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50.80. `pg_replication_slots`
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50.80. `pg_replication_slots`

Thepg_replication_slots view provides a listing of all replication slots that currently exist on the database cluster, along with their current state.

For more on replication slots, seeSection 25.2.6 andChapter 47.

Table 50.81. pg_replication_slots Columns

Column Type Description
`slot_namename` A unique, cluster-wide identifier for the replication slot
`pluginname` The base name of the shared object containing the output plugin this logical slot is using, or null for physical slots.
`slot_typetext` The slot type:`physical` or`logical`
`datoidoid` (references`pg_database`.`oid`) The OID of the database this slot is associated with, or null. Only logical slots have an associated database.
`databasename` (references`pg_database`.`datname`) The name of the database this slot is associated with, or null. Only logical slots have an associated database.
`temporarybool` 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.
`activebool` True if this slot is currently actively being used
`active_pidint4` The process ID of the session using this slot if the slot is currently actively being used.`NULL` if inactive.
`xminxid` The oldest transaction that this slot needs the database to retain.`VACUUM` cannot remove tuples deleted by any later transaction.
`catalog_xminxid` 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_lsnpg_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 thanmax_slot_wal_keep_size from the current LSN.`NULL` if the`LSN` of this slot has never been reserved.
`confirmed_flush_lsnpg_lsn` The address (`LSN`) up to which the logical slot's consumer has confirmed receiving data. Data older than this is not available anymore.`NULL` for physical slots.
`wal_statustext` 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 state can return to`reserved` or`extended`. `lost` means that some required WAL files have been removed and this slot is no longer usable. The last two states are seen only whenmax_slot_wal_keep_size is non-negative. If`restart_lsn` is NULL, this field is null.
`safe_wal_sizeint8` 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`.

Column Type

Description

slot_namename

A unique, cluster-wide identifier for the replication slot

pluginname

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

slot_typetext

The slot type:physical orlogical

datoidoid (referencespg_database.oid)

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

databasename (referencespg_database.datname)

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

temporarybool

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.

activebool

True if this slot is currently actively being used

active_pidint4

The process ID of the session using this slot if the slot is currently actively being used.NULL if inactive.

xminxid

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

catalog_xminxid

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_lsnpg_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 thanmax_slot_wal_keep_size from the current LSN.NULL if theLSN of this slot has never been reserved.

confirmed_flush_lsnpg_lsn

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

wal_statustext

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

reserved means that the claimed files are withinmax_wal_size.
extended means thatmax_wal_size is exceeded but the files are still retained, either by the replication slot or bywal_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 state can return toreserved orextended.
lost means that some required WAL files have been removed and this slot is no longer usable.

The last two states are seen only whenmax_slot_wal_keep_size is non-negative. Ifrestart_lsn is NULL, this field is null.

safe_wal_sizeint8

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 ifmax_slot_wal_keep_size is-1.

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50.80. pg_replication_slots

50.80. `pg_replication_slots`