On 11/6/19 1:55 PM, Grigory Smolkin wrote:
On 11/6/19 12:56 PM, Fujii Masao wrote:
On Wed, Nov 6, 2019 at 6:33 PM Grigory Smolkin
<g.smol...@postgrespro.ru> wrote:
On 11/6/19 10:39 AM, Peter Eisentraut wrote:
This seems to also be related to this discussion:
<https://www.postgresql.org/message-id/flat/993736dd3f1713ec1f63fc3b65383...@lako.no>
Yes, in a way. Strengthening current lax recovery behavior is a very
good idea.
I like this idea.
I don't like the name "latest". What does that mean? Other
documentation talks about the "end of the archive". What does that
mean? It means until restore_command errors. Let's think of a name
that reflects that better. Maybe "all_archive" or something like
that.
As with "immediate", "latest" reflects the latest possible state this
PostgreSQL instance can achieve when using PITR. I think it is simple
and easy to understand for an end user, which sees PITR as a way to go
from one state to another. In my experience, at least, which is, of
course, subjective.
But if we want an argument name to be technically accurate, then, I
think, something like "end-of-available-WAL"/"all-WAL", "end-of-WAL" is
a way to go.
What happens if this parameter is set to latest in the standby mode?
Or the combination of those settings should be prohibited?
Currently it will behave just like regular standby, so I think, to
avoid confusion and keep things simple, the combination of them should
be prohibited.
Thank you for pointing this out, I will work on it.
Attached new patch revision, now it is impossible to use recovery_target
'latest' in standby mode.
TAP test is updated to reflect this behavior.
The other way around, as I see it, is to define RECOVERY_TARGET_LATEST
as something more complex, for example, the latest possible endptr in
latest WAL segment. But it is tricky, because WAL archive may keeps
growing as recovery is progressing or, in case of standby, master
keeps sending more and more WAL.
Regards,
--
Grigory Smolkin
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 619ac8c50c..f0fa0b09c8 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3316,21 +3316,19 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
<variablelist>
<varlistentry id="guc-recovery-target" xreflabel="recovery_target">
- <term><varname>recovery_target</varname><literal> = 'immediate'</literal>
+ <term><varname>recovery_target</varname> (<type>string</type>)
<indexterm>
<primary><varname>recovery_target</varname> configuration parameter</primary>
</indexterm>
</term>
<listitem>
<para>
- This parameter specifies that recovery should end as soon as a
- consistent state is reached, i.e. as early as possible. When restoring
- from an online backup, this means the point where taking the backup
- ended.
- </para>
- <para>
- Technically, this is a string parameter, but <literal>'immediate'</literal>
- is currently the only allowed value.
+ This parameter determines how far recovery should proceed. The value
+ <literal>immediate</literal> means that recovery should end as soon as a consistent
+ state is reached, i.e. as early as possible. When restoring from an online
+ backup, this means the point where taking the backup ended.
+ The second possible value <literal>latest</literal> means that recovery
+ should proceed to the end of the available WAL log.
</para>
</listitem>
</varlistentry>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 77ad765989..6001b0aa34 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -5401,6 +5401,15 @@ validateRecoveryParameters(void)
errmsg("must specify restore_command when standby mode is not enabled")));
}
+ /* Combining standby mode with recovery to the end of WAL is
+ * impossible, because there is no end of WAL in this case.
+ */
+ if (StandbyModeRequested && recoveryTarget == RECOVERY_TARGET_LATEST)
+ ereport(FATAL,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("recovery to the end of WAL is not possible because standby mode is enabled")));
+
+
/*
* Override any inconsistent requests. Note that this is a change of
* behaviour in 9.5; prior to this we simply ignored a request to pause if
@@ -6350,6 +6359,9 @@ StartupXLOG(void)
else if (recoveryTarget == RECOVERY_TARGET_IMMEDIATE)
ereport(LOG,
(errmsg("starting point-in-time recovery to earliest consistent point")));
+ else if (recoveryTarget == RECOVERY_TARGET_LATEST)
+ ereport(LOG,
+ (errmsg("starting point-in-time recovery until all available WAL is applied")));
else
ereport(LOG,
(errmsg("starting archive recovery")));
@@ -7261,6 +7273,13 @@ StartupXLOG(void)
* end of main redo apply loop
*/
+ /*
+ * If all avaialble WAL is replayed,
+ * then RECOVERY_TARGET_LATEST is satisfied
+ */
+ if (recoveryTarget == RECOVERY_TARGET_LATEST)
+ reachedStopPoint = true;
+
if (reachedStopPoint)
{
if (!reachedConsistency)
@@ -7462,6 +7481,8 @@ StartupXLOG(void)
recoveryStopName);
else if (recoveryTarget == RECOVERY_TARGET_IMMEDIATE)
snprintf(reason, sizeof(reason), "reached consistency");
+ else if (recoveryTarget == RECOVERY_TARGET_LATEST)
+ snprintf(reason, sizeof(reason), "applied all available WAL");
else
snprintf(reason, sizeof(reason), "no recovery target specified");
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f0ed326a1b..e7288a79b6 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3503,7 +3503,10 @@ static struct config_string ConfigureNamesString[] =
{
{"recovery_target", PGC_POSTMASTER, WAL_RECOVERY_TARGET,
- gettext_noop("Set to \"immediate\" to end recovery as soon as a consistent state is reached."),
+ gettext_noop("Set to \"immediate\" to end recovery as "
+ "soon as a consistent state is reached or "
+ " to \"latest\" to end recovery after "
+ "replaying all available WAL in the archive."),
NULL
},
&recovery_target_string,
@@ -11498,9 +11501,10 @@ error_multiple_recovery_targets(void)
static bool
check_recovery_target(char **newval, void **extra, GucSource source)
{
- if (strcmp(*newval, "immediate") != 0 && strcmp(*newval, "") != 0)
+ if (strcmp(*newval, "immediate") != 0 && strcmp(*newval, "latest") != 0 &&
+ strcmp(*newval, "") != 0)
{
- GUC_check_errdetail("The only allowed value is \"immediate\".");
+ GUC_check_errdetail("The only allowed values are \"immediate\" and \"latest\".");
return false;
}
return true;
@@ -11510,11 +11514,17 @@ static void
assign_recovery_target(const char *newval, void *extra)
{
if (recoveryTarget != RECOVERY_TARGET_UNSET &&
- recoveryTarget != RECOVERY_TARGET_IMMEDIATE)
+ recoveryTarget != RECOVERY_TARGET_IMMEDIATE &&
+ recoveryTarget != RECOVERY_TARGET_LATEST)
error_multiple_recovery_targets();
if (newval && strcmp(newval, "") != 0)
- recoveryTarget = RECOVERY_TARGET_IMMEDIATE;
+ {
+ if (strcmp(newval, "immediate") == 0)
+ recoveryTarget = RECOVERY_TARGET_IMMEDIATE;
+ else if (strcmp(newval, "latest") == 0)
+ recoveryTarget = RECOVERY_TARGET_LATEST;
+ }
else
recoveryTarget = RECOVERY_TARGET_UNSET;
}
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index d519252aad..55e7e4bd2c 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -84,7 +84,8 @@ typedef enum
RECOVERY_TARGET_TIME,
RECOVERY_TARGET_NAME,
RECOVERY_TARGET_LSN,
- RECOVERY_TARGET_IMMEDIATE
+ RECOVERY_TARGET_IMMEDIATE,
+ RECOVERY_TARGET_LATEST
} RecoveryTargetType;
/*
diff --git a/src/test/recovery/t/003_recovery_targets.pl b/src/test/recovery/t/003_recovery_targets.pl
index d8fbd50011..05f5f9889c 100644
--- a/src/test/recovery/t/003_recovery_targets.pl
+++ b/src/test/recovery/t/003_recovery_targets.pl
@@ -3,7 +3,7 @@ use strict;
use warnings;
use PostgresNode;
use TestLib;
-use Test::More tests => 8;
+use Test::More tests => 9;
# Create and test a standby from given backup, with a certain recovery target.
# Choose $until_lsn later than the transaction commit that causes the row
@@ -26,6 +26,23 @@ sub test_recovery_standby
$node_standby->append_conf('postgresql.conf', qq($param_item));
}
+ # It is expected for recovery target latest to fail on standby
+ if ($test_name eq 'latest target')
+ {
+ $node_standby->start(fail_ok => 1);
+ $node_standby->clean_node;
+
+ $node_standby = get_new_node($node_name);
+ $node_standby->init_from_backup($node_master, 'my_backup',
+ has_restoring => 1);
+ unlink($node_standby->data_dir . '/standby.signal');
+
+ foreach my $param_item (@$recovery_params)
+ {
+ $node_standby->append_conf('postgresql.conf', qq($param_item));
+ }
+ }
+
$node_standby->start;
# Wait until standby has replayed enough data
@@ -77,7 +94,7 @@ my $lsn3 =
$node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn();");
my $recovery_time = $node_master->safe_psql('postgres', "SELECT now()");
-# Even more data, this time with a recovery target name
+# More data, with a recovery target name
$node_master->safe_psql('postgres',
"INSERT INTO tab_int VALUES (generate_series(3001,4000))");
my $recovery_name = "my_target";
@@ -86,14 +103,17 @@ my $lsn4 =
$node_master->safe_psql('postgres',
"SELECT pg_create_restore_point('$recovery_name');");
-# And now for a recovery target LSN
+# Even more data, this time with a recovery target LSN
$node_master->safe_psql('postgres',
"INSERT INTO tab_int VALUES (generate_series(4001,5000))");
my $lsn5 = my $recovery_lsn =
$node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
+# And now for a recovery target 'latest'
$node_master->safe_psql('postgres',
"INSERT INTO tab_int VALUES (generate_series(5001,6000))");
+my $lsn6 =
+ $node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn();");
# Force archiving of WAL file
$node_master->safe_psql('postgres', "SELECT pg_switch_wal()");
@@ -114,6 +134,9 @@ test_recovery_standby('name', 'standby_4', $node_master, \@recovery_params,
@recovery_params = ("recovery_target_lsn = '$recovery_lsn'");
test_recovery_standby('LSN', 'standby_5', $node_master, \@recovery_params,
"5000", $lsn5);
+@recovery_params = ("recovery_target = 'latest'");
+test_recovery_standby('latest target', 'standby_6', $node_master, \@recovery_params,
+ "6000", $lsn6);
# Multiple targets
#
@@ -126,9 +149,9 @@ test_recovery_standby('LSN', 'standby_5', $node_master, \@recovery_params,
"recovery_target_name = ''",
"recovery_target_time = '$recovery_time'");
test_recovery_standby('multiple overriding settings',
- 'standby_6', $node_master, \@recovery_params, "3000", $lsn3);
+ 'standby_7', $node_master, \@recovery_params, "3000", $lsn3);
-my $node_standby = get_new_node('standby_7');
+my $node_standby = get_new_node('standby_8');
$node_standby->init_from_backup($node_master, 'my_backup',
has_restoring => 1);
$node_standby->append_conf(
