When ORing two AND-OR formulas the range optimizer could miss
a conjunct in one of AND-OR formulas in the result. If the
index merge union plan to access a table is formed by this
formula that, in general, is not inferred from the original
where/on condition,the query could return an incorrect result set.
A crash may happenin the cases when the range optimizer tried to OR
two index merge such that the second one contained less range trees
than the first one.
The bug was introduced by the patch of MWL#24:
"index_merge: fair choice between index_merge union and range access".
that blocked building index merge plans for the queries with where
conditions of the form
(key1|2_p1=c AND range(key1_p2)) OR (key1|2_p1=c AND range(key2_p2)).
The problem was discovered by Sergey Petrunia when he reviewed the patch
for WL#24.
Added new test cases. One of them failed to produce an index merge plan
before the patch was applied.
"index_merge: fair choice between index_merge union and range access"
mysql-test/include/world.inc:
A new include file to upload the world database.
mysql-test/include/world_schema.inc:
A new include file to create tables of the world database.
mysql-test/r/index_merge_myisam.result:
The results for test cases testing the optimizations added in WL#24 for MyISAM.
mysql-test/r/range_vs_index_merge.result:
The results for test cases testing the optimizations added in WL#24 for InnoDB.
mysql-test/t/range_vs_index_merge.test:
Test cases to test the optimizations added in WL#24 for MyISAM.
mysql-test/t/range_vs_index_merge_innodb.test:
Test cases to test the optimizations added in WL#24 for InnoDB.
sql/sql_list.h:
Fixed a bug that did not allow adding a non-empty list to an empty list.
