[GitHub] [cassandra] yifan-c commented on a change in pull request #404: New/fql

[GitBox <gi...@apache.org>]

yifan-c commented on a change in pull request #404: New/fql
URL: https://github.com/apache/cassandra/pull/404#discussion_r374925783
 
 

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 File path: doc/source/new/fqllogging.rst
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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.
+
+Full Query Logging
+------------------ 
+
+Apache Cassandra 4.0 adds a new feature to support a means of logging all queries as they were invoked (`CASSANDRA-13983
+<https://issues.apache.org/jira/browse/CASSANDRA-13983>`_). For correctness testing it's useful to be able to capture production traffic so that it can be replayed against both the old and new versions of Cassandra while comparing the results.
+
+Cassandra 4.0 includes an implementation of a full query logging (FQL) that uses chronicle-queue to implement a rotating log of queries. Some of the features of FQL are:
+
+- Single thread asynchronously writes log entries to disk to reduce impact on query latency
+- Heap memory usage bounded by a weighted queue with configurable maximum weight sitting in front of logging thread
+- If the weighted queue is full producers can be blocked or samples can be dropped
+- Disk utilization is bounded by deleting old log segments once a configurable size is reached
+- The on disk serialization uses a flexible schema binary format (chronicle-wire) making it easy to skip unrecognized fields, add new ones, and omit old ones.
+- Can be enabled and configured via JMX, disabled, and reset (delete on disk data), logging path is configurable via both JMX and YAML
+- Introduce new ``fqltool`` in ``/bin`` that currently implements ``Dump`` which can dump in a readable format full query logs as well as follow active full query logs. FQL ``Replay`` and ``Compare`` are also available.
+
+Cassandra 4.0 has a binary full query log based on Chronicle Queue that can be controlled using ``nodetool enablefullquerylog``, ``disablefullquerylog``, and ``resetfullquerylog``. The log contains all queries invoked, approximate time they were invoked, any parameters necessary to bind wildcard values, and all query options. A readable version of the log can be dumped or tailed using the new ``bin/fqltool`` utility. The full query log is designed to be safe to use in production and limits utilization of heap memory and disk space with limits you can specify when enabling the log.
+
+Objective
+^^^^^^^^^^ 
+Full Query Logging logs all requests to the CQL interface. The full query logs could be used for debugging, performance benchmarking, testing and auditing CQL queries. The audit logs also include CQL requests but full query logging is dedicated to CQL requests only with features such as FQL Replay and FQL Compare that are not available in audit logging.  
+
+Full Query Logger
+^^^^^^^^^^^^^^^^^^ 
+The Full Query Logger is a logger that logs entire query contents after the query finishes. FQL only logs the queries that successfully complete. The other queries (e.g. timed out, failed) are not to be logged. Queries are logged in one of two modes: single query or batch of queries. The log for an invocation of a batch of queries includes the following attributes:
+
+::
+
+ type - The type of the batch
+ queries - CQL text of the queries
+ values - Values to bind to as parameters for the queries
+ queryOptions - Options associated with the query invocation
+ queryState - Timestamp state associated with the query invocation
+ batchTimeMillis - Approximate time in milliseconds since the epoch since the batch was invoked
+ 
+ The log for single CQL query includes the following attributes:
 
 Review comment:
   Please remove the heading spaces so this line is not included in the code block

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