Hello. I found that c203d6cf81 hit this and this is the rebased
version on the current master.
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center
>From 3dac5baf787dc949cfb22a698a0d72b6eb48e75e Mon Sep 17 00:00:00 2001
From: Kyotaro Horiguchi <horiguchi.kyot...@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 | 320 +++++++++++++++++++++++++++++---
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, 480 insertions(+), 88 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index d7279248e7..8fd2c2948e 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"
@@ -57,6 +79,7 @@
#include "catalog/catalog.h"
#include "catalog/namespace.h"
#include "catalog/index.h"
+#include "catalog/storage.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "port/atomics.h"
@@ -2400,12 +2423,6 @@ 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.
*
@@ -2436,6 +2453,7 @@ 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)
@@ -2509,7 +2527,7 @@ 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;
@@ -2710,12 +2728,10 @@ 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);
@@ -2730,7 +2746,7 @@ 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);
/*
@@ -2765,6 +2781,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
Buffer vmbuffer = InvalidBuffer;
bool all_visible_cleared = false;
int nthispage;
+ bool needwal;
CHECK_FOR_INTERRUPTS();
@@ -2776,6 +2793,7 @@ 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();
@@ -3332,7 +3350,7 @@ 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;
@@ -4307,7 +4325,8 @@ l2:
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer) ||
+ BufferNeedsWAL(relation, newbuf))
{
XLogRecPtr recptr;
@@ -5276,7 +5295,7 @@ 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;
@@ -6020,7 +6039,7 @@ l4:
MarkBufferDirty(buf);
/* XLOG stuff */
- if (RelationNeedsWAL(rel))
+ if (BufferNeedsWAL(rel, buf))
{
xl_heap_lock_updated xlrec;
XLogRecPtr recptr;
@@ -6174,7 +6193,7 @@ 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;
@@ -6307,7 +6326,7 @@ 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;
@@ -6416,7 +6435,7 @@ heap_inplace_update(Relation relation, HeapTuple tuple)
MarkBufferDirty(buffer);
/* XLOG stuff */
- if (RelationNeedsWAL(relation))
+ if (BufferNeedsWAL(relation, buffer))
{
xl_heap_inplace xlrec;
XLogRecPtr recptr;
@@ -7602,7 +7621,7 @@ 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;
@@ -7650,7 +7669,7 @@ 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);
@@ -7735,7 +7754,7 @@ 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();
@@ -8826,8 +8845,13 @@ 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);
@@ -8881,6 +8905,8 @@ 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);
@@ -9317,9 +9343,16 @@ 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.
@@ -9429,3 +9462,33 @@ 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 f67d7d15df..6dd2ae5254 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 7d466c2588..7471d7461b 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -652,9 +652,7 @@ 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 b251e69703..4a46444f33 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 b88d4ccf74..976fbeb02f 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2001,6 +2001,9 @@ 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
@@ -2229,6 +2232,9 @@ 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
@@ -2542,6 +2548,7 @@ 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 cff49bae9e..e9abd49070 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"
@@ -63,6 +64,49 @@ 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;
+ /* 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;
+ }
- xlrec.blkno = nblocks;
- xlrec.rnode = rel->rd_node;
- xlrec.flags = SMGR_TRUNCATE_ALL;
+ rel->no_pending_sync= false;
+ rel->pending_sync = pending;
+ }
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, sizeof(xlrec));
+ 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;
- lsn = XLogInsert(RM_SMGR_ID,
- XLOG_SMGR_TRUNCATE | XLR_SPECIAL_REL_UPDATE);
+ xlrec.blkno = nblocks;
+ xlrec.rnode = rel->rd_node;
- /*
- * 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);
+ 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.
*
@@ -368,6 +458,24 @@ 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.
*
@@ -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 a42861da0d..de9fc12615 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -2352,8 +2352,7 @@ 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
@@ -2385,7 +2384,7 @@ CopyFrom(CopyState cstate)
{
hi_options |= HEAP_INSERT_SKIP_FSM;
if (!XLogIsNeeded())
- hi_options |= HEAP_INSERT_SKIP_WAL;
+ heap_register_sync(cstate->rel);
}
/*
@@ -2821,11 +2820,11 @@ 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 3d82edbf58..a3c3518c69 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 23892b1b81..f1b48583ba 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -464,7 +464,7 @@ 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 */
@@ -507,9 +507,7 @@ 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 83a881eff3..ee8c80f34f 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -4481,8 +4481,9 @@ 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
{
@@ -4755,8 +4756,6 @@ 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);
}
@@ -10811,11 +10810,12 @@ 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 f9da24c491..78909bc519 100644
--- a/src/backend/commands/vacuumlazy.c
+++ b/src/backend/commands/vacuumlazy.c
@@ -900,7 +900,7 @@ 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);
@@ -1170,7 +1170,7 @@ lazy_scan_heap(Relation onerel, int options, LVRelStats *vacrelstats,
}
/* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(onerel))
+ if (BufferNeedsWAL(onerel, buf))
{
XLogRecPtr recptr;
@@ -1531,7 +1531,7 @@ 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 01eabe5706..1095f6c721 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 48f92dc430..399390e6c1 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -76,6 +76,7 @@
#include "pgstat.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"
@@ -417,6 +418,10 @@ 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;
@@ -2072,6 +2077,10 @@ 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
*/
@@ -3402,6 +3411,10 @@ 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 4c0256b18a..fff3fd42aa 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;
@@ -180,6 +179,7 @@ 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 ef52d85803..49d93cd01f 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 3cce3906a0..9fae7c6ae5 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 c26c395b0b..040ae3a07a 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -218,6 +218,14 @@ 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;
--
2.16.3
