com.datastax.driver.mapping.schemasync.SchemaSync Maven / Gradle / Ivy
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/*
* Copyright (C) 2014 Eugene Valchkou.
*
* Licensed 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.datastax.driver.mapping.schemasync;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ColumnMetadata;
import com.datastax.driver.core.KeyspaceMetadata;
import com.datastax.driver.core.RegularStatement;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.TableMetadata;
import com.datastax.driver.mapping.EntityFieldMetaData;
import com.datastax.driver.mapping.EntityTypeMetadata;
import com.datastax.driver.mapping.EntityTypeParser;
/**
* Static methods to synchronize entities' definition with Cassandra tables
*/
public final class SchemaSync {
private SchemaSync() {}
public static synchronized void sync(String keyspace, Session session, Class clazz) {
EntityTypeMetadata entityMetadata = EntityTypeParser.getEntityMetadata(clazz);
if (entityMetadata.isSynced()) return;
String table = entityMetadata.getTableName();
session.execute("USE "+keyspace);
Cluster cluster = session.getCluster();
KeyspaceMetadata keyspaceMetadata = cluster.getMetadata().getKeyspace(keyspace);
TableMetadata tableMetadata = keyspaceMetadata.getTable(table);
List statements;
if (tableMetadata == null) {
statements = createTableStatements(keyspace, entityMetadata);
} else {
statements = alterTableStatements(keyspace, session, entityMetadata);
}
for (RegularStatement stmt: statements) {
session.execute(stmt);
}
entityMetadata.markSynced();
}
public static void sync(String keyspace, Session session, Class[] classes) {
for (Class clazz: classes) {
sync(keyspace, session, clazz);
}
}
public static void drop(String keyspace, Session session, Class[] classes) {
for (Class clazz: classes) {
drop(keyspace, session, clazz);
}
}
public static synchronized void drop(String keyspace, Session session, Class clazz) {
EntityTypeMetadata entityMetadata = EntityTypeParser.getEntityMetadata(clazz);
entityMetadata.markUnSynced();
String table = entityMetadata.getTableName();
Cluster cluster = session.getCluster();
KeyspaceMetadata keyspaceMetadata = cluster.getMetadata().getKeyspace(keyspace);
TableMetadata tableMetadata = keyspaceMetadata.getTable(table);
if (tableMetadata != null) {
// drop indexes
for (ColumnMetadata columnMetadata: tableMetadata.getColumns()) {
if (columnMetadata.getIndex() != null) {
session.execute(new DropIndex(columnMetadata.getName(), columnMetadata.getIndex().getName()));
}
}
// drop table
session.execute(new DropTable(keyspace, entityMetadata));
}
}
/**
* Built create statements on the provided class for table and indexes.
*
* Statement will contain one CREATE TABLE and many or zero CREATE INDEX statements
*
* @param class the class to generate statements for.
* @return a new {@code List}.
*/
private static List createTableStatements(String keyspace, EntityTypeMetadata entityMetadata) {
List statements = new ArrayList();
statements.add(new CreateTable(keyspace, entityMetadata));
Map indexes = entityMetadata.getIndexes();
if (indexes != null) {
for (String columnName: indexes.keySet()) {
String indexName = indexes.get(columnName);
statements.add(new CreateIndex(keyspace, entityMetadata.getTableName(), columnName, indexName));
}
}
return statements;
}
/**
* Compare TableMetadata against Entity metadata and generate alter statements if necessary.
*
* Cannot alter clustered and primary key columns.
*
* @param class the class to generate statements for or indexed
* @return a new {@code List}.
*/
private static List alterTableStatements(String keyspace, Session session, EntityTypeMetadata entityMetadata) {
List statements = new ArrayList();
// get EntityTypeMetadata
String table = entityMetadata.getTableName();
// get TableMetadata - requires connection to cassandra
Cluster cluster = session.getCluster();
KeyspaceMetadata keyspaceMetadata = cluster.getMetadata().getKeyspace(keyspace);
TableMetadata tableMetadata = keyspaceMetadata.getTable(table);
// build statements for a new column or a columns with changed datatype.
for (EntityFieldMetaData field: entityMetadata.getFields()) {
String column = field.getColumnName();
String fieldType = field.getDataType().name();
ColumnMetadata columnMetadata = tableMetadata.getColumn(column);
String colIndex = null;
if (columnMetadata!= null && columnMetadata.getIndex() != null) {
colIndex = columnMetadata.getIndex().getName();
}
String fieldIndex = null;
if (entityMetadata.getIndex(column) != null) {
fieldIndex = entityMetadata.getIndex(column);
}
if (columnMetadata == null) {
// if column not exists in TableMetadata then add column
String colType = fieldType;
if (field.isGenericType()) {
colType = field.getGenericDef();
}
AlterTable statement = new AlterTable.Builder().addColumn(keyspace, table, column, colType);
statements.add(statement);
} else if (colIndex!=null || fieldIndex!=null) {
if (colIndex == null) {
statements.add(new CreateIndex(keyspace, table, column, entityMetadata.getIndex(column)));
} else if (fieldIndex == null) {
statements.add(new DropIndex(column, columnMetadata.getIndex().getName()));
} else if (!fieldIndex.equals(colIndex)) {
statements.add(new DropIndex(column, columnMetadata.getIndex().getName()));
statements.add(new CreateIndex(keyspace, table, column, entityMetadata.getIndex(column)));
}
} else if (!fieldType.equals(columnMetadata.getType().getName().name())) {
// can't change datatype for clustered columns
if (tableMetadata.getClusteringColumns().contains(columnMetadata)) {
continue;
}
// can't change datatype for PK columns
if (tableMetadata.getPrimaryKey().contains(columnMetadata)) {
continue;
}
// drop index if any
if (columnMetadata.getIndex() != null) {
statements.add(new DropIndex(column, columnMetadata.getIndex().getName()));
}
// alter column datatype
statements.add(new AlterTable.Builder().alterColumn(keyspace, table, column, fieldType));
// create index if any
if (entityMetadata.getIndex(column) != null) {
statements.add(new CreateIndex(keyspace, table, column, entityMetadata.getIndex(column)));
}
}
}
// column is in Cassandra but not in entity anymore
for (ColumnMetadata colmeta: tableMetadata.getColumns()) {
colmeta.getName();
boolean exists = false;
for (EntityFieldMetaData field: entityMetadata.getFields()) {
if (colmeta.getName().equalsIgnoreCase(field.getColumnName())) {
exists = true;
break;
}
}
if (!exists) {
AlterTable statement = new AlterTable.Builder().dropColumn(keyspace, table, colmeta.getName());
statements.add(statement);
}
}
return statements;
}
}