Add support for Bool type for ClickHouse connector

docs/src/main/sphinx/connector/clickhouse.md

@@ -183,9 +183,12 @@ to the following table:
 * - ClickHouse type
   - Trino type
   - Notes
+* - `Bool`
+  - `BOOLEAN`
+  -
 * - `Int8`
   - `TINYINT`
-  - `TINYINT`, `BOOL`, `BOOLEAN`, and `INT1` are aliases of `Int8`
+  - `TINYINT` and `INT1` are aliases of `Int8`
 * - `Int16`
   - `SMALLINT`
   -  `SMALLINT` and `INT2` are aliases of `Int16`
@@ -262,11 +265,11 @@ to the following table:
   - ClickHouse type
   - Notes
 * - `BOOLEAN`
-  - `UInt8`
+  - `Bool`
   -
 * - `TINYINT`
   - `Int8`
-  - `TINYINT`, `BOOL`, `BOOLEAN`, and `INT1` are aliases of `Int8`
+  - `TINYINT` and `INT1` are aliases of `Int8`
 * - `SMALLINT`
   - `Int16`
   -  `SMALLINT` and `INT2` are aliases of `Int16`

plugin/trino-clickhouse/src/main/java/io/trino/plugin/clickhouse/ClickHouseClient.java

@@ -137,6 +137,7 @@
 import static io.trino.plugin.jdbc.PredicatePushdownController.FULL_PUSHDOWN;
 import static io.trino.plugin.jdbc.StandardColumnMappings.bigintColumnMapping;
 import static io.trino.plugin.jdbc.StandardColumnMappings.bigintWriteFunction;
+import static io.trino.plugin.jdbc.StandardColumnMappings.booleanColumnMapping;
 import static io.trino.plugin.jdbc.StandardColumnMappings.booleanWriteFunction;
 import static io.trino.plugin.jdbc.StandardColumnMappings.dateReadFunctionUsingLocalDate;
 import static io.trino.plugin.jdbc.StandardColumnMappings.decimalColumnMapping;
@@ -638,6 +639,8 @@ public Optional<ColumnMapping> toColumnMapping(ConnectorSession session, Connect
         ClickHouseColumn column = ClickHouseColumn.of("", jdbcTypeName);
         ClickHouseDataType columnDataType = column.getDataType();
         switch (columnDataType) {
+            case Bool:
+                return Optional.of(booleanColumnMapping());
             case UInt8:
                 return Optional.of(ColumnMapping.longMapping(SMALLINT, ResultSet::getShort, uInt8WriteFunction(getClickHouseServerVersion(session))));
             case UInt16:
@@ -757,8 +760,7 @@ public Optional<ColumnMapping> toColumnMapping(ConnectorSession session, Connect
     public WriteMapping toWriteMapping(ConnectorSession session, Type type)
     {
         if (type == BOOLEAN) {
-            // ClickHouse is no separate type for boolean values. Use UInt8 type, restricted to the values 0 or 1.
-            return WriteMapping.booleanMapping("UInt8", booleanWriteFunction());
+            return WriteMapping.booleanMapping("Bool", booleanWriteFunction());
         }
         if (type == TINYINT) {
             return WriteMapping.longMapping("Int8", tinyintWriteFunction());

plugin/trino-clickhouse/src/test/java/io/trino/plugin/clickhouse/BaseClickHouseTypeMapping.java

@@ -43,6 +43,7 @@
 import static io.trino.plugin.jdbc.TypeHandlingJdbcSessionProperties.UNSUPPORTED_TYPE_HANDLING;
 import static io.trino.plugin.jdbc.UnsupportedTypeHandling.CONVERT_TO_VARCHAR;
 import static io.trino.spi.type.BigintType.BIGINT;
+import static io.trino.spi.type.BooleanType.BOOLEAN;
 import static io.trino.spi.type.DateType.DATE;
 import static io.trino.spi.type.DecimalType.createDecimalType;
 import static io.trino.spi.type.DoubleType.DOUBLE;
@@ -106,6 +107,28 @@ private static void checkIsDoubled(ZoneId zone, LocalDateTime dateTime)
         verify(zone.getRules().getValidOffsets(dateTime).size() == 2, "Expected %s to be doubled in %s", dateTime, zone);
     }
 
+    @Test
+    public void testTrinoBoolean()
+    {
+        SqlDataTypeTest.create()
+                .addRoundTrip("boolean", "true", BOOLEAN, "true")
+                .addRoundTrip("boolean", "false", BOOLEAN, "false")
+                .addRoundTrip("boolean", "NULL", BOOLEAN, "CAST(NULL AS BOOLEAN)")
+                .execute(getQueryRunner(), trinoCreateAsSelect("test_boolean"))
+                .execute(getQueryRunner(), trinoCreateAndInsert("test_boolean"));
+    }
+
+    @Test
+    public void testBool()
+    {
+        SqlDataTypeTest.create()
+                .addRoundTrip("bool", "true", BOOLEAN, "true")
+                .addRoundTrip("bool", "false", BOOLEAN, "false")
+                .addRoundTrip("Nullable(bool)", "NULL", BOOLEAN, "CAST(NULL AS BOOLEAN)")
+                .execute(getQueryRunner(), clickhouseCreateAndInsert("tpch.test_boolean"))
+                .execute(getQueryRunner(), clickhouseCreateAndTrinoInsert("tpch.test_boolean"));
+    }
+
     @Test
     public void testTinyint()
     {

plugin/trino-clickhouse/src/test/java/io/trino/plugin/clickhouse/TestClickHouseConnectorTest.java

@@ -486,7 +486,7 @@ public void testTableProperty()
                 .isEqualTo(format("" +
                         "CREATE TABLE clickhouse.tpch.%s (\n" +
                         "   id integer NOT NULL,\n" +
-                        "   x smallint NOT NULL,\n" +
+                        "   x boolean NOT NULL,\n" +
                         "   y varchar NOT NULL\n" +
                         ")\n" +
                         "WITH (\n" +