[MCOL-1698] Add Distinct capability to specific UDAnF Window Functions Created: 2018-09-06 Updated: 2018-12-10 Resolved: 2018-12-10 |
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| Status: | Closed |
| Project: | MariaDB ColumnStore |
| Component/s: | ExeMgr |
| Affects Version/s: | 1.1.5 |
| Fix Version/s: | 1.1.7 |
| Type: | New Feature | Priority: | Major |
| Reporter: | David Hall (Inactive) | Assignee: | David Hall (Inactive) |
| Resolution: | Fixed | Votes: | 1 |
| Labels: | None | ||
| Issue Links: |
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| Sprint: | 2018-17, 2018-18, 2018-19, 2018-20, 2018-21 | ||||||||
| Description |
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Currently, there's no way to create a UDAnF that creates a DISTINCT result. The parser won't pass DISTINCT when an aggregate is used as an analytic function. This ticket is to add a DISTINCT flag to the UDAnF context so that a UDAnF can be created that is always DISTINCT. It's also possible to create a multi-parm aggregate that could use one of the parameters to indicate distinctness. This ticket does not cover the case of UDAF – the use of a function as an aggregate, not a Window Function. UDAnF created with this feature should have the UDAF_OVER_REQUIRED flag set in the runflags, as the distinctness would be ignored by aggregate use and would definitely confuse a user. |
| Comments |
| Comment by David Hall (Inactive) [ 2018-12-10 ] |
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This was merged in 1.1.6 and there is no more work to do. The purpose of this feature is to implement the distinct_count() aggregate function because Server can't parse DISTINCT on UDF. When it does, this feature will be used to handle that as well. For use as an Aggregate, the DISTINCT functionality will need to be added to the Aggregate UDAF logic, which it currently isn't. At least I don't think it would work. |
| Comment by David Hall (Inactive) [ 2018-12-10 ] |
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Closing because this has been in the release for a while already. |