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Make pg_basebackup use temporary replication slots 

Temporary replication slots will be used by default when wal streaming
is used and no slot name is specified with -S. If a slot name is
specified, then a permanent slot with that name is used. If --no-slot is
specified, then no permanent or temporary slot will be used.

Temporary slots are only used on 10.0 and newer, of course.
This commit is contained in:
Magnus Hagander 2017-01-16 13:56:43 +01:00
parent 8fa6019b40
commit e7b020f786
9 changed files with 101 additions and 8 deletions
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25
doc/src/sgml/ref/pg_basebackup.sgml
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@ -240,6 +240,31 @@ PostgreSQL documentation
the server does not remove any necessary WAL data in the time between
the end of the base backup and the start of streaming replication.
</para>
<para>
If this option is not specified and the server supports temporary
replication slots (version 10 and later), then a temporary replication
slot is automatically used for WAL streaming.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-slot</option></term>
<listitem>
<para>
This option prevents the creation of a temporary replication slot
during the backup even if it's supported by the server.
</para>
<para>
Temporary replication slots are created by default if no slot name
is given with the option <option>-S</option> when using log streaming.
</para>
<para>
The main purpose of this option is to allow taking a base backup when
the server is out of free replication slots. Using replication slots
is almost always preferred, because it prevents needed WAL from being
removed by the server during the backup.
</para>
</listitem>
</varlistentry>

45
src/bin/pg_basebackup/pg_basebackup.c
View File

@ -61,6 +61,11 @@ typedef struct TablespaceList
*/
#define MINIMUM_VERSION_FOR_PG_WAL 100000
/*
* Temporary replication slots are supported from version 10.
*/
#define MINIMUM_VERSION_FOR_TEMP_SLOTS 100000
/*
* Different ways to include WAL
*/
@ -88,6 +93,8 @@ static bool do_sync = true;
static int standby_message_timeout = 10 * 1000; /* 10 sec = default */
static pg_time_t last_progress_report = 0;
static int32 maxrate = 0; /* no limit by default */
static char *replication_slot = NULL;
static bool temp_replication_slot = true;
static bool success = false;
static bool made_new_pgdata = false;
@ -332,6 +339,7 @@ usage(void)
printf(_(" -R, --write-recovery-conf\n"
" write recovery.conf after backup\n"));
printf(_(" -S, --slot=SLOTNAME replication slot to use\n"));
printf(_(" --no-slot prevent creation of temporary replication slot\n"));
printf(_(" -T, --tablespace-mapping=OLDDIR=NEWDIR\n"
" relocate tablespace in OLDDIR to NEWDIR\n"));
printf(_(" -X, --xlog-method=none|fetch|stream\n"
@ -460,6 +468,7 @@ typedef struct
char xlog[MAXPGPATH]; /* directory or tarfile depending on mode */
char *sysidentifier;
int timeline;
bool temp_slot;
} logstreamer_param;
static int
@ -479,6 +488,10 @@ LogStreamerMain(logstreamer_param *param)
stream.do_sync = do_sync;
stream.mark_done = true;
stream.partial_suffix = NULL;
stream.replication_slot = replication_slot;
stream.temp_slot = param->temp_slot;
if (stream.temp_slot && !stream.replication_slot)
stream.replication_slot = psprintf("pg_basebackup_%d", (int) getpid());
if (format == 'p')
stream.walmethod = CreateWalDirectoryMethod(param->xlog, do_sync);
@ -565,6 +578,11 @@ StartLogStreamer(char *startpos, uint32 timeline, char *sysidentifier)
PQserverVersion(conn) < MINIMUM_VERSION_FOR_PG_WAL ?
"pg_xlog" : "pg_wal");
/* Temporary replication slots are only supported in 10 and newer */
if (PQserverVersion(conn) < MINIMUM_VERSION_FOR_TEMP_SLOTS)
param->temp_slot = false;
else
param->temp_slot = temp_replication_slot;
if (format == 'p')
{
@ -2063,11 +2081,13 @@ main(int argc, char **argv)
{"verbose", no_argument, NULL, 'v'},
{"progress", no_argument, NULL, 'P'},
{"xlogdir", required_argument, NULL, 1},
{"no-slot", no_argument, NULL, 2},
{NULL, 0, NULL, 0}
};
int c;
int option_index;
bool no_slot = false;
progname = get_progname(argv[0]);
set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_basebackup"));
@ -2117,7 +2137,16 @@ main(int argc, char **argv)
writerecoveryconf = true;
break;
case 'S':
/*
* When specifying replication slot name, use a permanent
* slot.
*/
replication_slot = pg_strdup(optarg);
temp_replication_slot = false;
break;
case 2:
no_slot = true;
break;
case 'T':
tablespace_list_append(optarg);
@ -2277,7 +2306,7 @@ main(int argc, char **argv)
exit(1);
}
if (replication_slot && includewal != STREAM_WAL)
if ((replication_slot || no_slot) && includewal != STREAM_WAL)
{
fprintf(stderr,
_("%s: replication slots can only be used with WAL streaming\n"),
@ -2287,6 +2316,20 @@ main(int argc, char **argv)
exit(1);
}
if (no_slot)
{
if (replication_slot)
{
fprintf(stderr,
_("%s: --no-slot cannot be used with slot name\n"),
progname);
fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
progname);
exit(1);
}
temp_replication_slot = false;
}
if (strcmp(xlog_dir, "") != 0)
{
if (format != 'p')

3
src/bin/pg_basebackup/pg_receivexlog.c
View File

@ -41,6 +41,7 @@ static bool do_create_slot = false;
static bool slot_exists_ok = false;
static bool do_drop_slot = false;
static bool synchronous = false;
static char *replication_slot = NULL;
static void usage(void);
@ -340,6 +341,8 @@ StreamLog(void)
stream.mark_done = false;
stream.walmethod = CreateWalDirectoryMethod(basedir, stream.do_sync);
stream.partial_suffix = ".partial";
stream.replication_slot = replication_slot;
stream.temp_slot = false;
ReceiveXlogStream(conn, &stream);

1
src/bin/pg_basebackup/pg_recvlogical.c
View File

@ -45,6 +45,7 @@ static bool do_create_slot = false;
static bool slot_exists_ok = false;
static bool do_start_slot = false;
static bool do_drop_slot = false;
static char *replication_slot = NULL;
/* filled pairwise with option, value. value may be NULL */
static char **options;

22
src/bin/pg_basebackup/receivelog.c
View File

@ -455,10 +455,10 @@ ReceiveXlogStream(PGconn *conn, StreamCtl *stream)
* synchronous_standby_names, but we've protected them against it so
* far, so let's continue to do so unless specifically requested.
*/
if (replication_slot != NULL)
if (stream->replication_slot != NULL)
{
reportFlushPosition = true;
sprintf(slotcmd, "SLOT \"%s\" ", replication_slot);
sprintf(slotcmd, "SLOT \"%s\" ", stream->replication_slot);
}
else
{
@ -508,6 +508,24 @@ ReceiveXlogStream(PGconn *conn, StreamCtl *stream)
PQclear(res);
}
/*
* Create temporary replication slot if one is needed
*/
if (stream->temp_slot)
{
snprintf(query, sizeof(query),
"CREATE_REPLICATION_SLOT \"%s\" TEMPORARY PHYSICAL RESERVE_WAL",
stream->replication_slot);
res = PQexec(conn, query);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr, _("%s: could not create temporary replication slot \"%s\": %s"),
progname, stream->replication_slot, PQerrorMessage(conn));
PQclear(res);
return false;
}
}
/*
* initialize flush position to starting point, it's the caller's
* responsibility that that's sane.

6
src/bin/pg_basebackup/receivelog.h
View File

@ -37,13 +37,15 @@ typedef struct StreamCtl
* often */
bool synchronous; /* Flush immediately WAL data on write */
bool mark_done; /* Mark segment as done in generated archive */
bool do_sync; /* Flush to disk to ensure consistent state
* of data */
bool do_sync; /* Flush to disk to ensure consistent state of
* data */
stream_stop_callback stream_stop; /* Stop streaming when returns true */
WalWriteMethod *walmethod; /* How to write the WAL */
char *partial_suffix; /* Suffix appended to partially received files */
char *replication_slot; /* Replication slot to use, or NULL */
bool temp_slot; /* Create temporary replication slot */
} StreamCtl;

1
src/bin/pg_basebackup/streamutil.c
View File

@ -38,7 +38,6 @@ char *connection_string = NULL;
char *dbhost = NULL;
char *dbuser = NULL;
char *dbport = NULL;
char *replication_slot = NULL;
char *dbname = NULL;
int dbgetpassword = 0; /* 0=auto, -1=never, 1=always */
static bool have_password = false;

1
src/bin/pg_basebackup/streamutil.h
View File

@ -23,7 +23,6 @@ extern char *dbuser;
extern char *dbport;
extern char *dbname;
extern int dbgetpassword;
extern char *replication_slot;
/* Connection kept global so we can disconnect easily */
extern PGconn *conn;

5
src/bin/pg_basebackup/t/010_pg_basebackup.pl
View File

@ -4,7 +4,7 @@ use Cwd;
use Config;
use PostgresNode;
use TestLib;
use Test::More tests => 71;
use Test::More tests => 72;
program_help_ok('pg_basebackup');
program_version_ok('pg_basebackup');
@ -244,6 +244,9 @@ $node->command_ok(
[ 'pg_basebackup', '-D', "$tempdir/backupxst", '-X', 'stream', '-Ft' ],
'pg_basebackup -X stream runs in tar mode');
ok(-f "$tempdir/backupxst/pg_wal.tar", "tar file was created");
$node->command_ok(
[ 'pg_basebackup', '-D', "$tempdir/backupnoslot", '-X', 'stream', '--no-slot' ],
'pg_basebackup -X stream runs with --no-slot');
$node->command_fails(
[ 'pg_basebackup', '-D', "$tempdir/fail", '-S', 'slot1' ],