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Teach xlogreader to follow timeline switches

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Uses page-based mechanism to ensure we’re using the correct timeline.

Tests are included to exercise the functionality using a cold disk-level copy
of the master that's started up as a replica with slots intact, but the
intended use of the functionality is with later features.

Craig Ringer, reviewed by Simon Riggs and Andres Freund
This commit is contained in:
Simon Riggs
2017-03-22 07:05:12 +00:00
parent 9ca2dd578d
commit 1148e22a82
7 changed files with 364 additions and 19 deletions
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8
src/backend/replication/logical/logicalfuncs.c
View File

@@ -235,11 +235,14 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
rsinfo->setResult = p->tupstore;
rsinfo->setDesc = p->tupdesc;
/* compute the current end-of-wal */
/*
* Compute the current end-of-wal and maintain ThisTimeLineID.
* RecoveryInProgress() will update ThisTimeLineID on promotion.
*/
if (!RecoveryInProgress())
end_of_wal = GetFlushRecPtr();
else
end_of_wal = GetXLogReplayRecPtr(NULL);
end_of_wal = GetXLogReplayRecPtr(&ThisTimeLineID);
ReplicationSlotAcquire(NameStr(*name));
@@ -280,6 +283,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
/* invalidate non-timetravel entries */
InvalidateSystemCaches();
/* Decode until we run out of records */
while ((startptr != InvalidXLogRecPtr && startptr < end_of_wal) ||
(ctx->reader->EndRecPtr != InvalidXLogRecPtr && ctx->reader->EndRecPtr < end_of_wal))
{

11
src/backend/replication/walsender.c
View File

@@ -48,6 +48,7 @@
#include "access/transam.h"
#include "access/xact.h"
#include "access/xlog_internal.h"
#include "access/xlogutils.h"
#include "catalog/pg_type.h"
#include "commands/dbcommands.h"
@@ -721,6 +722,12 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
XLogRecPtr flushptr;
int count;
XLogReadDetermineTimeline(state, targetPagePtr, reqLen);
sendTimeLineIsHistoric = (state->currTLI != ThisTimeLineID);
sendTimeLine = state->currTLI;
sendTimeLineValidUpto = state->currTLIValidUntil;
sendTimeLineNextTLI = state->nextTLI;
/* make sure we have enough WAL available */
flushptr = WalSndWaitForWal(targetPagePtr + reqLen);
@@ -974,10 +981,6 @@ StartLogicalReplication(StartReplicationCmd *cmd)
pq_endmessage(&buf);
pq_flush();
/* setup state for XLogReadPage */
sendTimeLineIsHistoric = false;
sendTimeLine = ThisTimeLineID;
/*
* Initialize position to the last ack'ed one, then the xlog records begin
* to be shipped from that position.