From 7816d13563b74379c9db618e46883c6db5fc0680 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Thu, 24 Nov 2016 15:39:55 -0300 Subject: [PATCH] Fix commit_ts for FrozenXid and BootstrapXid Previously, requesting commit timestamp for transactions FrozenTransactionId and BootstrapTransactionId resulted in an error. But since those values can validly appear in committed tuples' Xmin, this behavior is unhelpful and error prone: each caller would have to special-case those values before requesting timestamp data for an Xid. We already have a perfectly good interface for returning "the Xid you requested is too old for us to have commit TS data for it", so let's use that instead. Backpatch to 9.5, where commit timestamps appeared. Author: Craig Ringer Discussion: https://www.postgresql.org/message-id/CAMsr+YFM5Q=+ry3mKvWEqRTxrB0iU3qUSRnS28nz6FJYtBwhJg@mail.gmail.com --- src/backend/access/transam/commit_ts.c | 11 +++++++++-- .../modules/commit_ts/expected/commit_timestamp.out | 12 ++++++++++-- .../commit_ts/expected/commit_timestamp_1.out | 12 ++++++++++-- 3 files changed, 29 insertions(+), 6 deletions(-) diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c index 38dba8cef4..eec7377975 100644 --- a/src/backend/access/transam/commit_ts.c +++ b/src/backend/access/transam/commit_ts.c @@ -288,11 +288,18 @@ TransactionIdGetCommitTsData(TransactionId xid, TimestampTz *ts, TransactionId oldestCommitTsXid; TransactionId newestCommitTsXid; - /* error if the given Xid doesn't normally commit */ - if (!TransactionIdIsNormal(xid)) + if (!TransactionIdIsValid(xid)) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("cannot retrieve commit timestamp for transaction %u", xid))); + else if (!TransactionIdIsNormal(xid)) + { + /* frozen and bootstrap xids are always committed far in the past */ + *ts = 0; + if (nodeid) + *nodeid = 0; + return false; + } LWLockAcquire(CommitTsLock, LW_SHARED); diff --git a/src/test/modules/commit_ts/expected/commit_timestamp.out b/src/test/modules/commit_ts/expected/commit_timestamp.out index 99f3322c42..5b7783b58f 100644 --- a/src/test/modules/commit_ts/expected/commit_timestamp.out +++ b/src/test/modules/commit_ts/expected/commit_timestamp.out @@ -28,9 +28,17 @@ DROP TABLE committs_test; SELECT pg_xact_commit_timestamp('0'::xid); ERROR: cannot retrieve commit timestamp for transaction 0 SELECT pg_xact_commit_timestamp('1'::xid); -ERROR: cannot retrieve commit timestamp for transaction 1 + pg_xact_commit_timestamp +-------------------------- + +(1 row) + SELECT pg_xact_commit_timestamp('2'::xid); -ERROR: cannot retrieve commit timestamp for transaction 2 + pg_xact_commit_timestamp +-------------------------- + +(1 row) + SELECT x.xid::text::bigint > 0, x.timestamp > '-infinity'::timestamptz, x.timestamp <= now() FROM pg_last_committed_xact() x; ?column? | ?column? | ?column? ----------+----------+---------- diff --git a/src/test/modules/commit_ts/expected/commit_timestamp_1.out b/src/test/modules/commit_ts/expected/commit_timestamp_1.out index 2f1f41d209..c10b0abc2b 100644 --- a/src/test/modules/commit_ts/expected/commit_timestamp_1.out +++ b/src/test/modules/commit_ts/expected/commit_timestamp_1.out @@ -23,9 +23,17 @@ DROP TABLE committs_test; SELECT pg_xact_commit_timestamp('0'::xid); ERROR: cannot retrieve commit timestamp for transaction 0 SELECT pg_xact_commit_timestamp('1'::xid); -ERROR: cannot retrieve commit timestamp for transaction 1 + pg_xact_commit_timestamp +-------------------------- + +(1 row) + SELECT pg_xact_commit_timestamp('2'::xid); -ERROR: cannot retrieve commit timestamp for transaction 2 + pg_xact_commit_timestamp +-------------------------- + +(1 row) + SELECT x.xid::text::bigint > 0, x.timestamp > '-infinity'::timestamptz, x.timestamp <= now() FROM pg_last_committed_xact() x; ERROR: could not get commit timestamp data HINT: Make sure the configuration parameter "track_commit_timestamp" is set.