23.18.20 records_in_range

Purpose

For the given range how many records are estimated to be in this range.

Synopsis

virtual ha_rows records_in_range (	inx,
	min_key,
	max_key);

uint	inx ;
key_range *	min_key ;
key_range *	max_key ;

Description

This is the records_in_range method.

Given a starting key, and an ending key estimate the number of rows that will exist between the two. end_key may be empty which in case determine if start_key matches any rows.

Used by optimizer to calculate cost of using a particular index.

Called from opt_range.cc by check_quick_keys().

Parameters

• inx

• min_key

• max_key

Return Values

Return the approxamite number of rows.

Usage

Determine an approxamite count of the rows between the key values and return.

Default Implementation

 { return (ha_rows) 10; }