PostgreSQL 8.1.4 Documentation
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# 42.10. `pg_autovacuum`

The catalog `pg_autovacuum` stores optional per-relation configuration parameters for The auto-vacuum daemon. If there is an entry here for a particular relation, the given parameters will be used for autovacuuming that table. If no entry is present, the system-wide defaults will be used.

Table 42-10. `pg_autovacuum` Columns

Name | Type | References | Description
--- | --- | --- | ---
`vacrelid` | `oid` | ``pg_class`.oid` | The table this entry is for
`enabled` | `bool` |  | If false, this table is never autovacuumed
`vac_base_thresh` | `integer` |  | Minimum number of modified tuples before vacuum
`vac_scale_factor` | `float4` |  | Multiplier for reltuples to add to `vac_base_thresh`
`anl_base_thresh` | `integer` |  | Minimum number of modified tuples before analyze
`anl_scale_factor` | `float4` |  | Multiplier for reltuples to add to `anl_base_thresh`
`vac_cost_delay` | `integer` |  | Custom `vacuum_cost_delay` parameter
`vac_cost_limit` | `integer` |  | Custom `vacuum_cost_limit` parameter

The autovacuum daemon will initiate a `VACUUM` operation on a particular table when the number of updated or deleted tuples exceeds `vac_base_thresh` plus `vac_scale_factor` times the number of live tuples currently estimated to be in the relation. Similarly, it will initiate an `ANALYZE` operation when the number of inserted, updated or deleted tuples exceeds `anl_base_thresh` plus `anl_scale_factor` times the number of live tuples currently estimated to be in the relation.

Any of the numerical fields can contain `-1` (or indeed any negative value) to indicate that the system-wide default should be used for this particular value. Observe that the `vac_cost_delay` variable inherits its default value from the `autovacuum_vacuum_cost_delay` configuration parameter, or from `vacuum_cost_delay` if the former is set to a negative value. The same applies to `vac_cost_limit`.

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