# # MariaDB tests for EXPLAIN UPDATE/DELETE. # --disable_warnings drop table if exists t0; --enable_warnings create table t0 (a int) engine=myisam; insert into t0 values (1),(2),(3),(4),(5),(6),(7),(8); --echo # --echo # Tests for single-table DELETE --echo # explain select * from t0 where a=3; explain delete from t0 where a=3; --echo # DELETE without WHERE is a special case: explain delete from t0; create table t1 (a int, b int, filler char(100), key(a), key(b)); insert into t1 select A.a+10*B.a + 10*C.a, A.a+10*B.a + 10*C.a, 'filler' from t0 A, t0 B, t0 C; --echo # This should use an index, possible_keys=NULL because there is no WHERE explain delete from t1 order by a limit 2; --echo # This should use range, possible_keys={a,b} explain delete from t1 where a<20 and b < 10; --echo # This should use ALL + filesort explain delete from t1 order by a+1 limit 2; --echo # This should use range + using filesort explain delete from t1 where a<20 order by b limit 2; --echo # Try some subqueries: explain delete from t1 where a < (select max(a) from t0); explain delete from t1 where a < (select max(a) from t0 where a < t1.b); --echo # --echo # Tests for multi-table DELETE --echo # explain delete t1 from t0, t1 where t0.a = t1.a; drop table t0, t1;