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pg_basebackup: Add option to create replication slot

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When requesting a particular replication slot, the new pg_basebackup
option -C/--create-slot creates it before starting to replicate from it.

Further refactor the slot creation logic to include the temporary slot
creation logic into the same function.  Add new arguments is_temporary
and preserve_wal to CreateReplicationSlot().  Print in --verbose mode
that a slot has been created.

Author: Michael Banck <michael.banck@credativ.de>
This commit is contained in:
Peter Eisentraut 2017-09-26 16:07:52 -04:00
parent 59597e6485
commit 3709ca1cf0
9 changed files with 112 additions and 41 deletions
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16
doc/src/sgml/ref/pg_basebackup.sgml
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@ -382,6 +382,18 @@ PostgreSQL documentation
</listitem>
</varlistentry>
<varlistentry>
<term><option>-C</option></term>
<term><option>--create-slot</option></term>
<listitem>
<para>
This option causes the replication slot specified by the
option <literal>--slot</literal> to be created before starting the
backup. In this case, an error is raised if the slot already exists.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-l <replaceable class="parameter">label</replaceable></option></term>
<term><option>--label=<replaceable class="parameter">label</replaceable></option></term>
@ -462,6 +474,10 @@ 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>
The specified replication slot has to exist unless the
option <option>-C</option> is also used.
</para>
<para>
If this option is not specified and the server supports temporary
replication slots (version 10 and later), then a temporary replication

63
src/bin/pg_basebackup/pg_basebackup.c
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@ -93,6 +93,8 @@ 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 create_slot = false;
static bool no_slot = false;
static bool success = false;
static bool made_new_pgdata = false;
@ -346,6 +348,7 @@ usage(void)
printf(_("\nGeneral options:\n"));
printf(_(" -c, --checkpoint=fast|spread\n"
" set fast or spread checkpointing\n"));
printf(_(" -C, --create-slot create replication slot\n"));
printf(_(" -l, --label=LABEL set backup label\n"));
printf(_(" -n, --no-clean do not clean up after errors\n"));
printf(_(" -N, --no-sync do not wait for changes to be written safely to disk\n"));
@ -466,7 +469,6 @@ typedef struct
char xlog[MAXPGPATH]; /* directory or tarfile depending on mode */
char *sysidentifier;
int timeline;
bool temp_slot;
} logstreamer_param;
static int
@ -492,9 +494,6 @@ LogStreamerMain(logstreamer_param *param)
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) PQbackendPID(param->bgconn));
if (format == 'p')
stream.walmethod = CreateWalDirectoryMethod(param->xlog, 0, do_sync);
@ -583,9 +582,29 @@ StartLogStreamer(char *startpos, uint32 timeline, char *sysidentifier)
/* 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;
temp_replication_slot = false;
/*
* Create replication slot if requested
*/
if (temp_replication_slot && !replication_slot)
replication_slot = psprintf("pg_basebackup_%d", (int) PQbackendPID(param->bgconn));
if (temp_replication_slot || create_slot)
{
if (!CreateReplicationSlot(param->bgconn, replication_slot, NULL,
temp_replication_slot, true, true, false))
disconnect_and_exit(1);
if (verbose)
{
if (temp_replication_slot)
fprintf(stderr, _("%s: created temporary replication slot \"%s\"\n"),
progname, replication_slot);
else
fprintf(stderr, _("%s: created replication slot \"%s\"\n"),
progname, replication_slot);
}
}
if (format == 'p')
{
@ -2079,6 +2098,7 @@ main(int argc, char **argv)
{"pgdata", required_argument, NULL, 'D'},
{"format", required_argument, NULL, 'F'},
{"checkpoint", required_argument, NULL, 'c'},
{"create-slot", no_argument, NULL, 'C'},
{"max-rate", required_argument, NULL, 'r'},
{"write-recovery-conf", no_argument, NULL, 'R'},
{"slot", required_argument, NULL, 'S'},
@ -2105,7 +2125,6 @@ main(int argc, char **argv)
int c;
int option_index;
bool no_slot = false;
progname = get_progname(argv[0]);
set_pglocale_pgservice(argv[0], PG_TEXTDOMAIN("pg_basebackup"));
@ -2127,11 +2146,14 @@ main(int argc, char **argv)
atexit(cleanup_directories_atexit);
while ((c = getopt_long(argc, argv, "D:F:r:RT:X:l:nNzZ:d:c:h:p:U:s:S:wWvP",
while ((c = getopt_long(argc, argv, "CD:F:r:RS:T:X:l:nNzZ:d:c:h:p:U:s:wWvP",
long_options, &option_index)) != -1)
{
switch (c)
{
case 'C':
create_slot = true;
break;
case 'D':
basedir = pg_strdup(optarg);
break;
@ -2348,6 +2370,29 @@ main(int argc, char **argv)
temp_replication_slot = false;
}
if (create_slot)
{
if (!replication_slot)
{
fprintf(stderr,
_("%s: --create-slot needs a slot to be specified using --slot\n"),
progname);
fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
progname);
exit(1);
}
if (no_slot)
{
fprintf(stderr,
_("%s: --create-slot and --no-slot are incompatible options\n"),
progname);
fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
progname);
exit(1);
}
}
if (xlog_dir)
{
if (format != 'p')

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

@ -431,7 +431,6 @@ StreamLog(void)
stream.do_sync);
stream.partial_suffix = ".partial";
stream.replication_slot = replication_slot;
stream.temp_slot = false;
ReceiveXlogStream(conn, &stream);
@ -728,7 +727,7 @@ main(int argc, char **argv)
_("%s: creating replication slot \"%s\"\n"),
progname, replication_slot);
if (!CreateReplicationSlot(conn, replication_slot, NULL, true,
if (!CreateReplicationSlot(conn, replication_slot, NULL, false, true, false,
slot_exists_ok))
disconnect_and_exit(1);
disconnect_and_exit(0);

4
src/bin/pg_basebackup/pg_recvlogical.c
View File

@ -979,8 +979,8 @@ main(int argc, char **argv)
_("%s: creating replication slot \"%s\"\n"),
progname, replication_slot);
if (!CreateReplicationSlot(conn, replication_slot, plugin,
false, slot_exists_ok))
if (!CreateReplicationSlot(conn, replication_slot, plugin, false,
false, false, slot_exists_ok))
disconnect_and_exit(1);
startpos = InvalidXLogRecPtr;
}

18
src/bin/pg_basebackup/receivelog.c
View File

@ -522,24 +522,6 @@ 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.

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

@ -47,7 +47,6 @@ typedef struct StreamCtl
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;

16
src/bin/pg_basebackup/streamutil.c
View File

@ -398,7 +398,8 @@ RunIdentifySystem(PGconn *conn, char **sysid, TimeLineID *starttli,
*/
bool
CreateReplicationSlot(PGconn *conn, const char *slot_name, const char *plugin,
bool is_physical, bool slot_exists_ok)
bool is_temporary, bool is_physical, bool reserve_wal,
bool slot_exists_ok)
{
PQExpBuffer query;
PGresult *res;
@ -410,13 +411,18 @@ CreateReplicationSlot(PGconn *conn, const char *slot_name, const char *plugin,
Assert(slot_name != NULL);
/* Build query */
appendPQExpBuffer(query, "CREATE_REPLICATION_SLOT \"%s\"", slot_name);
if (is_temporary)
appendPQExpBuffer(query, " TEMPORARY");
if (is_physical)
appendPQExpBuffer(query, "CREATE_REPLICATION_SLOT \"%s\" PHYSICAL",
slot_name);
{
appendPQExpBuffer(query, " PHYSICAL");
if (reserve_wal)
appendPQExpBuffer(query, " RESERVE_WAL");
}
else
{
appendPQExpBuffer(query, "CREATE_REPLICATION_SLOT \"%s\" LOGICAL \"%s\"",
slot_name, plugin);
appendPQExpBuffer(query, " LOGICAL \"%s\"", plugin);
if (PQserverVersion(conn) >= 100000)
/* pg_recvlogical doesn't use an exported snapshot, so suppress */
appendPQExpBuffer(query, " NOEXPORT_SNAPSHOT");

5
src/bin/pg_basebackup/streamutil.h
View File

@ -33,8 +33,9 @@ extern PGconn *GetConnection(void);
/* Replication commands */
extern bool CreateReplicationSlot(PGconn *conn, const char *slot_name,
const char *plugin, bool is_physical,
bool slot_exists_ok);
const char *plugin, bool is_temporary,
bool is_physical, bool reserve_wal,
bool slot_exists_ok);
extern bool DropReplicationSlot(PGconn *conn, const char *slot_name);
extern bool RunIdentifySystem(PGconn *conn, char **sysid,
TimeLineID *starttli,

27
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 => 72;
use Test::More tests => 78;
program_help_ok('pg_basebackup');
program_version_ok('pg_basebackup');
@ -259,9 +259,32 @@ $node->command_fails(
[ 'pg_basebackup', '-D',
"$tempdir/backupxs_sl_fail", '-X',
'stream', '-S',
'slot1' ],
'slot0' ],
'pg_basebackup fails with nonexistent replication slot');
$node->command_fails(
[ 'pg_basebackup', '-D', "$tempdir/backupxs_slot", '-C' ],
'pg_basebackup -C fails without slot name');
$node->command_fails(
[ 'pg_basebackup', '-D', "$tempdir/backupxs_slot", '-C', '-S', 'slot0', '--no-slot' ],
'pg_basebackup fails with -C -S --no-slot');
$node->command_ok(
[ 'pg_basebackup', '-D', "$tempdir/backupxs_slot", '-C', '-S', 'slot0' ],
'pg_basebackup -C runs');
is($node->safe_psql('postgres', q{SELECT slot_name FROM pg_replication_slots WHERE slot_name = 'slot0'}),
'slot0',
'replication slot was created');
isnt($node->safe_psql('postgres', q{SELECT restart_lsn FROM pg_replication_slots WHERE slot_name = 'slot0'}),
'',
'restart LSN of new slot is not null');
$node->command_fails(
[ 'pg_basebackup', '-D', "$tempdir/backupxs_slot1", '-C', '-S', 'slot0' ],
'pg_basebackup fails with -C -S and a previously existing slot');
$node->safe_psql('postgres',
q{SELECT * FROM pg_create_physical_replication_slot('slot1')});
my $lsn = $node->safe_psql('postgres',