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Rename "pg_xlog" directory to "pg_wal".

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"xlog" is not a particularly clear abbreviation for "write-ahead log",
and it sometimes confuses users into believe that the contents of the
"pg_xlog" directory are not critical data, leading to unpleasant
consequences.  So, rename the directory to "pg_wal".

This patch modifies pg_upgrade and pg_basebackup to understand both
the old and new directory layouts; the former is necessary given the
purpose of the tool, while the latter merely avoids an unnecessary
backward-compatibility break.

We may wish to consider renaming other programs, switches, and
functions which still use the old "xlog" naming to also refer to
"wal".  However, that's still under discussion, so let's do just this
much for now.

Discussion: CAB7nPqTeC-8+zux8_-4ZD46V7YPwooeFxgndfsq5Rg8ibLVm1A@mail.gmail.com

Michael Paquier
This commit is contained in:
Robert Haas
2016-10-20 11:24:37 -04:00
parent ec7db2b483
commit f82ec32ac3
37 changed files with 276 additions and 223 deletions
Download Patch File Download Diff File Expand all files Collapse all files

80
src/bin/pg_basebackup/pg_basebackup.c
View File

@@ -55,6 +55,12 @@ typedef struct TablespaceList
TablespaceListCell *tail;
} TablespaceList;
/*
* pg_xlog has been renamed to pg_wal in version 10. This version number
* should be compared with PQserverVersion().
*/
#define MINIMUM_VERSION_FOR_PG_WAL 100000
/* Global options */
static char *basedir = NULL;
static TablespaceList tablespace_dirs = {NULL, NULL};
@@ -526,15 +532,22 @@ StartLogStreamer(char *startpos, uint32 timeline, char *sysidentifier)
/* Error message already written in GetConnection() */
exit(1);
snprintf(param->xlogdir, sizeof(param->xlogdir), "%s/pg_xlog", basedir);
/* In post-10 cluster, pg_xlog has been renamed to pg_wal */
snprintf(param->xlogdir, sizeof(param->xlogdir), "%s/%s",
basedir,
PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
"pg_xlog" : "pg_wal");
/*
* Create pg_xlog/archive_status (and thus pg_xlog) so we can write to
* basedir/pg_xlog as the directory entry in the tar file may arrive
* later.
* Create pg_wal/archive_status or pg_xlog/archive_status (and thus
* pg_wal or pg_xlog) depending on the target server so we can write to
* basedir/pg_wal or basedir/pg_xlog as the directory entry in the tar
* file may arrive later.
*/
snprintf(statusdir, sizeof(statusdir), "%s/pg_xlog/archive_status",
basedir);
snprintf(statusdir, sizeof(statusdir), "%s/%s/archive_status",
basedir,
PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
"pg_xlog" : "pg_wal");
if (pg_mkdir_p(statusdir, S_IRWXU) != 0 && errno != EEXIST)
{
@@ -1338,15 +1351,17 @@ ReceiveAndUnpackTarFile(PGconn *conn, PGresult *res, int rownum)
if (mkdir(filename, S_IRWXU) != 0)
{
/*
* When streaming WAL, pg_xlog will have been created
* by the wal receiver process. Also, when transaction
* log directory location was specified, pg_xlog has
* already been created as a symbolic link before
* starting the actual backup. So just ignore creation
* failures on related directories.
* When streaming WAL, pg_wal (or pg_xlog for pre-9.6
* clusters) will have been created by the wal receiver
* process. Also, when transaction log directory location
* was specified, pg_wal (or pg_xlog) has already been
* created as a symbolic link before starting the actual
* backup. So just ignore creation failures on related
* directories.
*/
if (!((pg_str_endswith(filename, "/pg_xlog") ||
pg_str_endswith(filename, "/archive_status")) &&
if (!((pg_str_endswith(filename, "/pg_wal") ||
pg_str_endswith(filename, "/pg_xlog")||
pg_str_endswith(filename, "/archive_status")) &&
errno == EEXIST))
{
fprintf(stderr,
@@ -1634,15 +1649,10 @@ BaseBackup(void)
char xlogend[64];
int minServerMajor,
maxServerMajor;
int serverMajor;
int serverVersion,
serverMajor;
/*
* Connect in replication mode to the server
*/
conn = GetConnection();
if (!conn)
/* Error message already written in GetConnection() */
exit(1);
Assert(conn != NULL);
/*
* Check server version. BASE_BACKUP command was introduced in 9.1, so we
@@ -1650,7 +1660,8 @@ BaseBackup(void)
*/
minServerMajor = 901;
maxServerMajor = PG_VERSION_NUM / 100;
serverMajor = PQserverVersion(conn) / 100;
serverVersion = PQserverVersion(conn);
serverMajor = serverVersion / 100;
if (serverMajor < minServerMajor || serverMajor > maxServerMajor)
{
const char *serverver = PQparameterStatus(conn, "server_version");
@@ -1979,7 +1990,7 @@ BaseBackup(void)
}
else
{
(void) fsync_pgdata(basedir, progname);
(void) fsync_pgdata(basedir, progname, serverVersion);
}
}
@@ -2296,6 +2307,14 @@ main(int argc, char **argv)
if (format == 'p' || strcmp(basedir, "-") != 0)
verify_dir_is_empty_or_create(basedir, &made_new_pgdata, &found_existing_pgdata);
/* connection in replication mode to server */
conn = GetConnection();
if (!conn)
{
/* Error message already written in GetConnection() */
exit(1);
}
/* Create transaction log symlink, if required */
if (strcmp(xlog_dir, "") != 0)
{
@@ -2303,19 +2322,24 @@ main(int argc, char **argv)
verify_dir_is_empty_or_create(xlog_dir, &made_new_xlogdir, &found_existing_xlogdir);
/* form name of the place where the symlink must go */
linkloc = psprintf("%s/pg_xlog", basedir);
/*
* Form name of the place where the symlink must go. pg_xlog has
* been renamed to pg_wal in post-10 clusters.
*/
linkloc = psprintf("%s/%s", basedir,
PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
"pg_xlog" : "pg_wal");
#ifdef HAVE_SYMLINK
if (symlink(xlog_dir, linkloc) != 0)
{
fprintf(stderr, _("%s: could not create symbolic link \"%s\": %s\n"),
progname, linkloc, strerror(errno));
exit(1);
disconnect_and_exit(1);
}
#else
fprintf(stderr, _("%s: symlinks are not supported on this platform\n"));
exit(1);
disconnect_and_exit(1);
#endif
free(linkloc);
}