pingcap/tidb
Auf GitHub ansehenshow `CARTESIAN JOIN` inappropriately in some cases
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#20.261 geöffnet am 28. Sept. 2020
good first issuehelp wantedsig/plannertype/enhancement
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Beschreibung
Development Task
mysql> desc select /*+ tidb_hj(t1) */ * from t t1 inner join t t2 where t1.a=t2.a and t1.a=1;
+---------------------------+---------+------+---------------+----------------------+
| id | estRows | task | access object | operator info |
+---------------------------+---------+------+---------------+----------------------+
| HashJoin_7 | 1.00 | root | | CARTESIAN inner join |
| ├─Point_Get_10(Build) | 1.00 | root | table:t | handle:1 |
| └─Point_Get_9(Probe) | 1.00 | root | table:t | handle:1 |
+---------------------------+---------+------+---------------+----------------------+
3 rows in set (0.00 sec)
In the case above, it's not a cartesian join, but there is a CARTESIAN in the result.