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  1. IMPALA
  2. IMPALA-1788

Consider replacing constant exprs with literal equivalents

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    Description

      Evaluating expressions that are the same for every row can be very expensive (note these numbers are taken from the debug build, so maybe this is not an issue in release?):

      (15:33:02@desktop) ~/src/cloudera/impala (cdh5-trunk) $ impala-shell.sh -q "SELECT 1.2345678 FROM tpch.lineitem" -B 2>&1 > /dev/null
...
Fetched 6001215 row(s) in 61.33s

(15:34:06@desktop) ~/src/cloudera/impala (cdh5-trunk) $ impala-shell.sh -q "SELECT CAST('1.2345678' AS DOUBLE) FROM tpch.lineitem" -B 2>&1 > /dev/null
...
Fetched 6001215 row(s) in 74.86s

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          breaks

          Bug - A problem which impairs or prevents the functions of the product. IMPALA-5594 Impala should not reference shaded classes from Kudu jar

          • Blocker - Blocks development and/or testing work, production could not run
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. IMPALA-6435 Codegen crash when UNIONing CHAR(n) literals

          • Blocker - Blocks development and/or testing work, production could not run
          • Resolved
          is related to

          Bug - A problem which impairs or prevents the functions of the product. IMPALA-6114 Incorrect type deduction causing analysis exception to be thrown

          • Major - Major loss of function.
          • Resolved
          relates to

          Bug - A problem which impairs or prevents the functions of the product. IMPALA-2095 from_unixtime(constant) is evaluated on every row -- slower than hive

          • Major - Major loss of function.
          • Resolved

          Improvement - An improvement or enhancement to an existing feature or task. IMPALA-1861 Conditional functions with constant arguments should be simplified during analysis

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

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              alex.behm Alexander Behm
              henryr Henry Robinson
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                Updated:
                Resolved: