[MCOL-198] ORDER BY in subquery does not work as expected (wrong results) Created: 2016-06-24 Updated: 2016-12-22 Resolved: 2016-12-22 |
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| Status: | Closed |
| Project: | MariaDB ColumnStore |
| Component/s: | MariaDB Server |
| Affects Version/s: | None |
| Fix Version/s: | Icebox |
| Type: | Bug | Priority: | Major |
| Reporter: | Justin Swanhart (Inactive) | Assignee: | Unassigned |
| Resolution: | Won't Fix | Votes: | 0 |
| Labels: | community | ||
| Description |
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From: https://groups.google.com/forum/#!topic/mariadb-columnstore/xEWtv_bWlwI Hi all, while testing I found that the following query type produces unexpected (I'd say wrong) results. SELECT .. FROM (SELECT .. FROM .. ORDER BY 1) LIMIT 10 That is, if an inner query has an ORDER BY clause and the outer query a LIMIT clause then the ordering is not preserved. This behavior is different from say the InnoDB storage engine. Is that intentional? Regards, |
| Comments |
| Comment by David Thompson (Inactive) [ 2016-12-22 ] |
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MariaDB server also does not promise to support this. For columnstore it is even harder to support once you factor in distributed execution. Order by is only supported on the outer sql. Many times what people are trying do here with databases that support this is to simulate window functions where they are not supported. Almost certainly what is being tried to be done here can be better expressed with a window function. |