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  1. Core Server
  2. SERVER-32206

Catalog change to declare an index as multikey must be timestamped.

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    Details

    • Type: Task
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 3.7.2
    • Component/s: Storage
    • Backwards Compatibility:
      Fully Compatible
    • Sprint:
      Repl 2018-01-15, Repl 2018-01-29, Repl 2018-02-12

      Description

      There are two cases to resolve. The first is easier. The second is a little trickier:

      When a document is inserted/updated into a collection that can require multiple entries in an index (e.g: the value of an indexed field is an array), the index's "multikey" field must be set to true.

      This update is currently done as a side-transaction to avoid write conflicts. Being a side-transaction throws away the ability to inherit a timestamp from the insert/update request.

      Proposed solutions can be classified as:

      1. Remove the side transaction. Solutions here have varying degrees of effort to still allow for serialization of updates to the document to prevent a worst case scenario where progress slows down (stops?)
      2. Assign a timestamp to the write that is at least as early as any updates that are part of the request requiring this update.
        • A bit more clever, introduce an error case when inserts require the multikey field to be changed to true. Top-level handlers should translate this error to setting multikey to true (in a "before?-transaction") followed by performing the insert. An explicit timestamp would still need to be chosen, but there might be less plumbing required to make the timestamp and transaction meet.

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              Assignee:
              judah.schvimer Judah Schvimer
              Reporter:
              daniel.gottlieb Daniel Gottlieb
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