[CALCITE-6220] Rewrite MIN/MAX(bool) as BOOL_AND/BOOL_OR for Postgres…

…, Redshift
wnob · Jan 25, 2024 · 26b5e9b · 26b5e9b
1 parent 91a8ab8
commit 26b5e9b
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Showing 5 changed files with 75 additions and 2 deletions.
diff --git a/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java b/core/src/main/java/org/apache/calcite/rel/rel2sql/RelToSqlConverter.java
@@ -81,6 +81,7 @@
 import org.apache.calcite.sql.SqlUpdate;
 import org.apache.calcite.sql.SqlUtil;
 import org.apache.calcite.sql.fun.SqlInternalOperators;
+import org.apache.calcite.sql.fun.SqlMinMaxAggFunction;
 import org.apache.calcite.sql.fun.SqlSingleValueAggFunction;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
 import org.apache.calcite.sql.parser.SqlParserPos;
@@ -577,6 +578,8 @@ protected Builder buildAggregate(Aggregate e, Builder builder,
       RelDataType aggCallRelDataType = aggCall.getType();
       if (aggCall.getAggregation() instanceof SqlSingleValueAggFunction) {
         aggCallSqlNode = dialect.rewriteSingleValueExpr(aggCallSqlNode, aggCallRelDataType);
+      } else if (aggCall.getAggregation() instanceof SqlMinMaxAggFunction) {
+        aggCallSqlNode = dialect.rewriteMaxMinExpr(aggCallSqlNode, aggCallRelDataType);
       }
       addSelect(selectList, aggCallSqlNode, e.getRowType());
     }

diff --git a/core/src/main/java/org/apache/calcite/sql/SqlDialect.java b/core/src/main/java/org/apache/calcite/sql/SqlDialect.java
@@ -31,10 +31,12 @@
 import org.apache.calcite.rex.RexNode;
 import org.apache.calcite.sql.dialect.JethroDataSqlDialect;
 import org.apache.calcite.sql.fun.SqlInternalOperators;
+import org.apache.calcite.sql.fun.SqlLibraryOperators;
 import org.apache.calcite.sql.fun.SqlStdOperatorTable;
 import org.apache.calcite.sql.parser.SqlParser;
 import org.apache.calcite.sql.parser.SqlParserPos;
 import org.apache.calcite.sql.type.AbstractSqlType;
+import org.apache.calcite.sql.type.SqlTypeName;
 import org.apache.calcite.sql.type.SqlTypeUtil;
 import org.apache.calcite.sql.validate.SqlConformance;
 import org.apache.calcite.sql.validate.SqlConformanceEnum;
@@ -864,14 +866,44 @@ public boolean supportsDataType(RelDataType type) {
     return SqlTypeUtil.convertTypeToSpec(type);
   }
 
-  /** Rewrite SINGLE_VALUE into expression based on database variants
+  /** Rewrites SINGLE_VALUE into expression based on database variants
    * E.g. HSQLDB, MYSQL, ORACLE, etc.
    */
   public SqlNode rewriteSingleValueExpr(SqlNode aggCall, RelDataType relDataType) {
     LOGGER.debug("SINGLE_VALUE rewrite not supported for {}", databaseProduct);
     return aggCall;
   }
 
+  /**
+   * Rewrites MAX(x)/MIN(x) as BOOL_OR(x)/BOOL_AND(x) for certain
+   * database variants (Postgres and Redshift, currently).
+   *
+   * @see #rewriteMaxMin(SqlNode, RelDataType)
+   */
+  public SqlNode rewriteMaxMinExpr(SqlNode aggCall, RelDataType relDataType) {
+    return aggCall;
+  }
+
+  /**
+   * Helper for rewrites of MAX/MIN.
+   * Some dialects (e.g. Postgres and Redshift), rewrite as
+   * BOOL_OR/BOOL_AND if the return type is BOOLEAN.
+   */
+  protected static SqlNode rewriteMaxMin(SqlNode aggCall, RelDataType relDataType) {
+    // The behavior of this method depends on the argument type,
+    // and whether it is MIN/MAX
+    final SqlTypeName type = relDataType.getSqlTypeName();
+    final boolean isMax = aggCall.getKind() == SqlKind.MAX;
+    // If the type is BOOLEAN, create a new call to the correct operator
+    if (type == SqlTypeName.BOOLEAN) {
+      final SqlOperator op = isMax ? SqlLibraryOperators.BOOL_OR : SqlLibraryOperators.BOOL_AND;
+      final SqlNode operand = ((SqlBasicCall) aggCall).operand(0);
+      return op.createCall(SqlParserPos.ZERO, operand);
+    }
+    // Otherwise, just return as it arrived
+    return aggCall;
+  }
+
   /**
    * Returns the SqlNode for emulating the null direction for the given field
    * or <code>null</code> if no emulation needs to be done.

diff --git a/core/src/main/java/org/apache/calcite/sql/dialect/PostgresqlSqlDialect.java b/core/src/main/java/org/apache/calcite/sql/dialect/PostgresqlSqlDialect.java
@@ -173,12 +173,15 @@ public PostgresqlSqlDialect(Context context) {
               timeUnitNode.getParserPosition());
       SqlFloorFunction.unparseDatetimeFunction(writer, call2, "DATE_TRUNC", false);
       break;
-
     default:
       super.unparseCall(writer, call, leftPrec, rightPrec);
     }
   }
 
+  @Override public SqlNode rewriteMaxMinExpr(SqlNode aggCall, RelDataType relDataType) {
+    return rewriteMaxMin(aggCall, relDataType);
+  }
+
   @Override public boolean supportsGroupByLiteral() {
     return false;
   }

diff --git a/core/src/main/java/org/apache/calcite/sql/dialect/RedshiftSqlDialect.java b/core/src/main/java/org/apache/calcite/sql/dialect/RedshiftSqlDialect.java
@@ -107,6 +107,10 @@ public RedshiftSqlDialect(Context context) {
         SqlParserPos.ZERO);
   }
 
+  @Override public SqlNode rewriteMaxMinExpr(SqlNode aggCall, RelDataType relDataType) {
+    return rewriteMaxMin(aggCall, relDataType);
+  }
+
   @Override public boolean supportsGroupByLiteral() {
     return false;
   }

diff --git a/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java b/core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
@@ -6683,6 +6683,37 @@ private void checkLiteral2(String expression, String expected) {
     sql(query).withLibrary(SqlLibrary.SNOWFLAKE).withSnowflake().ok(expectedSnowflake);
   }
 
+  /** Test case for
+   * <a href="https://issues.apache.org/jira/browse/CALCITE-6220">[CALCITE-6220]
+   * Rewrite MIN/MAX(bool) as BOOL_AND/BOOL_OR for Postgres, Redshift</a>. */
+  @Test void testMaxMinOnBooleanColumn() {
+    final String query = "select max(\"brand_name\" = 'a'), "
+        + "min(\"brand_name\" = 'a'), "
+        + "min(\"brand_name\")\n"
+        + "from \"product\"";
+    final String expected = "SELECT MAX(\"brand_name\" = 'a'), "
+        + "MIN(\"brand_name\" = 'a'), "
+        + "MIN(\"brand_name\")\n"
+        + "FROM \"foodmart\".\"product\"";
+    final String expectedBigQuery = "SELECT MAX(brand_name = 'a'), "
+        + "MIN(brand_name = 'a'), "
+        + "MIN(brand_name)\n"
+        + "FROM foodmart.product";
+    final String expectedPostgres = "SELECT BOOL_OR(\"brand_name\" = 'a'), "
+        + "BOOL_AND(\"brand_name\" = 'a'), "
+        + "MIN(\"brand_name\")\n"
+        + "FROM \"foodmart\".\"product\"";
+    final String expectedRedshift = "SELECT BOOL_OR(\"brand_name\" = 'a'), "
+        + "BOOL_AND(\"brand_name\" = 'a'), "
+        + "MIN(\"brand_name\")\n"
+        + "FROM \"foodmart\".\"product\"";
+    sql(query)
+      .ok(expected)
+      .withBigQuery().ok(expectedBigQuery)
+      .withPostgresql().ok(expectedPostgres)
+      .withRedshift().ok(expectedPostgres);
+  }
+
   /** Test case for
    * <a href="https://issues.apache.org/jira/browse/CALCITE-6156">[CALCITE-6156]
    * Add ENDSWITH, STARTSWITH functions (enabled in Postgres, Snowflake libraries)</a>. */