From 1e1259df48373934be43049d8aa4dad328e96b96 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Mon, 5 Apr 2021 21:21:14 -0700 Subject: [PATCH] snapshot caching vs subtransactions. --- src/backend/storage/ipc/procarray.c | 8 ++++++ src/test/regress/expected/mvcc.out | 42 +++++++++++++++++++++++++++ src/test/regress/parallel_schedule | 2 +- src/test/regress/serial_schedule | 1 + src/test/regress/sql/mvcc.sql | 44 +++++++++++++++++++++++++++++ 5 files changed, 96 insertions(+), 1 deletion(-) create mode 100644 src/test/regress/expected/mvcc.out create mode 100644 src/test/regress/sql/mvcc.sql diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index e113a85aed4..bf776286de0 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -1210,6 +1210,11 @@ ProcArrayApplyRecoveryInfo(RunningTransactions running) */ MaintainLatestCompletedXidRecovery(running->latestCompletedXid); + /* + * NB: No need to increment ShmemVariableCache->xactCompletionCount here, + * nobody can see it yet. + */ + LWLockRelease(ProcArrayLock); /* ShmemVariableCache->nextXid must be beyond any observed xid. */ @@ -3915,6 +3920,9 @@ XidCacheRemoveRunningXids(TransactionId xid, /* Also advance global latestCompletedXid while holding the lock */ MaintainLatestCompletedXid(latestXid); + /* ... and xactCompletionCount */ + ShmemVariableCache->xactCompletionCount++; + LWLockRelease(ProcArrayLock); } diff --git a/src/test/regress/expected/mvcc.out b/src/test/regress/expected/mvcc.out new file mode 100644 index 00000000000..16ed4ddf2d8 --- /dev/null +++ b/src/test/regress/expected/mvcc.out @@ -0,0 +1,42 @@ +-- +-- Verify that index scans encountering dead rows produced by an +-- aborted subtransaction of the current transaction can utilize the +-- kill_prio_tuple optimization +-- +-- NB: The table size is currently *not* expected to stay the same, we +-- don't have logic to trigger opportunistic pruning in cases like +-- this. +BEGIN; +SET LOCAL enable_seqscan = false; +SET LOCAL enable_indexonlyscan = false; +SET LOCAL enable_bitmapscan = false; +-- Can't easily use a unique index, since dead tuples can be found +-- independent of the kill_prior_tuples optimization. +CREATE TABLE clean_aborted_self(key int, data text); +CREATE INDEX clean_aborted_self_key ON clean_aborted_self(key); +INSERT INTO clean_aborted_self (key, data) VALUES (-1, 'just to allocate metapage'); +-- save index size from before the changes, for comparison +SELECT pg_relation_size('clean_aborted_self_key') AS clean_aborted_self_key_before \gset +DO $$ +BEGIN + -- iterate often enough to see index growth even on larger-than-default page sizes + FOR i IN 1..100 LOOP + BEGIN + -- perform index scan over all the inserted keys to get them to be seen as dead + IF EXISTS(SELECT * FROM clean_aborted_self WHERE key > 0 AND key < 100) THEN + RAISE data_corrupted USING MESSAGE = 'these rows should not exist'; + END IF; + INSERT INTO clean_aborted_self SELECT g.i, 'rolling back in a sec' FROM generate_series(1, 100) g(i); + -- just some error that's not normally thrown + RAISE reading_sql_data_not_permitted USING MESSAGE = 'round and round again'; + EXCEPTION WHEN reading_sql_data_not_permitted THEN END; + END LOOP; +END;$$; +-- show sizes only if they differ +SELECT :clean_aborted_self_key_before AS size_before, pg_relation_size('clean_aborted_self_key') size_after +WHERE :clean_aborted_self_key_before != pg_relation_size('clean_aborted_self_key'); + size_before | size_after +-------------+------------ +(0 rows) + +ROLLBACK; diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule index 2e898390892..a0913008577 100644 --- a/src/test/regress/parallel_schedule +++ b/src/test/regress/parallel_schedule @@ -29,7 +29,7 @@ test: strings numerology point lseg line box path polygon circle date time timet # geometry depends on point, lseg, box, path, polygon and circle # horology depends on interval, timetz, timestamp, timestamptz # ---------- -test: geometry horology regex type_sanity opr_sanity misc_sanity comments expressions unicode xid +test: geometry horology regex type_sanity opr_sanity misc_sanity comments expressions unicode xid mvcc # ---------- # These four each depend on the previous one diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule index a46f3d01789..56448476015 100644 --- a/src/test/regress/serial_schedule +++ b/src/test/regress/serial_schedule @@ -11,6 +11,7 @@ test: int4 test: int8 test: oid test: xid +test: mvcc test: float4 test: float8 test: bit diff --git a/src/test/regress/sql/mvcc.sql b/src/test/regress/sql/mvcc.sql new file mode 100644 index 00000000000..b22a86dc5e5 --- /dev/null +++ b/src/test/regress/sql/mvcc.sql @@ -0,0 +1,44 @@ +-- +-- Verify that index scans encountering dead rows produced by an +-- aborted subtransaction of the current transaction can utilize the +-- kill_prio_tuple optimization +-- +-- NB: The table size is currently *not* expected to stay the same, we +-- don't have logic to trigger opportunistic pruning in cases like +-- this. +BEGIN; + +SET LOCAL enable_seqscan = false; +SET LOCAL enable_indexonlyscan = false; +SET LOCAL enable_bitmapscan = false; + +-- Can't easily use a unique index, since dead tuples can be found +-- independent of the kill_prior_tuples optimization. +CREATE TABLE clean_aborted_self(key int, data text); +CREATE INDEX clean_aborted_self_key ON clean_aborted_self(key); +INSERT INTO clean_aborted_self (key, data) VALUES (-1, 'just to allocate metapage'); + +-- save index size from before the changes, for comparison +SELECT pg_relation_size('clean_aborted_self_key') AS clean_aborted_self_key_before \gset + +DO $$ +BEGIN + -- iterate often enough to see index growth even on larger-than-default page sizes + FOR i IN 1..100 LOOP + BEGIN + -- perform index scan over all the inserted keys to get them to be seen as dead + IF EXISTS(SELECT * FROM clean_aborted_self WHERE key > 0 AND key < 100) THEN + RAISE data_corrupted USING MESSAGE = 'these rows should not exist'; + END IF; + INSERT INTO clean_aborted_self SELECT g.i, 'rolling back in a sec' FROM generate_series(1, 100) g(i); + -- just some error that's not normally thrown + RAISE reading_sql_data_not_permitted USING MESSAGE = 'round and round again'; + EXCEPTION WHEN reading_sql_data_not_permitted THEN END; + END LOOP; +END;$$; + +-- show sizes only if they differ +SELECT :clean_aborted_self_key_before AS size_before, pg_relation_size('clean_aborted_self_key') size_after +WHERE :clean_aborted_self_key_before != pg_relation_size('clean_aborted_self_key'); + +ROLLBACK; -- 2.31.0.121.g9198c13e34