How to diagnose and fix the 22025 invalid_escape_sequence error code in Postgres.

The 22025 error code in PostgreSQL, labeled as invalid_escape_sequence, indicates that an escape sequence used in a string expression is incorrect or not recognized by PostgreSQL. This error often occurs when using the LIKE or SIMILAR TO operators or when dealing with regular expressions and bytea data types.

To diagnose and fix this error, follow these steps:

  1. Check Escape Characters: Ensure that escape characters within string literals are properly doubled. In PostgreSQL, the backslash (\) is used as an escape character, and it must be escaped itself by using two backslashes (\\). For example, to search for a literal backslash in a LIKE query, you’d need to use \\\\ as the pattern.
  2. Use Escape String Syntax (E’…’): When dealing with special escape sequences, use the PostgreSQL escape string syntax by prefixing the string with E. For example, to represent a newline character, use E'\n'.
  3. Set Standard Conforming Strings: PostgreSQL allows you to control the behavior of escape string interpretation through the standard_conforming_strings parameter. When this parameter is set to on, strings are treated as standard conforming and backslashes are treated as ordinary characters. To use escape sequences, you must use the E prefix mentioned above.
  4. Regular Expressions: When using regular expressions, ensure that your pattern follows the PostgreSQL regular expression syntax. Invalid regular expression patterns can result in the 22025 error.

Examples of how to fix the 22025 error:

  • LIKE Operator:
  -- Incorrect: Causes 22025 error if standard_conforming_strings is on
  SELECT 'abc\\def' LIKE 'abc\def';

  -- Fix: Use double backslashes if standard_conforming_strings is on
  SELECT 'abc\\def' LIKE 'abc\\def'; -- Correct
  • Escape String Syntax:
  -- Incorrect: Causes 22025 error
  SELECT 'abc\ndef' LIKE 'abc\ndef';

  -- Fix: Use the E'...' syntax for escape sequences
  SELECT E'abc\ndef' LIKE E'abc\ndef'; -- Correct
  • Regular Expressions:
  -- Incorrect: Causes 22025 error
  SELECT 'abc' ~ 'a\sc';

  -- Fix: Escape the backslash in the regular expression pattern
  SELECT 'abc' ~ 'a\\sc'; -- Correct
  • Bytea Data Type:
  -- Incorrect: Causes 22025 error
  SELECT E'\\x'::bytea;

  -- Fix: Provide a valid bytea escape sequence
  SELECT E'\\xDEADBEEF'::bytea; -- Correct

When fixing the 22025 error, it’s important to identify where the invalid escape sequence is in your query and apply the correct escaping method. Always test your patterns to ensure they match the expected results and comply with PostgreSQL’s escape sequence rules.

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