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[CALCITE-7778] JDBC adapter for MSSQL generates % for MOD without preserving grouping, giving wrong results #5259

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[CALCITE-7778] JDBC adapter for MSSQL generates % for MOD without preserving grouping, giving wrong results #5259

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4e26a2d
[CALCITE-7778] JDBC adapter for MSSQL generates % for MOD without pre…
wasabii Sep 12, 2026
ddd9f4b
Shorten the javadoc on unparseWithOperator
wasabii Sep 12, 2026
0066090
Rename unparseWithOperator to unparseWithBinaryOperator
wasabii Sep 14, 2026
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7 changes: 3 additions & 4 deletions core/src/main/java/org/apache/calcite/sql/dialect/MssqlSqlDialect.java
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Original file line number Diff line number Diff line change
Expand Up @@ -35,8 +35,6 @@
import org.apache.calcite.sql.SqlLiteral;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlNodeList;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.SqlSyntax;
import org.apache.calcite.sql.SqlUtil;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.fun.SqlLibraryOperators;
Expand All @@ -49,6 +47,7 @@
import org.checkerframework.checker.nullness.qual.Nullable;

import static org.apache.calcite.util.RelToSqlConverterUtil.unparseBoolLiteralToCondition;
import static org.apache.calcite.util.RelToSqlConverterUtil.unparseWithBinaryOperator;

import static java.util.Objects.requireNonNull;

Expand Down Expand Up @@ -222,8 +221,8 @@ private static SqlNode createDatetimeCastSpec(String typeAlias, RelDataType type
unparseFloor(writer, call);
break;
case MOD:
SqlOperator op = SqlStdOperatorTable.PERCENT_REMAINDER;
SqlSyntax.BINARY.unparse(writer, op, call, leftPrec, rightPrec);
unparseWithBinaryOperator(writer, SqlStdOperatorTable.PERCENT_REMAINDER, call,
leftPrec, rightPrec);
break;
case SAFE_CAST:
// MSSQL uses TRY_CAST instead of SAFE_CAST (BigQuery)
Expand Down
22 changes: 22 additions & 0 deletions core/src/main/java/org/apache/calcite/util/RelToSqlConverterUtil.java
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Expand Up @@ -31,7 +31,9 @@
import org.apache.calcite.sql.SqlLiteral;
import org.apache.calcite.sql.SqlMapTypeNameSpec;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.SqlSpecialOperator;
import org.apache.calcite.sql.SqlSyntax;
import org.apache.calcite.sql.SqlTypeNameSpec;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.fun.SqlStdOperatorTable;
Expand Down Expand Up @@ -339,6 +341,26 @@ public static void unparseBoolLiteralToCondition(SqlWriter writer, boolean value
writer.endList(frame);
}

/**
* Writes a two-operand call with an operator other than its own,
* parenthesized as that operator requires.
*
* <p>{@link SqlCall#unparse} chooses the parentheses from the call's own

@mihaibudiu mihaibudiu Sep 14, 2026

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I would shorten this comment to say that this will use parentheses when necessary.

@mihaibudiu mihaibudiu Sep 14, 2026

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I wonder what happens if not all SQL dialects have the same operation precedence...

@wasabii wasabii Sep 14, 2026

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Upon staring at it longer, I don't think dialects have any ability to hold per operator precedence, do they?

@wasabii wasabii Sep 14, 2026

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That's frankly probably a good thing to add! If done, we'd pass getLeftPrec and getRightPrec through that I guess.

@wasabii wasabii Sep 14, 2026

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Actually. There are a bunch of special operators floating around for specific SQL languages. I guess if this got hit after those were substituted in, it would be fine, if those carried their own special precedence.

@mihaibudiu mihaibudiu Sep 14, 2026

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In calcite operators cannot change precedences, but I am saying is that the calcite unparse will decide whether to use parens based on the Calcite rules, which may not match the target dialect rules.

* operator before the dialect is consulted, so an operator that binds less
* tightly needs them added here.
*/
public static void unparseWithBinaryOperator(SqlWriter writer, SqlOperator operator,
SqlCall call, int leftPrec, int rightPrec) {
if (leftPrec > operator.getLeftPrec()
|| (operator.getRightPrec() <= rightPrec && rightPrec != 0)) {
final SqlWriter.Frame frame = writer.startList("(", ")");
SqlSyntax.BINARY.unparse(writer, operator, call, 0, 0);
writer.endList(frame);
} else {
SqlSyntax.BINARY.unparse(writer, operator, call, leftPrec, rightPrec);
}
}

/**
* Transformation Map type from {@code MAP<VARCHAR,VARCHAR>} to {@code Map(VARCHAR,VARCHAR)}.
*/
Expand Down
16 changes: 16 additions & 0 deletions core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
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Expand Up @@ -11820,6 +11820,22 @@ private void checkLiteral2(String expression, String expected) {
sql(query).dialect(MssqlSqlDialect.DEFAULT).ok(mssqlExpected);
}

/** Test case for
* <a href="https://issues.apache.org/jira/browse/CALCITE-7778">[CALCITE-7778]
* JDBC adapter for MSSQL generates % for MOD without preserving grouping,
* giving wrong results</a>. */
@Test void testModFunctionGroupingForMSSQL() {
final String from = "\nFROM (VALUES (0)) AS [t] ([ZERO])";
sql("select 100 / mod(11, 3)").dialect(MssqlSqlDialect.DEFAULT)
.ok("SELECT 100 / (11 % 3)" + from);
sql("select 100 * mod(11, 3)").dialect(MssqlSqlDialect.DEFAULT)
.ok("SELECT 100 * (11 % 3)" + from);
sql("select mod(100, mod(11, 3))").dialect(MssqlSqlDialect.DEFAULT)
.ok("SELECT 100 % (11 % 3)" + from);
// % already binds more tightly than -, so no parentheses are needed
sql("select 100 - mod(11, 3)").dialect(MssqlSqlDialect.DEFAULT)
.ok("SELECT 100 - 11 % 3" + from);
}

/** Test case for
* <a href="https://issues.apache.org/jira/browse/CALCITE-6655">[CALCITE-6655]
Expand Down
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