From 3e2b3f3b20ce83737f3421ab3c7794853724266d Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Wed, 14 Jun 2023 13:41:37 +1200 Subject: [PATCH] Remove old_snapshot_threshold. Remove the old_snapshot_threshold feature, better known for its error "snapshot too old". Unfortunately it had a number of problems, and we agreed to remove it. There is no doubt that it was useful, and someone might propose a new implementation in the future. XXX draft, may contain nuts Discussion: https://postgr.es/m/CACG%3DezYV%2BEvO135fLRdVn-ZusfVsTY6cH1OZqWtezuEYH6ciQA%40mail.gmail.com --- contrib/Makefile | 1 - contrib/bloom/blscan.c | 1 - contrib/meson.build | 1 - contrib/old_snapshot/Makefile | 21 - contrib/old_snapshot/meson.build | 23 - contrib/old_snapshot/old_snapshot--1.0.sql | 14 - contrib/old_snapshot/old_snapshot.control | 5 - contrib/old_snapshot/time_mapping.c | 142 ------ doc/src/sgml/config.sgml | 69 --- doc/src/sgml/contrib.sgml | 1 - doc/src/sgml/filelist.sgml | 1 - doc/src/sgml/monitoring.sgml | 4 - doc/src/sgml/oldsnapshot.sgml | 33 -- src/backend/access/brin/brin_revmap.c | 7 - src/backend/access/gin/ginbtree.c | 2 - src/backend/access/gin/ginget.c | 4 - src/backend/access/gist/gistget.c | 1 - src/backend/access/hash/hashsearch.c | 6 - src/backend/access/heap/heapam.c | 9 - src/backend/access/heap/pruneheap.c | 120 +---- src/backend/access/heap/vacuumlazy.c | 5 +- src/backend/access/nbtree/nbtsearch.c | 9 - src/backend/access/spgist/spgscan.c | 1 - src/backend/catalog/index.c | 20 +- src/backend/commands/vacuum.c | 19 - src/backend/storage/buffer/bufmgr.c | 17 - src/backend/storage/ipc/ipci.c | 2 - src/backend/storage/ipc/procarray.c | 36 +- src/backend/storage/lmgr/lwlocknames.txt | 2 +- src/backend/utils/errcodes.txt | 4 - src/backend/utils/misc/guc_tables.c | 11 - src/backend/utils/misc/postgresql.conf.sample | 2 - src/backend/utils/time/snapmgr.c | 468 ------------------ src/include/access/heapam.h | 2 - src/include/storage/bufmgr.h | 36 -- src/include/utils/old_snapshot.h | 75 --- src/include/utils/snapmgr.h | 49 -- src/test/modules/Makefile | 1 - src/test/modules/meson.build | 1 - src/test/modules/snapshot_too_old/.gitignore | 3 - src/test/modules/snapshot_too_old/Makefile | 28 -- .../expected/sto_using_cursor.out | 19 - .../expected/sto_using_hash_index.out | 19 - .../expected/sto_using_select.out | 18 - src/test/modules/snapshot_too_old/meson.build | 19 - .../specs/sto_using_cursor.spec | 38 -- .../specs/sto_using_hash_index.spec | 31 -- .../specs/sto_using_select.spec | 37 -- src/test/modules/snapshot_too_old/sto.conf | 2 - src/tools/pgindent/typedefs.list | 2 - 50 files changed, 19 insertions(+), 1422 deletions(-) delete mode 100644 contrib/old_snapshot/Makefile delete mode 100644 contrib/old_snapshot/meson.build delete mode 100644 contrib/old_snapshot/old_snapshot--1.0.sql delete mode 100644 contrib/old_snapshot/old_snapshot.control delete mode 100644 contrib/old_snapshot/time_mapping.c delete mode 100644 doc/src/sgml/oldsnapshot.sgml delete mode 100644 src/include/utils/old_snapshot.h delete mode 100644 src/test/modules/snapshot_too_old/.gitignore delete mode 100644 src/test/modules/snapshot_too_old/Makefile delete mode 100644 src/test/modules/snapshot_too_old/expected/sto_using_cursor.out delete mode 100644 src/test/modules/snapshot_too_old/expected/sto_using_hash_index.out delete mode 100644 src/test/modules/snapshot_too_old/expected/sto_using_select.out delete mode 100644 src/test/modules/snapshot_too_old/meson.build delete mode 100644 src/test/modules/snapshot_too_old/specs/sto_using_cursor.spec delete mode 100644 src/test/modules/snapshot_too_old/specs/sto_using_hash_index.spec delete mode 100644 src/test/modules/snapshot_too_old/specs/sto_using_select.spec delete mode 100644 src/test/modules/snapshot_too_old/sto.conf diff --git a/contrib/Makefile b/contrib/Makefile index bbf220407b..da4e2316a3 100644 --- a/contrib/Makefile +++ b/contrib/Makefile @@ -29,7 +29,6 @@ SUBDIRS = \ lo \ ltree \ oid2name \ - old_snapshot \ pageinspect \ passwordcheck \ pg_buffercache \ diff --git a/contrib/bloom/blscan.c b/contrib/bloom/blscan.c index 6cc7d07164..61d1f66b38 100644 --- a/contrib/bloom/blscan.c +++ b/contrib/bloom/blscan.c @@ -132,7 +132,6 @@ blgetbitmap(IndexScanDesc scan, TIDBitmap *tbm) LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page); if (!PageIsNew(page) && !BloomPageIsDeleted(page)) { diff --git a/contrib/meson.build b/contrib/meson.build index bd4a57c43c..84d4e18561 100644 --- a/contrib/meson.build +++ b/contrib/meson.build @@ -37,7 +37,6 @@ subdir('lo') subdir('ltree') subdir('ltree_plpython') subdir('oid2name') -subdir('old_snapshot') subdir('pageinspect') subdir('passwordcheck') subdir('pg_buffercache') diff --git a/contrib/old_snapshot/Makefile b/contrib/old_snapshot/Makefile deleted file mode 100644 index adb557532f..0000000000 --- a/contrib/old_snapshot/Makefile +++ /dev/null @@ -1,21 +0,0 @@ -# contrib/old_snapshot/Makefile - -MODULE_big = old_snapshot -OBJS = \ - $(WIN32RES) \ - time_mapping.o - -EXTENSION = old_snapshot -DATA = old_snapshot--1.0.sql -PGFILEDESC = "old_snapshot - utilities in support of old_snapshot_threshold" - -ifdef USE_PGXS -PG_CONFIG = pg_config -PGXS := $(shell $(PG_CONFIG) --pgxs) -include $(PGXS) -else -subdir = contrib/old_snapshot -top_builddir = ../.. -include $(top_builddir)/src/Makefile.global -include $(top_srcdir)/contrib/contrib-global.mk -endif diff --git a/contrib/old_snapshot/meson.build b/contrib/old_snapshot/meson.build deleted file mode 100644 index fe5fb9027a..0000000000 --- a/contrib/old_snapshot/meson.build +++ /dev/null @@ -1,23 +0,0 @@ -# Copyright (c) 2022-2023, PostgreSQL Global Development Group - -old_snapshot_sources = files( - 'time_mapping.c', -) - -if host_system == 'windows' - old_snapshot_sources += rc_lib_gen.process(win32ver_rc, extra_args: [ - '--NAME', 'old_snapshot', - '--FILEDESC', 'old_snapshot - utilities in support of old_snapshot_threshold',]) -endif - -old_snapshot = shared_module('old_snapshot', - old_snapshot_sources, - kwargs: contrib_mod_args, -) -contrib_targets += old_snapshot - -install_data( - 'old_snapshot.control', - 'old_snapshot--1.0.sql', - kwargs: contrib_data_args, -) diff --git a/contrib/old_snapshot/old_snapshot--1.0.sql b/contrib/old_snapshot/old_snapshot--1.0.sql deleted file mode 100644 index 9ebb8829e3..0000000000 --- a/contrib/old_snapshot/old_snapshot--1.0.sql +++ /dev/null @@ -1,14 +0,0 @@ -/* contrib/old_snapshot/old_snapshot--1.0.sql */ - --- complain if script is sourced in psql, rather than via CREATE EXTENSION -\echo Use "CREATE EXTENSION old_snapshot" to load this file. \quit - --- Show visibility map and page-level visibility information for each block. -CREATE FUNCTION pg_old_snapshot_time_mapping(array_offset OUT int4, - end_timestamp OUT timestamptz, - newest_xmin OUT xid) -RETURNS SETOF record -AS 'MODULE_PATHNAME', 'pg_old_snapshot_time_mapping' -LANGUAGE C STRICT; - --- XXX. Do we want REVOKE commands here? diff --git a/contrib/old_snapshot/old_snapshot.control b/contrib/old_snapshot/old_snapshot.control deleted file mode 100644 index 491eec536c..0000000000 --- a/contrib/old_snapshot/old_snapshot.control +++ /dev/null @@ -1,5 +0,0 @@ -# old_snapshot extension -comment = 'utilities in support of old_snapshot_threshold' -default_version = '1.0' -module_pathname = '$libdir/old_snapshot' -relocatable = true diff --git a/contrib/old_snapshot/time_mapping.c b/contrib/old_snapshot/time_mapping.c deleted file mode 100644 index 352308cd49..0000000000 --- a/contrib/old_snapshot/time_mapping.c +++ /dev/null @@ -1,142 +0,0 @@ -/*------------------------------------------------------------------------- - * - * time_mapping.c - * time to XID mapping information - * - * Copyright (c) 2020-2023, PostgreSQL Global Development Group - * - * contrib/old_snapshot/time_mapping.c - *------------------------------------------------------------------------- - */ -#include "postgres.h" - -#include "funcapi.h" -#include "storage/lwlock.h" -#include "utils/old_snapshot.h" -#include "utils/snapmgr.h" -#include "utils/timestamp.h" - -/* - * Backend-private copy of the information from oldSnapshotControl which relates - * to the time to XID mapping, plus an index so that we can iterate. - * - * Note that the length of the xid_by_minute array is given by - * OLD_SNAPSHOT_TIME_MAP_ENTRIES (which is not a compile-time constant). - */ -typedef struct -{ - int current_index; - int head_offset; - TimestampTz head_timestamp; - int count_used; - TransactionId xid_by_minute[FLEXIBLE_ARRAY_MEMBER]; -} OldSnapshotTimeMapping; - -#define NUM_TIME_MAPPING_COLUMNS 3 - -PG_MODULE_MAGIC; -PG_FUNCTION_INFO_V1(pg_old_snapshot_time_mapping); - -static OldSnapshotTimeMapping *GetOldSnapshotTimeMapping(void); -static HeapTuple MakeOldSnapshotTimeMappingTuple(TupleDesc tupdesc, - OldSnapshotTimeMapping *mapping); - -/* - * SQL-callable set-returning function. - */ -Datum -pg_old_snapshot_time_mapping(PG_FUNCTION_ARGS) -{ - FuncCallContext *funcctx; - OldSnapshotTimeMapping *mapping; - - if (SRF_IS_FIRSTCALL()) - { - MemoryContext oldcontext; - TupleDesc tupdesc; - - funcctx = SRF_FIRSTCALL_INIT(); - oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx); - mapping = GetOldSnapshotTimeMapping(); - funcctx->user_fctx = mapping; - if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) - elog(ERROR, "return type must be a row type"); - funcctx->tuple_desc = tupdesc; - MemoryContextSwitchTo(oldcontext); - } - - funcctx = SRF_PERCALL_SETUP(); - mapping = (OldSnapshotTimeMapping *) funcctx->user_fctx; - - while (mapping->current_index < mapping->count_used) - { - HeapTuple tuple; - - tuple = MakeOldSnapshotTimeMappingTuple(funcctx->tuple_desc, mapping); - ++mapping->current_index; - SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple)); - } - - SRF_RETURN_DONE(funcctx); -} - -/* - * Get the old snapshot time mapping data from shared memory. - */ -static OldSnapshotTimeMapping * -GetOldSnapshotTimeMapping(void) -{ - OldSnapshotTimeMapping *mapping; - - mapping = palloc(offsetof(OldSnapshotTimeMapping, xid_by_minute) - + sizeof(TransactionId) * OLD_SNAPSHOT_TIME_MAP_ENTRIES); - mapping->current_index = 0; - - LWLockAcquire(OldSnapshotTimeMapLock, LW_SHARED); - mapping->head_offset = oldSnapshotControl->head_offset; - mapping->head_timestamp = oldSnapshotControl->head_timestamp; - mapping->count_used = oldSnapshotControl->count_used; - for (int i = 0; i < OLD_SNAPSHOT_TIME_MAP_ENTRIES; ++i) - mapping->xid_by_minute[i] = oldSnapshotControl->xid_by_minute[i]; - LWLockRelease(OldSnapshotTimeMapLock); - - return mapping; -} - -/* - * Convert one entry from the old snapshot time mapping to a HeapTuple. - */ -static HeapTuple -MakeOldSnapshotTimeMappingTuple(TupleDesc tupdesc, OldSnapshotTimeMapping *mapping) -{ - Datum values[NUM_TIME_MAPPING_COLUMNS]; - bool nulls[NUM_TIME_MAPPING_COLUMNS]; - int array_position; - TimestampTz timestamp; - - /* - * Figure out the array position corresponding to the current index. - * - * Index 0 means the oldest entry in the mapping, which is stored at - * mapping->head_offset. Index 1 means the next-oldest entry, which is a - * the following index, and so on. We wrap around when we reach the end of - * the array. - */ - array_position = (mapping->head_offset + mapping->current_index) - % OLD_SNAPSHOT_TIME_MAP_ENTRIES; - - /* - * No explicit timestamp is stored for any entry other than the oldest - * one, but each entry corresponds to 1-minute period, so we can just add. - */ - timestamp = TimestampTzPlusMilliseconds(mapping->head_timestamp, - mapping->current_index * 60000); - - /* Initialize nulls and values arrays. */ - memset(nulls, 0, sizeof(nulls)); - values[0] = Int32GetDatum(array_position); - values[1] = TimestampTzGetDatum(timestamp); - values[2] = TransactionIdGetDatum(mapping->xid_by_minute[array_position]); - - return heap_form_tuple(tupdesc, values, nulls); -} diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 6262cb7bb2..b9cb8c0f93 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -2760,65 +2760,6 @@ include_dir 'conf.d' - - - old_snapshot_threshold (integer) - - old_snapshot_threshold configuration parameter - - - - - Sets the minimum amount of time that a query snapshot can be used - without risk of a snapshot too old error occurring - when using the snapshot. Data that has been dead for longer than - this threshold is allowed to be vacuumed away. This can help - prevent bloat in the face of snapshots which remain in use for a - long time. To prevent incorrect results due to cleanup of data which - would otherwise be visible to the snapshot, an error is generated - when the snapshot is older than this threshold and the snapshot is - used to read a page which has been modified since the snapshot was - built. - - - - If this value is specified without units, it is taken as minutes. - A value of -1 (the default) disables this feature, - effectively setting the snapshot age limit to infinity. - This parameter can only be set at server start. - - - - Useful values for production work probably range from a small number - of hours to a few days. Small values (such as 0 or - 1min) are only allowed because they may sometimes be - useful for testing. While a setting as high as 60d is - allowed, please note that in many workloads extreme bloat or - transaction ID wraparound may occur in much shorter time frames. - - - - When this feature is enabled, freed space at the end of a relation - cannot be released to the operating system, since that could remove - information needed to detect the snapshot too old - condition. All space allocated to a relation remains associated with - that relation for reuse only within that relation unless explicitly - freed (for example, with VACUUM FULL). - - - - This setting does not attempt to guarantee that an error will be - generated under any particular circumstances. In fact, if the - correct results can be generated from (for example) a cursor which - has materialized a result set, no error will be generated even if the - underlying rows in the referenced table have been vacuumed away. - Some tables cannot safely be vacuumed early, and so will not be - affected by this setting, such as system catalogs. For such tables - this setting will neither reduce bloat nor create a possibility - of a snapshot too old error on scanning. - - - @@ -4834,16 +4775,6 @@ ANY num_sync ( - diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 5cfdc70c03..b82ff67953 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -2089,10 +2089,6 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser OidGen Waiting to allocate a new OID. - - OldSnapshotTimeMap - Waiting to read or update old snapshot control information. - ParallelAppend Waiting to choose the next subplan during Parallel Append plan diff --git a/doc/src/sgml/oldsnapshot.sgml b/doc/src/sgml/oldsnapshot.sgml deleted file mode 100644 index 2e37087738..0000000000 --- a/doc/src/sgml/oldsnapshot.sgml +++ /dev/null @@ -1,33 +0,0 @@ - - - - old_snapshot — inspect <literal>old_snapshot_threshold</literal> state - - - old_snapshot - - - - The old_snapshot module allows inspection - of the server state that is used to implement - . - - - - Functions - - - - pg_old_snapshot_time_mapping(array_offset OUT int4, end_timestamp OUT timestamptz, newest_xmin OUT xid) returns setof record - - - Returns all of the entries in the server's timestamp to XID mapping. - Each entry represents the newest xmin of any snapshot taken in the - corresponding minute. - - - - - - - diff --git a/src/backend/access/brin/brin_revmap.c b/src/backend/access/brin/brin_revmap.c index f4271ba31c..de90ead228 100644 --- a/src/backend/access/brin/brin_revmap.c +++ b/src/backend/access/brin/brin_revmap.c @@ -79,7 +79,6 @@ brinRevmapInitialize(Relation idxrel, BlockNumber *pagesPerRange, meta = ReadBuffer(idxrel, BRIN_METAPAGE_BLKNO); LockBuffer(meta, BUFFER_LOCK_SHARE); page = BufferGetPage(meta); - TestForOldSnapshot(snapshot, idxrel, page); metadata = (BrinMetaPageData *) PageGetContents(page); revmap = palloc(sizeof(BrinRevmap)); @@ -277,7 +276,6 @@ brinGetTupleForHeapBlock(BrinRevmap *revmap, BlockNumber heapBlk, } LockBuffer(*buf, mode); page = BufferGetPage(*buf); - TestForOldSnapshot(snapshot, idxRel, page); /* If we land on a revmap page, start over */ if (BRIN_IS_REGULAR_PAGE(page)) @@ -372,11 +370,6 @@ brinRevmapDesummarizeRange(Relation idxrel, BlockNumber heapBlk) LockBuffer(regBuf, BUFFER_LOCK_EXCLUSIVE); regPg = BufferGetPage(regBuf); - /* - * We're only removing data, not reading it, so there's no need to - * TestForOldSnapshot here. - */ - /* if this is no longer a regular page, tell caller to start over */ if (!BRIN_IS_REGULAR_PAGE(regPg)) { diff --git a/src/backend/access/gin/ginbtree.c b/src/backend/access/gin/ginbtree.c index 35490c7283..7d097c75e0 100644 --- a/src/backend/access/gin/ginbtree.c +++ b/src/backend/access/gin/ginbtree.c @@ -100,7 +100,6 @@ ginFindLeafPage(GinBtree btree, bool searchMode, stack->off = InvalidOffsetNumber; page = BufferGetPage(stack->buffer); - TestForOldSnapshot(snapshot, btree->index, page); access = ginTraverseLock(stack->buffer, searchMode); @@ -127,7 +126,6 @@ ginFindLeafPage(GinBtree btree, bool searchMode, stack->buffer = ginStepRight(stack->buffer, btree->index, access); stack->blkno = rightlink; page = BufferGetPage(stack->buffer); - TestForOldSnapshot(snapshot, btree->index, page); if (!searchMode && GinPageIsIncompleteSplit(page)) ginFinishSplit(btree, stack, false, NULL); diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c index cb676a710f..bf82aa9b85 100644 --- a/src/backend/access/gin/ginget.c +++ b/src/backend/access/gin/ginget.c @@ -156,7 +156,6 @@ collectMatchBitmap(GinBtreeData *btree, GinBtreeStack *stack, return true; page = BufferGetPage(stack->buffer); - TestForOldSnapshot(snapshot, btree->index, page); itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, stack->off)); /* @@ -1458,7 +1457,6 @@ scanGetCandidate(IndexScanDesc scan, pendingPosition *pos) for (;;) { page = BufferGetPage(pos->pendingBuffer); - TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page); maxoff = PageGetMaxOffsetNumber(page); if (pos->firstOffset > maxoff) @@ -1639,7 +1637,6 @@ collectMatchesForHeapRow(IndexScanDesc scan, pendingPosition *pos) sizeof(bool) * (pos->lastOffset - pos->firstOffset)); page = BufferGetPage(pos->pendingBuffer); - TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page); for (i = 0; i < so->nkeys; i++) { @@ -1842,7 +1839,6 @@ scanPendingInsert(IndexScanDesc scan, TIDBitmap *tbm, int64 *ntids) LockBuffer(metabuffer, GIN_SHARE); page = BufferGetPage(metabuffer); - TestForOldSnapshot(scan->xs_snapshot, scan->indexRelation, page); blkno = GinPageGetMeta(page)->head; /* diff --git a/src/backend/access/gist/gistget.c b/src/backend/access/gist/gistget.c index e2c9b5f069..3134917428 100644 --- a/src/backend/access/gist/gistget.c +++ b/src/backend/access/gist/gistget.c @@ -346,7 +346,6 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, PredicateLockPage(r, BufferGetBlockNumber(buffer), scan->xs_snapshot); gistcheckpage(scan->indexRelation, buffer); page = BufferGetPage(buffer); - TestForOldSnapshot(scan->xs_snapshot, r, page); opaque = GistPageGetOpaque(page); /* diff --git a/src/backend/access/hash/hashsearch.c b/src/backend/access/hash/hashsearch.c index 9ea2a42a07..0a031bfd18 100644 --- a/src/backend/access/hash/hashsearch.c +++ b/src/backend/access/hash/hashsearch.c @@ -71,7 +71,6 @@ _hash_next(IndexScanDesc scan, ScanDirection dir) if (BlockNumberIsValid(blkno)) { buf = _hash_getbuf(rel, blkno, HASH_READ, LH_OVERFLOW_PAGE); - TestForOldSnapshot(scan->xs_snapshot, rel, BufferGetPage(buf)); if (!_hash_readpage(scan, &buf, dir)) end_of_scan = true; } @@ -91,7 +90,6 @@ _hash_next(IndexScanDesc scan, ScanDirection dir) { buf = _hash_getbuf(rel, blkno, HASH_READ, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE); - TestForOldSnapshot(scan->xs_snapshot, rel, BufferGetPage(buf)); /* * We always maintain the pin on bucket page for whole scan @@ -186,7 +184,6 @@ _hash_readnext(IndexScanDesc scan, if (block_found) { *pagep = BufferGetPage(*bufp); - TestForOldSnapshot(scan->xs_snapshot, rel, *pagep); *opaquep = HashPageGetOpaque(*pagep); } } @@ -232,7 +229,6 @@ _hash_readprev(IndexScanDesc scan, *bufp = _hash_getbuf(rel, blkno, HASH_READ, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE); *pagep = BufferGetPage(*bufp); - TestForOldSnapshot(scan->xs_snapshot, rel, *pagep); *opaquep = HashPageGetOpaque(*pagep); /* @@ -351,7 +347,6 @@ _hash_first(IndexScanDesc scan, ScanDirection dir) buf = _hash_getbucketbuf_from_hashkey(rel, hashkey, HASH_READ, NULL); PredicateLockPage(rel, BufferGetBlockNumber(buf), scan->xs_snapshot); page = BufferGetPage(buf); - TestForOldSnapshot(scan->xs_snapshot, rel, page); opaque = HashPageGetOpaque(page); bucket = opaque->hasho_bucket; @@ -387,7 +382,6 @@ _hash_first(IndexScanDesc scan, ScanDirection dir) LockBuffer(buf, BUFFER_LOCK_UNLOCK); old_buf = _hash_getbuf(rel, old_blkno, HASH_READ, LH_BUCKET_PAGE); - TestForOldSnapshot(scan->xs_snapshot, rel, BufferGetPage(old_buf)); /* * remember the split bucket buffer so as to use it later for diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 7ed72abe59..e002dcbdcd 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -425,7 +425,6 @@ heapgetpage(TableScanDesc sscan, BlockNumber block) LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, scan->rs_base.rs_rd, page); lines = PageGetMaxOffsetNumber(page); ntup = 0; @@ -565,8 +564,6 @@ heapgettup_start_page(HeapScanDesc scan, ScanDirection dir, int *linesleft, /* Caller is responsible for ensuring buffer is locked if needed */ page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); - *linesleft = PageGetMaxOffsetNumber(page) - FirstOffsetNumber + 1; if (ScanDirectionIsForward(dir)) @@ -598,8 +595,6 @@ heapgettup_continue_page(HeapScanDesc scan, ScanDirection dir, int *linesleft, /* Caller is responsible for ensuring buffer is locked if needed */ page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); - if (ScanDirectionIsForward(dir)) { *lineoff = OffsetNumberNext(scan->rs_coffset); @@ -864,7 +859,6 @@ heapgettup_pagemode(HeapScanDesc scan, /* continue from previously returned page/tuple */ block = scan->rs_cblock; /* current page */ page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); lineindex = scan->rs_cindex + dir; if (ScanDirectionIsForward(dir)) @@ -884,7 +878,6 @@ heapgettup_pagemode(HeapScanDesc scan, { heapgetpage((TableScanDesc) scan, block); page = BufferGetPage(scan->rs_cbuf); - TestForOldSnapshot(scan->rs_base.rs_snapshot, scan->rs_base.rs_rd, page); linesleft = scan->rs_ntuples; lineindex = ScanDirectionIsForward(dir) ? 0 : linesleft - 1; @@ -1372,7 +1365,6 @@ heap_fetch(Relation relation, */ LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, relation, page); /* * We'd better check for out-of-range offnum in case of VACUUM since the @@ -1663,7 +1655,6 @@ heap_get_latest_tid(TableScanDesc sscan, buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid)); LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, relation, page); /* * Check for bogus item number. This is not treated as an error diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c index 47b9e20915..b0881131c9 100644 --- a/src/backend/access/heap/pruneheap.c +++ b/src/backend/access/heap/pruneheap.c @@ -36,18 +36,6 @@ typedef struct /* tuple visibility test, initialized for the relation */ GlobalVisState *vistest; - /* - * Thresholds set by TransactionIdLimitedForOldSnapshots() if they have - * been computed (done on demand, and only if - * OldSnapshotThresholdActive()). The first time a tuple is about to be - * removed based on the limited horizon, old_snap_used is set to true, and - * SetOldSnapshotThresholdTimestamp() is called. See - * heap_prune_satisfies_vacuum(). - */ - TimestampTz old_snap_ts; - TransactionId old_snap_xmin; - bool old_snap_used; - TransactionId new_prune_xid; /* new prune hint value for page */ TransactionId snapshotConflictHorizon; /* latest xid removed */ int nredirected; /* numbers of entries in arrays below */ @@ -110,8 +98,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer) Page page = BufferGetPage(buffer); TransactionId prune_xid; GlobalVisState *vistest; - TransactionId limited_xmin = InvalidTransactionId; - TimestampTz limited_ts = 0; Size minfree; /* @@ -122,15 +108,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer) if (RecoveryInProgress()) return; - /* - * XXX: Magic to keep old_snapshot_threshold tests appear "working". They - * currently are broken, and discussion of what to do about them is - * ongoing. See - * https://www.postgresql.org/message-id/20200403001235.e6jfdll3gh2ygbuc%40alap3.anarazel.de - */ - if (old_snapshot_threshold == 0) - SnapshotTooOldMagicForTest(); - /* * First check whether there's any chance there's something to prune, * determining the appropriate horizon is a waste if there's no prune_xid @@ -143,35 +120,11 @@ heap_page_prune_opt(Relation relation, Buffer buffer) /* * Check whether prune_xid indicates that there may be dead rows that can * be cleaned up. - * - * It is OK to check the old snapshot limit before acquiring the cleanup - * lock because the worst that can happen is that we are not quite as - * aggressive about the cleanup (by however many transaction IDs are - * consumed between this point and acquiring the lock). This allows us to - * save significant overhead in the case where the page is found not to be - * prunable. - * - * Even if old_snapshot_threshold is set, we first check whether the page - * can be pruned without. Both because - * TransactionIdLimitedForOldSnapshots() is not cheap, and because not - * unnecessarily relying on old_snapshot_threshold avoids causing - * conflicts. */ vistest = GlobalVisTestFor(relation); if (!GlobalVisTestIsRemovableXid(vistest, prune_xid)) - { - if (!OldSnapshotThresholdActive()) - return; - - if (!TransactionIdLimitedForOldSnapshots(GlobalVisTestNonRemovableHorizon(vistest), - relation, - &limited_xmin, &limited_ts)) - return; - - if (!TransactionIdPrecedes(prune_xid, limited_xmin)) - return; - } + return; /* * We prune when a previous UPDATE failed to find enough space on the page @@ -205,8 +158,8 @@ heap_page_prune_opt(Relation relation, Buffer buffer) int ndeleted, nnewlpdead; - ndeleted = heap_page_prune(relation, buffer, vistest, limited_xmin, - limited_ts, &nnewlpdead, NULL); + ndeleted = heap_page_prune(relation, buffer, vistest, + &nnewlpdead, NULL); /* * Report the number of tuples reclaimed to pgstats. This is @@ -249,9 +202,7 @@ heap_page_prune_opt(Relation relation, Buffer buffer) * * vistest is used to distinguish whether tuples are DEAD or RECENTLY_DEAD * (see heap_prune_satisfies_vacuum and - * HeapTupleSatisfiesVacuum). old_snap_xmin / old_snap_ts need to - * either have been set by TransactionIdLimitedForOldSnapshots, or - * InvalidTransactionId/0 respectively. + * HeapTupleSatisfiesVacuum). * * Sets *nnewlpdead for caller, indicating the number of items that were * newly set LP_DEAD during prune operation. @@ -264,8 +215,6 @@ heap_page_prune_opt(Relation relation, Buffer buffer) int heap_page_prune(Relation relation, Buffer buffer, GlobalVisState *vistest, - TransactionId old_snap_xmin, - TimestampTz old_snap_ts, int *nnewlpdead, OffsetNumber *off_loc) { @@ -291,9 +240,6 @@ heap_page_prune(Relation relation, Buffer buffer, prstate.new_prune_xid = InvalidTransactionId; prstate.rel = relation; prstate.vistest = vistest; - prstate.old_snap_xmin = old_snap_xmin; - prstate.old_snap_ts = old_snap_ts; - prstate.old_snap_used = false; prstate.snapshotConflictHorizon = InvalidTransactionId; prstate.nredirected = prstate.ndead = prstate.nunused = 0; memset(prstate.marked, 0, sizeof(prstate.marked)); @@ -481,19 +427,6 @@ heap_page_prune(Relation relation, Buffer buffer, /* * Perform visibility checks for heap pruning. - * - * This is more complicated than just using GlobalVisTestIsRemovableXid() - * because of old_snapshot_threshold. We only want to increase the threshold - * that triggers errors for old snapshots when we actually decide to remove a - * row based on the limited horizon. - * - * Due to its cost we also only want to call - * TransactionIdLimitedForOldSnapshots() if necessary, i.e. we might not have - * done so in heap_page_prune_opt() if pd_prune_xid was old enough. But we - * still want to be able to remove rows that are too new to be removed - * according to prstate->vistest, but that can be removed based on - * old_snapshot_threshold. So we call TransactionIdLimitedForOldSnapshots() on - * demand in here, if appropriate. */ static HTSV_Result heap_prune_satisfies_vacuum(PruneState *prstate, HeapTuple tup, Buffer buffer) @@ -507,52 +440,11 @@ heap_prune_satisfies_vacuum(PruneState *prstate, HeapTuple tup, Buffer buffer) return res; /* - * If we are already relying on the limited xmin, there is no need to - * delay doing so anymore. - */ - if (prstate->old_snap_used) - { - Assert(TransactionIdIsValid(prstate->old_snap_xmin)); - - if (TransactionIdPrecedes(dead_after, prstate->old_snap_xmin)) - res = HEAPTUPLE_DEAD; - return res; - } - - /* - * First check if GlobalVisTestIsRemovableXid() is sufficient to find the - * row dead. If not, and old_snapshot_threshold is enabled, try to use the - * lowered horizon. + * Check if GlobalVisTestIsRemovableXid() is sufficient to find the row + * dead. */ if (GlobalVisTestIsRemovableXid(prstate->vistest, dead_after)) res = HEAPTUPLE_DEAD; - else if (OldSnapshotThresholdActive()) - { - /* haven't determined limited horizon yet, requests */ - if (!TransactionIdIsValid(prstate->old_snap_xmin)) - { - TransactionId horizon = - GlobalVisTestNonRemovableHorizon(prstate->vistest); - - TransactionIdLimitedForOldSnapshots(horizon, prstate->rel, - &prstate->old_snap_xmin, - &prstate->old_snap_ts); - } - - if (TransactionIdIsValid(prstate->old_snap_xmin) && - TransactionIdPrecedes(dead_after, prstate->old_snap_xmin)) - { - /* - * About to remove row based on snapshot_too_old. Need to raise - * the threshold so problematic accesses would error. - */ - Assert(!prstate->old_snap_used); - SetOldSnapshotThresholdTimestamp(prstate->old_snap_ts, - prstate->old_snap_xmin); - prstate->old_snap_used = true; - res = HEAPTUPLE_DEAD; - } - } return res; } diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c index 4eb953f904..d2f5f33e99 100644 --- a/src/backend/access/heap/vacuumlazy.c +++ b/src/backend/access/heap/vacuumlazy.c @@ -1588,7 +1588,7 @@ retry: * that were deleted from indexes. */ tuples_deleted = heap_page_prune(rel, buf, vacrel->vistest, - InvalidTransactionId, 0, &nnewlpdead, + &nnewlpdead, &vacrel->offnum); /* @@ -2823,8 +2823,7 @@ should_attempt_truncation(LVRelState *vacrel) { BlockNumber possibly_freeable; - if (!vacrel->do_rel_truncate || VacuumFailsafeActive || - old_snapshot_threshold >= 0) + if (!vacrel->do_rel_truncate || VacuumFailsafeActive) return false; possibly_freeable = vacrel->rel_pages - vacrel->nonempty_pages; diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c index 7e05e58676..d3ad49733c 100644 --- a/src/backend/access/nbtree/nbtsearch.c +++ b/src/backend/access/nbtree/nbtsearch.c @@ -277,7 +277,6 @@ _bt_moveright(Relation rel, for (;;) { page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); if (P_RIGHTMOST(opaque)) @@ -2016,7 +2015,6 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir) /* step right one page */ so->currPos.buf = _bt_getbuf(rel, blkno, BT_READ); page = BufferGetPage(so->currPos.buf); - TestForOldSnapshot(scan->xs_snapshot, rel, page); opaque = BTPageGetOpaque(page); /* check for deleted page */ if (!P_IGNORE(opaque)) @@ -2119,7 +2117,6 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir) * and do it all again. */ page = BufferGetPage(so->currPos.buf); - TestForOldSnapshot(scan->xs_snapshot, rel, page); opaque = BTPageGetOpaque(page); if (!P_IGNORE(opaque)) { @@ -2225,7 +2222,6 @@ _bt_walk_left(Relation rel, Buffer buf, Snapshot snapshot) CHECK_FOR_INTERRUPTS(); buf = _bt_getbuf(rel, blkno, BT_READ); page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); /* @@ -2252,14 +2248,12 @@ _bt_walk_left(Relation rel, Buffer buf, Snapshot snapshot) blkno = opaque->btpo_next; buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ); page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); } /* Return to the original page to see what's up */ buf = _bt_relandgetbuf(rel, buf, obknum, BT_READ); page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); if (P_ISDELETED(opaque)) { @@ -2277,7 +2271,6 @@ _bt_walk_left(Relation rel, Buffer buf, Snapshot snapshot) blkno = opaque->btpo_next; buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ); page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); if (!P_ISDELETED(opaque)) break; @@ -2338,7 +2331,6 @@ _bt_get_endpoint(Relation rel, uint32 level, bool rightmost, return InvalidBuffer; page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); for (;;) @@ -2358,7 +2350,6 @@ _bt_get_endpoint(Relation rel, uint32 level, bool rightmost, RelationGetRelationName(rel)); buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ); page = BufferGetPage(buf); - TestForOldSnapshot(snapshot, rel, page); opaque = BTPageGetOpaque(page); } diff --git a/src/backend/access/spgist/spgscan.c b/src/backend/access/spgist/spgscan.c index cbfaf0c00a..17cab0087f 100644 --- a/src/backend/access/spgist/spgscan.c +++ b/src/backend/access/spgist/spgscan.c @@ -862,7 +862,6 @@ redirect: /* else new pointer points to the same page, no work needed */ page = BufferGetPage(buffer); - TestForOldSnapshot(snapshot, index, page); isnull = SpGistPageStoresNulls(page) ? true : false; diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c index 352e43d0e6..42a66b4e76 100644 --- a/src/backend/catalog/index.c +++ b/src/backend/catalog/index.c @@ -3050,8 +3050,7 @@ index_build(Relation heapRelation, /* * If we found any potentially broken HOT chains, mark the index as not * being usable until the current transaction is below the event horizon. - * See src/backend/access/heap/README.HOT for discussion. Also set this - * if early pruning/vacuuming is enabled for the heap relation. While it + * See src/backend/access/heap/README.HOT for discussion. While it * might become safe to use the index earlier based on actual cleanup * activity and other active transactions, the test for that would be much * more complex and would require some form of blocking, so keep it simple @@ -3067,7 +3066,7 @@ index_build(Relation heapRelation, * * We also need not set indcheckxmin during a concurrent index build, * because we won't set indisvalid true until all transactions that care - * about the broken HOT chains or early pruning/vacuuming are gone. + * about the broken HOT chains are gone. * * Therefore, this code path can only be taken during non-concurrent * CREATE INDEX. Thus the fact that heap_update will set the pg_index @@ -3076,7 +3075,7 @@ index_build(Relation heapRelation, * about any concurrent readers of the tuple; no other transaction can see * it yet. */ - if ((indexInfo->ii_BrokenHotChain || EarlyPruningEnabled(heapRelation)) && + if (indexInfo->ii_BrokenHotChain && !isreindex && !indexInfo->ii_Concurrent) { @@ -3761,11 +3760,6 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence, * reindexing pg_index itself, we must not try to update tuples in it. * pg_index's indexes should always have these flags in their clean state, * so that won't happen. - * - * If early pruning/vacuuming is enabled for the heap relation, the - * usability horizon must be advanced to the current transaction on every - * build or rebuild. pg_index is OK in this regard because catalog tables - * are not subject to early cleanup. */ if (!skipped_constraint) { @@ -3773,7 +3767,6 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence, HeapTuple indexTuple; Form_pg_index indexForm; bool index_bad; - bool early_pruning_enabled = EarlyPruningEnabled(heapRelation); pg_index = table_open(IndexRelationId, RowExclusiveLock); @@ -3787,12 +3780,11 @@ reindex_index(Oid indexId, bool skip_constraint_checks, char persistence, !indexForm->indisready || !indexForm->indislive); if (index_bad || - (indexForm->indcheckxmin && !indexInfo->ii_BrokenHotChain) || - early_pruning_enabled) + (indexForm->indcheckxmin && !indexInfo->ii_BrokenHotChain)) { - if (!indexInfo->ii_BrokenHotChain && !early_pruning_enabled) + if (!indexInfo->ii_BrokenHotChain) indexForm->indcheckxmin = false; - else if (index_bad || early_pruning_enabled) + else if (index_bad) indexForm->indcheckxmin = true; indexForm->indisvalid = true; indexForm->indisready = true; diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index a843f9ad92..0652cdfdfb 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -1113,25 +1113,6 @@ vacuum_get_cutoffs(Relation rel, const VacuumParams *params, */ cutoffs->OldestXmin = GetOldestNonRemovableTransactionId(rel); - if (OldSnapshotThresholdActive()) - { - TransactionId limit_xmin; - TimestampTz limit_ts; - - if (TransactionIdLimitedForOldSnapshots(cutoffs->OldestXmin, rel, - &limit_xmin, &limit_ts)) - { - /* - * TODO: We should only set the threshold if we are pruning on the - * basis of the increased limits. Not as crucial here as it is - * for opportunistic pruning (which often happens at a much higher - * frequency), but would still be a significant improvement. - */ - SetOldSnapshotThresholdTimestamp(limit_ts, limit_xmin); - cutoffs->OldestXmin = limit_xmin; - } - } - Assert(TransactionIdIsNormal(cutoffs->OldestXmin)); /* Acquire OldestMxact */ diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 3c59bbd04e..8eb6d07943 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -5575,20 +5575,3 @@ IssuePendingWritebacks(WritebackContext *wb_context, IOContext io_context) wb_context->nr_pending = 0; } - - -/* - * Implement slower/larger portions of TestForOldSnapshot - * - * Smaller/faster portions are put inline, but the entire set of logic is too - * big for that. - */ -void -TestForOldSnapshot_impl(Snapshot snapshot, Relation relation) -{ - if (RelationAllowsEarlyPruning(relation) - && (snapshot)->whenTaken < GetOldSnapshotThresholdTimestamp()) - ereport(ERROR, - (errcode(ERRCODE_SNAPSHOT_TOO_OLD), - errmsg("snapshot too old"))); -} diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c index 8f1ded7338..a0c7b0f027 100644 --- a/src/backend/storage/ipc/ipci.c +++ b/src/backend/storage/ipc/ipci.c @@ -137,7 +137,6 @@ CalculateShmemSize(int *num_semaphores) size = add_size(size, WalRcvShmemSize()); size = add_size(size, PgArchShmemSize()); size = add_size(size, ApplyLauncherShmemSize()); - size = add_size(size, SnapMgrShmemSize()); size = add_size(size, BTreeShmemSize()); size = add_size(size, SyncScanShmemSize()); size = add_size(size, AsyncShmemSize()); @@ -289,7 +288,6 @@ CreateSharedMemoryAndSemaphores(void) /* * Set up other modules that need some shared memory space */ - SnapMgrInit(); BTreeShmemInit(); SyncScanShmemInit(); AsyncShmemInit(); diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index 8c8d728ba8..8f68a16051 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -2066,34 +2066,6 @@ GetMaxSnapshotSubxidCount(void) return TOTAL_MAX_CACHED_SUBXIDS; } -/* - * Initialize old_snapshot_threshold specific parts of a newly build snapshot. - */ -static void -GetSnapshotDataInitOldSnapshot(Snapshot snapshot) -{ - if (!OldSnapshotThresholdActive()) - { - /* - * If not using "snapshot too old" feature, fill related fields with - * dummy values that don't require any locking. - */ - snapshot->lsn = InvalidXLogRecPtr; - snapshot->whenTaken = 0; - } - else - { - /* - * Capture the current time and WAL stream location in case this - * snapshot becomes old enough to need to fall back on the special - * "old snapshot" logic. - */ - snapshot->lsn = GetXLogInsertRecPtr(); - snapshot->whenTaken = GetSnapshotCurrentTimestamp(); - MaintainOldSnapshotTimeMapping(snapshot->whenTaken, snapshot->xmin); - } -} - /* * Helper function for GetSnapshotData() that checks if the bulk of the * visibility information in the snapshot is still valid. If so, it updates @@ -2147,8 +2119,8 @@ GetSnapshotDataReuse(Snapshot snapshot) snapshot->active_count = 0; snapshot->regd_count = 0; snapshot->copied = false; - - GetSnapshotDataInitOldSnapshot(snapshot); + snapshot->lsn = InvalidXLogRecPtr; + snapshot->whenTaken = 0; return true; } @@ -2529,8 +2501,8 @@ GetSnapshotData(Snapshot snapshot) snapshot->active_count = 0; snapshot->regd_count = 0; snapshot->copied = false; - - GetSnapshotDataInitOldSnapshot(snapshot); + snapshot->lsn = InvalidXLogRecPtr; + snapshot->whenTaken = 0; return snapshot; } diff --git a/src/backend/storage/lmgr/lwlocknames.txt b/src/backend/storage/lmgr/lwlocknames.txt index 6c7cf6c295..036ee3f49c 100644 --- a/src/backend/storage/lmgr/lwlocknames.txt +++ b/src/backend/storage/lmgr/lwlocknames.txt @@ -47,7 +47,7 @@ CommitTsSLRULock 38 CommitTsLock 39 ReplicationOriginLock 40 MultiXactTruncationLock 41 -OldSnapshotTimeMapLock 42 +# 42 was OldSnapshotTimeMapLock LogicalRepWorkerLock 43 XactTruncationLock 44 # 45 was XactTruncationLock until removal of BackendRandomLock diff --git a/src/backend/utils/errcodes.txt b/src/backend/utils/errcodes.txt index 3d244af130..8e97a0150f 100644 --- a/src/backend/utils/errcodes.txt +++ b/src/backend/utils/errcodes.txt @@ -439,10 +439,6 @@ Section: Class 58 - System Error (errors external to PostgreSQL itself) 58P01 E ERRCODE_UNDEFINED_FILE undefined_file 58P02 E ERRCODE_DUPLICATE_FILE duplicate_file -Section: Class 72 - Snapshot Failure -# (class borrowed from Oracle) -72000 E ERRCODE_SNAPSHOT_TOO_OLD snapshot_too_old - Section: Class F0 - Configuration File Error # (PostgreSQL-specific error class) diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index 71e27f8eb0..1513d7e395 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -3280,17 +3280,6 @@ struct config_int ConfigureNamesInt[] = check_autovacuum_work_mem, NULL, NULL }, - { - {"old_snapshot_threshold", PGC_POSTMASTER, RESOURCES_ASYNCHRONOUS, - gettext_noop("Time before a snapshot is too old to read pages changed after the snapshot was taken."), - gettext_noop("A value of -1 disables this feature."), - GUC_UNIT_MIN - }, - &old_snapshot_threshold, - -1, -1, MINS_PER_HOUR * HOURS_PER_DAY * 60, - NULL, NULL, NULL - }, - { {"tcp_keepalives_idle", PGC_USERSET, CONN_AUTH_TCP, gettext_noop("Time between issuing TCP keepalives."), diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index e4c0269fa3..c06c0503a9 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -198,8 +198,6 @@ #max_parallel_workers = 8 # maximum number of max_worker_processes that # can be used in parallel operations #parallel_leader_participation = on -#old_snapshot_threshold = -1 # 1min-60d; -1 disables; 0 is immediate - # (change requires restart) #------------------------------------------------------------------------------ diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index 3a419e348f..b20440ee21 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -65,7 +65,6 @@ #include "storage/spin.h" #include "utils/builtins.h" #include "utils/memutils.h" -#include "utils/old_snapshot.h" #include "utils/rel.h" #include "utils/resowner_private.h" #include "utils/snapmgr.h" @@ -73,14 +72,6 @@ #include "utils/timestamp.h" -/* - * GUC parameters - */ -int old_snapshot_threshold; /* number of minutes, -1 disables */ - -volatile OldSnapshotControlData *oldSnapshotControl; - - /* * CurrentSnapshot points to the only snapshot taken in transaction-snapshot * mode, and to the latest one taken in a read-committed transaction. @@ -170,7 +161,6 @@ typedef struct ExportedSnapshot static List *exportedSnapshots = NIL; /* Prototypes for local functions */ -static TimestampTz AlignTimestampToMinuteBoundary(TimestampTz ts); static Snapshot CopySnapshot(Snapshot snapshot); static void FreeSnapshot(Snapshot snapshot); static void SnapshotResetXmin(void); @@ -194,50 +184,6 @@ typedef struct SerializedSnapshotData XLogRecPtr lsn; } SerializedSnapshotData; -Size -SnapMgrShmemSize(void) -{ - Size size; - - size = offsetof(OldSnapshotControlData, xid_by_minute); - if (old_snapshot_threshold > 0) - size = add_size(size, mul_size(sizeof(TransactionId), - OLD_SNAPSHOT_TIME_MAP_ENTRIES)); - - return size; -} - -/* - * Initialize for managing old snapshot detection. - */ -void -SnapMgrInit(void) -{ - bool found; - - /* - * Create or attach to the OldSnapshotControlData structure. - */ - oldSnapshotControl = (volatile OldSnapshotControlData *) - ShmemInitStruct("OldSnapshotControlData", - SnapMgrShmemSize(), &found); - - if (!found) - { - SpinLockInit(&oldSnapshotControl->mutex_current); - oldSnapshotControl->current_timestamp = 0; - SpinLockInit(&oldSnapshotControl->mutex_latest_xmin); - oldSnapshotControl->latest_xmin = InvalidTransactionId; - oldSnapshotControl->next_map_update = 0; - SpinLockInit(&oldSnapshotControl->mutex_threshold); - oldSnapshotControl->threshold_timestamp = 0; - oldSnapshotControl->threshold_xid = InvalidTransactionId; - oldSnapshotControl->head_offset = 0; - oldSnapshotControl->head_timestamp = 0; - oldSnapshotControl->count_used = 0; - } -} - /* * GetTransactionSnapshot * Get the appropriate snapshot for a new query in a transaction. @@ -1656,420 +1602,6 @@ HaveRegisteredOrActiveSnapshot(void) } -/* - * Return a timestamp that is exactly on a minute boundary. - * - * If the argument is already aligned, return that value, otherwise move to - * the next minute boundary following the given time. - */ -static TimestampTz -AlignTimestampToMinuteBoundary(TimestampTz ts) -{ - TimestampTz retval = ts + (USECS_PER_MINUTE - 1); - - return retval - (retval % USECS_PER_MINUTE); -} - -/* - * Get current timestamp for snapshots - * - * This is basically GetCurrentTimestamp(), but with a guarantee that - * the result never moves backward. - */ -TimestampTz -GetSnapshotCurrentTimestamp(void) -{ - TimestampTz now = GetCurrentTimestamp(); - - /* - * Don't let time move backward; if it hasn't advanced, use the old value. - */ - SpinLockAcquire(&oldSnapshotControl->mutex_current); - if (now <= oldSnapshotControl->current_timestamp) - now = oldSnapshotControl->current_timestamp; - else - oldSnapshotControl->current_timestamp = now; - SpinLockRelease(&oldSnapshotControl->mutex_current); - - return now; -} - -/* - * Get timestamp through which vacuum may have processed based on last stored - * value for threshold_timestamp. - * - * XXX: So far, we never trust that a 64-bit value can be read atomically; if - * that ever changes, we could get rid of the spinlock here. - */ -TimestampTz -GetOldSnapshotThresholdTimestamp(void) -{ - TimestampTz threshold_timestamp; - - SpinLockAcquire(&oldSnapshotControl->mutex_threshold); - threshold_timestamp = oldSnapshotControl->threshold_timestamp; - SpinLockRelease(&oldSnapshotControl->mutex_threshold); - - return threshold_timestamp; -} - -void -SetOldSnapshotThresholdTimestamp(TimestampTz ts, TransactionId xlimit) -{ - SpinLockAcquire(&oldSnapshotControl->mutex_threshold); - Assert(oldSnapshotControl->threshold_timestamp <= ts); - Assert(TransactionIdPrecedesOrEquals(oldSnapshotControl->threshold_xid, xlimit)); - oldSnapshotControl->threshold_timestamp = ts; - oldSnapshotControl->threshold_xid = xlimit; - SpinLockRelease(&oldSnapshotControl->mutex_threshold); -} - -/* - * XXX: Magic to keep old_snapshot_threshold tests appear "working". They - * currently are broken, and discussion of what to do about them is - * ongoing. See - * https://www.postgresql.org/message-id/20200403001235.e6jfdll3gh2ygbuc%40alap3.anarazel.de - */ -void -SnapshotTooOldMagicForTest(void) -{ - TimestampTz ts = GetSnapshotCurrentTimestamp(); - - Assert(old_snapshot_threshold == 0); - - ts -= 5 * USECS_PER_SEC; - - SpinLockAcquire(&oldSnapshotControl->mutex_threshold); - oldSnapshotControl->threshold_timestamp = ts; - SpinLockRelease(&oldSnapshotControl->mutex_threshold); -} - -/* - * If there is a valid mapping for the timestamp, set *xlimitp to - * that. Returns whether there is such a mapping. - */ -static bool -GetOldSnapshotFromTimeMapping(TimestampTz ts, TransactionId *xlimitp) -{ - bool in_mapping = false; - - Assert(ts == AlignTimestampToMinuteBoundary(ts)); - - LWLockAcquire(OldSnapshotTimeMapLock, LW_SHARED); - - if (oldSnapshotControl->count_used > 0 - && ts >= oldSnapshotControl->head_timestamp) - { - int offset; - - offset = ((ts - oldSnapshotControl->head_timestamp) - / USECS_PER_MINUTE); - if (offset > oldSnapshotControl->count_used - 1) - offset = oldSnapshotControl->count_used - 1; - offset = (oldSnapshotControl->head_offset + offset) - % OLD_SNAPSHOT_TIME_MAP_ENTRIES; - - *xlimitp = oldSnapshotControl->xid_by_minute[offset]; - - in_mapping = true; - } - - LWLockRelease(OldSnapshotTimeMapLock); - - return in_mapping; -} - -/* - * TransactionIdLimitedForOldSnapshots - * - * Apply old snapshot limit. This is intended to be called for page pruning - * and table vacuuming, to allow old_snapshot_threshold to override the normal - * global xmin value. Actual testing for snapshot too old will be based on - * whether a snapshot timestamp is prior to the threshold timestamp set in - * this function. - * - * If the limited horizon allows a cleanup action that otherwise would not be - * possible, SetOldSnapshotThresholdTimestamp(*limit_ts, *limit_xid) needs to - * be called before that cleanup action. - */ -bool -TransactionIdLimitedForOldSnapshots(TransactionId recentXmin, - Relation relation, - TransactionId *limit_xid, - TimestampTz *limit_ts) -{ - TimestampTz ts; - TransactionId xlimit = recentXmin; - TransactionId latest_xmin; - TimestampTz next_map_update_ts; - TransactionId threshold_timestamp; - TransactionId threshold_xid; - - Assert(TransactionIdIsNormal(recentXmin)); - Assert(OldSnapshotThresholdActive()); - Assert(limit_ts != NULL && limit_xid != NULL); - - /* - * TestForOldSnapshot() assumes early pruning advances the page LSN, so we - * can't prune early when skipping WAL. - */ - if (!RelationAllowsEarlyPruning(relation) || !RelationNeedsWAL(relation)) - return false; - - ts = GetSnapshotCurrentTimestamp(); - - SpinLockAcquire(&oldSnapshotControl->mutex_latest_xmin); - latest_xmin = oldSnapshotControl->latest_xmin; - next_map_update_ts = oldSnapshotControl->next_map_update; - SpinLockRelease(&oldSnapshotControl->mutex_latest_xmin); - - /* - * Zero threshold always overrides to latest xmin, if valid. Without some - * heuristic it will find its own snapshot too old on, for example, a - * simple UPDATE -- which would make it useless for most testing, but - * there is no principled way to ensure that it doesn't fail in this way. - * Use a five-second delay to try to get useful testing behavior, but this - * may need adjustment. - */ - if (old_snapshot_threshold == 0) - { - if (TransactionIdPrecedes(latest_xmin, MyProc->xmin) - && TransactionIdFollows(latest_xmin, xlimit)) - xlimit = latest_xmin; - - ts -= 5 * USECS_PER_SEC; - } - else - { - ts = AlignTimestampToMinuteBoundary(ts) - - (old_snapshot_threshold * USECS_PER_MINUTE); - - /* Check for fast exit without LW locking. */ - SpinLockAcquire(&oldSnapshotControl->mutex_threshold); - threshold_timestamp = oldSnapshotControl->threshold_timestamp; - threshold_xid = oldSnapshotControl->threshold_xid; - SpinLockRelease(&oldSnapshotControl->mutex_threshold); - - if (ts == threshold_timestamp) - { - /* - * Current timestamp is in same bucket as the last limit that was - * applied. Reuse. - */ - xlimit = threshold_xid; - } - else if (ts == next_map_update_ts) - { - /* - * FIXME: This branch is super iffy - but that should probably - * fixed separately. - */ - xlimit = latest_xmin; - } - else if (GetOldSnapshotFromTimeMapping(ts, &xlimit)) - { - } - - /* - * Failsafe protection against vacuuming work of active transaction. - * - * This is not an assertion because we avoid the spinlock for - * performance, leaving open the possibility that xlimit could advance - * and be more current; but it seems prudent to apply this limit. It - * might make pruning a tiny bit less aggressive than it could be, but - * protects against data loss bugs. - */ - if (TransactionIdIsNormal(latest_xmin) - && TransactionIdPrecedes(latest_xmin, xlimit)) - xlimit = latest_xmin; - } - - if (TransactionIdIsValid(xlimit) && - TransactionIdFollowsOrEquals(xlimit, recentXmin)) - { - *limit_ts = ts; - *limit_xid = xlimit; - - return true; - } - - return false; -} - -/* - * Take care of the circular buffer that maps time to xid. - */ -void -MaintainOldSnapshotTimeMapping(TimestampTz whenTaken, TransactionId xmin) -{ - TimestampTz ts; - TransactionId latest_xmin; - TimestampTz update_ts; - bool map_update_required = false; - - /* Never call this function when old snapshot checking is disabled. */ - Assert(old_snapshot_threshold >= 0); - - ts = AlignTimestampToMinuteBoundary(whenTaken); - - /* - * Keep track of the latest xmin seen by any process. Update mapping with - * a new value when we have crossed a bucket boundary. - */ - SpinLockAcquire(&oldSnapshotControl->mutex_latest_xmin); - latest_xmin = oldSnapshotControl->latest_xmin; - update_ts = oldSnapshotControl->next_map_update; - if (ts > update_ts) - { - oldSnapshotControl->next_map_update = ts; - map_update_required = true; - } - if (TransactionIdFollows(xmin, latest_xmin)) - oldSnapshotControl->latest_xmin = xmin; - SpinLockRelease(&oldSnapshotControl->mutex_latest_xmin); - - /* We only needed to update the most recent xmin value. */ - if (!map_update_required) - return; - - /* No further tracking needed for 0 (used for testing). */ - if (old_snapshot_threshold == 0) - return; - - /* - * We don't want to do something stupid with unusual values, but we don't - * want to litter the log with warnings or break otherwise normal - * processing for this feature; so if something seems unreasonable, just - * log at DEBUG level and return without doing anything. - */ - if (whenTaken < 0) - { - elog(DEBUG1, - "MaintainOldSnapshotTimeMapping called with negative whenTaken = %ld", - (long) whenTaken); - return; - } - if (!TransactionIdIsNormal(xmin)) - { - elog(DEBUG1, - "MaintainOldSnapshotTimeMapping called with xmin = %lu", - (unsigned long) xmin); - return; - } - - LWLockAcquire(OldSnapshotTimeMapLock, LW_EXCLUSIVE); - - Assert(oldSnapshotControl->head_offset >= 0); - Assert(oldSnapshotControl->head_offset < OLD_SNAPSHOT_TIME_MAP_ENTRIES); - Assert((oldSnapshotControl->head_timestamp % USECS_PER_MINUTE) == 0); - Assert(oldSnapshotControl->count_used >= 0); - Assert(oldSnapshotControl->count_used <= OLD_SNAPSHOT_TIME_MAP_ENTRIES); - - if (oldSnapshotControl->count_used == 0) - { - /* set up first entry for empty mapping */ - oldSnapshotControl->head_offset = 0; - oldSnapshotControl->head_timestamp = ts; - oldSnapshotControl->count_used = 1; - oldSnapshotControl->xid_by_minute[0] = xmin; - } - else if (ts < oldSnapshotControl->head_timestamp) - { - /* old ts; log it at DEBUG */ - LWLockRelease(OldSnapshotTimeMapLock); - elog(DEBUG1, - "MaintainOldSnapshotTimeMapping called with old whenTaken = %ld", - (long) whenTaken); - return; - } - else if (ts <= (oldSnapshotControl->head_timestamp + - ((oldSnapshotControl->count_used - 1) - * USECS_PER_MINUTE))) - { - /* existing mapping; advance xid if possible */ - int bucket = (oldSnapshotControl->head_offset - + ((ts - oldSnapshotControl->head_timestamp) - / USECS_PER_MINUTE)) - % OLD_SNAPSHOT_TIME_MAP_ENTRIES; - - if (TransactionIdPrecedes(oldSnapshotControl->xid_by_minute[bucket], xmin)) - oldSnapshotControl->xid_by_minute[bucket] = xmin; - } - else - { - /* We need a new bucket, but it might not be the very next one. */ - int distance_to_new_tail; - int distance_to_current_tail; - int advance; - - /* - * Our goal is for the new "tail" of the mapping, that is, the entry - * which is newest and thus furthest from the "head" entry, to - * correspond to "ts". Since there's one entry per minute, the - * distance between the current head and the new tail is just the - * number of minutes of difference between ts and the current - * head_timestamp. - * - * The distance from the current head to the current tail is one less - * than the number of entries in the mapping, because the entry at the - * head_offset is for 0 minutes after head_timestamp. - * - * The difference between these two values is the number of minutes by - * which we need to advance the mapping, either adding new entries or - * rotating old ones out. - */ - distance_to_new_tail = - (ts - oldSnapshotControl->head_timestamp) / USECS_PER_MINUTE; - distance_to_current_tail = - oldSnapshotControl->count_used - 1; - advance = distance_to_new_tail - distance_to_current_tail; - Assert(advance > 0); - - if (advance >= OLD_SNAPSHOT_TIME_MAP_ENTRIES) - { - /* Advance is so far that all old data is junk; start over. */ - oldSnapshotControl->head_offset = 0; - oldSnapshotControl->count_used = 1; - oldSnapshotControl->xid_by_minute[0] = xmin; - oldSnapshotControl->head_timestamp = ts; - } - else - { - /* Store the new value in one or more buckets. */ - int i; - - for (i = 0; i < advance; i++) - { - if (oldSnapshotControl->count_used == OLD_SNAPSHOT_TIME_MAP_ENTRIES) - { - /* Map full and new value replaces old head. */ - int old_head = oldSnapshotControl->head_offset; - - if (old_head == (OLD_SNAPSHOT_TIME_MAP_ENTRIES - 1)) - oldSnapshotControl->head_offset = 0; - else - oldSnapshotControl->head_offset = old_head + 1; - oldSnapshotControl->xid_by_minute[old_head] = xmin; - oldSnapshotControl->head_timestamp += USECS_PER_MINUTE; - } - else - { - /* Extend map to unused entry. */ - int new_tail = (oldSnapshotControl->head_offset - + oldSnapshotControl->count_used) - % OLD_SNAPSHOT_TIME_MAP_ENTRIES; - - oldSnapshotControl->count_used++; - oldSnapshotControl->xid_by_minute[new_tail] = xmin; - } - } - } - } - - LWLockRelease(OldSnapshotTimeMapLock); -} - - /* * Setup a snapshot that replaces normal catalog snapshots that allows catalog * access to behave just like it did at a certain point in the past. diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h index faf5026519..6598c4d7d8 100644 --- a/src/include/access/heapam.h +++ b/src/include/access/heapam.h @@ -286,8 +286,6 @@ struct GlobalVisState; extern void heap_page_prune_opt(Relation relation, Buffer buffer); extern int heap_page_prune(Relation relation, Buffer buffer, struct GlobalVisState *vistest, - TransactionId old_snap_xmin, - TimestampTz old_snap_ts, int *nnewlpdead, OffsetNumber *off_loc); extern void heap_page_prune_execute(Buffer buffer, diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index 0f5fb6be00..09b7f98e2c 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -250,8 +250,6 @@ extern void AbortBufferIO(Buffer buffer); extern bool BgBufferSync(struct WritebackContext *wb_context); -extern void TestForOldSnapshot_impl(Snapshot snapshot, Relation relation); - /* in buf_init.c */ extern void InitBufferPool(void); extern Size BufferShmemSize(void); @@ -347,9 +345,6 @@ BufferGetPageSize(Buffer buffer) /* * BufferGetPage * Returns the page associated with a buffer. - * - * When this is called as part of a scan, there may be a need for a nearby - * call to TestForOldSnapshot(). See the definition of that for details. */ static inline Page BufferGetPage(Buffer buffer) @@ -357,37 +352,6 @@ BufferGetPage(Buffer buffer) return (Page) BufferGetBlock(buffer); } -/* - * Check whether the given snapshot is too old to have safely read the given - * page from the given table. If so, throw a "snapshot too old" error. - * - * This test generally needs to be performed after every BufferGetPage() call - * that is executed as part of a scan. It is not needed for calls made for - * modifying the page (for example, to position to the right place to insert a - * new index tuple or for vacuuming). It may also be omitted where calls to - * lower-level functions will have already performed the test. - * - * Note that a NULL snapshot argument is allowed and causes a fast return - * without error; this is to support call sites which can be called from - * either scans or index modification areas. - * - * For best performance, keep the tests that are fastest and/or most likely to - * exclude a page from old snapshot testing near the front. - */ -static inline void -TestForOldSnapshot(Snapshot snapshot, Relation relation, Page page) -{ - Assert(relation != NULL); - - if (old_snapshot_threshold >= 0 - && (snapshot) != NULL - && ((snapshot)->snapshot_type == SNAPSHOT_MVCC - || (snapshot)->snapshot_type == SNAPSHOT_TOAST) - && !XLogRecPtrIsInvalid((snapshot)->lsn) - && PageGetLSN(page) > (snapshot)->lsn) - TestForOldSnapshot_impl(snapshot, relation); -} - #endif /* FRONTEND */ #endif /* BUFMGR_H */ diff --git a/src/include/utils/old_snapshot.h b/src/include/utils/old_snapshot.h deleted file mode 100644 index f1978a28e1..0000000000 --- a/src/include/utils/old_snapshot.h +++ /dev/null @@ -1,75 +0,0 @@ -/*------------------------------------------------------------------------- - * - * old_snapshot.h - * Data structures for 'snapshot too old' - * - * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group - * Portions Copyright (c) 1994, Regents of the University of California - * - * IDENTIFICATION - * src/include/utils/old_snapshot.h - * - *------------------------------------------------------------------------- - */ - -#ifndef OLD_SNAPSHOT_H -#define OLD_SNAPSHOT_H - -#include "datatype/timestamp.h" -#include "storage/s_lock.h" - -/* - * Structure for dealing with old_snapshot_threshold implementation. - */ -typedef struct OldSnapshotControlData -{ - /* - * Variables for old snapshot handling are shared among processes and are - * only allowed to move forward. - */ - slock_t mutex_current; /* protect current_timestamp */ - TimestampTz current_timestamp; /* latest snapshot timestamp */ - slock_t mutex_latest_xmin; /* protect latest_xmin and next_map_update */ - TransactionId latest_xmin; /* latest snapshot xmin */ - TimestampTz next_map_update; /* latest snapshot valid up to */ - slock_t mutex_threshold; /* protect threshold fields */ - TimestampTz threshold_timestamp; /* earlier snapshot is old */ - TransactionId threshold_xid; /* earlier xid may be gone */ - - /* - * Keep one xid per minute for old snapshot error handling. - * - * Use a circular buffer with a head offset, a count of entries currently - * used, and a timestamp corresponding to the xid at the head offset. A - * count_used value of zero means that there are no times stored; a - * count_used value of OLD_SNAPSHOT_TIME_MAP_ENTRIES means that the buffer - * is full and the head must be advanced to add new entries. Use - * timestamps aligned to minute boundaries, since that seems less - * surprising than aligning based on the first usage timestamp. The - * latest bucket is effectively stored within latest_xmin. The circular - * buffer is updated when we get a new xmin value that doesn't fall into - * the same interval. - * - * It is OK if the xid for a given time slot is from earlier than - * calculated by adding the number of minutes corresponding to the - * (possibly wrapped) distance from the head offset to the time of the - * head entry, since that just results in the vacuuming of old tuples - * being slightly less aggressive. It would not be OK for it to be off in - * the other direction, since it might result in vacuuming tuples that are - * still expected to be there. - * - * Use of an SLRU was considered but not chosen because it is more - * heavyweight than is needed for this, and would probably not be any less - * code to implement. - * - * Persistence is not needed. - */ - int head_offset; /* subscript of oldest tracked time */ - TimestampTz head_timestamp; /* time corresponding to head xid */ - int count_used; /* how many slots are in use */ - TransactionId xid_by_minute[FLEXIBLE_ARRAY_MEMBER]; -} OldSnapshotControlData; - -extern PGDLLIMPORT volatile OldSnapshotControlData *oldSnapshotControl; - -#endif diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 980d37a194..4dc94e7ec9 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -19,40 +19,6 @@ #include "utils/snapshot.h" -/* - * The structure used to map times to TransactionId values for the "snapshot - * too old" feature must have a few entries at the tail to hold old values; - * otherwise the lookup will often fail and the expected early pruning or - * vacuum will not usually occur. It is best if this padding is for a number - * of minutes greater than a thread would normally be stalled, but it's OK if - * early vacuum opportunities are occasionally missed, so there's no need to - * use an extreme value or get too fancy. 10 minutes seems plenty. - */ -#define OLD_SNAPSHOT_PADDING_ENTRIES 10 -#define OLD_SNAPSHOT_TIME_MAP_ENTRIES (old_snapshot_threshold + OLD_SNAPSHOT_PADDING_ENTRIES) - -/* - * Common definition of relation properties that allow early pruning/vacuuming - * when old_snapshot_threshold >= 0. - */ -#define RelationAllowsEarlyPruning(rel) \ -( \ - RelationIsPermanent(rel) && !IsCatalogRelation(rel) \ - && !RelationIsAccessibleInLogicalDecoding(rel) \ -) - -#define EarlyPruningEnabled(rel) (old_snapshot_threshold >= 0 && RelationAllowsEarlyPruning(rel)) - -/* GUC variables */ -extern PGDLLIMPORT int old_snapshot_threshold; - - -extern Size SnapMgrShmemSize(void); -extern void SnapMgrInit(void); -extern TimestampTz GetSnapshotCurrentTimestamp(void); -extern TimestampTz GetOldSnapshotThresholdTimestamp(void); -extern void SnapshotTooOldMagicForTest(void); - extern PGDLLIMPORT bool FirstSnapshotSet; extern PGDLLIMPORT TransactionId TransactionXmin; @@ -97,14 +63,6 @@ extern PGDLLIMPORT SnapshotData CatalogSnapshotData; ((snapshot)->snapshot_type == SNAPSHOT_MVCC || \ (snapshot)->snapshot_type == SNAPSHOT_HISTORIC_MVCC) -#ifndef FRONTEND -static inline bool -OldSnapshotThresholdActive(void) -{ - return old_snapshot_threshold >= 0; -} -#endif - extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); @@ -138,13 +96,6 @@ extern void DeleteAllExportedSnapshotFiles(void); extern void WaitForOlderSnapshots(TransactionId limitXmin, bool progress); extern bool ThereAreNoPriorRegisteredSnapshots(void); extern bool HaveRegisteredOrActiveSnapshot(void); -extern bool TransactionIdLimitedForOldSnapshots(TransactionId recentXmin, - Relation relation, - TransactionId *limit_xid, - TimestampTz *limit_ts); -extern void SetOldSnapshotThresholdTimestamp(TimestampTz ts, TransactionId xlimit); -extern void MaintainOldSnapshotTimeMapping(TimestampTz whenTaken, - TransactionId xmin); extern char *ExportSnapshot(Snapshot snapshot); diff --git a/src/test/modules/Makefile b/src/test/modules/Makefile index 6331c976dc..e81873cb5a 100644 --- a/src/test/modules/Makefile +++ b/src/test/modules/Makefile @@ -12,7 +12,6 @@ SUBDIRS = \ dummy_seclabel \ libpq_pipeline \ plsample \ - snapshot_too_old \ spgist_name_ops \ test_bloomfilter \ test_copy_callbacks \ diff --git a/src/test/modules/meson.build b/src/test/modules/meson.build index 17d369e378..fcd643f6f1 100644 --- a/src/test/modules/meson.build +++ b/src/test/modules/meson.build @@ -8,7 +8,6 @@ subdir('dummy_seclabel') subdir('ldap_password_func') subdir('libpq_pipeline') subdir('plsample') -subdir('snapshot_too_old') subdir('spgist_name_ops') subdir('ssl_passphrase_callback') subdir('test_bloomfilter') diff --git a/src/test/modules/snapshot_too_old/.gitignore b/src/test/modules/snapshot_too_old/.gitignore deleted file mode 100644 index ba2160b66c..0000000000 --- a/src/test/modules/snapshot_too_old/.gitignore +++ /dev/null @@ -1,3 +0,0 @@ -# Generated subdirectories -/output_iso/ -/tmp_check_iso/ diff --git a/src/test/modules/snapshot_too_old/Makefile b/src/test/modules/snapshot_too_old/Makefile deleted file mode 100644 index dfb4537f63..0000000000 --- a/src/test/modules/snapshot_too_old/Makefile +++ /dev/null @@ -1,28 +0,0 @@ -# src/test/modules/snapshot_too_old/Makefile - -# Note: because we don't tell the Makefile there are any regression tests, -# we have to clean those result files explicitly -EXTRA_CLEAN = $(pg_regress_clean_files) - -ISOLATION = sto_using_cursor sto_using_select sto_using_hash_index -ISOLATION_OPTS = --temp-config $(top_srcdir)/src/test/modules/snapshot_too_old/sto.conf - -# Disabled because these tests require "old_snapshot_threshold" >= 0, which -# typical installcheck users do not have (e.g. buildfarm clients). -NO_INSTALLCHECK = 1 - -ifdef USE_PGXS -PG_CONFIG = pg_config -PGXS := $(shell $(PG_CONFIG) --pgxs) -include $(PGXS) -else -subdir = src/test/modules/snapshot_too_old -top_builddir = ../../../.. -include $(top_builddir)/src/Makefile.global -include $(top_srcdir)/contrib/contrib-global.mk -endif - -# But it can nonetheless be very helpful to run tests on preexisting -# installation, allow to do so, but only if requested explicitly. -installcheck-force: - $(pg_isolation_regress_installcheck) $(ISOLATION) diff --git a/src/test/modules/snapshot_too_old/expected/sto_using_cursor.out b/src/test/modules/snapshot_too_old/expected/sto_using_cursor.out deleted file mode 100644 index 06fe4d0669..0000000000 --- a/src/test/modules/snapshot_too_old/expected/sto_using_cursor.out +++ /dev/null @@ -1,19 +0,0 @@ -Parsed test spec with 2 sessions - -starting permutation: s1decl s1f1 s1sleep s2u s1f2 -step s1decl: DECLARE cursor1 CURSOR FOR SELECT c FROM sto1; -step s1f1: FETCH FIRST FROM cursor1; -c -- -1 -(1 row) - -step s1sleep: SELECT setting, pg_sleep(6) FROM pg_settings WHERE name = 'old_snapshot_threshold'; -setting|pg_sleep --------+-------- - 0| -(1 row) - -step s2u: UPDATE sto1 SET c = 1001 WHERE c = 1; -step s1f2: FETCH FIRST FROM cursor1; -ERROR: snapshot too old diff --git a/src/test/modules/snapshot_too_old/expected/sto_using_hash_index.out b/src/test/modules/snapshot_too_old/expected/sto_using_hash_index.out deleted file mode 100644 index 11f827fbfe..0000000000 --- a/src/test/modules/snapshot_too_old/expected/sto_using_hash_index.out +++ /dev/null @@ -1,19 +0,0 @@ -Parsed test spec with 2 sessions - -starting permutation: noseq s1f1 s2sleep s2u s1f2 -step noseq: SET enable_seqscan = false; -step s1f1: SELECT c FROM sto1 where c = 1000; - c ----- -1000 -(1 row) - -step s2sleep: SELECT setting, pg_sleep(6) FROM pg_settings WHERE name = 'old_snapshot_threshold'; -setting|pg_sleep --------+-------- - 0| -(1 row) - -step s2u: UPDATE sto1 SET c = 1001 WHERE c = 1000; -step s1f2: SELECT c FROM sto1 where c = 1001; -ERROR: snapshot too old diff --git a/src/test/modules/snapshot_too_old/expected/sto_using_select.out b/src/test/modules/snapshot_too_old/expected/sto_using_select.out deleted file mode 100644 index e910e5c71e..0000000000 --- a/src/test/modules/snapshot_too_old/expected/sto_using_select.out +++ /dev/null @@ -1,18 +0,0 @@ -Parsed test spec with 2 sessions - -starting permutation: s1f1 s1sleep s2u s1f2 -step s1f1: SELECT c FROM sto1 ORDER BY c LIMIT 1; -c -- -1 -(1 row) - -step s1sleep: SELECT setting, pg_sleep(6) FROM pg_settings WHERE name = 'old_snapshot_threshold'; -setting|pg_sleep --------+-------- - 0| -(1 row) - -step s2u: UPDATE sto1 SET c = 1001 WHERE c = 1; -step s1f2: SELECT c FROM sto1 ORDER BY c LIMIT 1; -ERROR: snapshot too old diff --git a/src/test/modules/snapshot_too_old/meson.build b/src/test/modules/snapshot_too_old/meson.build deleted file mode 100644 index 6a2f4a0b72..0000000000 --- a/src/test/modules/snapshot_too_old/meson.build +++ /dev/null @@ -1,19 +0,0 @@ -# Copyright (c) 2022-2023, PostgreSQL Global Development Group - -tests += { - 'name': 'snapshot_too_old', - 'sd': meson.current_source_dir(), - 'bd': meson.current_build_dir(), - 'isolation': { - 'test_kwargs': {'priority': 40}, # sto tests are slow, start early - 'specs': [ - 'sto_using_cursor', - 'sto_using_select', - 'sto_using_hash_index', - ], - 'regress_args': ['--temp-config', files('sto.conf')], - # Disabled because these tests require "old_snapshot_threshold" >= 0, which - # typical runningcheck users do not have (e.g. buildfarm clients). - 'runningcheck': false, - }, -} diff --git a/src/test/modules/snapshot_too_old/specs/sto_using_cursor.spec b/src/test/modules/snapshot_too_old/specs/sto_using_cursor.spec deleted file mode 100644 index f3677a8fa9..0000000000 --- a/src/test/modules/snapshot_too_old/specs/sto_using_cursor.spec +++ /dev/null @@ -1,38 +0,0 @@ -# This test provokes a "snapshot too old" error using a cursor. -# -# The sleep is needed because with a threshold of zero a statement could error -# on changes it made. With more normal settings no external delay is needed, -# but we don't want these tests to run long enough to see that, since -# granularity is in minutes. -# -# Since results depend on the value of old_snapshot_threshold, sneak that into -# the line generated by the sleep, so that a surprising value isn't so hard -# to identify. - -setup -{ - CREATE TABLE sto1 (c int NOT NULL); - INSERT INTO sto1 SELECT generate_series(1, 1000); -} -setup -{ - VACUUM ANALYZE sto1; -} - -teardown -{ - DROP TABLE sto1; -} - -session "s1" -setup { BEGIN ISOLATION LEVEL REPEATABLE READ; } -step "s1decl" { DECLARE cursor1 CURSOR FOR SELECT c FROM sto1; } -step "s1f1" { FETCH FIRST FROM cursor1; } -step "s1sleep" { SELECT setting, pg_sleep(6) FROM pg_settings WHERE name = 'old_snapshot_threshold'; } -step "s1f2" { FETCH FIRST FROM cursor1; } -teardown { COMMIT; } - -session "s2" -step "s2u" { UPDATE sto1 SET c = 1001 WHERE c = 1; } - -permutation "s1decl" "s1f1" "s1sleep" "s2u" "s1f2" diff --git a/src/test/modules/snapshot_too_old/specs/sto_using_hash_index.spec b/src/test/modules/snapshot_too_old/specs/sto_using_hash_index.spec deleted file mode 100644 index 33d91ff852..0000000000 --- a/src/test/modules/snapshot_too_old/specs/sto_using_hash_index.spec +++ /dev/null @@ -1,31 +0,0 @@ -# This test is like sto_using_select, except that we test access via a -# hash index. - -setup -{ - CREATE TABLE sto1 (c int NOT NULL); - INSERT INTO sto1 SELECT generate_series(1, 1000); - CREATE INDEX idx_sto1 ON sto1 USING HASH (c); -} -setup -{ - VACUUM ANALYZE sto1; -} - -teardown -{ - DROP TABLE sto1; -} - -session "s1" -setup { BEGIN ISOLATION LEVEL REPEATABLE READ; } -step "noseq" { SET enable_seqscan = false; } -step "s1f1" { SELECT c FROM sto1 where c = 1000; } -step "s1f2" { SELECT c FROM sto1 where c = 1001; } -teardown { ROLLBACK; } - -session "s2" -step "s2sleep" { SELECT setting, pg_sleep(6) FROM pg_settings WHERE name = 'old_snapshot_threshold'; } -step "s2u" { UPDATE sto1 SET c = 1001 WHERE c = 1000; } - -permutation "noseq" "s1f1" "s2sleep" "s2u" "s1f2" diff --git a/src/test/modules/snapshot_too_old/specs/sto_using_select.spec b/src/test/modules/snapshot_too_old/specs/sto_using_select.spec deleted file mode 100644 index 80a31763ad..0000000000 --- a/src/test/modules/snapshot_too_old/specs/sto_using_select.spec +++ /dev/null @@ -1,37 +0,0 @@ -# This test provokes a "snapshot too old" error using SELECT statements. -# -# The sleep is needed because with a threshold of zero a statement could error -# on changes it made. With more normal settings no external delay is needed, -# but we don't want these tests to run long enough to see that, since -# granularity is in minutes. -# -# Since results depend on the value of old_snapshot_threshold, sneak that into -# the line generated by the sleep, so that a surprising value isn't so hard -# to identify. - -setup -{ - CREATE TABLE sto1 (c int NOT NULL); - INSERT INTO sto1 SELECT generate_series(1, 1000); -} -setup -{ - VACUUM ANALYZE sto1; -} - -teardown -{ - DROP TABLE sto1; -} - -session "s1" -setup { BEGIN ISOLATION LEVEL REPEATABLE READ; } -step "s1f1" { SELECT c FROM sto1 ORDER BY c LIMIT 1; } -step "s1sleep" { SELECT setting, pg_sleep(6) FROM pg_settings WHERE name = 'old_snapshot_threshold'; } -step "s1f2" { SELECT c FROM sto1 ORDER BY c LIMIT 1; } -teardown { COMMIT; } - -session "s2" -step "s2u" { UPDATE sto1 SET c = 1001 WHERE c = 1; } - -permutation "s1f1" "s1sleep" "s2u" "s1f2" diff --git a/src/test/modules/snapshot_too_old/sto.conf b/src/test/modules/snapshot_too_old/sto.conf deleted file mode 100644 index 7eeaeeb0dc..0000000000 --- a/src/test/modules/snapshot_too_old/sto.conf +++ /dev/null @@ -1,2 +0,0 @@ -autovacuum = off -old_snapshot_threshold = 0 diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 260854747b..be7c2f18d5 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -1656,8 +1656,6 @@ OffsetVarNodes_context Oid OidOptions OkeysState -OldSnapshotControlData -OldSnapshotTimeMapping OldToNewMapping OldToNewMappingData OnCommitAction -- 2.39.2