The mi_qual_const_depends_hostvar() accessor function

Syntax

mi_boolean 
mi_qual_const_depends_hostvar(MI_AM_QUAL_DESC *qualDesc)

qualDesc

Points to the qualification descriptor.

Usage

Call mi_qual_const_depends_hostvar() in the am_scancost purpose function to determine whether a qualification function contains a host variable but no explicit constant value.

Because the database server executes am_scancost before the application binds the host variable to a value, the qualification descriptor cannot provide a value in time to evaluate the cost of the scan.

If mi_qual_const_depends_hostvar() returns MI_TRUE, am_scancost can call mi_qual_setreopt(), which tells the database server to reoptimize before it executes the scan.

Return values

MI_TRUE

Indicates that a host variable provides values when the function executes.

MI_FALSE

Indicates that the qualification descriptor supplies the constant value.

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