Bug #13317 VIEW doesn't use index
Submitted: 19 Sep 2005 10:11 Modified: 28 Sep 2005 1:59
Reporter: Georg Richter Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Optimizer Severity:S2 (Serious)
Version:5.0.14 OS:Linux (SLES 9)
Assigned to: Sergey Petrunya

[19 Sep 2005 10:11] Georg Richter
Description:
A view based on a single table uses an index scan, while select on the same table uses a range index.

Explain output:
root@georg>explain select * from t1 where a in (3,4)  and b in (1,2,3) \G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t1
         type: range
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 8
          ref: NULL
         rows: 6
        Extra: Using where; Using index
1 row in set (0.00 sec)

root@georg>explain select * from v1 where a in (3,4)  and b in (1,2,3) \G
*************************** 1. row ***************************
           id: 1
  select_type: PRIMARY
        table: t1
         type: index
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 8
          ref: NULL
         rows: 20
        Extra: Using where; Using index
1 row in set (0.00 sec)

How to repeat:
create table t1 (a int, b int, primary key(a,b));
create view v1 as select a, b from t1;

INSERT INTO `t1` VALUES (0,0),(1,0),(2,0),(3,0),(4,0),(5,1),(6,1),(7,1),(8,1),(9,1),(10,2),(11,2),(12,2),(13,2),(14,2),(15,3),(16,3),(17,3),(18,3),(19,3);

explain select * from t1 where a in (3,4)  and b in (1,2,3);
explain select * from v1 where a in (3,4)  and b in (1,2,3);
[20 Sep 2005 22:04] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/30124
[21 Sep 2005 17:33] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/internals/30165
[24 Sep 2005 23:14] Sergey Petrunya
Fix pushed into 5.0.14  tree.
Bug description for the changelog:
  In queries over VIEWs that are processed using MERGE algorithm, range optimizer was unable to create ranges for "view.col IN (<constants>)" or "view.col BETWEEN const1 AND const2". This limitation is now removed.
[28 Sep 2005 1:59] Mike Hillyer
Added to 5.0.14 functionality change list:

<listitem>
        <para>
          Range scans can now be performed for queries on VIEWs such as
          <literal>column IN (&lt;constants&gt;)</literal> and <literal>column
            BETWEEN ConstantA AND ConstantB</literal>. (Bug #13317)
        </para>
      </listitem>