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Add a virtual table for exposing prepared statements metrics 

patch by Shailaja Koppu; reviewed by Ekaterina Dimitrova, Francisco Guerrero, Yifan Cai for CASSANDRA-17224
This commit is contained in:
Shailaja Koppu 2022-02-01 09:53:49 -08:00 committed by Yifan Cai
parent 23e88ad0c8
commit 945a4fc23a
5 changed files with 227 additions and 0 deletions
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1
CHANGES.txt
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@ -1,4 +1,5 @@
4.1
* Add a virtual table for exposing prepared statements metrics (CASSANDRA-17224)
* Remove python 2.x support from cqlsh (CASSANDRA-17242)
* Prewarm role and credential caches to avoid timeouts at startup (CASSANDRA-16958)
* Make capacity/validity/updateinterval/activeupdate for Auth Caches configurable via nodetool (CASSANDRA-17063)

18
doc/modules/cassandra/pages/new/virtualtables.adoc
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@ -74,6 +74,8 @@ recent_hit_rate_per_second, recent_request_rate_per_second, request_count, and s
|coordinator_write_latency |Records counts, keyspace_name, table_name, max, median, and per_second for coordinator writes.
|cql_metrcs |Metrics specific to CQL prepared statement caching.
|disk_usage |Records disk usage including disk_space, keyspace_name, and table_name, sorted by system keyspaces.
|internode_inbound |Lists information about the inbound internode messaging.
@ -99,6 +101,7 @@ recent_hit_rate_per_second, recent_request_rate_per_second, request_count, and s
|thread_pools |Lists metrics for each thread pool.
|tombstones_per_read |Records counts, keyspace_name, tablek_name, max, and median for tombstones.
|===
We shall discuss some of the virtual tables in more detail next.
@ -170,6 +173,21 @@ counters | 26214400 | 0 | 0 | NaN |
(4 rows)
....
=== CQL metrics Virtual Table
The `cql_metrics` virtual table lists metrics specific to CQL prepared statement caching. A query on `cql_metrics` virtual table lists below metrics.
....
cqlsh> select * from system_views.cql_metrics ;
name | value
------------------------------+-------
prepared_statements_count | 0
prepared_statements_evicted | 0
prepared_statements_executed | 0
prepared_statements_ratio | 0
regular_statements_executed | 17
....
=== Settings Virtual Table
The `settings` table is rather useful and lists all the current

81
src/java/org/apache/cassandra/db/virtual/CQLMetricsTable.java Normal file
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@ -0,0 +1,81 @@
/*
* 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.cassandra.db.virtual;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.db.marshal.DoubleType;
import org.apache.cassandra.db.marshal.UTF8Type;
import org.apache.cassandra.dht.LocalPartitioner;
import org.apache.cassandra.metrics.CQLMetrics;
import org.apache.cassandra.schema.TableMetadata;
import org.apache.cassandra.cql3.QueryProcessor;
final class CQLMetricsTable extends AbstractVirtualTable
{
public static final String TABLE_NAME = "cql_metrics";
public static final String PREPARED_STATEMENTS_COUNT = "prepared_statements_count";
public static final String PREPARED_STATEMENTS_EVICTED = "prepared_statements_evicted";
public static final String PREPARED_STATEMENTS_EXECUTED = "prepared_statements_executed";
public static final String PREPARED_STATEMENTS_RATIO = "prepared_statements_ratio";
public static final String REGULAR_STATEMENTS_EXECUTED = "regular_statements_executed";
public static final String NAME_COL = "name";
public static final String VALUE_COL = "value";
private final CQLMetrics cqlMetrics;
CQLMetricsTable(String keyspace)
{
this(keyspace, QueryProcessor.metrics);
}
// For dependency injection
@VisibleForTesting
CQLMetricsTable(String keyspace, CQLMetrics cqlMetrics)
{
super(TableMetadata.builder(keyspace, TABLE_NAME)
.comment("Metrics specific to CQL prepared statement caching")
.kind(TableMetadata.Kind.VIRTUAL)
.partitioner(new LocalPartitioner(UTF8Type.instance))
.addPartitionKeyColumn(NAME_COL, UTF8Type.instance)
.addRegularColumn(VALUE_COL, DoubleType.instance)
.build());
this.cqlMetrics = cqlMetrics;
}
@Override
public DataSet data()
{
SimpleDataSet result = new SimpleDataSet(metadata());
addRow(result, PREPARED_STATEMENTS_COUNT, cqlMetrics.preparedStatementsCount.getValue());
addRow(result, PREPARED_STATEMENTS_EVICTED, cqlMetrics.preparedStatementsEvicted.getCount());
addRow(result, PREPARED_STATEMENTS_EXECUTED, cqlMetrics.preparedStatementsExecuted.getCount());
addRow(result, PREPARED_STATEMENTS_RATIO, cqlMetrics.preparedStatementsRatio.getValue());
addRow(result, REGULAR_STATEMENTS_EXECUTED, cqlMetrics.regularStatementsExecuted.getCount());
return result;
}
private void addRow(SimpleDataSet dataSet, String name, double value)
{
dataSet.row(name)
.column(VALUE_COL, value);
}
}

1
src/java/org/apache/cassandra/db/virtual/SystemViewsKeyspace.java
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@ -43,6 +43,7 @@ public final class SystemViewsKeyspace extends VirtualKeyspace
.add(new NetworkPermissionsCacheKeysTable(VIRTUAL_VIEWS))
.add(new PermissionsCacheKeysTable(VIRTUAL_VIEWS))
.add(new RolesCacheKeysTable(VIRTUAL_VIEWS))
.add(new CQLMetricsTable(VIRTUAL_VIEWS))
.build());
}
}

126
test/unit/org/apache/cassandra/db/virtual/CQLMetricsTableTest.java Normal file
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@ -0,0 +1,126 @@
/*
* 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.cassandra.db.virtual;
import java.util.concurrent.atomic.AtomicInteger;
import com.google.common.collect.ImmutableList;
import com.datastax.driver.core.PreparedStatement;
import com.datastax.driver.core.ResultSet;
import com.datastax.driver.core.Session;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
import org.junit.BeforeClass;
import org.apache.cassandra.cql3.CQLTester;
import org.apache.cassandra.cql3.QueryProcessor;
import org.apache.cassandra.metrics.CQLMetrics;
public class CQLMetricsTableTest extends CQLTester
{
private static final String KS_NAME = "vts";
@BeforeClass
public static void setUpClass()
{
CQLTester.setUpClass();
}
private void queryAndValidateMetrics(CQLMetrics expectedMetrics) throws Throwable
{
String getMetricsQuery = "SELECT * FROM " + KS_NAME + "." + CQLMetricsTable.TABLE_NAME;
ResultSet vtsRows = executeNet(getMetricsQuery);
assertEquals(2, vtsRows.getColumnDefinitions().size());
AtomicInteger rowCount = new AtomicInteger(0);
vtsRows.forEach(r -> {
final double metricValue = r.getDouble(CQLMetricsTable.VALUE_COL);
switch (r.getString(CQLMetricsTable.NAME_COL))
{
case CQLMetricsTable.PREPARED_STATEMENTS_COUNT:
assertEquals(expectedMetrics.preparedStatementsCount.getValue(), metricValue, 0);
break;
case CQLMetricsTable.PREPARED_STATEMENTS_EVICTED:
assertEquals(expectedMetrics.preparedStatementsEvicted.getCount(), metricValue, 0);
break;
case CQLMetricsTable.PREPARED_STATEMENTS_EXECUTED:
assertEquals(expectedMetrics.preparedStatementsExecuted.getCount(), metricValue, 0);
break;
case CQLMetricsTable.PREPARED_STATEMENTS_RATIO:
assertEquals(expectedMetrics.preparedStatementsRatio.getValue(), metricValue, 0.01);
break;
case CQLMetricsTable.REGULAR_STATEMENTS_EXECUTED:
assertEquals(expectedMetrics.regularStatementsExecuted.getCount(), metricValue, 0);
break;
}
rowCount.getAndIncrement();
});
assertEquals(5, rowCount.get());
}
@Test
public void testUsingPrepareStmts() throws Throwable
{
CQLMetricsTable table = new CQLMetricsTable(KS_NAME);
VirtualKeyspaceRegistry.instance.register(new VirtualKeyspace(KS_NAME, ImmutableList.of(table)));
String ks = createKeyspace("CREATE KEYSPACE %s WITH replication={ 'class' : 'SimpleStrategy', 'replication_factor' : 1 }");
String tbl = createTable(ks, "CREATE TABLE %s (id int PRIMARY KEY, cid int, val text)");
Session session = sessionNet();
String insertCQL = "INSERT INTO " + ks + "." + tbl + " (id, cid, val) VALUES (?, ?, ?)";
PreparedStatement preparedInsert = session.prepare(insertCQL);
String selectCQL = "Select * from " + ks + "." + tbl + " where id = ?";
PreparedStatement preparedSelect = session.prepare(selectCQL);
for (int i = 0; i < 10; i++)
{
session.execute(preparedInsert.bind(i, i, "value" + i));
session.execute(preparedSelect.bind(i));
}
queryAndValidateMetrics(QueryProcessor.metrics);
}
@Test
public void testUsingInjectedValues() throws Throwable
{
CQLMetrics cqlMetrics = new CQLMetrics();
CQLMetricsTable table = new CQLMetricsTable(KS_NAME, cqlMetrics);
VirtualKeyspaceRegistry.instance.register(new VirtualKeyspace(KS_NAME, ImmutableList.of(table)));
// With initial injected values
cqlMetrics.preparedStatementsExecuted.inc(50);
cqlMetrics.regularStatementsExecuted.inc(100);
cqlMetrics.preparedStatementsEvicted.inc(25);
queryAndValidateMetrics(cqlMetrics);
// Test again with updated values
cqlMetrics.preparedStatementsExecuted.inc(150);
cqlMetrics.regularStatementsExecuted.inc(200);
cqlMetrics.preparedStatementsEvicted.inc(50);
queryAndValidateMetrics(cqlMetrics);
}
}