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  1. Core Server
  2. SERVER-22631

Improve efficiency of matching during an aggregation pipeline.

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    • Fully Compatible
    • Query 13 (04/22/16)

    Description

      It's currently very expensive to perform a $match within the aggregation pipeline. This is mostly because the aggregation pipeline works with Documents, which are incompatible with the current MatchExpression::matchesBSON interface, so we have to construct an entirely new BSONObj to match on. There are two things we could do to make this more efficient:

      1. Instead of converting the entire Document to BSON, we could only convert the fields needed by the match. For example, if the match was {a: {$gte: 4}}, we would only need the field a from the document.
      2. We could extend the MatchExpression interface to support matching Documents. A Document is logically equivalent to a BSONObj, so it would just be a matter of adapting the matching to use a different API with the object.

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          is duplicated by

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-22404 Extend MatchExpression to support matching Documents

          • Major - P3 - Major loss of function.
          • Closed
          is related to

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-25304 Allow a MatchExpression to match a Document

          • Major - P3 - Major loss of function.
          • Backlog

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-22402 Add dependency tracking to the $match stage

          • Major - P3 - Major loss of function.
          • Closed
          related to

          Bug - A problem which impairs or prevents the functions of the product. SERVER-27213 Two $match stages combine incorrectly, yielding incorrect results.

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-25911 Tune performance of $match stage

          • Major - P3 - Major loss of function.
          • Closed

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              benjamin.murphy Benjamin Murphy
              charlie.swanson@mongodb.com Charlie Swanson
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