Hello, hackers!
I`d like to propose a new argument for recovery_target parameter, which
will stand to recovering until all available WAL segments are applied.
Current PostgreSQL recovery default behavior(when no recovery target is
provided) does exactly that, but there are several shortcomings:
- without explicit recovery target standing for default behavior,
recovery_target_action is not coming to action at the end of recovery
- with PG12 changes, the life of all backup tools became very hard,
because now recovery parameters can be set outside of single config
file(recovery.conf), so it is impossible to ensure, that default
recovery behavior, desired in some cases, will not be silently
overwritten by some recovery parameter forgotten by user.
Proposed path is very simple and solves the aforementioned problems by
introducing new argument "latest" for recovery_target parameter.
Old recovery behavior is still available if no recovery target is
provided. I`m not sure, whether it should it be left as it is now, or not.
Another open question is what to do with recovery_target_inclusive if
recovery_target = "latest" is used.
--
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 0191ec84b1..49675c38da 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -3366,21 +3366,19 @@ 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 2e3cc51006..faab0b2b4c 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6345,6 +6345,9 @@ 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")));
@@ -7257,6 +7260,13 @@ 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)
@@ -7459,6 +7469,8 @@ 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 31a5ef0474..b652304683 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,
@@ -11527,9 +11530,10 @@ 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;
@@ -11539,11 +11543,17 @@ 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;
/*
