm)
+ XLogFlush(lsn);
+
+ rel->pending_sync->truncated_to = nblocks;
+ }
}
/* Do the real work */
smgrtruncate(rel->rd_smgr, MAIN_FORKNUM, nblocks);
}
+/* create the hash table to track pending at-commit fsyncs */
+static void
+createPendingSyncsHash(void)
+{
+ /* First time through: initialize the hash table */
+ HASHCTL ctl;
+
+ MemSet(&ctl, 0, sizeof(ctl));
+ ctl.keysize = sizeof(RelFileNode);
+ ctl.entrysize = sizeof(PendingRelSync);
+ ctl.hash = tag_hash;
+ pendingSyncs = hash_create("pending relation sync table", 5,
+ &ctl, HASH_ELEM | HASH_FUNCTION);
+}
+
/*
* smgrDoPendingDeletes() -- Take care of relation deletes at end of xact.
*
@@ -369,6 +459,24 @@ smgrDoPendingDeletes(bool isCommit)
}
/*
+ * RelationRemovePendingSync() -- remove pendingSync entry for a relation
+ */
+void
+RelationRemovePendingSync(Relation rel)
+{
+ bool found;
+
+ rel->pending_sync = NULL;
+ rel->no_pending_sync = true;
+ if (pendingSyncs)
+ {
+ elog(DEBUG2, "RelationRemovePendingSync: accessing hash");
+ hash_search(pendingSyncs, (void *) &rel->rd_node, HASH_REMOVE, &found);
+ }
+}
+
+
+/*
* smgrGetPendingDeletes() -- Get a list of non-temp relations to be deleted.
*
* The return value is the number of relations scheduled for termination.
@@ -419,6 +527,176 @@ smgrGetPendingDeletes(bool forCommit, RelFileNode **ptr)
return nrels;
}
+
+/*
+ * Remember that the given relation needs to be sync'd at commit, because we
+ * are going to skip WAL-logging subsequent actions to it.
+ */
+void
+RecordPendingSync(Relation rel)
+{
+ bool found = true;
+ BlockNumber nblocks;
+
+ Assert(RelationNeedsWAL(rel));
+
+ /* ignore no_pending_sync since new entry is created here */
+ if (!rel->pending_sync)
+ {
+ if (!pendingSyncs)
+ createPendingSyncsHash();
+
+ /* Look up or create an entry */
+ rel->no_pending_sync = false;
+ elog(DEBUG2, "RecordPendingSync: accessing hash");
+ rel->pending_sync =
+ (PendingRelSync *) hash_search(pendingSyncs,
+ (void *) &rel->rd_node,
+ HASH_ENTER, &found);
+ }
+
+ nblocks = RelationGetNumberOfBlocks(rel);
+ if (!found)
+ {
+ rel->pending_sync->truncated_to = InvalidBlockNumber;
+ rel->pending_sync->sync_above = nblocks;
+
+ elog(DEBUG2,
+ "registering new pending sync for rel %u/%u/%u at block %u",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ nblocks);
+
+ }
+ else if (rel->pending_sync->sync_above == InvalidBlockNumber)
+ {
+ elog(DEBUG2, "registering pending sync for rel %u/%u/%u at block %u",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ nblocks);
+ rel->pending_sync->sync_above = nblocks;
+ }
+ else
+ elog(DEBUG2,
+ "pending sync for rel %u/%u/%u was already registered at block %u (new %u)",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ rel->pending_sync->sync_above, nblocks);
+}
+
+/*
+ * Do changes to given heap page need to be WAL-logged?
+ *
+ * This takes into account any previous RecordPendingSync() requests.
+ *
+ * Note that it is required to check this before creating any WAL records for
+ * heap pages - it is not merely an optimization! WAL-logging a record, when
+ * we have already skipped a previous WAL record for the same page could lead
+ * to failure at WAL replay, as the "before" state expected by the record
+ * might not match what's on disk. Also, if the heap was truncated earlier, we
+ * must WAL-log any changes to the once-truncated blocks, because replaying
+ * the truncation record will destroy them.
+ */
+bool
+BufferNeedsWAL(Relation rel, Buffer buf)
+{
+ BlockNumber blkno = InvalidBlockNumber;
+
+ if (!RelationNeedsWAL(rel))
+ return false;
+
+ /*
+ * no point in doing further work if we know that we don't have pending
+ * sync
+ */
+ if (!pendingSyncs || rel->no_pending_sync)
+ return true;
+
+ Assert(BufferIsValid(buf));
+
+ elog(DEBUG2, "BufferNeedsWAL(r %d, b %d): hash = %p, ent=%p, neg = %d", rel->rd_id, BufferGetBlockNumber(buf),
pendingSyncs,rel->pending_sync, rel->no_pending_sync);
+
+ /* do the real work */
+ if (!rel->pending_sync)
+ {
+ bool found = false;
+
+ /*
+ * Hold the entry in rel. This relies on the fact that hash entry
+ * never moves.
+ */
+ rel->pending_sync =
+ (PendingRelSync *) hash_search(pendingSyncs,
+ (void *) &rel->rd_node,
+ HASH_FIND, &found);
+ elog(DEBUG2, "BufferNeedsWAL: accessing hash : %s", found ? "found" : "not found");
+ if (!found)
+ {
+ /* we don't have no one. don't access the hash no longer */
+ rel->no_pending_sync = true;
+ return true;
+ }
+ }
+
+ blkno = BufferGetBlockNumber(buf);
+ if (rel->pending_sync->sync_above == InvalidBlockNumber ||
+ rel->pending_sync->sync_above > blkno)
+ {
+ elog(DEBUG2, "not skipping WAL-logging for rel %u/%u/%u block %u, because sync_above is %u",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ blkno, rel->pending_sync->sync_above);
+ return true;
+ }
+
+ /*
+ * We have emitted a truncation record for this block.
+ */
+ if (rel->pending_sync->truncated_to != InvalidBlockNumber &&
+ rel->pending_sync->truncated_to <= blkno)
+ {
+ elog(DEBUG2, "not skipping WAL-logging for rel %u/%u/%u block %u, because it was truncated earlier in the same
xact",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ blkno);
+ return true;
+ }
+
+ elog(DEBUG2, "skipping WAL-logging for rel %u/%u/%u block %u",
+ rel->rd_node.spcNode, rel->rd_node.dbNode, rel->rd_node.relNode,
+ blkno);
+
+ return false;
+}
+
+/*
+ * Sync to disk any relations that we skipped WAL-logging for earlier.
+ */
+void
+smgrDoPendingSyncs(bool isCommit)
+{
+ if (!pendingSyncs)
+ return;
+
+ if (isCommit)
+ {
+ HASH_SEQ_STATUS status;
+ PendingRelSync *pending;
+
+ hash_seq_init(&status, pendingSyncs);
+
+ while ((pending = hash_seq_search(&status)) != NULL)
+ {
+ if (pending->sync_above != InvalidBlockNumber)
+ {
+ FlushRelationBuffersWithoutRelCache(pending->relnode, false);
+ smgrimmedsync(smgropen(pending->relnode, InvalidBackendId), MAIN_FORKNUM);
+
+ elog(DEBUG2, "syncing rel %u/%u/%u", pending->relnode.spcNode,
+ pending->relnode.dbNode, pending->relnode.relNode);
+ }
+ }
+ }
+
+ hash_destroy(pendingSyncs);
+ pendingSyncs = NULL;
+}
+
/*
* PostPrepare_smgr -- Clean up after a successful PREPARE
*
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 254be28..1ba8cce 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -2357,8 +2357,7 @@ CopyFrom(CopyState cstate)
* - 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 heap_sync at the bottom of this
- * routine first.
+ * If it does commit, commit will do heap_sync().
*
* As mentioned in comments in utils/rel.h, the in-same-transaction test
* is not always set correctly, since in rare cases rd_newRelfilenodeSubid
@@ -2390,7 +2389,7 @@ CopyFrom(CopyState cstate)
{
hi_options |= HEAP_INSERT_SKIP_FSM;
if (!XLogIsNeeded())
- hi_options |= HEAP_INSERT_SKIP_WAL;
+ heap_register_sync(cstate->rel);
}
/*
@@ -2887,11 +2886,11 @@ CopyFrom(CopyState cstate)
FreeExecutorState(estate);
/*
- * If we skipped writing WAL, then we need to sync the heap (but not
- * indexes since those use WAL anyway)
+ * If we skipped writing WAL, then we will sync the heap at the end of
+ * the transaction. (We used to do it here, but it was later found out
+ * that to be safe, we must also avoid WAL-logging any subsequent
+ * actions on the pages we skipped WAL for). Indexes always use WAL.
*/
- if (hi_options & HEAP_INSERT_SKIP_WAL)
- heap_sync(cstate->rel);
return processed;
}
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 4d77411..01bbb51 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -567,8 +567,9 @@ intorel_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
* We can skip WAL-logging the insertions, unless PITR or streaming
* replication is in use. We can skip the FSM in any case.
*/
- myState->hi_options = HEAP_INSERT_SKIP_FSM |
- (XLogIsNeeded() ? 0 : HEAP_INSERT_SKIP_WAL);
+ if (!XLogIsNeeded())
+ heap_register_sync(intoRelationDesc);
+ myState->hi_options = HEAP_INSERT_SKIP_FSM;
myState->bistate = GetBulkInsertState();
/* Not using WAL requires smgr_targblock be initially invalid */
@@ -617,9 +618,7 @@ intorel_shutdown(DestReceiver *self)
FreeBulkInsertState(myState->bistate);
- /* If we skipped using WAL, must heap_sync before commit */
- if (myState->hi_options & HEAP_INSERT_SKIP_WAL)
- heap_sync(myState->rel);
+ /* If we skipped using WAL, we will sync the relation at commit */
/* close rel, but keep lock until commit */
heap_close(myState->rel, NoLock);
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index d2e0376..5645a6e 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -477,7 +477,7 @@ transientrel_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
*/
myState->hi_options = HEAP_INSERT_SKIP_FSM | HEAP_INSERT_FROZEN;
if (!XLogIsNeeded())
- myState->hi_options |= HEAP_INSERT_SKIP_WAL;
+ heap_register_sync(transientrel);
myState->bistate = GetBulkInsertState();
/* Not using WAL requires smgr_targblock be initially invalid */
@@ -520,9 +520,7 @@ transientrel_shutdown(DestReceiver *self)
FreeBulkInsertState(myState->bistate);
- /* If we skipped using WAL, must heap_sync before commit */
- if (myState->hi_options & HEAP_INSERT_SKIP_WAL)
- heap_sync(myState->transientrel);
+ /* If we skipped using WAL, we will sync the relation at commit */
/* close transientrel, but keep lock until commit */
heap_close(myState->transientrel, NoLock);
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d979ce2..594d7bf 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4412,8 +4412,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
bistate = GetBulkInsertState();
hi_options = HEAP_INSERT_SKIP_FSM;
+
if (!XLogIsNeeded())
- hi_options |= HEAP_INSERT_SKIP_WAL;
+ heap_register_sync(newrel);
}
else
{
@@ -4686,8 +4687,6 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap, LOCKMODE lockmode)
FreeBulkInsertState(bistate);
/* If we skipped writing WAL, then we need to sync the heap. */
- if (hi_options & HEAP_INSERT_SKIP_WAL)
- heap_sync(newrel);
heap_close(newrel, NoLock);
}
@@ -10727,11 +10726,12 @@ ATExecSetTableSpace(Oid tableOid, Oid newTableSpace, LOCKMODE lockmode)
/*
* Create and copy all forks of the relation, and schedule unlinking of
- * old physical files.
+ * old physical files. Pending syncs for the old node is no longer needed.
*
* NOTE: any conflict in relfilenode value will be caught in
* RelationCreateStorage().
*/
+ RelationRemovePendingSync(rel);
RelationCreateStorage(newrnode, rel->rd_rel->relpersistence);
/* copy main fork */
diff --git a/src/backend/commands/vacuumlazy.c b/src/backend/commands/vacuumlazy.c
index 20ce431..82bbf05 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -902,7 +902,7 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats,
* page has been previously WAL-logged, and if not, do that
* now.
*/
- if (RelationNeedsWAL(onerel) &&
+ if (BufferNeedsWAL(onerel, buf) &&
PageGetLSN(page) == InvalidXLogRecPtr)
log_newpage_buffer(buf, true);
@@ -1129,7 +1129,7 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats,
}
/* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(onerel))
+ if (BufferNeedsWAL(onerel, buf))
{
XLogRecPtr recptr;
@@ -1487,7 +1487,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (RelationNeedsWAL(onerel))
+ if (BufferNeedsWAL(onerel, buffer))
{
XLogRecPtr recptr;
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 26df7cb..171b17b 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -451,6 +451,7 @@ static BufferDesc *BufferAlloc(SMgrRelation smgr,
BufferAccessStrategy strategy,
bool *foundPtr);
static void FlushBuffer(BufferDesc *buf, SMgrRelation reln);
+static void FlushRelationBuffers_common(SMgrRelation smgr, bool islocal);
static void AtProcExit_Buffers(int code, Datum arg);
static void CheckForBufferLeaks(void);
static int rnode_comparator(const void *p1, const void *p2);
@@ -3147,20 +3148,41 @@ 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))
+ FlushRelationBuffers_common(rel->rd_smgr, RelationUsesLocalBuffers(rel));
+}
+
+/*
+ * Like FlushRelationBuffers(), but the relation is specified by a
+ * RelFileNode
+ */
+void
+FlushRelationBuffersWithoutRelCache(RelFileNode rnode, bool islocal)
+{
+ FlushRelationBuffers_common(smgropen(rnode, InvalidBackendId), islocal);
+}
+
+/*
+ * Code shared between functions FlushRelationBuffers() and
+ * FlushRelationBuffersWithoutRelCache().
+ */
+static void
+FlushRelationBuffers_common(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))
{
@@ -3177,7 +3199,7 @@ FlushRelationBuffers(Relation rel)
PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
- smgrwrite(rel->rd_smgr,
+ smgrwrite(smgr,
bufHdr->tag.forkNum,
bufHdr->tag.blockNum,
localpage,
@@ -3207,18 +3229,18 @@ 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);
}
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 12a5f15..08711b5 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -73,6 +73,7 @@
#include "optimizer/var.h"
#include "rewrite/rewriteDefine.h"
#include "rewrite/rowsecurity.h"
+#include "storage/bufmgr.h"
#include "storage/lmgr.h"
#include "storage/smgr.h"
#include "utils/array.h"
@@ -414,6 +415,10 @@ AllocateRelationDesc(Form_pg_class relp)
/* which we mark as a reference-counted tupdesc */
relation->rd_att->tdrefcount = 1;
+ /* We don't know if pending sync for this relation exists so far */
+ relation->pending_sync = NULL;
+ relation->no_pending_sync = false;
+
MemoryContextSwitchTo(oldcxt);
return relation;
@@ -2043,6 +2048,10 @@ formrdesc(const char *relationName, Oid relationReltype,
relation->rd_rel->relhasindex = true;
}
+ /* We don't know if pending sync for this relation exists so far */
+ relation->pending_sync = NULL;
+ relation->no_pending_sync = false;
+
/*
* add new reldesc to relcache
*/
@@ -3367,6 +3376,10 @@ RelationBuildLocalRelation(const char *relname,
else
rel->rd_rel->relfilenode = relfilenode;
+ /* newly built relation has no pending sync */
+ rel->no_pending_sync = true;
+ rel->pending_sync = NULL;
+
RelationInitLockInfo(rel); /* see lmgr.c */
RelationInitPhysicalAddr(rel);
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 4e41024..79b964f 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -25,10 +25,9 @@
/* "options" flag bits for heap_insert */
-#define HEAP_INSERT_SKIP_WAL 0x0001
-#define HEAP_INSERT_SKIP_FSM 0x0002
-#define HEAP_INSERT_FROZEN 0x0004
-#define HEAP_INSERT_SPECULATIVE 0x0008
+#define HEAP_INSERT_SKIP_FSM 0x0001
+#define HEAP_INSERT_FROZEN 0x0002
+#define HEAP_INSERT_SPECULATIVE 0x0004
typedef struct BulkInsertStateData *BulkInsertState;
@@ -179,6 +178,7 @@ extern void simple_heap_delete(Relation relation, ItemPointer tid);
extern void simple_heap_update(Relation relation, ItemPointer otid,
HeapTuple tup);
+extern void heap_register_sync(Relation relation);
extern void heap_sync(Relation relation);
extern void heap_update_snapshot(HeapScanDesc scan, Snapshot snapshot);
diff --git a/src/include/catalog/storage.h b/src/include/catalog/storage.h
index a3a97db..03964e2 100644
--- a/src/include/catalog/storage.h
+++ b/src/include/catalog/storage.h
@@ -22,13 +22,16 @@ extern void 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 RelationRemovePendingSync(Relation rel);
/*
* These functions used to be in storage/smgr/smgr.c, which explains the
* naming
*/
extern void smgrDoPendingDeletes(bool isCommit);
extern int smgrGetPendingDeletes(bool forCommit, RelFileNode **ptr);
+extern void smgrDoPendingSyncs(bool isCommit);
+extern void RecordPendingSync(Relation rel);
+bool BufferNeedsWAL(Relation rel, Buffer buf);
extern void AtSubCommit_smgr(void);
extern void AtSubAbort_smgr(void);
extern void PostPrepare_smgr(void);
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index 98b63fc..598d1a0 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -190,6 +190,8 @@ extern BlockNumber RelationGetNumberOfBlocksInFork(Relation relation,
ForkNumber forkNum);
extern void FlushOneBuffer(Buffer buffer);
extern void FlushRelationBuffers(Relation rel);
+extern void FlushRelationBuffersWithoutRelCache(RelFileNode rnode,
+ bool islocal);
extern void FlushDatabaseBuffers(Oid dbid);
extern void DropRelFileNodeBuffers(RelFileNodeBackend rnode,
ForkNumber forkNum, BlockNumber firstDelBlock);
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 68fd6fb..507844f 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -216,6 +216,14 @@ typedef struct RelationData
/* use "struct" here to avoid needing to include pgstat.h: */
struct PgStat_TableStatus *pgstat_info; /* statistics collection area */
+
+ /*
+ * no_pending_sync is true if this relation is known not to have pending
+ * syncs. Elsewise searching for registered sync is required if
+ * pending_sync is NULL.
+ */
+ bool no_pending_sync;
+ struct PendingRelSync *pending_sync;
} RelationData;
--
2.9.2
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