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Make pg_receivexlog and pg_basebackup -X stream work across timeline switches.

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This mirrors the changes done earlier to the server in standby mode. When
receivelog reaches the end of a timeline, as reported by the server, it
fetches the timeline history file of the next timeline, and restarts
streaming from the new timeline by issuing a new START_STREAMING command.

When pg_receivexlog crosses a timeline, it leaves the .partial suffix on the
last segment on the old timeline. This helps you to tell apart a partial
segment left in the directory because of a timeline switch, and a completed
segment. If you just follow a single server, it won't make a difference, but
it can be significant in more complicated scenarios where new WAL is still
generated on the old timeline.

This includes two small changes to the streaming replication protocol:
First, when you reach the end of timeline while streaming, the server now
sends the TLI of the next timeline in the server's history to the client.
pg_receivexlog uses that as the next timeline, so that it doesn't need to
parse the timeline history file like a standby server does. Second, when
BASE_BACKUP command sends the begin and end WAL positions, it now also sends
the timeline IDs corresponding the positions.
This commit is contained in:
Heikki Linnakangas
2013-01-17 20:23:00 +02:00
parent 8ae35e9180
commit 0b6329130e
12 changed files with 699 additions and 312 deletions
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23
src/bin/pg_basebackup/pg_basebackup.c
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@@ -243,7 +243,7 @@ LogStreamerMain(logstreamer_param *param)
if (!ReceiveXlogStream(param->bgconn, param->startptr, param->timeline,
param->sysidentifier, param->xlogdir,
reached_end_position, standby_message_timeout,
true))
NULL))
/*
* Any errors will already have been reported in the function process,
@@ -1220,7 +1220,7 @@ BaseBackup(void)
{
PGresult *res;
char *sysidentifier;
uint32 timeline;
uint32 starttli;
char current_path[MAXPGPATH];
char escaped_label[MAXPGPATH];
int i;
@@ -1259,7 +1259,6 @@ BaseBackup(void)
disconnect_and_exit(1);
}
sysidentifier = pg_strdup(PQgetvalue(res, 0, 0));
timeline = atoi(PQgetvalue(res, 0, 1));
PQclear(res);
/*
@@ -1291,18 +1290,24 @@ BaseBackup(void)
progname, PQerrorMessage(conn));
disconnect_and_exit(1);
}
if (PQntuples(res) != 1)
if (PQntuples(res) != 1 || PQnfields(res) < 2)
{
fprintf(stderr, _("%s: no start point returned from server\n"),
progname);
fprintf(stderr,
_("%s: server returned unexpected response to BASE_BACKUP command; got %d rows and %d fields, expected %d rows and %d fields\n"),
progname, PQntuples(res), PQnfields(res), 1, 2);
disconnect_and_exit(1);
}
strcpy(xlogstart, PQgetvalue(res, 0, 0));
if (verbose && includewal)
fprintf(stderr, "transaction log start point: %s\n", xlogstart);
starttli = atoi(PQgetvalue(res, 0, 1));
PQclear(res);
MemSet(xlogend, 0, sizeof(xlogend));
if (verbose && includewal)
fprintf(stderr, _("transaction log start point: %s on timeline %u\n"),
xlogstart, starttli);
/*
* Get the header
*/
@@ -1358,7 +1363,7 @@ BaseBackup(void)
if (verbose)
fprintf(stderr, _("%s: starting background WAL receiver\n"),
progname);
StartLogStreamer(xlogstart, timeline, sysidentifier);
StartLogStreamer(xlogstart, starttli, sysidentifier);
}
/*