53.20. pg_replication_slots

slot_name name

A unique, cluster-wide identifier for the replication slot

plugin name

The base name of the shared object containing the output plugin this logical slot is using, or null for physical slots.

slot_type text

The slot type: physical or logical

datoid oid (references pg_database.oid)

The OID of the database this slot is associated with, or null. Only logical slots have an associated database.

database name (references pg_database.datname)

The name of the database this slot is associated with, or null. Only logical slots have an associated database.

temporary bool

True if this is a temporary replication slot. Temporary slots are not saved to disk and are automatically dropped on error or when the session has finished.

active bool

True if this slot is currently being streamed

active_pid int4

The process ID of the session streaming data for this slot. NULL if inactive.

xmin xid

The oldest transaction that this slot needs the database to retain. VACUUM cannot remove tuples deleted by any later transaction.

catalog_xmin xid

The oldest transaction affecting the system catalogs that this slot needs the database to retain. VACUUM cannot remove catalog tuples deleted by any later transaction.

restart_lsn pg_lsn

The address (LSN) of oldest WAL which still might be required by the consumer of this slot and thus won't be automatically removed during checkpoints unless this LSN gets behind more than [max_slot_wal_keep_size (integer)

    max_slot_wal_keep_size configuration parameter](braised:ref/runtime-config-replication#max-slot-wal-keep-size-integer-max-slot-wal-keep-size-configuration-parameter) from the current LSN. `NULL` if the `LSN` of this slot has never been reserved.

confirmed_flush_lsn pg_lsn

The address (LSN) up to which the logical slot's consumer has confirmed receiving data. Data corresponding to the transactions committed before this LSN is not available anymore. NULL for physical slots.

wal_status text

Availability of WAL files claimed by this slot. Possible values are:

• reserved means that the claimed files are within max_wal_size.

• extended means that max_wal_size is exceeded but the files are still retained, either by the replication slot or by wal_keep_size.

• unreserved means that the slot no longer retains the required WAL files and some of them are to be removed at the next checkpoint. This typically occurs when [max_slot_wal_keep_size (integer)

  max_slot_wal_keep_size configuration parameter](braised:ref/runtime-config-replication#max-slot-wal-keep-size-integer-max-slot-wal-keep-size-configuration-parameter) is set to a non-negative value. This state can return to reserved or extended.

• lost means that this slot is no longer usable. :::{/row}

safe_wal_size int8

The number of bytes that can be written to WAL such that this slot is not in danger of getting in state "lost". It is NULL for lost slots, as well as if max_slot_wal_keep_size is -1.

two_phase bool

True if the slot is enabled for decoding prepared transactions. Always false for physical slots.

two_phase_at pg_lsn

The address (LSN) from which the decoding of prepared transactions is enabled. NULL for logical slots where two_phase is false and for physical slots.

inactive_since timestamptz

The time when the slot became inactive. NULL if the slot is currently being streamed. If the slot becomes invalid, this value will never be updated. For standby slots that are being synced from a primary server (whose synced field is true), the inactive_since indicates the time when slot synchronization (see Replication Slot Synchronization) was most recently stopped. NULL if the slot has always been synchronized. This helps standby slots track when synchronization was interrupted.

conflicting bool

True if this logical slot conflicted with recovery (and so is now invalidated). When this column is true, check invalidation_reason column for the conflict reason. Always NULL for physical slots.

invalidation_reason text

The reason for the slot's invalidation. It is set for both logical and physical slots. NULL if the slot is not invalidated. Possible values are:

• wal_removed means that the required WAL has been removed.

• rows_removed means that the required rows have been removed. It is set only for logical slots.

• wal_level_insufficient means that the primary doesn't have a [wal_level (enum)

  wal_level configuration parameter](braised:ref/runtime-config-wal#wal-level-enum-wal-level-configuration-parameter) sufficient to perform logical decoding. It is set only for logical slots.

• idle_timeout means that the slot has remained inactive longer than the configured [idle_replication_slot_timeout (integer)

  idle_replication_slot_timeout configuration parameter](braised:ref/runtime-config-replication#idle-replication-slot-timeout-integer-idle-replication-slot-timeout-configuration-parameter) duration. :::{/row}

failover bool

True if this is a logical slot enabled to be synced to the standbys so that logical replication can be resumed from the new primary after failover. Always false for physical slots.

synced bool

True if this is a logical slot that was synced from a primary server. On a hot standby, the slots with the synced column marked as true can neither be used for logical decoding nor dropped manually. The value of this column has no meaning on the primary server; the column value on the primary is default false for all slots but may (if leftover from a promoted standby) also be true.