[MDEV-4120] UNIQUE indexes should not be considered for loose index scan Created: 2013-01-31 Updated: 2014-11-19 Resolved: 2013-08-21 |
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| Status: | Closed |
| Project: | MariaDB Server |
| Component/s: | None |
| Fix Version/s: | 10.0.5 |
| Type: | Task | Priority: | Minor |
| Reporter: | Timour Katchaounov (Inactive) | Assignee: | Timour Katchaounov (Inactive) |
| Resolution: | Fixed | Votes: | 0 |
| Labels: | None | ||
| Issue Links: |
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| Description |
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Currently the loose scan code in opt_range.cc considers all indexes as possible for the access method. Due to inexact statistics it may happen that a loose scan is selected over a unique index. This is clearly wrong since a "loose scan" over a unique index will read the same keys as a direct index scan, but the loose scan has more overhead. |
| Comments |
| Comment by Timour Katchaounov (Inactive) [ 2013-06-03 ] |
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Assigned to SergeyP for review. |
| Comment by Sergei Petrunia [ 2013-08-20 ] |
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Patch approved with comments (see email) |