[CALCITE-5194] Cannot parse parenthesized UNION in subquery

• Type: Bug
• Status: Closed
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 1.31.0
• Fix Version/s: 1.31.0
• Assignee: Julian Hyde
• Reporter: Vova Vysotskyi
• Created: 19/Jun/22 09:13
• Updated: 03/Aug/22 16:21
• Resolved: 11/Jul/22 20:15

Description

The following test:

  @Test void testUnionAllInSubquery() {
    final String sql = "select * from \n" +
        "((select columns[0] as col0 from emps t1) \n" +
        "union all \n" +
        "(select columns[0] c2 from emps t2))";
    final String expected = "SELECT *\n"
        + "FROM (SELECT `COLUMNS`[0] AS `COL0`\n"
        + "FROM `EMPS` AS `T1`\n"
        + "UNION ALL\n"
        + "SELECT `COLUMNS`[0] AS `C2`\n"
        + "FROM `EMPS` AS `T2`)";
    sql(sql).ok(expected);
  }

Fails with the following exception:

Caused by: org.apache.calcite.sql.parser.SqlParseException: Encountered "union" at line 3, column 1.
Was expecting one of:
    "AS" ...
    "CROSS" ...
    "FULL" ...
    "INNER" ...
    "JOIN" ...
    "LEFT" ...
    "MATCH_RECOGNIZE" ...
    "NATURAL" ...
    "OUTER" ...
    "RIGHT" ...
    "TABLESAMPLE" ...
    ")" ...
    <BRACKET_QUOTED_IDENTIFIER> ...
    <QUOTED_IDENTIFIER> ...
    <BACK_QUOTED_IDENTIFIER> ...
    <BIG_QUERY_BACK_QUOTED_IDENTIFIER> ...
    <HYPHENATED_IDENTIFIER> ...
    <IDENTIFIER> ...
    <UNICODE_QUOTED_IDENTIFIER> ...
    
	at org.apache.calcite.sql.parser.impl.SqlParserImpl.convertException(SqlParserImpl.java:398)
	at org.apache.calcite.sql.parser.impl.SqlParserImpl.normalizeException(SqlParserImpl.java:154)
	at org.apache.calcite.sql.parser.SqlParser.handleException(SqlParser.java:145)
	at org.apache.calcite.sql.parser.SqlParser.parseQuery(SqlParser.java:160)
	at org.apache.calcite.sql.parser.SqlParser.parseStmt(SqlParser.java:185)
	at org.apache.calcite.sql.parser.SqlParserTest$TesterImpl.parseStmtAndHandleEx(SqlParserTest.java:9863)
	... 72 more

This is a regression caused by changes from CALCITE-35

Issue Links

• is caused by: CALCITE-35 Support parenthesized sub-clause in JOIN
• is related to: CALCITE-5206 Parser allows MERGE with mismatched parentheses