aurora_stat_logical_wal_cache - Amazon Aurora
SyntaxArgumentsReturn typeUsage notesExamples

aurora_stat_logical_wal_cache

Shows logical write-ahead log (WAL) cache usage per slot.

Syntax

SELECT * FROM aurora_stat_logical_wal_cache()

Arguments

None

Return type

SETOF record with the following columns:

  • name – The name of the replication slot.

  • active_pid – ID of the walsender process.

  • cache_hit – The total number of wal cache hits since last reset.

  • cache_miss – The total number of wal cache misses since last reset.

  • blks_read – The total number of wal cache read requests.

  • hit_rate – The WAL cache hit rate (cache_hit / blks_read).

  • last_reset_timestamp – Last time that the counter was reset.

Usage notes

This function is available for the following versions.

  • Aurora PostgreSQL 14.7

  • Aurora PostgreSQL version 13.8 and higher

  • Aurora PostgreSQL version 12.12 and higher

  • Aurora PostgreSQLversion 11.17 and higher

Examples

The following example shows two replication slots with only one active. aurora_stat_logical_wal_cache function.

=> SELECT * 
     FROM aurora_stat_logical_wal_cache();
    name    | active_pid | cache_hit | cache_miss | blks_read | hit_rate |     last_reset_timestamp
------------+------------+-----------+------------+-----------+----------+-------------------------------
 test_slot1 |      79183 |        24 |          0 |        24 | 100.00%  | 2022-08-05 17:39:56.830635+00
 test_slot2 |            |         1 |          0 |         1 | 100.00%  | 2022-08-05 17:34:04.036795+00
(2 rows)