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Available in versions: Dev (3.20) | Latest (3.19) | 3.18 | 3.17

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

Repeated NOT

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

The NOT unary operator reverses itself, when called repeatedly, meaning that redundant NOT operators can be removed.

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

-- With Settings.transformPatternsNotNot active, this:
SELECT
  NOT (NOT (x = 1)),
  NOT (NOT (NOT (x = 1)))
FROM tab;

-- ... is transformed into the equivalent expression:
SELECT
  x = 1,       -- NOT (NOT (x = 1))
  NOT (x = 1), -- NOT (NOT (NOT (x = 1)))
FROM tab;

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