org.apache.flink.cdc.common.schema.Column Maven / Gradle / Ivy
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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 org.apache.flink.cdc.common.schema;
import org.apache.flink.cdc.common.annotation.PublicEvolving;
import org.apache.flink.cdc.common.types.DataType;
import javax.annotation.Nullable;
import java.io.Serializable;
import java.util.Objects;
import static org.apache.flink.cdc.common.utils.EncodingUtils.escapeIdentifier;
import static org.apache.flink.cdc.common.utils.EncodingUtils.escapeSingleQuotes;
/**
* Representation of a column in a {@link Schema}.
*
* A table column describes either a {@link PhysicalColumn} or {@link MetadataColumn}.
*/
@PublicEvolving
public abstract class Column implements Serializable {
private static final long serialVersionUID = 1L;
protected static final String FIELD_FORMAT_WITH_DESCRIPTION_NO_DEFAULT_VALUE_EXPRESSION =
"%s %s '%s'";
protected static final String FIELD_FORMAT_NO_DESCRIPTION_WITH_DEFAULT_VALUE_EXPRESSION =
"%s %s '%s'";
protected static final String FIELD_FORMAT_WITH_DESCRIPTION_WITH_DEFAULT_VALUE_EXPRESSION =
"%s %s '%s' '%s'";
protected static final String FIELD_FORMAT_NO_DESCRIPTION_NO_DEFAULT_VALUE_EXPRESSION = "%s %s";
protected final String name;
protected final DataType type;
protected final @Nullable String comment;
/**
* Save the literal value of the column's default value, For uncertain functions such as UUID(),
* the value is null, For the current time function such as CURRENT_TIMESTAMP(), the value is
* Unix Epoch time(1970-01-01 00:00:00).
*/
protected final @Nullable String defaultValueExpression;
protected Column(String name, DataType type, @Nullable String comment) {
this.name = name;
this.type = type;
this.comment = comment;
this.defaultValueExpression = null;
}
protected Column(
String name,
DataType type,
@Nullable String comment,
@Nullable String defaultValueExpression) {
this.name = name;
this.type = type;
this.comment = comment;
this.defaultValueExpression = defaultValueExpression;
}
/** Returns the name of this column. */
public String getName() {
return name;
}
/** Returns the data type of this column. */
public DataType getType() {
return type;
}
@Nullable
public String getComment() {
return comment;
}
@Nullable
public String getDefaultValueExpression() {
return defaultValueExpression;
}
/** Returns a string that summarizes this column for printing to a console. */
public String asSummaryString() {
if (comment == null) {
if (defaultValueExpression == null) {
return String.format(
FIELD_FORMAT_NO_DESCRIPTION_NO_DEFAULT_VALUE_EXPRESSION,
escapeIdentifier(name),
type.asSummaryString());
} else {
return String.format(
FIELD_FORMAT_NO_DESCRIPTION_WITH_DEFAULT_VALUE_EXPRESSION,
escapeIdentifier(name),
type.asSummaryString(),
defaultValueExpression);
}
} else {
if (defaultValueExpression == null) {
return String.format(
FIELD_FORMAT_WITH_DESCRIPTION_NO_DEFAULT_VALUE_EXPRESSION,
escapeIdentifier(name),
type.asSummaryString(),
escapeSingleQuotes(comment));
} else {
return String.format(
FIELD_FORMAT_WITH_DESCRIPTION_WITH_DEFAULT_VALUE_EXPRESSION,
escapeIdentifier(name),
type.asSummaryString(),
escapeSingleQuotes(comment),
defaultValueExpression);
}
}
}
/** Returns whether the given column is a physical column of a table or metadata column. */
public abstract boolean isPhysical();
/** Returns a copy of the column with a replaced {@link DataType}. */
public abstract Column copy(DataType newType);
/** Returns a copy of the column with a replaced name. */
public abstract Column copy(String newName);
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof Column)) {
return false;
}
Column column = (Column) o;
return name.equals(column.name)
&& type.equals(column.type)
&& Objects.equals(comment, column.comment)
&& Objects.equals(defaultValueExpression, column.defaultValueExpression);
}
@Override
public int hashCode() {
return Objects.hash(name, type, comment, defaultValueExpression);
}
@Override
public String toString() {
return asSummaryString();
}
/** Creates a physical column. */
public static PhysicalColumn physicalColumn(
String name,
DataType type,
@Nullable String comment,
@Nullable String defaultValueExpression) {
return new PhysicalColumn(name, type, comment, defaultValueExpression);
}
/** Creates a physical column. */
public static PhysicalColumn physicalColumn(
String name, DataType type, @Nullable String comment) {
return new PhysicalColumn(name, type, comment);
}
/** Creates a physical column. */
public static PhysicalColumn physicalColumn(String name, DataType type) {
return new PhysicalColumn(name, type, null);
}
/** Creates a metadata column. */
public static MetadataColumn metadataColumn(
String name, DataType type, @Nullable String metadataKey, @Nullable String comment) {
return new MetadataColumn(name, type, metadataKey, comment);
}
/** Creates a metadata column. */
public static MetadataColumn metadataColumn(
String name, DataType type, @Nullable String metadataKey) {
return new MetadataColumn(name, type, metadataKey, null);
}
/** Creates a metadata column. */
public static MetadataColumn metadataColumn(String name, DataType type) {
return new MetadataColumn(name, type, null, null);
}
}