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  1. MariaDB Server
  2. MDEV-27189

Optimizer Trace: save all info needed for replay

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      Description

      Optimizer trace contains a lot of info describing the query:

      • Original query text
      • Definitions of all used VIEWs
      • All kinds of estimates that the optimizer used:
        • records_in_range estimates
        • index statistics used by
        • selectivity estimates
        • table read costs
      • Indexes considered by the optimizer

      This makes it possible to debug an optimizer problem: re-run the optimizer and manually re-create the environment by "faking" the record counts and the estimates.

      There are two problems

      • 1. Optimizer trace is not fully self-contained.
      • 2. Re-creating the environment is labor-intensive (I wrote dirty patches that put the fake statistics in place)

      This task is about solving #1, and possibly #2.

      For #1, we need:

      • Column definitions (their datatypes. Basically, SQL definitions).
      • TODO: anything else?

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            Assignee:
            Unassigned Unassigned
            Reporter:
            psergei Sergei Petrunia
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