fix(set): handle PostgreSQL SET TIME ZONE alias and multi-value lists

[renecannao]

Summary

Two PostgreSQL SET parser bugs surfaced when ProxySQL's set_parser_algorithm=3 (ParserSQL) path was first actually exercised in CI (it had been silently no-op'd by a test-harness gap). Both are PG-dialect-only — MySQL behavior is unchanged.

Bug 1: SET TIME ZONE mis-parsed

Per the PG docs, SET TIME ZONE <value> is an alias for SET TimeZone = <value>. The tokenizer has no TK_TIME / TK_ZONE keyword, so the input lexed as IDENTIFIER("TIME") followed by IDENTIFIER("ZONE"). parse_variable_assignment() took TIME as the variable target and ZONE as the unquoted RHS identifier value, emitting the assignment time = ZONE and silently dropping everything that followed ('UTC', DEFAULT, an INTERVAL expression, …).

Fix: At the top of parse(), in PG dialect, peek for IDENTIFIER("TIME") followed by IDENTIFIER("ZONE") (case-insensitive via StringRef::equals_ci) and synthesise a timezone = <rhs> assignment. RHS is DEFAULT / LOCAL if those keywords are next, otherwise the expression parser's result.

Bug 2: PG multi-value list dropped after the first value

Per the PG docs:

SET configuration_parameter { TO | = } { value | 'value' | DEFAULT }
"Some configuration parameters take a list of values, such as
 search_path and datestyle."

parse() shared the MySQL-style comma loop, where each comma introduces a new variable assignment. For PG that is wrong — commas are value-list continuation for the same variable. Given SET search_path TO "$user", public, the loop tried to parse public as a new assignment, found no =/TO after it, returned nullptr, and the second value disappeared.

Fix: Dialect-split the post-assignment comma loop. MySQL keeps the existing behavior (parse_comma_item() for each comma). PostgreSQL appends each subsequent expression as an additional child of the same NODE_VAR_ASSIGNMENT node (alongside the first RHS). Downstream consumers walk all target->next_siblings to collect the full value list.

Test coverage

tests/test_set.cpp gains:

• 9 entries in pgsql_set_cases for the new SET shapes (bulk parse-success coverage)
• 5 TEST_F(PgSQLSetTest, SetTimeZone…) blocks verifying the variable name resolves to timezone (was time)
• 4 TEST_F(PgSQLSetTest, SetSearchPath…) / SetDatestyleMultiValue blocks verifying the assignment node has target + N value children (was target + 1)

Test results

make clean && make test
[==========] 1260 tests from 125 test suites ran.
[  PASSED  ] 1223 tests.
[  FAILED  ] 0 tests

(37 SKIPPED are integration tests needing live backends — same as baseline.)

Why now

Reported via ProxySQL CI baseline failures in TAP group set_parser_algorithm_3-g1:

• pgsql-set_parameter_validation_test-t — SET search_path produced empty value
• pgsql-set_statement_test-t — SET TIME ZONE not handled

Both pass after this fix lands and ProxySQL bumps the vendored tarball to v1.0.3.

Test plan

• make clean && make test → 1223/1223 pass
• All 9 new structural tests pass
• Validated end-to-end through ProxySQL's setparser_parsersql_test against a tarball built from this branch HEAD

Summary by CodeRabbit

• Bug Fixes

  • Enhanced parsing of PostgreSQL SET TIME ZONE statements to handle various input formats correctly.
  • Corrected handling of comma-separated values in PostgreSQL multi-value SET assignments.

• Tests

  • Expanded test suite with comprehensive coverage for PostgreSQL SET statement syntax variations.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 8032221f-d572-4392-b510-83bbefc139e8

📥 Commits

Reviewing files that changed from the base of the PR and between 1abe6be and 0c32f5e.

📒 Files selected for processing (2)

• include/sql_parser/set_parser.h
• tests/test_set.cpp

---

📝 Walkthrough

Walkthrough

The PR enhances the PostgreSQL SET parser to recognize SET TIME ZONE <value> as a special form generating a synthetic "timezone" variable assignment, and modifies comma-separated value handling to append expressions as child nodes rather than separate assignments. Tests validate both behaviors across string literals, defaults, offsets, and multi-value lists.

Changes

PostgreSQL SET Parser Enhancement

Layer / File(s)	Summary
SET TIME ZONE syntax and test data include/sql_parser/set_parser.h, tests/test_set.cpp	PostgreSQL-specific lookahead for SET TIME ZONE <value> produces a NODE_VAR_ASSIGNMENT targeting synthetic "timezone" variable; <value> parses as identifier (DEFAULT, LOCAL) or general expression. Test data expanded with TIME ZONE variants and multi-value cases for search_path and datestyle; test helpers extract variable names and node counts. Structural tests validate TIME ZONE assigns to "timezone" target across string literals, DEFAULT, numeric offsets, and LOCAL forms.
Comma-separated multi-value handling include/sql_parser/set_parser.h, tests/test_set.cpp	PostgreSQL comma-separated values after the first assignment now parse as expressions appended as additional child nodes of the same NODE_VAR_ASSIGNMENT, not separate assignments; non-PostgreSQL dialects continue using parse_comma_item() for separate assignments. Structural tests validate both TO and = forms with quoted identifiers like "$user" and multi-value lists such as datestyle TO 'ISO', 'mdy'.

Estimated Code Review Effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 A parser learns to zone the time,
Comma-child nodes in perfect rhyme,
Synthetic names in trees now grow,
Multi-values reap and sow!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly reflects the main changes: handling PostgreSQL SET TIME ZONE alias and multi-value lists in the parser.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/pg-set-time-zone-and-multi-value

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}