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This article focuses on "what are the configuration parameters related to the implementation plan in PostgreSQL". Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn "what are the configuration parameters related to the execution plan in PostgreSQL?"

ENABLE_* parameter

In pg, parameters that start with "ENABLE_*" provide ways to influence the query optimizer's choice of a different execution plan.

If the execution plan chosen by the optimizer for a particular query is not optimal, you can set these parameters to force the optimizer to choose a better execution plan to solve the problem temporarily.

However, the default values of these parameters are generally not changed in pg.

Enable_seqscan:boolean

Whether to select a full table scan. In fact, full table scanning is not completely disabled, but turning this variable off allows the optimizer to give priority to other methods when there are other methods.

Enable_indexscan:boolean

Whether to select index scan

Enable_bitmapscan:boolean

Whether to select bitmap scan

Enable_tidscan:boolean

Whether to select bitmap scan

Enable_nestloop:boolean

Whether to select a nested loop join when multiple table joins. If set to "off", the optimizer can only choose to take this path when the execution plan is connected by a nested loop.

However, if there are other connection methods to go, the optimizer will give priority to other methods.

Enable_hashjoin:boolean

When connecting with multiple tables, whether to select hash connection

Enable_mergejoin:boolean

When connecting with multiple tables, whether to select merge connection

Enable_hashagg:boolean

Whether to use hash aggregation

Enable_sort:boolean

Whether to use explicit sorting, if set to "off", the optimizer can only choose this path when there is only one path to sort in the execution plan.

However, if there are other connection methods to go, the optimizer will give priority to other methods.

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