Details
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Bug
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Resolution: Works as Designed
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Major - P3
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None
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None
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None
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None
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Query Integration
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ALL
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QI 2023-09-04
Description
In a timeseries pipeline, when we first have a $group stage on the $meta field and an accumulator on the $min as the first stage, and then have a $match on the _id as the second stage, the pipeline is rewritten to absorb the $match into the index scan and leave the $group stage.
In essence, the stages $_unpack -> $group(_id=$meta, min=$meta) -> $match (_id=1) gets reordered to $IXSCAN (with $meta=1) -> $group(_id=$meta, min=$meta)