# MyRocks Group Commit with Binary log

MyRocks supports group commit with the [binary log](https://mariadb.com/docs/server/server-management/server-monitoring-logs/binary-log) ([MDEV-11934](https://jira.mariadb.org/browse/MDEV-11934)).

## Counter Values to Watch

(The following is only necessary if you are studying MyRocks internals)

MariaDB's group commit counters are:

[Binlog\_commits](https://mariadb.com/docs/server/ha-and-performance/standard-replication/replication-and-binary-log-status-variables#binlog_commits) - how many transactions were written to the binary log

[Binlog\_group\_commits](https://mariadb.com/docs/server/ha-and-performance/standard-replication/replication-and-binary-log-status-variables#binlog_group_commits) - how many group commits happened. (e.g. if each group had two transactions, this is twice as small as [Binlog\_commits](https://mariadb.com/docs/server/ha-and-performance/standard-replication/replication-and-binary-log-status-variables#binlog_commits))

On the RocksDB side, there is one relevant counter:[Rocksdb\_wal\_synced](https://mariadb.com/docs/server/server-usage/storage-engines/myrocks-status-variables#rocksdb_wal_synced) - How many times RocksDB's WAL file was synced. (TODO: this is after group commit happened, right?)

## On the Value of rocksdb\_wal\_group\_syncs

FB/MySQL-5.6 has a [rocksdb\_wal\_group\_syncs](https://mariadb.com/docs/server/server-usage/storage-engines/myrocks-status-variables#rocksdb_wal_group_syncs) counter (The counter is provided by MyRocks, it is not a view of a RocksDB counter). It is increased in rocksdb\_flush\_wal() when doing the rdb->FlushWAL() call.

rocksdb\_flush\_wal() is called by MySQL's Group Commit when it wants to make the effect of several rocksdb\_prepare() calls persistent.

So, the value of [rocksdb\_wal\_group\_syncs](https://mariadb.com/docs/server/server-usage/storage-engines/myrocks-status-variables#rocksdb_wal_group_syncs) in FB/MySQL-5.6 is similar to [Binlog\_group\_commits](https://mariadb.com/docs/server/ha-and-performance/standard-replication/replication-and-binary-log-status-variables#binlog_group_commits) in MariaDB.

MariaDB doesn't have that call, each rocksdb\_prepare() call takes care of being persistent on its own.

Because of that, [rocksdb\_wal\_group\_syncs](https://mariadb.com/docs/server/server-usage/storage-engines/myrocks-status-variables#rocksdb_wal_group_syncs) is zero for MariaDB. (Currently, it is only incremented when the binlog is rotated).

## Examples

So for a workload with concurrency=50, n\_queries=10K, one gets

* Binlog\_commits=10K
* Binlog\_group\_commits=794
* Rocksdb\_wal\_synced=8362

This is on a RAM disk

For a workload with concurrency=50, n\_queries=10K, rotating laptop hdd, one gets

* Binlog\_commits= 10K
* Binlog\_group\_commits=1403
* Rocksdb\_wal\_synced=400

The test took 38 seconds, Number of syncs was 1400+400=1800, which gives 45 syncs/sec which looks normal for this slow rotating desktop hdd.

Note that the WAL was synced fewer times than there were binlog commit groups (?)

<sub>*This page is licensed: CC BY-SA / Gnu FDL*</sub>

{% @marketo/form formId="4316" %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://mariadb.com/docs/server/server-usage/storage-engines/myrocks/myrocks-and-group-commit-with-binary-log.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.