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SQL Parser and Optimizer
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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.hazelcast.org.apache.calcite.sql.dialect;

import com.hazelcast.org.apache.calcite.avatica.util.Casing;
import com.hazelcast.org.apache.calcite.rel.type.RelDataType;
import com.hazelcast.org.apache.calcite.rel.type.RelDataTypeSystem;
import com.hazelcast.org.apache.calcite.rel.type.RelDataTypeSystemImpl;
import com.hazelcast.org.apache.calcite.sql.SqlDataTypeSpec;
import com.hazelcast.org.apache.calcite.sql.SqlDialect;
import com.hazelcast.org.apache.calcite.sql.SqlNode;
import com.hazelcast.org.apache.calcite.sql.SqlUserDefinedTypeNameSpec;
import com.hazelcast.org.apache.calcite.sql.SqlWriter;
import com.hazelcast.org.apache.calcite.sql.parser.SqlParserPos;
import com.hazelcast.org.apache.calcite.sql.type.SqlTypeName;

import com.hazelcast.org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A SqlDialect implementation for the Redshift database.
 */
public class RedshiftSqlDialect extends SqlDialect {
  public static final RelDataTypeSystem TYPE_SYSTEM =
      new RelDataTypeSystemImpl() {
        @Override public int getMaxPrecision(SqlTypeName typeName) {
          switch (typeName) {
          case VARCHAR:
            return 65535;
          case CHAR:
            return 4096;
          default:
            return super.getMaxPrecision(typeName);
          }
        }

        @Override public int getMaxNumericPrecision() {
          return 38;
        }

        @Override public int getMaxNumericScale() {
          return 37;
        }
      };

  public static final SqlDialect.Context DEFAULT_CONTEXT = SqlDialect.EMPTY_CONTEXT
      .withDatabaseProduct(SqlDialect.DatabaseProduct.REDSHIFT)
      .withIdentifierQuoteString("\"")
      .withQuotedCasing(Casing.TO_LOWER)
      .withUnquotedCasing(Casing.TO_LOWER)
      .withCaseSensitive(false)
      .withDataTypeSystem(TYPE_SYSTEM);

  public static final SqlDialect DEFAULT = new RedshiftSqlDialect(DEFAULT_CONTEXT);

  /** Creates a RedshiftSqlDialect. */
  public RedshiftSqlDialect(Context context) {
    super(context);
  }

  @Override public void unparseOffsetFetch(SqlWriter writer, @Nullable SqlNode offset,
      @Nullable SqlNode fetch) {
    unparseFetchUsingLimit(writer, offset, fetch);
  }

  @Override public boolean supportsCharSet() {
    return false;
  }

  @Override public @Nullable SqlNode getCastSpec(RelDataType type) {
    String castSpec;
    switch (type.getSqlTypeName()) {
    case TINYINT:
      // Redshift has no tinyint (1 byte), so instead cast to smallint or int2 (2 bytes).
      // smallint does not work when enclosed in quotes (i.e.) as "smallint".
      // int2 however works within quotes (i.e.) as "int2".
      // Hence using int2.
      castSpec = "int2";
      break;
    case DOUBLE:
      // Redshift has a double type but it is named differently. It is named as double precision or
      // float8.
      // double precision does not work when enclosed in quotes (i.e.) as "double precision".
      // float8 however works within quotes (i.e.) as "float8".
      // Hence using float8.
      castSpec = "float8";
      break;
    default:
      return super.getCastSpec(type);
    }

    return new SqlDataTypeSpec(
        new SqlUserDefinedTypeNameSpec(castSpec, SqlParserPos.ZERO),
        SqlParserPos.ZERO);
  }

  @Override public boolean supportsGroupByLiteral() {
    return false;
  }

  @Override public boolean supportsAliasedValues() {
    return false;
  }
}