[SERVER-1215] speculatively evaluate multiple query plans for each $or clause (even after 101 matches found for query) Created: 10/Jun/10  Updated: 28/Jan/15  Resolved: 28/Jan/15

Status: Closed
Project: Core Server
Component/s: Querying
Affects Version/s: None
Fix Version/s: None

Type: Improvement Priority: Major - P3
Reporter: Aaron Staple Assignee: David Storch
Resolution: Duplicate Votes: 2
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Issue Links:
Duplicate
duplicates SERVER-13184 2.6 should explore same number of one... Closed
Participants:

 Description   

For non $or queries, the query optimizer attempts to speculatively evaluate a query using multiple indexes in parallel, until 101 matches are found with a single index.

For $or queries, each $or clause can potentially speculatively evaluate multiple indexes. However, after 101 total matches are found speculative evaluation is stopped and an index is chosen arbitrarily for each $or clause.

This ticket represents allowing speculative index evaluation in $or clauses even after the first 101 matches are found.



 Comments   
Comment by David Storch [ 28/Jan/15 ]

I believe this has been fixed with the introduction of the Subplanner, a query execution stage responsible for selecting the best query plan for each clause of a rooted $or query. The Subplanner was introduced for version 2.6.0 under SERVER-13184. Resolving as a duplicate.

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