Wiki / 配置参数

Determines the behavior when cumulative statistics are accessed multiple times within a transaction. When set to none, each access re-fetches counters from shared memory. When set to cache, the first access to statistics for an object caches those statistics until the end of the transaction unless pg_stat_clear_snapshot() is called. When set to snapshot, the first statistics access caches all statistics accessible in the current database, until the end of the transaction unless pg_stat_clear_snapshot() is called. Changing this parameter in a transaction discards the statistics snapshot. The default is cache. Note none is most suitable for monitoring systems. If values are only accessed once, it is the most efficient. cache ensures repeat accesses yield the same values, which is important for queries involving e.g. self-joins. snapshot can be useful when interactively inspecting statistics, but has higher overhead, particularly if many database objects exist.

英文手册覆盖始于 PostgreSQL 7.4. 来源历史与运行验证各自保留独立版本边界。

此版本暂无所选语言的定义，以下显示原始英文内容。

boot val

cache

category

Statistics / Cumulative Query and Index Statistics

context

user

documented

true

enumvals

none, cache, snapshot

extra desc

未知

lang

en

max val

未知

metadata version

18

min val

未知

name

stats_fetch_consistency

short desc

Sets the consistency of accesses to statistics data.

source

pg-settings-source-snapshot

unit

未知

vartype

enum