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Cassandra adapter for Calcite
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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.calcite.adapter.cassandra;
import org.apache.calcite.avatica.util.Casing;
import org.apache.calcite.jdbc.CalciteSchema;
import org.apache.calcite.rel.RelFieldCollation;
import org.apache.calcite.rel.type.RelDataTypeFactory;
import org.apache.calcite.rel.type.RelDataTypeImpl;
import org.apache.calcite.rel.type.RelDataTypeSystem;
import org.apache.calcite.rel.type.RelProtoDataType;
import org.apache.calcite.runtime.Hook;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.Table;
import org.apache.calcite.schema.impl.AbstractSchema;
import org.apache.calcite.schema.impl.MaterializedViewTable;
import org.apache.calcite.sql.SqlSelect;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.dialect.CalciteSqlDialect;
import org.apache.calcite.sql.parser.SqlParseException;
import org.apache.calcite.sql.parser.SqlParser;
import org.apache.calcite.sql.pretty.SqlPrettyWriter;
import org.apache.calcite.sql.type.SqlTypeFactoryImpl;
import org.apache.calcite.sql.type.SqlTypeName;
import org.apache.calcite.util.Pair;
import org.apache.calcite.util.Util;
import org.apache.calcite.util.trace.CalciteTrace;
import com.datastax.driver.core.AbstractTableMetadata;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ClusteringOrder;
import com.datastax.driver.core.ColumnMetadata;
import com.datastax.driver.core.DataType;
import com.datastax.driver.core.KeyspaceMetadata;
import com.datastax.driver.core.MaterializedViewMetadata;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.TableMetadata;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import org.slf4j.Logger;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
/**
* Schema mapped onto a Cassandra column family
*/
public class CassandraSchema extends AbstractSchema {
final Session session;
final String keyspace;
private final SchemaPlus parentSchema;
final String name;
final Hook.Closeable hook;
protected static final Logger LOGGER = CalciteTrace.getPlannerTracer();
private static final int DEFAULT_CASSANDRA_PORT = 9042;
/**
* Creates a Cassandra schema.
*
* @param host Cassandra host, e.g. "localhost"
* @param keyspace Cassandra keyspace name, e.g. "twissandra"
*/
public CassandraSchema(String host, String keyspace, SchemaPlus parentSchema, String name) {
this(host, DEFAULT_CASSANDRA_PORT, keyspace, null, null, parentSchema, name);
}
/**
* Creates a Cassandra schema.
*
* @param host Cassandra host, e.g. "localhost"
* @param port Cassandra port, e.g. 9042
* @param keyspace Cassandra keyspace name, e.g. "twissandra"
*/
public CassandraSchema(String host, int port, String keyspace,
SchemaPlus parentSchema, String name) {
this(host, port, keyspace, null, null, parentSchema, name);
}
/**
* Creates a Cassandra schema.
*
* @param host Cassandra host, e.g. "localhost"
* @param keyspace Cassandra keyspace name, e.g. "twissandra"
* @param username Cassandra username
* @param password Cassandra password
*/
public CassandraSchema(String host, String keyspace, String username, String password,
SchemaPlus parentSchema, String name) {
this(host, DEFAULT_CASSANDRA_PORT, keyspace, null, null, parentSchema, name);
}
/**
* Creates a Cassandra schema.
*
* @param host Cassandra host, e.g. "localhost"
* @param port Cassandra port, e.g. 9042
* @param keyspace Cassandra keyspace name, e.g. "twissandra"
* @param username Cassandra username
* @param password Cassandra password
*/
public CassandraSchema(String host, int port, String keyspace, String username, String password,
SchemaPlus parentSchema, String name) {
super();
this.keyspace = keyspace;
try {
Cluster cluster;
List contactPoints = new ArrayList<>(1);
contactPoints.add(new InetSocketAddress(host, port));
if (username != null && password != null) {
cluster = Cluster.builder().addContactPointsWithPorts(contactPoints)
.withCredentials(username, password).build();
} else {
cluster = Cluster.builder().addContactPointsWithPorts(contactPoints).build();
}
this.session = cluster.connect(keyspace);
} catch (Exception e) {
throw new RuntimeException(e);
}
this.parentSchema = parentSchema;
this.name = name;
this.hook = Hook.TRIMMED.add(node -> {
CassandraSchema.this.addMaterializedViews();
});
}
RelProtoDataType getRelDataType(String columnFamily, boolean view) {
List columns;
if (view) {
columns = getKeyspace().getMaterializedView(columnFamily).getColumns();
} else {
columns = getKeyspace().getTable(columnFamily).getColumns();
}
// Temporary type factory, just for the duration of this method. Allowable
// because we're creating a proto-type, not a type; before being used, the
// proto-type will be copied into a real type factory.
final RelDataTypeFactory typeFactory =
new SqlTypeFactoryImpl(RelDataTypeSystem.DEFAULT);
final RelDataTypeFactory.Builder fieldInfo = typeFactory.builder();
for (ColumnMetadata column : columns) {
final String columnName = column.getName();
final DataType type = column.getType();
// TODO: This mapping of types can be done much better
SqlTypeName typeName = SqlTypeName.ANY;
if (type == DataType.uuid() || type == DataType.timeuuid()) {
// We currently rely on this in CassandraFilter to detect UUID columns.
// That is, these fixed length literals should be unquoted in CQL.
typeName = SqlTypeName.CHAR;
} else if (type == DataType.ascii() || type == DataType.text()
|| type == DataType.varchar()) {
typeName = SqlTypeName.VARCHAR;
} else if (type == DataType.cint() || type == DataType.varint()) {
typeName = SqlTypeName.INTEGER;
} else if (type == DataType.bigint()) {
typeName = SqlTypeName.BIGINT;
} else if (type == DataType.cdouble() || type == DataType.cfloat()
|| type == DataType.decimal()) {
typeName = SqlTypeName.DOUBLE;
}
fieldInfo.add(columnName, typeFactory.createSqlType(typeName)).nullable(true);
}
return RelDataTypeImpl.proto(fieldInfo.build());
}
/**
* Get all primary key columns from the underlying CQL table
*
* @return A list of field names that are part of the partition and clustering keys
*/
Pair, List> getKeyFields(String columnFamily, boolean view) {
AbstractTableMetadata table;
if (view) {
table = getKeyspace().getMaterializedView(columnFamily);
} else {
table = getKeyspace().getTable(columnFamily);
}
List partitionKey = table.getPartitionKey();
List pKeyFields = new ArrayList<>();
for (ColumnMetadata column : partitionKey) {
pKeyFields.add(column.getName());
}
List clusteringKey = table.getClusteringColumns();
List cKeyFields = new ArrayList<>();
for (ColumnMetadata column : clusteringKey) {
cKeyFields.add(column.getName());
}
return Pair.of(ImmutableList.copyOf(pKeyFields),
ImmutableList.copyOf(cKeyFields));
}
/** Get the collation of all clustering key columns.
*
* @return A RelCollations representing the collation of all clustering keys
*/
public List getClusteringOrder(String columnFamily, boolean view) {
AbstractTableMetadata table;
if (view) {
table = getKeyspace().getMaterializedView(columnFamily);
} else {
table = getKeyspace().getTable(columnFamily);
}
List clusteringOrder = table.getClusteringOrder();
List keyCollations = new ArrayList<>();
int i = 0;
for (ClusteringOrder order : clusteringOrder) {
RelFieldCollation.Direction direction;
switch (order) {
case DESC:
direction = RelFieldCollation.Direction.DESCENDING;
break;
case ASC:
default:
direction = RelFieldCollation.Direction.ASCENDING;
break;
}
keyCollations.add(new RelFieldCollation(i, direction));
i++;
}
return keyCollations;
}
/** Add all materialized views defined in the schema to this column family
*/
private void addMaterializedViews() {
// Close the hook use to get us here
hook.close();
for (MaterializedViewMetadata view : getKeyspace().getMaterializedViews()) {
String tableName = view.getBaseTable().getName();
StringBuilder queryBuilder = new StringBuilder("SELECT ");
// Add all the selected columns to the query
List columnNames = new ArrayList<>();
for (ColumnMetadata column : view.getColumns()) {
columnNames.add("\"" + column.getName() + "\"");
}
queryBuilder.append(Util.toString(columnNames, "", ", ", ""));
queryBuilder.append(" FROM \"" + tableName + "\"");
// Get the where clause from the system schema
String whereQuery = "SELECT where_clause from system_schema.views "
+ "WHERE keyspace_name='" + keyspace + "' AND view_name='" + view.getName() + "'";
queryBuilder.append(" WHERE " + session.execute(whereQuery).one().getString(0));
// Parse and unparse the view query to get properly quoted field names
String query = queryBuilder.toString();
SqlParser.ConfigBuilder configBuilder = SqlParser.configBuilder();
configBuilder.setUnquotedCasing(Casing.UNCHANGED);
SqlSelect parsedQuery;
try {
parsedQuery = (SqlSelect) SqlParser.create(query, configBuilder.build()).parseQuery();
} catch (SqlParseException e) {
LOGGER.warn("Could not parse query {} for CQL view {}.{}",
query, keyspace, view.getName());
continue;
}
StringWriter stringWriter = new StringWriter(query.length());
PrintWriter printWriter = new PrintWriter(stringWriter);
SqlWriter writer = new SqlPrettyWriter(CalciteSqlDialect.DEFAULT, true, printWriter);
parsedQuery.unparse(writer, 0, 0);
query = stringWriter.toString();
// Add the view for this query
String viewName = "$" + getTableNames().size();
SchemaPlus schema = parentSchema.getSubSchema(name);
CalciteSchema calciteSchema = CalciteSchema.from(schema);
List viewPath = calciteSchema.path(viewName);
schema.add(viewName,
MaterializedViewTable.create(calciteSchema, query,
null, viewPath, view.getName(), true));
}
}
@Override protected Map getTableMap() {
final ImmutableMap.Builder builder = ImmutableMap.builder();
for (TableMetadata table : getKeyspace().getTables()) {
String tableName = table.getName();
builder.put(tableName, new CassandraTable(this, tableName));
for (MaterializedViewMetadata view : table.getViews()) {
String viewName = view.getName();
builder.put(viewName, new CassandraTable(this, viewName, true));
}
}
return builder.build();
}
private KeyspaceMetadata getKeyspace() {
return session.getCluster().getMetadata().getKeyspace(keyspace);
}
}
// End CassandraSchema.java