Details
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Improvement
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Status: Closed
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Major - P3
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Resolution: Fixed
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None
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None
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None
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Minor Change
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(copied to CRM)
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135
Description
At some point before 4.2 we stopped including the merge sort in the explain output - I believe because the merge sort started happening within the $mergeCursors, which is not created nor displayed in explain output.
We should somehow enhance the explain output to include the merge sort so that users don't mistakenly conclude that the merged output is not sorted.
4.0:
splitPipeline: {
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shardsPart: [
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{
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'$match': { mykey: { '$in': [ 0, 1, 3, 7 ] } }
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},
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{ '$sort': { sortKey: { favColour: 1 }, limit: 5 } }
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],
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mergerPart: [
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{
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'$sort': { sortKey: { favColour: 1 }, mergePresorted: true, limit: 5 }
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}
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]
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}
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4.2/4.4:
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splitPipeline: {
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shardsPart: [
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{
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'$match': { mykey: { '$in': [ 0, 1, 3, 7 ] } }
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},
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{ '$sort': { sortKey: { favColour: 1 }, limit: 5 } }
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],
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mergerPart: [ { '$limit': 5 } ]
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}
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Attachments
Issue Links
- depends on
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SERVER-58834 Update FCV constants in server code base following 5.1 branch
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- Closed
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- is depended on by
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TOOLS-3024 Investigate changes in SERVER-57383: Include merge sort in sharded aggregation explain output
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- Closed
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- is documented by
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- Backlog
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