Implement pg_wal_replay_wait() stored procedure
pg_wal_replay_wait() is to be used on standby and specifies waiting for the specific WAL location to be replayed before starting the transaction. This option is useful when the user makes some data changes on primary and needs a guarantee to see these changes on standby. The queue of waiters is stored in the shared memory array sorted by LSN. During replay of WAL waiters whose LSNs are already replayed are deleted from the shared memory array and woken up by setting of their latches. pg_wal_replay_wait() needs to wait without any snapshot held. Otherwise, the snapshot could prevent the replay of WAL records implying a kind of self-deadlock. This is why it is only possible to implement pg_wal_replay_wait() as a procedure working in a non-atomic context, not a function. Catversion is bumped. Discussion: https://postgr.es/m/eb12f9b03851bb2583adab5df9579b4b%40postgrespro.ru Author: Kartyshov Ivan, Alexander Korotkov Reviewed-by: Michael Paquier, Peter Eisentraut, Dilip Kumar, Amit Kapila Reviewed-by: Alexander Lakhin, Bharath Rupireddy, Euler Taveira
This commit is contained in:
Alexander Korotkov
parent
6faca9ae28
commit
06c418e163
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@ -28284,6 +28284,119 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
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the pause, the rate of WAL generation and available disk space.
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</para>
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<para>
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There are also procedures to control the progress of recovery.
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They are shown in <xref linkend="procedures-recovery-control-table"/>.
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These procedures may be executed only during recovery.
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</para>
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<table id="procedures-recovery-control-table">
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<title>Recovery Control Procedures</title>
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<tgroup cols="1">
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<thead>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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Procedure
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</para>
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<para>
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Description
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</para></entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry role="func_table_entry"><para role="func_signature">
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<indexterm>
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<primary>pg_wal_replay_wait</primary>
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</indexterm>
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<function>pg_wal_replay_wait</function> (
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<parameter>target_lsn</parameter> <type>pg_lsn</type>,
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<parameter>timeout</parameter> <type>bigint</type> <literal>DEFAULT</literal> <literal>0</literal>)
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<returnvalue>void</returnvalue>
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</para>
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<para>
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If <parameter>timeout</parameter> is not specified or zero, this
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procedure returns once WAL is replayed upto
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<literal>target_lsn</literal>.
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If the <parameter>timeout</parameter> is specified (in
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milliseconds) and greater than zero, the procedure waits until the
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server actually replays the WAL upto <literal>target_lsn</literal> or
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until the given time has passed. On timeout, an error is emitted.
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</para></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para>
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<function>pg_wal_replay_wait</function> waits till
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<parameter>target_lsn</parameter> to be replayed on standby.
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That is, after this function execution, the value returned by
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<function>pg_last_wal_replay_lsn</function> should be greater or equal
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to the <parameter>target_lsn</parameter> value. This is useful to achieve
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read-your-writes-consistency, while using async replica for reads and
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primary for writes. In that case <acronym>lsn</acronym> of the last
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modification should be stored on the client application side or the
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connection pooler side.
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</para>
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<para>
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You can use <function>pg_wal_replay_wait</function> to wait for
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the <type>pg_lsn</type> value. For example, an application could update
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the <literal>movie</literal> table and get the <acronym>lsn</acronym> after
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changes just made. This example uses <function>pg_current_wal_insert_lsn</function>
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on primary server to get the <acronym>lsn</acronym> given that
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<varname>synchronous_commit</varname> could be set to
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<literal>off</literal>.
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<programlisting>
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postgres=# UPDATE movie SET genre = 'Dramatic' WHERE genre = 'Drama';
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UPDATE 100
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postgres=# SELECT pg_current_wal_insert_lsn();
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pg_current_wal_insert_lsn
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--------------------
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0/306EE20
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(1 row)
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</programlisting>
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Then an application could run <function>pg_wal_replay_wait</function>
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with the <acronym>lsn</acronym> obtained from primary. After that the
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changes made of primary should be guaranteed to be visible on replica.
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<programlisting>
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postgres=# CALL pg_wal_replay_wait('0/306EE20');
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CALL
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postgres=# SELECT * FROM movie WHERE genre = 'Drama';
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genre
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-------
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(0 rows)
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</programlisting>
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It may also happen that target <acronym>lsn</acronym> is not achieved
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within the timeout. In that case the error is thrown.
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<programlisting>
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postgres=# CALL pg_wal_replay_wait('0/306EE20', 100);
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ERROR: timed out while waiting for target LSN 0/306EE20 to be replayed; current replay LSN 0/306EA60
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</programlisting>
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</para>
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<para>
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<function>pg_wal_replay_wait</function> can't be used within
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the transaction, another procedure or function. Any of them holds a
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snapshot, which could prevent the replay of WAL records.
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<programlisting>
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postgres=# BEGIN;
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BEGIN
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postgres=*# CALL pg_wal_replay_wait('0/306EE20');
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ERROR: pg_wal_replay_wait() must be only called in non-atomic context
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DETAIL: Make sure pg_wal_replay_wait() isn't called within a transaction, another procedure, or a function.
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</programlisting>
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</para>
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</sect2>
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<sect2 id="functions-snapshot-synchronization">
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@ -66,6 +66,7 @@
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#include "catalog/catversion.h"
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#include "catalog/pg_control.h"
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#include "catalog/pg_database.h"
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#include "commands/waitlsn.h"
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#include "common/controldata_utils.h"
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#include "common/file_utils.h"
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#include "executor/instrument.h"
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@ -6040,6 +6041,12 @@ StartupXLOG(void)
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UpdateControlFile();
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LWLockRelease(ControlFileLock);
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/*
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* Wake up all waiters for replay LSN. They need to report an error that
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* recovery was ended before achieving the target LSN.
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*/
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WaitLSNSetLatches(InvalidXLogRecPtr);
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/*
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* Shutdown the recovery environment. This must occur after
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* RecoverPreparedTransactions() (see notes in lock_twophase_recover())
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@ -43,6 +43,7 @@
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#include "backup/basebackup.h"
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#include "catalog/pg_control.h"
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#include "commands/tablespace.h"
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#include "commands/waitlsn.h"
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#include "common/file_utils.h"
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#include "miscadmin.h"
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#include "pgstat.h"
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@ -1828,6 +1829,16 @@ PerformWalRecovery(void)
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break;
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}
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/*
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* If we replayed an LSN that someone was waiting for then walk
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* over the shared memory array and set latches to notify the
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* waiters.
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*/
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if (waitLSN &&
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(XLogRecoveryCtl->lastReplayedEndRecPtr >=
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pg_atomic_read_u64(&waitLSN->minLSN)))
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WaitLSNSetLatches(XLogRecoveryCtl->lastReplayedEndRecPtr);
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/* Else, try to fetch the next WAL record */
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record = ReadRecord(xlogprefetcher, LOG, false, replayTLI);
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} while (record != NULL);
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@ -414,6 +414,9 @@ CREATE OR REPLACE FUNCTION
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json_populate_recordset(base anyelement, from_json json, use_json_as_text boolean DEFAULT false)
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RETURNS SETOF anyelement LANGUAGE internal STABLE ROWS 100 AS 'json_populate_recordset' PARALLEL SAFE;
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CREATE OR REPLACE PROCEDURE pg_wal_replay_wait(target_lsn pg_lsn, timeout int8 DEFAULT 0)
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LANGUAGE internal AS 'pg_wal_replay_wait';
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CREATE OR REPLACE FUNCTION pg_logical_slot_get_changes(
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IN slot_name name, IN upto_lsn pg_lsn, IN upto_nchanges int, VARIADIC options text[] DEFAULT '{}',
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OUT lsn pg_lsn, OUT xid xid, OUT data text)
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@ -61,6 +61,7 @@ OBJS = \
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vacuum.o \
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vacuumparallel.o \
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variable.o \
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view.o
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view.o \
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waitlsn.o
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include $(top_srcdir)/src/backend/common.mk
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@ -50,4 +50,5 @@ backend_sources += files(
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'vacuumparallel.c',
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'variable.c',
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'view.c',
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'waitlsn.c',
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)
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@ -0,0 +1,348 @@
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/*-------------------------------------------------------------------------
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*
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* waitlsn.c
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* Implements waiting for the given LSN, which is used in
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* CALL pg_wal_replay_wait(target_lsn pg_lsn, timeout float8).
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*
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* Copyright (c) 2024, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/commands/waitlsn.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <float.h>
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#include <math.h>
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#include "pgstat.h"
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#include "fmgr.h"
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#include "access/transam.h"
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#include "access/xact.h"
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#include "access/xlog.h"
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#include "access/xlogdefs.h"
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#include "access/xlogrecovery.h"
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#include "catalog/pg_type.h"
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#include "commands/waitlsn.h"
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#include "executor/spi.h"
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#include "funcapi.h"
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#include "miscadmin.h"
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#include "storage/ipc.h"
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#include "storage/latch.h"
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#include "storage/pmsignal.h"
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#include "storage/proc.h"
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#include "storage/shmem.h"
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#include "storage/sinvaladt.h"
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#include "utils/builtins.h"
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#include "utils/pg_lsn.h"
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#include "utils/snapmgr.h"
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#include "utils/timestamp.h"
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#include "utils/fmgrprotos.h"
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/* Add to / delete from shared memory array */
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static void addLSNWaiter(XLogRecPtr lsn);
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static void deleteLSNWaiter(void);
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struct WaitLSNState *waitLSN = NULL;
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static volatile sig_atomic_t haveShmemItem = false;
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/*
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* Report the amount of shared memory space needed for WaitLSNState
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*/
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Size
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WaitLSNShmemSize(void)
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{
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Size size;
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size = offsetof(WaitLSNState, procInfos);
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size = add_size(size, mul_size(MaxBackends, sizeof(WaitLSNProcInfo)));
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return size;
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}
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/* Initialize the WaitLSNState in the shared memory */
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void
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WaitLSNShmemInit(void)
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{
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bool found;
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waitLSN = (WaitLSNState *) ShmemInitStruct("WaitLSNState",
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WaitLSNShmemSize(),
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&found);
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if (!found)
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{
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SpinLockInit(&waitLSN->mutex);
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waitLSN->numWaitedProcs = 0;
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pg_atomic_init_u64(&waitLSN->minLSN, PG_UINT64_MAX);
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}
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}
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/*
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* Add the information about the LSN waiter backend to the shared memory
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* array.
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*/
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static void
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addLSNWaiter(XLogRecPtr lsn)
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{
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WaitLSNProcInfo cur;
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int i;
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SpinLockAcquire(&waitLSN->mutex);
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cur.procnum = MyProcNumber;
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cur.waitLSN = lsn;
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for (i = 0; i < waitLSN->numWaitedProcs; i++)
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{
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if (waitLSN->procInfos[i].waitLSN >= cur.waitLSN)
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{
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WaitLSNProcInfo tmp;
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tmp = waitLSN->procInfos[i];
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waitLSN->procInfos[i] = cur;
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cur = tmp;
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}
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}
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waitLSN->procInfos[i] = cur;
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waitLSN->numWaitedProcs++;
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pg_atomic_write_u64(&waitLSN->minLSN, waitLSN->procInfos[i].waitLSN);
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SpinLockRelease(&waitLSN->mutex);
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}
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/*
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* Delete the information about the LSN waiter backend from the shared memory
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* array.
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*/
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static void
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deleteLSNWaiter(void)
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{
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int i;
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bool found = false;
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SpinLockAcquire(&waitLSN->mutex);
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for (i = 0; i < waitLSN->numWaitedProcs; i++)
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{
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if (waitLSN->procInfos[i].procnum == MyProcNumber)
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found = true;
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if (found && i < waitLSN->numWaitedProcs - 1)
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{
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waitLSN->procInfos[i] = waitLSN->procInfos[i + 1];
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}
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}
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if (!found)
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{
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SpinLockRelease(&waitLSN->mutex);
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return;
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}
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waitLSN->numWaitedProcs--;
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if (waitLSN->numWaitedProcs != 0)
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pg_atomic_write_u64(&waitLSN->minLSN, waitLSN->procInfos[i].waitLSN);
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else
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pg_atomic_write_u64(&waitLSN->minLSN, PG_UINT64_MAX);
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SpinLockRelease(&waitLSN->mutex);
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}
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/*
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* Set latches of LSN waiters whose LSN has been replayed. Set latches of all
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* LSN waiters when InvalidXLogRecPtr is given.
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*/
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void
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WaitLSNSetLatches(XLogRecPtr currentLSN)
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{
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int i;
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int *wakeUpProcNums;
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int numWakeUpProcs;
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wakeUpProcNums = palloc(sizeof(int) * MaxBackends);
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SpinLockAcquire(&waitLSN->mutex);
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/*
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* Remember processes, whose waited LSNs are already replayed. We should
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* set their latches later after spinlock release.
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*/
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for (i = 0; i < waitLSN->numWaitedProcs; i++)
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{
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if (!XLogRecPtrIsInvalid(currentLSN) &&
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waitLSN->procInfos[i].waitLSN > currentLSN)
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break;
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wakeUpProcNums[i] = waitLSN->procInfos[i].procnum;
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}
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/*
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* Immediately remove those processes from the shmem array. Otherwise,
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* shmem array items will be here till corresponding processes wake up and
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* delete themselves.
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*/
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numWakeUpProcs = i;
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for (i = 0; i < waitLSN->numWaitedProcs - numWakeUpProcs; i++)
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waitLSN->procInfos[i] = waitLSN->procInfos[i + numWakeUpProcs];
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waitLSN->numWaitedProcs -= numWakeUpProcs;
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if (waitLSN->numWaitedProcs != 0)
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pg_atomic_write_u64(&waitLSN->minLSN, waitLSN->procInfos[i].waitLSN);
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else
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pg_atomic_write_u64(&waitLSN->minLSN, PG_UINT64_MAX);
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SpinLockRelease(&waitLSN->mutex);
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/*
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* Set latches for processes, whose waited LSNs are already replayed. This
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* involves spinlocks. So, we shouldn't do this under a spinlock.
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*/
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for (i = 0; i < numWakeUpProcs; i++)
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{
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PGPROC *backend;
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backend = GetPGProcByNumber(wakeUpProcNums[i]);
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SetLatch(&backend->procLatch);
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}
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pfree(wakeUpProcNums);
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}
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/*
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* Delete our item from shmem array if any.
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*/
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void
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WaitLSNCleanup(void)
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{
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if (haveShmemItem)
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deleteLSNWaiter();
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}
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/*
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* Wait using MyLatch till the given LSN is replayed, the postmaster dies or
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* timeout happens.
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*/
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void
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WaitForLSN(XLogRecPtr targetLSN, int64 timeout)
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{
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XLogRecPtr currentLSN;
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TimestampTz endtime;
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/* Shouldn't be called when shmem isn't initialized */
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Assert(waitLSN);
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/* Should be only called by a backend */
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Assert(MyBackendType == B_BACKEND);
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if (!RecoveryInProgress())
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ereport(ERROR,
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(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
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errmsg("recovery is not in progress"),
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errhint("Waiting for LSN can only be executed during recovery.")));
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/* If target LSN is already replayed, exit immediately */
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if (targetLSN <= GetXLogReplayRecPtr(NULL))
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return;
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if (timeout > 0)
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endtime = TimestampTzPlusMilliseconds(GetCurrentTimestamp(), timeout);
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addLSNWaiter(targetLSN);
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haveShmemItem = true;
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for (;;)
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{
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int rc;
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int latch_events = WL_LATCH_SET | WL_EXIT_ON_PM_DEATH;
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long delay_ms = 0;
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/* Check if the waited LSN has been replayed */
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currentLSN = GetXLogReplayRecPtr(NULL);
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if (targetLSN <= currentLSN)
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break;
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|
||||
/* Recheck that recovery is still in-progress */
|
||||
if (!RecoveryInProgress())
|
||||
ereport(ERROR,
|
||||
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
|
||||
errmsg("recovery is not in progress"),
|
||||
errdetail("Recovery ended before replaying the target LSN %X/%X; last replay LSN %X/%X.",
|
||||
LSN_FORMAT_ARGS(targetLSN),
|
||||
LSN_FORMAT_ARGS(currentLSN))));
|
||||
|
||||
if (timeout > 0)
|
||||
{
|
||||
delay_ms = (endtime - GetCurrentTimestamp()) / 1000;
|
||||
latch_events |= WL_TIMEOUT;
|
||||
if (delay_ms <= 0)
|
||||
break;
|
||||
}
|
||||
|
||||
CHECK_FOR_INTERRUPTS();
|
||||
|
||||
rc = WaitLatch(MyLatch, latch_events, delay_ms,
|
||||
WAIT_EVENT_WAIT_FOR_WAL_REPLAY);
|
||||
|
||||
if (rc & WL_LATCH_SET)
|
||||
ResetLatch(MyLatch);
|
||||
}
|
||||
|
||||
if (targetLSN > currentLSN)
|
||||
{
|
||||
deleteLSNWaiter();
|
||||
haveShmemItem = false;
|
||||
ereport(ERROR,
|
||||
(errcode(ERRCODE_QUERY_CANCELED),
|
||||
errmsg("timed out while waiting for target LSN %X/%X to be replayed; current replay LSN %X/%X",
|
||||
LSN_FORMAT_ARGS(targetLSN),
|
||||
LSN_FORMAT_ARGS(currentLSN))));
|
||||
}
|
||||
else
|
||||
{
|
||||
haveShmemItem = false;
|
||||
}
|
||||
}
|
||||
|
||||
Datum
|
||||
pg_wal_replay_wait(PG_FUNCTION_ARGS)
|
||||
{
|
||||
XLogRecPtr target_lsn = PG_GETARG_LSN(0);
|
||||
int64 timeout = PG_GETARG_INT64(1);
|
||||
CallContext *context = (CallContext *) fcinfo->context;
|
||||
|
||||
if (timeout < 0)
|
||||
ereport(ERROR,
|
||||
(errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),
|
||||
errmsg("\"timeout\" must not be negative")));
|
||||
|
||||
/*
|
||||
* We are going to wait for the LSN replay. We should first care that we
|
||||
* don't hold a snapshot and correspondingly our MyProc->xmin is invalid.
|
||||
* Otherwise, our snapshot could prevent the replay of WAL records
|
||||
* implying a kind of self-deadlock. This is the reason why
|
||||
* pg_wal_replay_wait() is a procedure, not a function.
|
||||
*
|
||||
* At first, we check that pg_wal_replay_wait() is called in a non-atomic
|
||||
* context. That is, a procedure call isn't wrapped into a transaction,
|
||||
* another procedure call, or a function call.
|
||||
*
|
||||
* Secondly, according to PlannedStmtRequiresSnapshot(), even in an atomic
|
||||
* context, CallStmt is processed with a snapshot. Thankfully, we can pop
|
||||
* this snapshot, because PortalRunUtility() can tolerate this.
|
||||
*/
|
||||
if (context->atomic)
|
||||
ereport(ERROR,
|
||||
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
|
||||
errmsg("pg_wal_replay_wait() must be only called in non-atomic context"),
|
||||
errdetail("Make sure pg_wal_replay_wait() isn't called within a transaction, another procedure, or a function.")));
|
||||
|
||||
if (ActiveSnapshotSet())
|
||||
PopActiveSnapshot();
|
||||
Assert(!ActiveSnapshotSet());
|
||||
InvalidateCatalogSnapshot();
|
||||
Assert(MyProc->xmin == InvalidTransactionId);
|
||||
|
||||
(void) WaitForLSN(target_lsn, timeout);
|
||||
|
||||
PG_RETURN_VOID();
|
||||
}
|
||||
|
|
@ -25,6 +25,7 @@
|
|||
#include "access/xlogprefetcher.h"
|
||||
#include "access/xlogrecovery.h"
|
||||
#include "commands/async.h"
|
||||
#include "commands/waitlsn.h"
|
||||
#include "miscadmin.h"
|
||||
#include "pgstat.h"
|
||||
#include "postmaster/autovacuum.h"
|
||||
|
|
@ -152,6 +153,7 @@ CalculateShmemSize(int *num_semaphores)
|
|||
size = add_size(size, WaitEventExtensionShmemSize());
|
||||
size = add_size(size, InjectionPointShmemSize());
|
||||
size = add_size(size, SlotSyncShmemSize());
|
||||
size = add_size(size, WaitLSNShmemSize());
|
||||
#ifdef EXEC_BACKEND
|
||||
size = add_size(size, ShmemBackendArraySize());
|
||||
#endif
|
||||
|
|
@ -244,6 +246,11 @@ CreateSharedMemoryAndSemaphores(void)
|
|||
/* Initialize subsystems */
|
||||
CreateOrAttachShmemStructs();
|
||||
|
||||
/*
|
||||
* Init array of Latches in shared memory for wait lsn
|
||||
*/
|
||||
WaitLSNShmemInit();
|
||||
|
||||
#ifdef EXEC_BACKEND
|
||||
|
||||
/*
|
||||
|
|
|
|||
|
|
@ -36,6 +36,7 @@
|
|||
#include "access/transam.h"
|
||||
#include "access/twophase.h"
|
||||
#include "access/xlogutils.h"
|
||||
#include "commands/waitlsn.h"
|
||||
#include "miscadmin.h"
|
||||
#include "pgstat.h"
|
||||
#include "postmaster/autovacuum.h"
|
||||
|
|
@ -862,6 +863,11 @@ ProcKill(int code, Datum arg)
|
|||
*/
|
||||
LWLockReleaseAll();
|
||||
|
||||
/*
|
||||
* Cleanup waiting for LSN if any.
|
||||
*/
|
||||
WaitLSNCleanup();
|
||||
|
||||
/* Cancel any pending condition variable sleep, too */
|
||||
ConditionVariableCancelSleep();
|
||||
|
||||
|
|
|
|||
|
|
@ -79,6 +79,7 @@ LIBPQWALRECEIVER_CONNECT "Waiting in WAL receiver to establish connection to rem
|
|||
LIBPQWALRECEIVER_RECEIVE "Waiting in WAL receiver to receive data from remote server."
|
||||
SSL_OPEN_SERVER "Waiting for SSL while attempting connection."
|
||||
WAIT_FOR_STANDBY_CONFIRMATION "Waiting for WAL to be received and flushed by the physical standby."
|
||||
WAIT_FOR_WAL_REPLAY "Waiting for a replay of the particular WAL position on the physical standby."
|
||||
WAL_SENDER_WAIT_FOR_WAL "Waiting for WAL to be flushed in WAL sender process."
|
||||
WAL_SENDER_WRITE_DATA "Waiting for any activity when processing replies from WAL receiver in WAL sender process."
|
||||
|
||||
|
|
|
|||
|
|
@ -57,6 +57,6 @@
|
|||
*/
|
||||
|
||||
/* yyyymmddN */
|
||||
#define CATALOG_VERSION_NO 202404021
|
||||
#define CATALOG_VERSION_NO 202404022
|
||||
|
||||
#endif
|
||||
|
|
|
|||
|
|
@ -12153,6 +12153,11 @@
|
|||
prorettype => 'bytea', proargtypes => 'pg_brin_minmax_multi_summary',
|
||||
prosrc => 'brin_minmax_multi_summary_send' },
|
||||
|
||||
{ oid => '16387', descr => 'wait for LSN with timeout',
|
||||
proname => 'pg_wal_replay_wait', prokind => 'p', prorettype => 'void',
|
||||
proargtypes => 'pg_lsn int8', proargnames => '{target_lsn,timeout}',
|
||||
prosrc => 'pg_wal_replay_wait' },
|
||||
|
||||
{ oid => '6291', descr => 'arbitrary value from among input values',
|
||||
proname => 'any_value', prokind => 'a', proisstrict => 'f',
|
||||
prorettype => 'anyelement', proargtypes => 'anyelement',
|
||||
|
|
|
|||
|
|
@ -0,0 +1,43 @@
|
|||
/*-------------------------------------------------------------------------
|
||||
*
|
||||
* waitlsn.h
|
||||
* Declarations for LSN waiting routines.
|
||||
*
|
||||
* Copyright (c) 2024, PostgreSQL Global Development Group
|
||||
*
|
||||
* src/include/commands/waitlsn.h
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
#ifndef WAIT_LSN_H
|
||||
#define WAIT_LSN_H
|
||||
|
||||
#include "postgres.h"
|
||||
#include "port/atomics.h"
|
||||
#include "storage/spin.h"
|
||||
#include "tcop/dest.h"
|
||||
|
||||
/* Shared memory structures */
|
||||
typedef struct WaitLSNProcInfo
|
||||
{
|
||||
int procnum;
|
||||
XLogRecPtr waitLSN;
|
||||
} WaitLSNProcInfo;
|
||||
|
||||
typedef struct WaitLSNState
|
||||
{
|
||||
pg_atomic_uint64 minLSN;
|
||||
slock_t mutex;
|
||||
int numWaitedProcs;
|
||||
WaitLSNProcInfo procInfos[FLEXIBLE_ARRAY_MEMBER];
|
||||
} WaitLSNState;
|
||||
|
||||
extern PGDLLIMPORT struct WaitLSNState *waitLSN;
|
||||
|
||||
extern void WaitForLSN(XLogRecPtr targetLSN, int64 timeout);
|
||||
extern Size WaitLSNShmemSize(void);
|
||||
extern void WaitLSNShmemInit(void);
|
||||
extern void WaitLSNSetLatches(XLogRecPtr currentLSN);
|
||||
extern void WaitLSNCleanup(void);
|
||||
|
||||
#endif /* WAIT_LSN_H */
|
||||
|
|
@ -51,6 +51,7 @@ tests += {
|
|||
't/040_standby_failover_slots_sync.pl',
|
||||
't/041_checkpoint_at_promote.pl',
|
||||
't/042_low_level_backup.pl',
|
||||
't/043_wal_replay_wait.pl',
|
||||
],
|
||||
},
|
||||
}
|
||||
|
|
|
|||
|
|
@ -0,0 +1,97 @@
|
|||
# Checks waiting for the lsn replay on standby using
|
||||
# pg_wal_replay_wait() procedure.
|
||||
use strict;
|
||||
use warnings;
|
||||
|
||||
use PostgreSQL::Test::Cluster;
|
||||
use PostgreSQL::Test::Utils;
|
||||
use Test::More;
|
||||
|
||||
# Initialize primary node
|
||||
my $node_primary = PostgreSQL::Test::Cluster->new('primary');
|
||||
$node_primary->init(allows_streaming => 1);
|
||||
$node_primary->start;
|
||||
|
||||
# And some content and take a backup
|
||||
$node_primary->safe_psql('postgres',
|
||||
"CREATE TABLE wait_test AS SELECT generate_series(1,10) AS a");
|
||||
my $backup_name = 'my_backup';
|
||||
$node_primary->backup($backup_name);
|
||||
|
||||
# Create a streaming standby with a 1 second delay from the backup
|
||||
my $node_standby = PostgreSQL::Test::Cluster->new('standby');
|
||||
my $delay = 1;
|
||||
$node_standby->init_from_backup($node_primary, $backup_name,
|
||||
has_streaming => 1);
|
||||
$node_standby->append_conf(
|
||||
'postgresql.conf', qq[
|
||||
recovery_min_apply_delay = '${delay}s'
|
||||
]);
|
||||
$node_standby->start;
|
||||
|
||||
|
||||
# Make sure that pg_wal_replay_wait() works: add new content to
|
||||
# primary and memorize primary's insert LSN, then wait for that LSN to be
|
||||
# replayed on standby.
|
||||
$node_primary->safe_psql('postgres',
|
||||
"INSERT INTO wait_test VALUES (generate_series(11, 20))");
|
||||
my $lsn1 =
|
||||
$node_primary->safe_psql('postgres', "SELECT pg_current_wal_insert_lsn()");
|
||||
my $output = $node_standby->safe_psql(
|
||||
'postgres', qq[
|
||||
CALL pg_wal_replay_wait('${lsn1}', 1000000);
|
||||
SELECT pg_lsn_cmp(pg_last_wal_replay_lsn(), '${lsn1}'::pg_lsn);
|
||||
]);
|
||||
|
||||
# Make sure the current LSN on standby is at least as big as the LSN we
|
||||
# observed on primary's before.
|
||||
ok($output >= 0,
|
||||
"standby reached the same LSN as primary after pg_wal_replay_wait()");
|
||||
|
||||
# Check that new data is visible after calling pg_wal_replay_wait()
|
||||
$node_primary->safe_psql('postgres',
|
||||
"INSERT INTO wait_test VALUES (generate_series(21, 30))");
|
||||
my $lsn2 =
|
||||
$node_primary->safe_psql('postgres', "SELECT pg_current_wal_insert_lsn()");
|
||||
$output = $node_standby->safe_psql(
|
||||
'postgres', qq[
|
||||
CALL pg_wal_replay_wait('${lsn2}');
|
||||
SELECT count(*) FROM wait_test;
|
||||
]);
|
||||
|
||||
# Make sure the current LSN on standby and is the same as primary's LSN
|
||||
ok($output eq 30, "standby reached the same LSN as primary");
|
||||
|
||||
# Check that waiting for unreachable LSN triggers the timeout. The
|
||||
# unreachable LSN must be well in advance. So WAL records issued by
|
||||
# the concurrent autovacuum could not affect that.
|
||||
my $lsn3 =
|
||||
$node_primary->safe_psql('postgres',
|
||||
"SELECT pg_current_wal_insert_lsn() + 10000000000");
|
||||
my $stderr;
|
||||
$node_standby->safe_psql('postgres',
|
||||
"CALL pg_wal_replay_wait('${lsn2}', 10);");
|
||||
$node_standby->psql(
|
||||
'postgres',
|
||||
"CALL pg_wal_replay_wait('${lsn3}', 1000);",
|
||||
stderr => \$stderr);
|
||||
ok( $stderr =~ /timed out while waiting for target LSN/,
|
||||
"get timeout on waiting for unreachable LSN");
|
||||
|
||||
# Check that the standby promotion terminates the wait on LSN. Start
|
||||
# waiting for unreachable LSN then promote. Check the log for the relevant
|
||||
# error message.
|
||||
my $psql_session = $node_standby->background_psql('postgres');
|
||||
$psql_session->query_until(
|
||||
qr/start/, qq[
|
||||
\\echo start
|
||||
CALL pg_wal_replay_wait('${lsn3}');
|
||||
]);
|
||||
|
||||
my $log_offset = -s $node_standby->logfile;
|
||||
$node_standby->promote;
|
||||
$node_standby->wait_for_log('recovery is not in progress', $log_offset);
|
||||
|
||||
$node_standby->stop;
|
||||
$node_primary->stop;
|
||||
done_testing();
|
||||
|
|
@ -3059,6 +3059,8 @@ WaitEventIO
|
|||
WaitEventIPC
|
||||
WaitEventSet
|
||||
WaitEventTimeout
|
||||
WaitLSNProcInfo
|
||||
WaitLSNState
|
||||
WaitPMResult
|
||||
WalCloseMethod
|
||||
WalCompression
|
||||
|
|
|
|||
Loading…
Reference in New Issue