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  1. Calcite
  2. CALCITE-1638

Simplify $x=$x to true

        Details

        • Type: Improvement
        • Status: Closed
        • Priority: Minor
        • Resolution: Fixed
        • Affects Version/s: None
        • Fix Version/s: 1.12.0
        • Component/s: core
        • Labels:
          None

          Description

          = is reflexive and we can simplify it to true if the operands are equal

            Issue Links

            is related to

            Improvement - An improvement or enhancement to an existing feature or task. CALCITE-1668 Simplify "1 = 1" to true, "1 > 2" to false

            • Minor - Minor loss of function, or other problem where easy workaround is present.
            • Closed

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              julianhyde Julian Hyde added a comment -

              As it happens I've already done this, as part of https://github.com/julianhyde/calcite/commit/c8e266521328a115e2075aea335ae655c099f8a8. The correct rewrite IMHO is "$x = $x" → "$x is not null". (And the latter will get simplified to true if x is not null.) I'll commit it as part of the fix for CALCITE-1494.

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              julianhyde Julian Hyde added a comment - As it happens I've already done this, as part of https://github.com/julianhyde/calcite/commit/c8e266521328a115e2075aea335ae655c099f8a8 . The correct rewrite IMHO is "$x = $x" → "$x is not null". (And the latter will get simplified to true if x is not null.) I'll commit it as part of the fix for CALCITE-1494 .
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              julianhyde Julian Hyde added a comment -

              Correction: The correct rewrite is "$x = $x" → "case when $x is not null then true else unknown end". But in most cases unknown and false have the same effect.

              By the way. I don't have a firm ETA when that commit will be pushed to master. If you want to extract just the parts related to the "$x = $x" rewrite (including the tests I added) and commit separately, be my guest.

              Show
              julianhyde Julian Hyde added a comment - Correction: The correct rewrite is "$x = $x" → "case when $x is not null then true else unknown end". But in most cases unknown and false have the same effect. By the way. I don't have a firm ETA when that commit will be pushed to master. If you want to extract just the parts related to the "$x = $x" rewrite (including the tests I added) and commit separately, be my guest.
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              julianhyde Julian Hyde added a comment -

              Fixed in http://git-wip-us.apache.org/repos/asf/calcite/commit/34997ad1.

              The change also simplifies "x < x", "x <= x", "x > x", "x >= x", "x != x".

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              julianhyde Julian Hyde added a comment - Fixed in http://git-wip-us.apache.org/repos/asf/calcite/commit/34997ad1 . The change also simplifies "x < x", "x <= x", "x > x", "x >= x", "x != x".
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              julianhyde Julian Hyde added a comment -

              Resolved in release 1.12.0 (2017-03-24).

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              julianhyde Julian Hyde added a comment - Resolved in release 1.12.0 (2017-03-24).

                People

                • Assignee:
                  julianhyde Julian Hyde
                  Reporter:
                  jbalint@gmail.com Jess Balint
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                  Dates

                  • Created:
                    Updated:
                    Resolved:

                    Development