</para>
<para>
Number of times the slot synchronization is skipped. Slot
- synchronization occur only on standby servers and thus this column has
+ synchronization occurs only on standby servers and thus this column has
no meaning on the primary server.
</para>
</entry>
</para>
<para>
Time at which last slot synchronization was skipped. Slot
- synchronization occur only on standby servers and thus this column has
+ synchronization occurs only on standby servers and thus this column has
no meaning on the primary server.
</para>
</entry>
</para></entry>
</row>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>slotsync_skip_reason</structfield><type>text</type>
+ </para>
+ <para>
+ The reason for the last slot synchronization skip. Slot
+ synchronization occurs only on standby servers and thus this column has
+ no meaning on the primary server. It is relevant mainly for logical slots
+ on standby servers whose <structfield>synced</structfield> field is
+ <literal>true</literal>. It is <literal>NULL</literal> if slot
+ synchronization is successful.
+ Possible values are:
+ <itemizedlist spacing="compact">
+ <listitem>
+ <para>
+ <literal>wal_or_rows_removed</literal> means that the required WALs or
+ catalog rows have already been removed or are at the risk of removal
+ from the standby.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>wal_not_flushed</literal> means that the standby had not
+ flushed the WAL corresponding to the position reserved on the failover
+ slot.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>no_consistent_snapshot</literal> means that the standby could
+ not build a consistent snapshot to decode WALs from
+ <structfield>restart_lsn</structfield>.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ <literal>slot_invalidated</literal> means that the synced slot is
+ invalidated.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para></entry>
+ </row>
</tbody>
</tgroup>
</table>
L.conflicting,
L.invalidation_reason,
L.failover,
- L.synced
+ L.synced,
+ L.slotsync_skip_reason
FROM pg_get_replication_slots() AS L
LEFT JOIN pg_database D ON (L.datoid = D.oid);
static void slotsync_failure_callback(int code, Datum arg);
static void update_synced_slots_inactive_since(void);
+/*
+ * Update slot sync skip stats. This function requires the caller to acquire
+ * the slot.
+ */
+static void
+update_slotsync_skip_stats(SlotSyncSkipReason skip_reason)
+{
+ ReplicationSlot *slot;
+
+ Assert(MyReplicationSlot);
+
+ slot = MyReplicationSlot;
+
+ /*
+ * Update the slot sync related stats in pg_stat_replication_slot when a
+ * slot sync is skipped
+ */
+ if (skip_reason != SS_SKIP_NONE)
+ pgstat_report_replslotsync(slot);
+
+ /* Update the slot sync skip reason */
+ if (slot->slotsync_skip_reason != skip_reason)
+ {
+ SpinLockAcquire(&slot->mutex);
+ slot->slotsync_skip_reason = skip_reason;
+ SpinLockRelease(&slot->mutex);
+ }
+}
+
/*
* If necessary, update the local synced slot's metadata based on the data
* from the remote slot.
ReplicationSlot *slot = MyReplicationSlot;
bool updated_xmin_or_lsn = false;
bool updated_config = false;
+ SlotSyncSkipReason skip_reason = SS_SKIP_NONE;
Assert(slot->data.invalidated == RS_INVAL_NONE);
slot->data.catalog_xmin))
{
/* Update slot sync skip stats */
- pgstat_report_replslotsync(slot);
+ update_slotsync_skip_stats(SS_SKIP_WAL_OR_ROWS_REMOVED);
/*
* This can happen in following situations:
* persisted. See update_and_persist_local_synced_slot().
*/
if (found_consistent_snapshot && !(*found_consistent_snapshot))
- pgstat_report_replslotsync(slot);
+ skip_reason = SS_SKIP_NO_CONSISTENT_SNAPSHOT;
}
updated_xmin_or_lsn = true;
}
+ /* Update slot sync skip stats */
+ update_slotsync_skip_stats(skip_reason);
+
if (remote_dbid != slot->data.database ||
remote_slot->two_phase != slot->data.two_phase ||
remote_slot->failover != slot->data.failover ||
/* Skip the sync of an invalidated slot */
if (slot->data.invalidated != RS_INVAL_NONE)
{
- pgstat_report_replslotsync(slot);
+ update_slotsync_skip_stats(SS_SKIP_INVALID);
ReplicationSlotRelease();
return slot_updated;
*/
if (remote_slot->confirmed_lsn > latestFlushPtr)
{
- pgstat_report_replslotsync(slot);
+ update_slotsync_skip_stats(SS_SKIP_WAL_NOT_FLUSHED);
/*
* Can get here only if GUC 'synchronized_standby_slots' on the
*/
if (remote_slot->confirmed_lsn > latestFlushPtr)
{
- pgstat_report_replslotsync(slot);
+ update_slotsync_skip_stats(SS_SKIP_WAL_NOT_FLUSHED);
/*
* Can get here only if GUC 'synchronized_standby_slots' on the
slot->last_saved_confirmed_flush = InvalidXLogRecPtr;
slot->last_saved_restart_lsn = InvalidXLogRecPtr;
slot->inactive_since = 0;
+ slot->slotsync_skip_reason = SS_SKIP_NONE;
/*
* Create the slot on disk. We haven't actually marked the slot allocated
#include "utils/guc.h"
#include "utils/pg_lsn.h"
+/*
+ * Map SlotSyncSkipReason enum values to human-readable names.
+ */
+static const char *SlotSyncSkipReasonNames[] = {
+ [SS_SKIP_NONE] = "none",
+ [SS_SKIP_WAL_NOT_FLUSHED] = "wal_not_flushed",
+ [SS_SKIP_WAL_OR_ROWS_REMOVED] = "wal_or_rows_removed",
+ [SS_SKIP_NO_CONSISTENT_SNAPSHOT] = "no_consistent_snapshot",
+ [SS_SKIP_INVALID] = "slot_invalidated"
+};
+
/*
* Helper function for creating a new physical replication slot with
* given arguments. Note that this function doesn't release the created
Datum
pg_get_replication_slots(PG_FUNCTION_ARGS)
{
-#define PG_GET_REPLICATION_SLOTS_COLS 20
+#define PG_GET_REPLICATION_SLOTS_COLS 21
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
XLogRecPtr currlsn;
int slotno;
values[i++] = BoolGetDatum(slot_contents.data.synced);
+ if (slot_contents.slotsync_skip_reason == SS_SKIP_NONE)
+ nulls[i++] = true;
+ else
+ values[i++] = CStringGetTextDatum(SlotSyncSkipReasonNames[slot_contents.slotsync_skip_reason]);
+
Assert(i == PG_GET_REPLICATION_SLOTS_COLS);
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
PgStatShared_ReplSlot *shstatent;
PgStat_StatReplSlotEntry *statent;
- /* Slot sync stats are valid only for logical slots on standby. */
- Assert(SlotIsLogical(slot));
+ /* Slot sync stats are valid only for synced logical slots on standby. */
+ Assert(slot->data.synced);
Assert(RecoveryInProgress());
entry_ref = pgstat_get_entry_ref_locked(PGSTAT_KIND_REPLSLOT, InvalidOid,
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 202511251
+#define CATALOG_VERSION_NO 202511281
#endif
proname => 'pg_get_replication_slots', prorows => '10', proisstrict => 'f',
proretset => 't', provolatile => 's', prorettype => 'record',
proargtypes => '',
- proallargtypes => '{name,name,text,oid,bool,bool,int4,xid,xid,pg_lsn,pg_lsn,text,int8,bool,pg_lsn,timestamptz,bool,text,bool,bool}',
- proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
- proargnames => '{slot_name,plugin,slot_type,datoid,temporary,active,active_pid,xmin,catalog_xmin,restart_lsn,confirmed_flush_lsn,wal_status,safe_wal_size,two_phase,two_phase_at,inactive_since,conflicting,invalidation_reason,failover,synced}',
+ proallargtypes => '{name,name,text,oid,bool,bool,int4,xid,xid,pg_lsn,pg_lsn,text,int8,bool,pg_lsn,timestamptz,bool,text,bool,bool,text}',
+ proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+ proargnames => '{slot_name,plugin,slot_type,datoid,temporary,active,active_pid,xmin,catalog_xmin,restart_lsn,confirmed_flush_lsn,wal_status,safe_wal_size,two_phase,two_phase_at,inactive_since,conflicting,invalidation_reason,failover,synced,slotsync_skip_reason}',
prosrc => 'pg_get_replication_slots' },
{ oid => '3786', descr => 'set up a logical replication slot',
proname => 'pg_create_logical_replication_slot', provolatile => 'v',
/* Maximum number of invalidation causes */
#define RS_INVAL_MAX_CAUSES 4
+/*
+ * When the slot synchronization worker is running, or when
+ * pg_sync_replication_slots is executed, slot synchronization may be
+ * skipped. This enum defines the possible reasons for skipping slot
+ * synchronization.
+ */
+typedef enum SlotSyncSkipReason
+{
+ SS_SKIP_NONE, /* No skip */
+ SS_SKIP_WAL_NOT_FLUSHED, /* Standby did not flush the wal corresponding
+ * to confirmed flush of remote slot */
+ SS_SKIP_WAL_OR_ROWS_REMOVED, /* Remote slot is behind; required WAL or
+ * rows may be removed or at risk */
+ SS_SKIP_NO_CONSISTENT_SNAPSHOT, /* Standby could not build a consistent
+ * snapshot */
+ SS_SKIP_INVALID /* Local slot is invalid */
+} SlotSyncSkipReason;
+
/*
* On-Disk data of a replication slot, preserved across restarts.
*/
*/
XLogRecPtr last_saved_restart_lsn;
+ /*
+ * Reason for the most recent slot synchronization skip.
+ *
+ * Slot sync skips can occur for both temporary and persistent replication
+ * slots. They are more common for temporary slots, but persistent slots
+ * may also skip synchronization in rare cases (e.g.,
+ * SS_SKIP_WAL_NOT_FLUSHED or SS_SKIP_WAL_OR_ROWS_REMOVED).
+ *
+ * Since, temporary slots are dropped after server restart, persisting
+ * slotsync_skip_reason provides no practical benefit.
+ */
+ SlotSyncSkipReason slotsync_skip_reason;
} ReplicationSlot;
#define SlotIsPhysical(slot) ((slot)->data.database == InvalidOid)
$standby2->wait_for_log(
qr/could not synchronize replication slot \"lsub1_slot\"/, $log_offset);
+# Confirm that the slotsync skip reason is updated
+$result = $standby2->safe_psql('postgres',
+ "SELECT slotsync_skip_reason FROM pg_replication_slots WHERE slot_name = 'lsub1_slot'"
+);
+is($result, 'wal_or_rows_removed', "check slot sync skip reason");
+
# Confirm that the slotsync skip statistics is updated
$result = $standby2->safe_psql('postgres',
"SELECT slotsync_skip_count > 0 FROM pg_stat_replication_slots WHERE slot_name = 'lsub1_slot'"
l.conflicting,
l.invalidation_reason,
l.failover,
- l.synced
- FROM (pg_get_replication_slots() l(slot_name, plugin, slot_type, datoid, temporary, active, active_pid, xmin, catalog_xmin, restart_lsn, confirmed_flush_lsn, wal_status, safe_wal_size, two_phase, two_phase_at, inactive_since, conflicting, invalidation_reason, failover, synced)
+ l.synced,
+ l.slotsync_skip_reason
+ FROM (pg_get_replication_slots() l(slot_name, plugin, slot_type, datoid, temporary, active, active_pid, xmin, catalog_xmin, restart_lsn, confirmed_flush_lsn, wal_status, safe_wal_size, two_phase, two_phase_at, inactive_since, conflicting, invalidation_reason, failover, synced, slotsync_skip_reason)
LEFT JOIN pg_database d ON ((l.datoid = d.oid)));
pg_roles| SELECT pg_authid.rolname,
pg_authid.rolsuper,
SlotInvalidationCauseMap
SlotNumber
SlotSyncCtxStruct
+SlotSyncSkipReason
SlruCtl
SlruCtlData
SlruErrorCause
projects / postgresql.git / commitdiff