Get started with TokuDB¶

Starting with Percona Server for MySQL 8.0.28-19 (2022-05-12), the TokuDB storage engine is no longer supported. For more information, see the TokuDB Introduction and TokuDB version changes.

Operating Systems

TokuDB is currently supported on 64-bit Linux only.
Memory

TokuDB requires at least 1GB of main memory.

For the best results, run with at least 2GB of main memory.
Disk space and configuration

Make sure to allocate enough disk space for data, indexes and logs.

Due to high compression, TokuDB may achieve up to 25x space savings on dataand indexes over InnoDB.

Creating Tables and Loading Data¶

TokuDB tables are created the same way as other tables in MySQL by specifying ENGINE=TokuDB in the table definition. For example, the following command creates a table with a single column and uses the TokuDB storage engine to store its data:

mysql> CREATE TABLE table (
id INT(11) NOT NULL) ENGINE=TokuDB;

Loading data¶

Once TokuDB tables have been created, data can be inserted or loaded using standard MySQL insert or bulk load operations. For example, the following command loads data from a file into the table:

mysql> LOAD DATA INFILE file
INTO TABLE table;

Note

For more information about loading data, see the MySQL 8.0 reference manual.

Migrating Data from an Existing Database¶

Use the following command to convert an existing table for the TokuDB storage engine:

mysql> ALTER TABLE table
ENGINE=TokuDB;

Bulk Loading Data¶

The TokuDB bulk loader imports data much faster than regular MySQL with InnoDB. To make use of the loader you need flat files in either comma separated or tab separated format. The MySQL LOAD DATA INFILE statement will invoke the bulk loader if the table is empty. Keep in mind that while this is the most convenient and, in most cases, the fastest way to initialize a TokuDB table, it may not be replication safe if applied to the source.

To obtain the logical backup and then bulk load into TokuDB, follow these steps:

Create a logical backup of the original table. The easiest way to achieve this is using SELECT … INTO OUTFILE. Keep in mind that the file will be created on the server: SELECT \* FROM table INTO OUTFILE ‘file.csv’;
Copy the output file either to the destination server or the client machine from which you plan to load it.
Load the data into the server using LOAD DATA INFILE. If loading from a machine other than the server use the keyword LOCAL to point to the file on local machine. Keep in mind that you will need enough disk space on the temporary directory on the server since the local file will be copied onto the server by the MySQL client utility: LOAD DATA [LOCAL] INFILE ‘file.csv’;

It is possible to create the CSV file using either mysqldump or the MySQL client utility as well, in which case the resulting file will reside on a local directory. In these 2 cases you have to make sure to use the correct command line options to create a file compatible with LOAD DATA INFILE.

The bulk loader will use more space than normal for logs and temporary files while running, make sure that your file system has enough disk space to process your load. As a rule of thumb, it should be approximately 1.5 times the size of the raw data.

Note

Please read the original MySQL Documentation to understand the needed privileges and replication issues around LOAD DATA INFILE.

Considerations to Run TokuDB in Production¶

In most cases, the default options should be left in-place to run TokuDB, however it is a good idea to review some of the configuration parameters.

Memory allocation¶

TokuDB will allocate 50% of the installed RAM for its own cache (global variable tokudb_cache_size). While this is optimal in most situations, there are cases where it may lead to memory over allocation. If the system tries to allocate more memory than is available, the machine will begin swapping and run much slower than normal.

It is necessary to set the tokudb_cache_size to a value other than the default in the following cases:

Running other memory heavy processes on the same server as TokuDB

In many cases, the database process needs to share the system with other
server processes like additional database instances, http server, application
server, e-mail server, monitoring systems and others. In order to properly
configure TokuDB’s memory consumption, it’s important to understand how much
free memory will be left and assign a sensible value for *TokuDB*. There is
no fixed rule, but a conservative choice would be 50% of available RAM while
all the other processes are running. If the result is under 2 GB, you should
consider moving some of the other processes to a different system or using a
dedicated database server.

tokudb_cache_size is a static variable, so it needs to be set
before starting the server and cannot be changed while the server is
running. For example, to set up TokuDB’s cache to 4G, add the following line
to your `my.cnf` file:

```
tokudb_cache_size = 4G
```

System using InnoDB and TokuDB

When using both the *TokuDB* and *InnoDB* storage engines, you need to manage
the cache size for each. For example, on a server with 16 GB of RAM you could
use the following values in your configuration file:

```
innodb_buffer_pool_size = 2G
tokudb_cache_size = 8G
```

Using TokuDB with Federated or FederatedX tables

The Federated engine in *MySQL* and FederatedX in *MariaDB* allow you to
connect to a table on a remote server and query it as if it were a local
table (please see the MySQL Documentation: 14.11. The FEDERATED Storage
Engine for details). When accessing the remote table, these engines could
import the complete table contents to the local server to execute a query. In
this case, you will have to make sure that there is enough free memory on the
server to handle these remote tables. For example, if your remote table is 8
GB in size, the server has to have more than 8 GB of free RAM to process
queries against that table without going into swapping or causing a kernel
panic and crash the *MySQL* process. There are no parameters to limit the
amount of memory that the Federated or FederatedX engine will allocate while
importing the remote dataset.

Specifying the Location for Files¶

As with InnoDB, it is possible to specify different locations than the default for TokuDB’s data, log and temporary files. This way you may distribute the load and control the disk space. The following variables control file location:

tokudb_data_dir: This variable defines the directory where the TokuDB tables are stored. The default location for TokuDB’s data files is the MySQL data directory.
tokudb_log_dir: This variable defines the directory where the TokuDB log files are stored. The default location for TokuDB’s log files is the MySQL data directory. Configuring a separate log directory is somewhat involved and should be done only if absolutely necessary. We recommend to keep the data and log files under the same directory.
tokudb_tmp_dir: This variable defines the directory where the TokuDB bulk loader stores temporary files. The bulk loader can create large temporary files while it is loading a table, so putting these temporary files on a disk separate from the data directory can be useful. For example, it can make sense to use a high-performance disk for the data directory and a very inexpensive disk for the temporary directory. The default location for TokuDB’s temporary files is the MySQL data directory.

Table Maintenance¶

The fractal tree provides fast performance by inserting small messages in the buffers in the fractal trees instead of requiring a potential IO for an update on every row in the table as required by a B-tree. Additional background information on how fractal trees operate can be found here. For tables whose workload pattern is a high number of sequential deletes, it may be beneficial to flush these delete messages down to the basement nodes in order to allow for faster access. The way to perform this operation is via the OPTIMIZE command.

The following extensions to the OPTIMIZE command have been added in TokuDB version 7.5.5:

Hot Optimize Throttling¶

By default, table optimization will run with all available resources. To limit the amount of resources, it is possible to limit the speed of table optimization. The tokudb_optimize_throttle session variable determines an upper bound on how many fractal tree leaf nodes per second are optimized. The default is 0 (no upper bound) with a valid range of [0,1000000]. For example, to limit the table optimization to 1 leaf node per second, use the following setting: SET tokudb_optimize_throttle=1;

Optimize a Single Index of a Table¶

To optimize a single index in a table, the tokudb_optimize_index_name session variable can be set to select the index by name. For example, to optimize the primary key of a table:

mysql> SET tokudb_optimize_index_name='primary';
OPTIMIZE TABLE t;

Optimize a Subset of a Fractal Tree Index¶

For patterns where the left side of the tree has many deletions (a common pattern with increasing id or date values), it may be useful to delete a percentage of the tree. In this case, it is possible to optimize a subset of a fractal tree starting at the left side. The tokudb_optimize_index_fraction session variable controls the size of the sub tree. Valid values are in the range [0.0,1.0] with default 1.0 (optimize the whole tree). For example, to optimize the leftmost 10% of the primary key:

SET tokudb_optimize_index_name='primary';
SET tokudb_optimize_index_fraction=0.1;
OPTIMIZE TABLE t;

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Last update: 2024-11-15