How to diagnose and fix the 22019 invalid_escape_character error code in Postgres.

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The 22019 error code in PostgreSQL indicates “invalid_escape_character,” which is an error that occurs when an invalid escape character is used in a string literal, particularly in LIKE or similar string matching queries.

To diagnose and fix this error, consider the following:

  1. Check Escape Characters: When using the LIKE or ILIKE operators, or when working with regular expressions, ensure that any escape characters are valid and correctly used. In PostgreSQL, the backslash (\) is the default escape character.
  2. Use Double Backslashes: If you’re using standard_conforming_strings (which is the default in modern PostgreSQL), you will need to use double backslashes (\\) to represent a literal backslash in a string.
  3. Set Escape Character Explicitly: You can explicitly set the escape character in a LIKE query by using the ESCAPE clause if you need to use a different character.

Here are some examples that demonstrate how to avoid the 22019 error:

  • Correct Use of Escape Character in LIKE:
  -- Assuming standard_conforming_strings is on:
  SELECT 'abc\\def' LIKE 'abc\\\\def';
  -- This will return true, as the double backslashes are correctly escaped.
  • Correct Use of Escape Character in a Pattern:
  SELECT 'abc_def' LIKE 'abc\_def' ESCAPE '\';
  -- This will return true, as the underscore is correctly escaped.
  • Using an Alternative Escape Character:
  SELECT 'abc-def' LIKE 'abc$-def' ESCAPE '$';
  -- This will return true, as the dash is treated as a literal character.
  • Avoiding Invalid Escape Sequences:
  -- This will result in an error:
  -- SELECT 'abc\def' LIKE 'abc\def';

  -- Instead, you should use:
  SELECT 'abc\\def' LIKE 'abc\\def';
  -- This will return true, as the backslashes are correctly escaped.
  • Handling Escape Characters in Regular Expressions:
  -- Assuming standard_conforming_strings is on:
  SELECT 'abc\\def' ~ 'abc\\\\def';
  -- This will return true, as the pattern matches the string with escaped backslashes.

To avoid this error, always ensure that your escape sequences are valid and correctly used according to PostgreSQL’s rules and the setting of standard_conforming_strings. If you’re unsure about the escape character handling in your PostgreSQL environment, you can check the current setting of standard_conforming_strings by running:

SHOW standard_conforming_strings;

For more information on escape characters and the LIKE clause in PostgreSQL, you can refer to the PostgreSQL documentation.

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