Xie Bo created IGNITE-13316:
-------------------------------

             Summary: The left join table's index is not used in Ignite SQL 
execution
                 Key: IGNITE-13316
                 URL: https://issues.apache.org/jira/browse/IGNITE-13316
             Project: Ignite
          Issue Type: Improvement
          Components: springdata
    Affects Versions: 2.8.1
            Reporter: Xie Bo


 

SELECT * FROM issue LEFT JOIN issue_fixed_version ver ON issue.id=ver.id WHERE 
*issue.id in (select distinct id from issue_fixed_version where fixed_version = 
'4.15')*;
 12 rows selected (*0.062 seconds*)
 ________________________________________
 SELECT * FROM issue LEFT JOIN issue_fixed_version ver ON issue.id=ver.id WHERE 
*ver.FIXED_VERSION = '4.15'*;
 12 rows selected (*2.015 second*s)

________________________________________

Note: 'issue' is a table with over a million rows and 'issue_fixed_version' is 
another table with much less rows. There is an index on 'FIXED_VERSION' column 
in 'issue_fixed_version' table.

The above 2 SQLs do the same thing but have different performance. The first 
SQL's explain plan shows that the index (on 'FIXED_VERSION' column in 
'issue_fixed_version' table) is used and then its performance is good; the 
second SQL's explain plan shows that the index (on 'FIXED_VERSION' column in 
'issue_fixed_version' table) is not used, why? Any way to force the second SQL 
to use the index (on 'FIXED_VERSION' column in 'issue_fixed_version' table)?



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