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Type: Improvement
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Resolution: Done
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Priority: Major - P3
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Affects Version/s: 3.3.11
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Component/s: Write Ops
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Fully Compatible
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Query 2017-03-27, Query 2017-04-17
Requiring a query to determine the length of a document's array and calculate the appropriate positive integer index introduces a race condition. By allowing negative indexes (indicating distance from the end) on the $position modifier, this race condition could be avoided.
This would match Python semantics for list manipulation. An example, given the following document:
{ acl: [ {grant: True, user: "amcgregor"}, {grant: True, user: "bdole"}, {grant: False} ] }
And the following update operation:
{
$push: {
acl: {
$each: [ { grant: True, user: "algore" } ],
$position: -1
}
}
}
The resulting document should be:
{ acl: [ {grant: True, user: "amcgregor"}, {grant: True, user: "bdole"}, {grant: True, user: "algore"}, {grant: False} ] }
The default insert location, the end (when $position is omitted or exceeds the length of the array), is unaffected.
Thank you for your consideration!
- depends on
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SERVER-27089 Extend the update subsystem to support more expressive updates to array fields
- Closed
- related to
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SERVER-27089 Extend the update subsystem to support more expressive updates to array fields
- Closed
- links to