SQL summary: isolate select state, fix bugs#16017
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trask merged 3 commits intoopen-telemetry:mainfrom Jan 30, 2026
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| Arguments.of( | ||
| "SELECT * FROM a, (SELECT * FROM b), c", | ||
| expect("SELECT", null, "SELECT a SELECT b c")), | ||
| Arguments.of( | ||
| "SELECT * FROM (SELECT * FROM inner1), (SELECT * FROM inner2), outer_table", | ||
| expect("SELECT", null, "SELECT SELECT inner1 SELECT inner2 outer_table"))); |
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these didn't work previously
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| private void pushOperation() { | ||
| operationStack.push(operation); | ||
| subqueryStartLevels.push(parenLevel); | ||
| operation = none; |
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what if you have SELECT * FROM (TABLE)
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I don't think this is valid SQL?
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you can try it our in https://www.db-fiddle.com/ it works on mysql but doesn't on postgres
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| /** Called when an identifier is seen - cancels pending subquery (it's a parenthesized table name). */ | ||
| private void cancelPendingSubqueryIfNeeded() { | ||
| pendingSubqueryPush = false; |
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commenting this line out doesn't seem to make any tests fail
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Follow-up to @laurit's #15986 (comment)
Problem
Subqueries were sharing state with their outer queries, causing several bugs:
SELECT * FROM a, (SELECT * FROM b), cwould miss "c" because the subquery's completion interfered with the outer FROM clause stateUNION/INTERSECT/EXCEPThandling was settingoperation = none, which broke the outer query's operation trackingINSERT INTO t SELECT * FROM (VALUES (1))would incorrectly append "VALUES" to the summarySolution
Introduced an operation stack to properly isolate subquery state:
operationStack(ArrayDeque): Pushes current operation when entering a subquery, pops when exitingsubqueryStartLevels(ArrayDeque): Tracks paren levels where subqueries beginWhen a subquery completes, the outer query's state is restored and updated to account for the subquery as one "table reference" in the FROM clause.
Additional cleanup
Simplified the
Selectclass state from 12 fields to 6:mainTableSetAlreadyidentifierCount > 0inImplicitJoinidentifiersAfterCommaidentifierCountexpectingSubqueryOrTablecaptureTableList || captureSingleTableinColumnAliasListcolumnAliasListParenLevel >= 0identifiersAfterJoinidentifierCountRenamed fields for clarity:
expectingTableName→captureTableList(FROM clause mode)expectingJoinTableName→captureSingleTable(JOIN clause mode)Testing
Added test cases for subquery state isolation:
SELECT * FROM a, (SELECT * FROM b), c→"SELECT a b c"SELECT * FROM (SELECT * FROM inner1), (SELECT * FROM inner2), outer_table→ captures all tables