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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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14
doc/src/sgml/protocol.sgml
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@@ -1418,8 +1418,10 @@ The commands accepted in walsender mode are:
<para>
After streaming all the WAL on a timeline that is not the latest one,
the server will end streaming by exiting the COPY mode. When the client
acknowledges this by also exiting COPY mode, the server responds with a
CommandComplete message, and is ready to accept a new command.
acknowledges this by also exiting COPY mode, the server sends a
single-row, single-column result set indicating the next timeline in
this server's history. That is followed by a CommandComplete message,
and the server is ready to accept a new command.
</para>
<para>
@@ -1784,7 +1786,9 @@ The commands accepted in walsender mode are:
</para>
<para>
The first ordinary result set contains the starting position of the
backup, given in XLogRecPtr format as a single column in a single row.
backup, in a single row with two columns. The first column contains
the start position given in XLogRecPtr format, and the second column
contains the corresponding timeline ID.
</para>
<para>
The second ordinary result set has one row for each tablespace.
@@ -1827,7 +1831,9 @@ The commands accepted in walsender mode are:
<quote>ustar interchange format</> specified in the POSIX 1003.1-2008
standard) dump of the tablespace contents, except that the two trailing
blocks of zeroes specified in the standard are omitted.
After the tar data is complete, a final ordinary result set will be sent.
After the tar data is complete, a final ordinary result set will be sent,
containing the WAL end position of the backup, in the same format as
the start position.
</para>
<para>