fix: PG parser fails on LIKE ? ESCAPE '\\' generated by JPA

[daguimu]

Problem

PostgreSQL SQL parser fails when parsing LIKE ? ESCAPE '\' syntax generated by Spring Data JPA/Hibernate Containing queries. The WallFilter throws ParserException: ERROR because the PG lexer incorrectly treats \ as an escape character inside string literals.

Reproduction SQL:

SELECT id, name FROM t WHERE name LIKE ? ESCAPE '\' AND group_id = ?

Root cause: PGLexer.scanString() overrode the base Lexer.scanString() to treat \ as an escape character. When encountering '\', the lexer interprets \' as an escaped quote, so the string literal never terminates — it consumes the rest of the SQL and produces an ERROR token.

In standard PostgreSQL (standard_conforming_strings = on, default since PostgreSQL 9.1 / 2011), backslash is not an escape character in regular string literals. Only E-prefixed strings (E'\\') use backslash escaping.

Fix

• Remove the scanString() override from PGLexer, so it uses the base Lexer.scanString() which treats \ as a regular character
• Remove the now-unused LITERAL_CHARS import
• Update one test resource file (postgresql/0.txt) that used deprecated \' quote escaping to use standard SQL '' escaping

Tests Added

9 new test cases in Issue6413.java:

• test_like_escape_backslash — exact SQL from bug report (JPA-generated)
• test_like_escape_backslash_simple — minimal reproduction
• test_like_escape_non_backslash_still_works — other escape chars (#, !, ~)
• test_string_with_backslash_in_pg — standard PG string containing \
• test_string_with_double_backslash_in_pg — string containing \\
• test_like_escape_backslash_with_wall_filter — verifies WallFilter path (original failure)
• test_not_like_escape_backslash — NOT LIKE variant
• test_ilike_with_backslash_string — PG-specific ILIKE
• test_pg_double_single_quote_still_works — standard '' escape still works

All tests run against postgresql, greenplum, and edb dialects where applicable.

Impact

• Fixes parsing of JPA/Hibernate generated SQL with ESCAPE '\'
• Aligns PG string literal parsing with PostgreSQL's default standard_conforming_strings = on
• No regression in existing PG test suite (39 tests pass)

Fixes #6413

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}