# aurora\$1stat\$1logical\$1wal\$1cache
<a name="aurora_stat_logical_wal_cache"></a>

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

## Syntax
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```
SELECT * FROM aurora_stat_logical_wal_cache()
```

## Arguments
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None

## Return type
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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\$1hit / blks\$1read). 
+ `last_reset_timestamp` – Last time that the counter was reset. 

## Usage notes
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This function is available for the following Aurora PostgreSQL versions.
+ 15.2 and all higher versions
+ 14.7 and higher versions
+ 13.8 and higher versions
+ 12.12 and higher versions
+ 11.17 and higher versions

## Examples
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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)
```