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create table t1 (a int primary key, b int, index bindex(b));
insert into t1 values (1,2),(2,2),(3,NULL),(4,NULL);
--replace_column 9 #
explain select * from t1 force index (bindex) where b is NULL;
select * from t1 force index (bindex) where b is NULL;
drop table t1;
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