pg_replication_slots - PolarDB - Alibaba Cloud Documentation Center

The pg_replication_slots view provides a list of all replication slots in the database cluster and the state of these replication slots.

Overview

The pg_replication_slots view contains the following columns:

Column name	Type	Description
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 that the logical slot is using. This value is empty for physical slots.
slot_type	text	The type of the replication slot. Valid values: `physical` and `logical`.
datoid	oid	The OID of the database with which this slot is associated. This value is empty for physical slots. Only a logical slot have an associated database.
database	name	The name of the database with which this slot is associated. This value is empty for physical slots. Only a logical slot have an associated database.
temporary	bool	The value is `true` if this is a temporary replication slot. Otherwise, the value is `false`. Temporary slots are not saved to disk and are automatically removed when errors occur or when the session ends.
active	bool	The value is `true` if the replication slot is being used. Otherwise, the value is `false`.
active_pid	int4	The process ID of the session that uses this slot if the slot is being used. The value is `NULL` if the slot is 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 won't be automatically removed during checkpoints. The value is `NULL` if the `LSN` of this slot has never been reserved.
confirmed_flush_lsn	pg_lsn	The address (`LSN`) to which the consumer of this slot has confirmed receiving data. Data corresponding to the transactions committed before this address is no longer available. The value is `NULL` for physical slots.
wal_status	text	The availability of WAL files claimed by this slot. Valid values: `reserved`: The claimed files are smaller than the value of the `max_wal_size` parameter. `extended`: The claimed files exceed the value of the `max_wal_size` parameter, but the files are still retained either by the replication slot or the `wal_keep_size` parameter. `unreserved`: The slot no longer retains the required WAL files and some of the files are to be removed at the next checkpoint. This state can returned to `reserved` or `extended`. `lost`: Some required WAL files are removed and this slot is no longer available. Note The unreserved and lost states are displayed only when the `max_slot_wal_keep_size` parameter is non-negative. If the value of `restart_lsn` is NULL, this value is empty.
safe_wal_size	int8	The number of bytes that can be written to WAL to ensure that this slot is not in the lost state. If the slot is in the lost state or the value of the `max_slot_wal_keep_size` parameter is -1, the value is NULL.