JOIN_SIMPLIFICATION_THRESHOLD Option

Controls the minimum number of tables being joined together before any join optimizer simplifications are applied.

Allowed Values

1 – 64

Default

15

Scope

Can be set temporary for an individual connection or for the PUBLIC group. Takes effect immediately.

Description

The query optimizer simplifies its optimization of join order by separate handling of both lookup tables (that is, nonselective dimension tables) and tables that are effective Cartesian products. After simplification, it optimizes the remaining tables for join order, up to the limit set by MAX_JOIN_ENUMERATION.

Setting this option to a value greater than the current value for MAX_JOIN_ENUMERATION has no effect.

Setting this value below the value for MAX_JOIN_ENUMERATION might improve the time required to optimize queries containing many joins, but may also prevent the optimizer from finding the best possible join plan.

Normally, you should not need to change this value. If you do, Sybase recommends setting JOIN_SIMPLIFICATION_THRESHOLD as a temporary or user option, and to a value of at least 9.

Related reference
MAX_JOIN_ENUMERATION Option