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| author | Alexander Korotkov <akorotkov@postgresql.org> | 2020-04-07 23:51:10 +0300 |
|---|---|---|
| committer | Alexander Korotkov <akorotkov@postgresql.org> | 2020-04-07 23:51:10 +0300 |
| commit | 0f5ca02f53ac2b211d8518f0882c49284c0c9610 (patch) | |
| tree | a5dce13eaa64e00a6ec95b913a155efe7f91c99c /src/backend/access/transam/xlog.c | |
| parent | 357889eb17bb9c9336c4f324ceb1651da616fe57 (diff) | |
| download | postgresql-0f5ca02f53ac2b211d8518f0882c49284c0c9610.tar.gz postgresql-0f5ca02f53ac2b211d8518f0882c49284c0c9610.zip | |
Implement waiting for given lsn at transaction start
This commit adds following optional clause to BEGIN and START TRANSACTION
commands.
WAIT FOR LSN lsn [ TIMEOUT timeout ]
New clause pospones transaction start till given lsn is applied on standby.
This clause allows user be sure, that changes previously made on primary would
be visible on standby.
New shared memory struct is used to track awaited lsn per backend. Recovery
process wakes up backend once required lsn is applied.
Author: Ivan Kartyshov, Anna Akenteva
Reviewed-by: Craig Ringer, Thomas Munro, Robert Haas, Kyotaro Horiguchi
Reviewed-by: Masahiko Sawada, Ants Aasma, Dmitry Ivanov, Simon Riggs
Reviewed-by: Amit Kapila, Alexander Korotkov
Discussion: https://postgr.es/m/0240c26c-9f84-30ea-fca9-93ab2df5f305%40postgrespro.ru
Diffstat (limited to 'src/backend/access/transam/xlog.c')
| -rw-r--r-- | src/backend/access/transam/xlog.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index ec55d68d272..1651e15e898 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -42,6 +42,7 @@ #include "catalog/pg_database.h" #include "commands/progress.h" #include "commands/tablespace.h" +#include "commands/wait.h" #include "common/controldata_utils.h" #include "executor/instrument.h" #include "miscadmin.h" @@ -7154,6 +7155,7 @@ StartupXLOG(void) do { bool switchedTLI = false; + XLogRecPtr minWaitedLSN; #ifdef WAL_DEBUG if (XLOG_DEBUG || @@ -7357,6 +7359,17 @@ StartupXLOG(void) break; } + /* + * If we replayed an LSN that someone was waiting for, set + * latches in shared memory array to notify the waiter. + */ + minWaitedLSN = WaitLSNGetMin(); + if (!XLogRecPtrIsInvalid(minWaitedLSN) && + minWaitedLSN <= XLogCtl->lastReplayedEndRecPtr) + { + WaitLSNSetLatch(XLogCtl->lastReplayedEndRecPtr); + } + /* Else, try to fetch the next WAL record */ record = ReadRecord(xlogreader, LOG, false); } while (record != NULL); |