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Improve some check logic in pg_receivewal

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The following things are improved:
- Fetch the system identifier from the source server before any
WAL streaming loop.  This triggers extra checks to make sure that
pg_receivewal is still connected to a server with the same system ID
with a correct timeline.
- Switch umask() (for file creation mode mask) and RetrieveWalSegSize()
(to fetch the size of WAL segments) a bit later before the initial
stream attempt.  If the connection was done with a database,
pg_receivewal would fail but those commands were still executed, which
was a waste.  The slot creation and drop are now done before retrieving
the segment size.

Author: Bharath Rupireddy
Reviewed-by: Ronan Dunklau, Michael Paquier
Discussion: https://postgr.es/m/CALj2ACX00YYeyBfoi55Cy=NrP-FcfMgiYYx1qRUEib3yjCVoaA@mail.gmail.com
This commit is contained in:
Michael Paquier 2021-09-18 10:42:13 +09:00
parent d7897abf9e
commit 499c9b1266
1 changed files with 18 additions and 15 deletions
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33
src/bin/pg_basebackup/pg_receivewal.c
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@ -372,6 +372,7 @@ StreamLog(void)
XLogRecPtr serverpos;
TimeLineID servertli;
StreamCtl stream;
char *sysidentifier;
MemSet(&stream, 0, sizeof(stream));
@ -399,7 +400,7 @@ StreamLog(void)
* at the same time, necessary if not valid data can be found in the
* existing output directory.
*/
if (!RunIdentifySystem(conn, NULL, &servertli, &serverpos, NULL))
if (!RunIdentifySystem(conn, &sysidentifier, &servertli, &serverpos, NULL))
exit(1);
/*
@ -435,6 +436,7 @@ StreamLog(void)
stream.do_sync);
stream.partial_suffix = ".partial";
stream.replication_slot = replication_slot;
stream.sysidentifier = sysidentifier;
ReceiveXlogStream(conn, &stream);
@ -449,6 +451,7 @@ StreamLog(void)
FreeWalDirectoryMethod();
pg_free(stream.walmethod);
pg_free(stream.sysidentifier);
}
/*
@ -687,20 +690,6 @@ main(int argc, char **argv)
if (!RunIdentifySystem(conn, NULL, NULL, NULL, &db_name))
exit(1);
/*
* Set umask so that directories/files are created with the same
* permissions as directories/files in the source data directory.
*
* pg_mode_mask is set to owner-only by default and then updated in
* GetConnection() where we get the mode from the server-side with
* RetrieveDataDirCreatePerm() and then call SetDataDirectoryCreatePerm().
*/
umask(pg_mode_mask);
/* determine remote server's xlog segment size */
if (!RetrieveWalSegSize(conn))
exit(1);
/*
* Check that there is a database associated with connection, none should
* be defined in this context.
@ -712,6 +701,16 @@ main(int argc, char **argv)
exit(1);
}
/*
* Set umask so that directories/files are created with the same
* permissions as directories/files in the source data directory.
*
* pg_mode_mask is set to owner-only by default and then updated in
* GetConnection() where we get the mode from the server-side with
* RetrieveDataDirCreatePerm() and then call SetDataDirectoryCreatePerm().
*/
umask(pg_mode_mask);
/*
* Drop a replication slot.
*/
@ -737,6 +736,10 @@ main(int argc, char **argv)
exit(0);
}
/* determine remote server's xlog segment size */
if (!RetrieveWalSegSize(conn))
exit(1);
/*
* Don't close the connection here so that subsequent StreamLog() can
* reuse it.