[CSHARP-1838] Merge multiple .Where() clauses to a single $match before querying Created: 25/Nov/16 Updated: 11/Jan/17 Resolved: 11/Jan/17 |
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| Status: | Closed |
| Project: | C# Driver |
| Component/s: | Linq |
| Affects Version/s: | 2.3 |
| Fix Version/s: | None |
| Type: | Improvement | Priority: | Major - P3 |
| Reporter: | Sten Blomstrand | Assignee: | Robert Stam |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Issue Links: |
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| Backwards Compatibility: | Fully Compatible | ||||||||
| Description |
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My first issue here so please correct me if I make any mistakes posting it. The aggregation framework that the 2.* driver maps to only uses indexes for the first match (https://docs.mongodb.com/v3.2/reference/operator/aggregation/match/). I often pass aroung IQueryable to multiple layers in my applications that combine .Where(...) clauses to filter the result (depending on user input, access level etc). The resulting query that the driver produces translates every .Where() clause to a $match. This results in poor performance since the indexes are only used for the first $match. Would it be possible for the driver to combine these $match'es to a single $match? |
| Comments |
| Comment by Robert Stam [ 11/Jan/17 ] |
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Looks like the server implemented this optimization a long time ago, in version 2.6: |
| Comment by Sten Blomstrand [ 05/Dec/16 ] |
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I what version did this change? |
| Comment by Robert Stam [ 30/Nov/16 ] |
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Have you tried this with the current version of the server? The server is supposed to merge $match stages in which case it should not be necessary for any drivers to do that. |