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Support parenthesized table joins in FROM clause#97650
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Standard SQL allows parentheses around joined table expressions: `SELECT * FROM (t1 CROSS JOIN t2)`. ClickHouse previously rejected this with a syntax error because `ParserSubquery` only accepted SELECT/EXPLAIN inside parentheses. The fix adds a fallback in `ParserTableExpression`: when all normal parse attempts fail and the position is at `(`, try to parse the content as `ParserTablesInSelectQuery`. If it contains a join (more than one table element), convert it to `SELECT * FROM <tables>` and wrap as a subquery. Single-table parenthesization `(t1)` is not matched to avoid ambiguity with expression parentheses. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Standard SQL allows parentheses around joined table expressions in FROM clauses:
ClickHouse previously rejected this with
SYNTAX_ERRORbecauseParserSubqueryonly accepted SELECT/EXPLAIN inside parentheses. This is valid syntax in PostgreSQL, MySQL, DuckDB, and SQLite.The fix adds a fallback in
ParserTableExpression: when all normal parse attempts fail (subquery, function, identifier) and the position is at(, try parsing the content asParserTablesInSelectQuery. If it contains a join (more than one table element), convert it toSELECT * FROM <tables>and wrap as a subquery. Single-table parenthesization(t1)is intentionally not matched to avoid ambiguity with expression parentheses.Test plan
tests/queries/0_stateless/03985_parenthesized_from_join.sqlcovering CROSS JOIN, INNER JOIN with ON, alias on the parenthesized expression, and nested usage(SELECT ...), ORDER BY with tuple parens, IN with subqueries, CREATE TABLE with ORDER BY all work correctlyORDER BY (col1, col2)in metadata load correctly (the initial approach of modifyingParserSubquerybroke this — fixed by only modifyingParserTableExpression)Changelog category (leave one):
Changelog entry (a user-readable short description of the changes that goes into CHANGELOG.md):
Support parenthesized table join expressions in FROM clause, e.g.
SELECT * FROM (t1 CROSS JOIN t2).🤖 Generated with Claude Code
Version info
26.3.1.93