Wiki / 配置参数

Allows the use of parallel queries for testing purposes even in cases where no performance benefit is expected. The allowed values of force_parallel_mode are off (use parallel mode only when it is expected to improve performance), on (force parallel query for all queries for which it is thought to be safe), and regress (like on, but with additional behavior changes as explained below). More specifically, setting this value to on will add a Gather node to the top of any query plan for which this appears to be safe, so that the query runs inside of a parallel worker. Even when a parallel worker is not available or cannot be used, operations such as starting a subtransaction that would be prohibited in a parallel query context will be prohibited unless the planner believes that this will cause the query to fail. If failures or unexpected results occur when this option is set, some functions used by the query may need to be marked PARALLEL UNSAFE (or, possibly, PARALLEL RESTRICTED). Setting this value to regress has all of the same effects as setting it to on plus some additional effects that are intended to facilitate automated regression testing. Normally, messages from a parallel worker include a context line indicating that, but a setting of regress suppresses this line so that the output is the same as in non-parallel execution. Also, the Gather nodes added to plans by this setting are hidden in EXPLAIN output so that the output matches what would be obtained if this setting were turned off.

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

off

category

Developer Options

context

user

documented

true

enumvals

off, on, regress

extra desc

If possible, run query using a parallel worker and with parallel restrictions.

lang

en

max val

未知

metadata version

15

min val

未知

name

force_parallel_mode

short desc

Forces use of parallel query facilities.

source

pg-settings-source-snapshot

unit

未知

vartype

enum