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Posted to notifications@shardingsphere.apache.org by GitBox <gi...@apache.org> on 2019/06/03 11:59:24 UTC
[GitHub] [incubator-shardingsphere] wbliubin opened a new issue #2491: Group
by in SQL statements takes a long time , the index seems to be not working...
wbliubin opened a new issue #2491: Group by in SQL statements takes a long time ,the index seems to be not working...
URL: https://github.com/apache/incubator-shardingsphere/issues/2491
## Bug Report
### Which version of ShardingSphere did you use?
4.0.0-RC1
### Which project did you use? Sharding-JDBC or Sharding-Proxy?
Sharding-JDBC
### Expected behavior
I have a sql , eg:
`SELECT
a.tid
FROM A a Left join B b on a.tid = b.tid
WHERE a.user_id= 1234567890
AND a.sid = 1234567890
AND b.user_id= 1234567890
AND b.sid = 1234567890
GROUP BY
a.tid
ORDER BY
a.tid DESC
limit 10`
1. The execution time of the database client is only 0.004s,
### Actual behavior
2. But , in Sharding-JDBC project ,it takes 4s~9s !
### Reason analyze (If you can)
3. this SQL takes 0.01s~0.1 to get rid of the "group by" inside ,I mean, the index seems to be not working...
### Steps to reproduce the behavior, such as: SQL to execute, sharding rule configuration, when exception occur etc.
### Example codes for reproduce this issue (such as a github link).
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