[CALCITE-5806] add a String data type (enabled in Apache Spark and BigQuery)

core/src/main/codegen/default_config.fmpp

@@ -314,6 +314,7 @@ parser: {
     "SQL_VARCHAR"
     "STATE"
     "STATEMENT"
+    "STRING"
     "STRING_AGG"
     "STRUCTURE"
     "STYLE"

core/src/main/codegen/templates/Parser.jj

@@ -5757,6 +5757,8 @@ SqlTypeNameSpec SqlTypeName1(Span s) :
         [ <PRECISION> ] { sqlTypeName = SqlTypeName.DOUBLE; }
     |
         <FLOAT> { s.add(this); sqlTypeName = SqlTypeName.FLOAT; }
+    |
+        <STRING> { s.add(this); sqlTypeName = SqlTypeName.STRING; }
     )
     {
         return new SqlBasicTypeNameSpec(sqlTypeName, s.end(this));
@@ -8494,6 +8496,7 @@ SqlPostfixOperator PostfixRowOperator() :
 |   < SYSTEM: "SYSTEM" >
 |   < SYSTEM_TIME: "SYSTEM_TIME" >
 |   < SYSTEM_USER: "SYSTEM_USER" >
+|   < STRING: "STRING" >
 |   < TABLE: "TABLE" > { beforeTableName(); }
 |   < TABLE_NAME: "TABLE_NAME" >
 |   < TABLESAMPLE: "TABLESAMPLE" >

core/src/main/java/org/apache/calcite/rex/RexBuilder.java

@@ -1629,6 +1629,8 @@ public RexNode makeLiteral(@Nullable Object value, RelDataType type,
       } else {
         return literal;
       }
+    case STRING:
+      return makePreciseStringLiteral((String) value);
     case BINARY:
       return makeBinaryLiteral(
           padRight((ByteString) value, type.getPrecision()));
@@ -1802,6 +1804,8 @@ public RexNode makeLiteral(@Nullable Object value, RelDataType type,
       assert type.getCharset() != null : type + ".getCharset() must not be null";
       return new NlsString((String) o, type.getCharset().name(),
           type.getCollation());
+    case STRING:
+      return o;
     case TIME:
       if (o instanceof TimeString) {
         return o;

core/src/main/java/org/apache/calcite/rex/RexLiteral.java

@@ -375,6 +375,8 @@ public static boolean valueMatchesType(
       return (value instanceof NlsString)
           && (((NlsString) value).getCharset() != null)
           && (((NlsString) value).getCollation() != null);
+    case STRING:
+      return value instanceof String;
     case SARG:
       return value instanceof Sarg;
     case SYMBOL:

core/src/main/java/org/apache/calcite/sql/SqlDialect.java

@@ -815,7 +815,12 @@ public CalendarPolicy getCalendarPolicy() {
 
   /** Returns whether this dialect supports a given type. */
   public boolean supportsDataType(RelDataType type) {
-    return true;
+    switch (type.getSqlTypeName()) {
+    case STRING:
+      return false;
+    default:
+      return true;
+    }
   }
 
  /** Returns SqlNode for type in "cast(column as type)", which might be

core/src/main/java/org/apache/calcite/sql/dialect/BigQuerySqlDialect.java

@@ -126,6 +126,10 @@ public BigQuerySqlDialect(SqlDialect.Context context) {
     return false;
   }
 
+  @Override public boolean supportsDataType(RelDataType type) {
+    return true;
+  }
+
   @Override public SqlParser.Config configureParser(
       SqlParser.Config configBuilder) {
     return super.configureParser(configBuilder)

core/src/main/java/org/apache/calcite/sql/dialect/SparkSqlDialect.java

@@ -18,6 +18,7 @@
 
 import org.apache.calcite.avatica.util.TimeUnitRange;
 import org.apache.calcite.config.NullCollation;
+import org.apache.calcite.rel.type.RelDataType;
 import org.apache.calcite.sql.JoinType;
 import org.apache.calcite.sql.SqlBasicFunction;
 import org.apache.calcite.sql.SqlCall;
@@ -67,6 +68,10 @@ public SparkSqlDialect(SqlDialect.Context context) {
     return false;
   }
 
+  @Override public boolean supportsDataType(RelDataType type) {
+    return true;
+  }
+
   @Override public JoinType emulateJoinTypeForCrossJoin() {
     return JoinType.CROSS;
   }

core/src/main/java/org/apache/calcite/sql/type/SqlTypeAssignmentRule.java

@@ -150,6 +150,9 @@ private SqlTypeAssignmentRule(
     rule.add(SqlTypeName.VARCHAR);
     rules.add(SqlTypeName.VARCHAR, rule);
 
+    // STRING is assignable from...
+    rules.add(SqlTypeName.STRING, rule);
+
     // BOOLEAN is assignable from...
     rules.add(SqlTypeName.BOOLEAN, EnumSet.of(SqlTypeName.BOOLEAN));
 

core/src/main/java/org/apache/calcite/sql/type/SqlTypeName.java

@@ -127,7 +127,8 @@ public enum SqlTypeName {
    * do not flag it 'special' (internal). */
   GEOMETRY(PrecScale.NO_NO, false, ExtraSqlTypes.GEOMETRY, SqlTypeFamily.GEO),
   MEASURE(PrecScale.NO_NO, true, Types.OTHER, SqlTypeFamily.ANY),
-  SARG(PrecScale.NO_NO, true, Types.OTHER, SqlTypeFamily.ANY);
+  SARG(PrecScale.NO_NO, true, Types.OTHER, SqlTypeFamily.ANY),
+  STRING(PrecScale.NO_NO, true, Types.OTHER, SqlTypeFamily.STRING);
 
   public static final int MAX_DATETIME_PRECISION = 3;
 
@@ -159,7 +160,7 @@ public enum SqlTypeName {
           INTERVAL_DAY_SECOND, INTERVAL_HOUR, INTERVAL_HOUR_MINUTE,
           INTERVAL_HOUR_SECOND, INTERVAL_MINUTE, INTERVAL_MINUTE_SECOND,
           INTERVAL_SECOND, TIME_WITH_LOCAL_TIME_ZONE, TIMESTAMP_WITH_LOCAL_TIME_ZONE,
-          FLOAT, MULTISET, DISTINCT, STRUCTURED, ROW, CURSOR, COLUMN_LIST);
+          FLOAT, MULTISET, DISTINCT, STRUCTURED, ROW, CURSOR, COLUMN_LIST, STRING);
 
   public static final List<SqlTypeName> BOOLEAN_TYPES =
       ImmutableList.of(BOOLEAN);
@@ -183,7 +184,7 @@ public enum SqlTypeName {
       combine(APPROX_TYPES, ImmutableList.of(DECIMAL));
 
   public static final List<SqlTypeName> CHAR_TYPES =
-      ImmutableList.of(CHAR, VARCHAR);
+      ImmutableList.of(CHAR, VARCHAR, STRING);
 
   public static final List<SqlTypeName> STRING_TYPES =
       combine(CHAR_TYPES, BINARY_TYPES);

core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java

@@ -2127,7 +2127,8 @@ private SqlDialect nonOrdinalDialect() {
             + "cast(cast(\"employee_id\" as varchar) as decimal), "
             + "cast(cast(\"employee_id\" as varchar) as date), "
             + "cast(cast(\"employee_id\" as varchar) as time), "
-            + "cast(cast(\"employee_id\" as varchar) as boolean) "
+            + "cast(cast(\"employee_id\" as varchar) as boolean), "
+            + "cast(cast(\"employee_id\" as varchar) as string) "
             + "from \"foodmart\".\"reserve_employee\" ";
     final String expected = "SELECT CAST(CAST(employee_id AS STRING) AS INT64), "
             + "CAST(CAST(employee_id AS STRING) AS INT64), "
@@ -2142,7 +2143,8 @@ private SqlDialect nonOrdinalDialect() {
             + "CAST(CAST(employee_id AS STRING) AS NUMERIC), "
             + "CAST(CAST(employee_id AS STRING) AS DATE), "
             + "CAST(CAST(employee_id AS STRING) AS TIME), "
-            + "CAST(CAST(employee_id AS STRING) AS BOOL)\n"
+            + "CAST(CAST(employee_id AS STRING) AS BOOL), "
+            + "CAST(CAST(employee_id AS STRING) AS STRING)\n"
             + "FROM foodmart.reserve_employee";
     sql(query).withBigQuery().ok(expected);
   }
@@ -6757,12 +6759,20 @@ private void checkLiteral2(String expression, String expected) {
         new SqlTypeFactoryImpl(RelDataTypeSystem.DEFAULT);
     final RelDataType booleanDataType = typeFactory.createSqlType(SqlTypeName.BOOLEAN);
     final RelDataType integerDataType = typeFactory.createSqlType(SqlTypeName.INTEGER);
+    final RelDataType stringDataType = typeFactory.createSqlType(SqlTypeName.STRING);
     final SqlDialect oracleDialect = DatabaseProduct.ORACLE.getDialect();
-    assertFalse(oracleDialect.supportsDataType(booleanDataType));
+    assertFalse(oracleDialect.supportsDataType(stringDataType));
     assertTrue(oracleDialect.supportsDataType(integerDataType));
+    assertFalse(oracleDialect.supportsDataType(booleanDataType));
     final SqlDialect postgresqlDialect = DatabaseProduct.POSTGRESQL.getDialect();
     assertTrue(postgresqlDialect.supportsDataType(booleanDataType));
     assertTrue(postgresqlDialect.supportsDataType(integerDataType));
+    assertFalse(oracleDialect.supportsDataType(stringDataType));
+    final SqlDialect sparkSqlDialect = DatabaseProduct.SPARK.getDialect();
+    assertTrue(sparkSqlDialect.supportsDataType(stringDataType));
+    final SqlDialect bigQuerySqlDialect = DatabaseProduct.BIG_QUERY.getDialect();
+    assertTrue(bigQuerySqlDialect.supportsDataType(stringDataType));
+
   }
 
   /** Test case for

core/src/test/java/org/apache/calcite/rex/RexBuilderTest.java

@@ -699,6 +699,8 @@ private void checkDate(RexLiteral literal) {
         new SqlTypeFactoryImpl(RelDataTypeSystem.DEFAULT);
     final RelDataType varchar =
         typeFactory.createSqlType(SqlTypeName.VARCHAR);
+    final RelDataType string =
+        typeFactory.createSqlType(SqlTypeName.STRING);
     final RexBuilder builder = new RexBuilder(typeFactory);
 
     final NlsString latin1 = new NlsString("foobar", "LATIN1", SqlCollation.IMPLICIT);
@@ -737,6 +739,9 @@ private void checkDate(RexLiteral literal) {
     assertEquals("_LATIN1'foobar'", literal.toString());
     literal = builder.makeLiteral(utf8, varchar);
     assertEquals("_UTF8'foobar'", literal.toString());
+
+    literal = builder.makeLiteral("foobar", string);
+    assertEquals("'foobar'", literal.toString());
   }
 
   /** Tests {@link RexBuilder#makeExactLiteral(java.math.BigDecimal)}. */

core/src/test/java/org/apache/calcite/rex/RexProgramTest.java

@@ -2677,6 +2677,9 @@ private SqlOperator getNoDeterministicOperator() {
     literals.add(rexBuilder.makeLiteral(true));
     literals.add(rexBuilder.makeLiteral(false));
     literals.add(rexBuilder.makeLiteral("hello world"));
+    literals.add(
+        rexBuilder.makeLiteral("hello string",
+            typeFactory.createSqlType(SqlTypeName.STRING)));
     literals.add(rexBuilder.makeLiteral("1969-07-20 12:34:56"));
     literals.add(rexBuilder.makeLiteral("1969-07-20"));
     literals.add(rexBuilder.makeLiteral("12:34:45"));
@@ -2710,6 +2713,7 @@ private SqlOperator getNoDeterministicOperator() {
     types.add(typeFactory.createSqlType(SqlTypeName.TIMESTAMP));
     types.add(typeFactory.createSqlType(SqlTypeName.TIME));
     types.add(typeFactory.createSqlType(SqlTypeName.DATE));
+    types.add(typeFactory.createSqlType(SqlTypeName.STRING));
 
     for (RelDataType fromType : types) {
       for (RelDataType toType : types) {

site/_docs/reference.md

@@ -1010,6 +1010,7 @@ STATEMENT,
 **STDDEV_POP**,
 **STDDEV_SAMP**,
 **STREAM**,
+STRING,
 STRING_AGG,
 STRUCTURE,
 STYLE,

testkit/src/main/java/org/apache/calcite/sql/parser/SqlParserTest.java

@@ -1803,6 +1803,8 @@ void checkPeriodPredicate(Checker checker) {
         .ok("CAST(`X` AS DECIMAL(1, 1))");
     expr("cast(x as char(1))")
         .ok("CAST(`X` AS CHAR(1))");
+    expr("cast(x as string)")
+        .ok("CAST(`X` AS STRING)");
     expr("cast(x as binary(1))")
         .ok("CAST(`X` AS BINARY(1))");
     expr("cast(x as varbinary(1))")