How to diagnose and fix the 2200D invalid_escape_octet error code in Postgres.

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The 2200D: invalid_escape_octet error in PostgreSQL occurs when a string contains an invalid escape sequence, typically within a bytea literal or an escape string literal. In PostgreSQL, escape sequences are used to represent special characters, and they must be valid according to the database’s encoding rules.

To diagnose and fix this error, you should:

  1. Identify the Invalid Escape Sequence: Check the string that caused the error for any backslashes (\) followed by characters that do not form a valid escape sequence.
  2. Correct the Escape Sequence: Ensure that every escape sequence in the string is valid. For bytea literals in PostgreSQL, you typically need to use double backslashes (\\) to represent a single backslash character.
  3. Use the Correct String Format: If you are using E'...' syntax for an escaped string literal, make sure that the escape sequences within are correct. For example, E'\n' represents a newline character.
  4. Adjust the Bytea Output Format: If you are dealing with bytea data types, be aware that PostgreSQL has two output formats: hex and escape. The default is hex, but if you are using escape (which can be set with the bytea_output parameter), make sure that the escape sequences are correct.

Here are some examples of how the 2200D error might occur and how to resolve it:

  • Incorrect Bytea Escape Sequence:
  SELECT E'\\x' AS broken_bytea;

This will cause an error because \\x is not a valid escape sequence for a bytea literal. To fix it, you should use valid bytea escape sequences:

  SELECT E'\\\\x' AS valid_bytea;
  • Incorrect Escape String Literal:
  SELECT E'Hello\\World' AS broken_string;

This will result in an error because \\W is not recognized as a valid escape sequence. To fix it, if you intended to have a literal backslash followed by “World”, you would need to use double backslashes:

  SELECT E'Hello\\\\World' AS valid_string;
  • Invalid Escape Octet in a Function Argument:
  SELECT convert_from(BYTEA 'abc\001def', 'UTF8');

If the above function call results in an invalid_escape_octet error, it might be because the escape sequence is not valid for the given encoding. You would need to ensure that the bytea literal is correctly formatted and valid for the specified encoding.

For more information on PostgreSQL error codes and handling bytea data types, you can refer to the PostgreSQL documentation. When dealing with string literals and bytea types in PostgreSQL, always verify that your escape sequences are correct for the context in which they are used.

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