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ANALYZE-stmt may print 0 in r_rows column:
create table t1(a int);
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insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
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create table t2 (a int, key(a));
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insert into t2 values (0),(1);
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analyze select * from t1 straight_join t2 force index(a) where t2.a=t1.a;
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id select_type table type possible_keys key key_len ref rows r_rows filtered r_filtered Extra
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1 SIMPLE t1 ALL NULL NULL NULL NULL 10 10 100.00 100.00 Using where
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1 SIMPLE t2 ref a a 5 test.t1.a 2 0 100.00 100.00 Using index
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this happens when some index lookups do not yield a row.
We should change r_rows to show fractions.
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