[MDEV-14979] Pushdown conditions for ORDER BY and LIMIT Created: 2018-01-17 Updated: 2018-08-27 Resolved: 2018-06-16 |
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| Status: | Closed |
| Project: | MariaDB Server |
| Component/s: | N/A |
| Fix Version/s: | N/A |
| Type: | Task | Priority: | Critical |
| Reporter: | Andrew Hutchings (Inactive) | Assignee: | Unassigned |
| Resolution: | Not a Bug | Votes: | 0 |
| Labels: | None | ||
| Description |
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Pushdown conditions for ORDER BY and LIMIT are needed as part of the ColumnStore generic engine project. This task is to track that. |
| Comments |
| Comment by Ralf Gebhardt [ 2018-06-07 ] |
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Clarification needed as there is an existing API for this |
| Comment by Andrew Hutchings (Inactive) [ 2018-06-16 ] |
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What we need already exists in select_lex.order_list but we aren't using it fully. We don't want to fully turn off filesort because there is the potential for cases such as a final join happening in mysqld. There may be a case for an optimization of an engine passing a flag stating "everything you get from me is already sorted" when it encounters an ORDER BY it can work with but that is more of a nice to have and ColumnStore needs to implement some faux-key handling first. |