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WORKLOG TASK
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TASK...........: Better choice between range and index_merge/intersection
options
CREATION DATE..: Wed, 27 May 2009, 15:20
SUPERVISOR.....: Monty
IMPLEMENTOR....: Psergey
COPIES TO......:
CATEGORY.......: Server-RawIdeaBin
TASK ID........: 26 (http://askmonty.org/worklog/?tid=26)
VERSION........: Server-9.x
STATUS.........: Un-Assigned
PRIORITY.......: 60
WORKED HOURS...: 0
ESTIMATE.......: 0 (hours remain)
ORIG. ESTIMATE.: 0
PROGRESS NOTES:
DESCRIPTION:
The optimizer does a cost-based choice between possible range and
index_merge/intersection scans. There are some issues with it:
- index_merge/intersection gets chosen even when there is a single
multi-part index that covers all keys. Measurements show that this is
a poor choice.
- The picked index_merge/intersection can use a redundant set of indexes:
it will be intersect(idx1, ..., idxN) where all columns in idxN are covered
by other used indexes.
This WL is to fix these limitations.
ESTIMATED WORK TIME
ESTIMATED COMPLETION DATE
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WorkLog (v3.5.9)
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