Parse PostgreSQL parenthesized EXPLAIN ( option [, ...] )#4
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alexey-milovidov wants to merge 1 commit into
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Parse PostgreSQL parenthesized EXPLAIN ( option [, ...] )#4alexey-milovidov wants to merge 1 commit into
alexey-milovidov wants to merge 1 commit into
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PostgreSQL and the PostgreSQL-compatible dialects CockroachDB, RisingWave
and Materialize accept the parenthesized EXPLAIN option form:
EXPLAIN (VERBOSE, COSTS OFF, FORMAT JSON) SELECT ...
Previously this failed to parse ("Expected identifier, got LParen"), which
blocked a large fraction of real PostgreSQL EXPLAIN statements from being
transpiled.
The options are planner/output directives with no cross-dialect meaning, so
they are parsed and discarded here - consistent with the existing
normalization of EXPLAIN to DESCRIBE. The ANALYZE option is folded into the
DESCRIBE style so that "EXPLAIN (ANALYZE) ..." matches bare
"EXPLAIN ANALYZE ...". A parenthesized subquery ("EXPLAIN (SELECT ...)") is
still parsed as a subquery target.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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What
Adds support for PostgreSQL's parenthesized
EXPLAINoption syntax:This form is also accepted by the PostgreSQL-compatible dialects CockroachDB, RisingWave and Materialize.
Why
Before this change the parenthesized form failed to parse:
While transpiling PostgreSQL's regression test suite (
src/test/regress, ~53k statements) to ClickHouse viatranspile, this single gap caused the majority ofEXPLAINtranspilation errors (~2.7k statements): everyEXPLAIN (...)in the suite failed before its inner statement could be reached.How
The options (
ANALYZE,VERBOSE,COSTS,BUFFERS,SETTINGS,WAL,TIMING,SUMMARY,MEMORY,GENERIC_PLAN,SERIALIZE,FORMAT) are planner/output directives with no cross-dialect meaning, so they are parsed and discarded — consistent with the existing normalization ofEXPLAINtoDESCRIBE. TheANALYZEoption is folded into theDESCRIBEstyle so thatEXPLAIN (ANALYZE) ...behaves like bareEXPLAIN ANALYZE .... A parenthesized subquery (EXPLAIN (SELECT ...)) is still parsed as a subquery target, not an option list.The new parsing is gated to the PostgreSQL-family dialects (PostgreSQL, CockroachDB, RisingWave, Materialize), so no other dialect's behavior changes.
Tests
Adds
crates/polyglot-sql/tests/postgres_explain_options.rs(7 tests) covering option discard,ANALYZEfolding (includingANALYZE false/off), subquery disambiguation, PostgreSQL→ClickHouse transpilation, and the PG-compatible dialects. The fullpolyglot-sqlsuite passes; the only failing test,tpch_query2_transpile_postgres_to_fabric, is pre-existing onmainand unrelated to this change.Upstream PR: tobilg#315