Available in versions: Dev (3.18) | Latest (3.17)

This is experimental functionality, and as such subject to change. Use at your own risk!

This documentation is for the unreleased development version of jOOQ. Click on the above version links to get this documentation for a supported version of jOOQ.

Idempotent function repetition

Applies to ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

When SQL is complex or generated, there may be accidental repetitions of functions that do not have any effects on the result. Such repetitions can be removed by a single function application.

Using Settings.transformPatternsIdempotentFunctionRepetition, the following transformations can be achieved:

-- With Settings.transformPatternsIdempotentFunctionRepetition active, this:
SELECT 
  LTRIM(LTRIM(x)),
  RTRIM(RTRIM(x)),
  TRIM(TRIM(x)),
  TRIM(LTRIM(x)),
  TRIM(RTRIM(x)),
  RTRIM(TRIM(x)),
  LTRIM(TRIM(x)),
  UPPER(UPPER(x)),
  LOWER(LOWER(x)),
  ABS(ABS(x)),
  SIGN(SIGN(x)),
  CEIL(CEIL(x)),
  FLOOR(FLOOR(x)),
  ROUND(ROUND(x)),
  TRUNC(TRUNC(x)),
  CAST(CAST(x AS type) AS type)
FROM tab;

-- ... is transformed into the equivalent expression:
SELECT 
  LTRIM(x),       -- LTRIM(LTRIM(x))
  RTRIM(x),       -- RTRIM(RTRIM(x))
  TRIM(x),        -- TRIM(TRIM(x))
  TRIM(x),        -- TRIM(LTRIM(x))
  TRIM(x),        -- TRIM(RTRIM(x))
  TRIM(x),        -- RTRIM(TRIM(x))
  TRIM(x),        -- LTRIM(TRIM(x))
  UPPER(x),       -- UPPER(UPPER(x))
  LOWER(x),       -- LOWER(LOWER(x))
  ABS(x),         -- ABS(ABS(x))
  SIGN(x),        -- SIGN(SIGN(x))
  CEIL(x),        -- CEIL(CEIL(x))
  FLOOR(x),       -- FLOOR(FLOOR(x))
  ROUND(x),       -- ROUND(ROUND(x))
  TRUNC(x),       -- TRUNC(TRUNC(x))
  CAST(x AS type) -- CAST(CAST(x AS type) AS type)
FROM tab;

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