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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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41
src/backend/replication/basebackup.c
View File

@ -55,7 +55,7 @@ static void SendBackupHeader(List *tablespaces);
static void base_backup_cleanup(int code, Datum arg);
static void perform_base_backup(basebackup_options *opt, DIR *tblspcdir);
static void parse_basebackup_options(List *options, basebackup_options *opt);
static void SendXlogRecPtrResult(XLogRecPtr ptr);
static void SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli);
static int compareWalFileNames(const void *a, const void *b);
/* Was the backup currently in-progress initiated in recovery mode? */
@ -94,13 +94,16 @@ static void
perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
{
XLogRecPtr startptr;
TimeLineID starttli;
XLogRecPtr endptr;
TimeLineID endtli;
char *labelfile;
backup_started_in_recovery = RecoveryInProgress();
startptr = do_pg_start_backup(opt->label, opt->fastcheckpoint, &labelfile);
SendXlogRecPtrResult(startptr);
startptr = do_pg_start_backup(opt->label, opt->fastcheckpoint, &starttli,
&labelfile);
SendXlogRecPtrResult(startptr, starttli);
PG_ENSURE_ERROR_CLEANUP(base_backup_cleanup, (Datum) 0);
{
@ -218,7 +221,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
}
PG_END_ENSURE_ERROR_CLEANUP(base_backup_cleanup, (Datum) 0);
endptr = do_pg_stop_backup(labelfile, !opt->nowait);
endptr = do_pg_stop_backup(labelfile, !opt->nowait, &endtli);
if (opt->includewal)
{
@ -426,7 +429,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir)
/* Send CopyDone message for the last tar file */
pq_putemptymessage('c');
}
SendXlogRecPtrResult(endptr);
SendXlogRecPtrResult(endptr, endtli);
}
/*
@ -635,17 +638,15 @@ SendBackupHeader(List *tablespaces)
* XlogRecPtr record (in text format)
*/
static void
SendXlogRecPtrResult(XLogRecPtr ptr)
SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
{
StringInfoData buf;
char str[MAXFNAMELEN];
snprintf(str, sizeof(str), "%X/%X", (uint32) (ptr >> 32), (uint32) ptr);
pq_beginmessage(&buf, 'T'); /* RowDescription */
pq_sendint(&buf, 1, 2); /* 1 field */
pq_sendint(&buf, 2, 2); /* 2 fields */
/* Field header */
/* Field headers */
pq_sendstring(&buf, "recptr");
pq_sendint(&buf, 0, 4); /* table oid */
pq_sendint(&buf, 0, 2); /* attnum */
@ -653,11 +654,29 @@ SendXlogRecPtrResult(XLogRecPtr ptr)
pq_sendint(&buf, -1, 2);
pq_sendint(&buf, 0, 4);
pq_sendint(&buf, 0, 2);
pq_sendstring(&buf, "tli");
pq_sendint(&buf, 0, 4); /* table oid */
pq_sendint(&buf, 0, 2); /* attnum */
/*
* int8 may seem like a surprising data type for this, but in thory int4
* would not be wide enough for this, as TimeLineID is unsigned.
*/
pq_sendint(&buf, INT8OID, 4); /* type oid */
pq_sendint(&buf, -1, 2);
pq_sendint(&buf, 0, 4);
pq_sendint(&buf, 0, 2);
pq_endmessage(&buf);
/* Data row */
pq_beginmessage(&buf, 'D');
pq_sendint(&buf, 1, 2); /* number of columns */
pq_sendint(&buf, 2, 2); /* number of columns */
snprintf(str, sizeof(str), "%X/%X", (uint32) (ptr >> 32), (uint32) ptr);
pq_sendint(&buf, strlen(str), 4); /* length */
pq_sendbytes(&buf, str, strlen(str));
snprintf(str, sizeof(str), "%u", tli);
pq_sendint(&buf, strlen(str), 4); /* length */
pq_sendbytes(&buf, str, strlen(str));
pq_endmessage(&buf);