The applicability criteria for this algorithm are similar to
those for the Index Merge method intersection algorithm. The
algorithm can be employed when the table's
WHERE clause was converted to several range
conditions on different keys combined with
OR, and each condition is one of
the following:
In this form, where the index has exactly
Nparts (that is, all index parts are covered):key_part1=const1ANDkey_part2=const2... ANDkey_partN=constNAny range condition over a primary key of an
InnoDBtable.A condition for which the Index Merge method intersection algorithm is applicable.
Examples:
SELECT * FROM t1 WHEREkey1=1 ORkey2=2 ORkey3=3; SELECT * FROMinnodb_tableWHERE (key1=1 ANDkey2=2) OR (key3='foo' ANDkey4='bar') ANDkey5=5;