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TokuDB introduction

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 TokuDB version changes.

TokuDB is a highly scalable, zero-maintenance downtime MySQL storage engine that delivers indexing-based query acceleration, improved replication performance, unparalleled compression, and live schema modification. The TokuDB storage engine is a scalable, ACID and MVCC compliant storage engine that provides indexing-based query improvements, offers online schema modifications, and reduces replica lag for both hard disk drives and flash memory. This storage engine is specifically designed for high performance on write-intensive workloads which is achieved with Fractal Tree indexing.

Percona Server for MySQL is compatible with the separately available TokuDB storage engine package. The TokuDB engine must be separately downloaded and then enabled as a plug-in component. This package can be installed alongside with standard Percona Server for MySQL releases and does not require any specially adapted version of Percona Server for MySQL.


Only the Percona supplied TokuDB engine should be used with Percona Server for MySQL. A TokuDB engine downloadedfrom other sources is not compatible. TokuDB file formats are not the same across MySQL variants. Migrating from one variant to any other variant requires a logical data dump and reload.

Additional features unique to TokuDB include:

  • Up to 25x Data Compression

  • Fast Inserts

  • Eliminates Replica Lag with Read Free Replication

  • Hot Schema Changes

  • Hot Index Creation - TokuDB tables support insertions, deletions and queries with no down time while indexes are being added to that table

  • Hot column addition, deletion, expansion, and rename - TokuDB tables support insertions, deletions and queries without down-time when an alter table adds, deletes, expands, or renames columns

  • On-line Backup


The TokuDB storage engine does not support the nowait and skip locked modifiers introduced in the InnoDB storage engine with MySQL 8.0.

For more information on installing and using TokuDB click on the following links:

Getting the Most from TokuDB


*TokuDB* compresses all data on disk, including indexes. Compression
lowers cost by reducing the amount of storage required and frees up disk
space for additional indexes to achieve improved query performance. Depending
on the compressibility of the data, we have seen compression ratios up to 25x
for high compression. Compression can also lead to improved performance since
less data needs to be read from and written to disk.

Fast Insertions and Deletions

TokuDB’s Fractal Tree technology enables fast
indexed insertions and deletions. Fractal Trees match B-trees in their
indexing sweet spot (sequential data) and are up to two orders of magnitude
faster for random data with high cardinality.

Eliminates Replica Lag

*TokuDB* replication replicas can be configured to process
the replication stream with virtually no read IO. Uniqueness checking is
performed on the *TokuDB* source and can be skipped on all *TokuDB*
replica. Also, row based replication ensures that all before and after row
images are captured in the binary logs, so the *TokuDB* replicas can harness
the power of Fractal Tree indexes and bypass traditional read-modify-write
behavior. This “Read Free Replication” ensures that replication replicas do not
fall behind the source and can be used for read scaling, backups, and
disaster recovery, without sharding, expensive hardware, or limits on what
can be replicated.

Hot Index Creation

*TokuDB* allows the addition of indexes to an existing table
while inserts and queries are being performed on that table. This means that
*MySQL* can be run continuously with no blocking of queries or insertions
while indexes are added and eliminates the down-time that index changes would
otherwise require.

Hot Column Addition, Deletion, Expansion and Rename

*TokuDB* allows the addition
of new columns to an existing table, the deletion of existing columns from an
existing table, the expansion of `char`, `varchar`, `varbinary`, and
`integer` type columns in an existing table, and the renaming of an
existing column while inserts and queries are being performed on that table.

Online (Hot) Backup

The *TokuDB* can create backups of online database servers without downtime.

Fast Indexing

In practice, slow indexing often leads users to choose a smaller
number of sub-optimal indexes in order to keep up with incoming data
rates. These sub-optimal indexes result in disproportionately slower queries,
since the difference in speed between a query with an index and the same
query when no index is available can be many orders of magnitude. Thus, fast
indexing means fast queries.

Clustering Keys and Other Indexing Improvements

*TokuDB* tables are clustered on
the primary key. *TokuDB* also supports clustering secondary keys, providing
better performance on a broader range of queries. A clustering key includes
(or clusters) all of the columns in a table along with the key. As a result,
one can efficiently retrieve any column when doing a range query on a
clustering key. Also, with *TokuDB*, an auto-increment column can be used in
any index and in any position within an index. Lastly, *TokuDB* indexes can
include up to 32 columns.

Less Aging/Fragmentation

*TokuDB* can run much longer, likely indefinitely,
without the need to perform the customary practice of dump/reload or
`OPTIMIZE TABLE` to restore database performance. The key is the
fundamental difference with which the Fractal Tree stores data on
disk. Since, by default, the Fractal Tree will store data in 4MB chunks
(pre-compression), as compared to InnoDB’s 16KB, *TokuDB* has the ability to
avoid “database disorder” up to 250x better than InnoDB.

Bulk Loader

*TokuDB* uses a parallel loader to create tables and offline
indexes. This parallel loader will use multiple cores for fast offline table
and index creation.

Full-Featured Database

*TokuDB* supports fully ACID-compliant transactions, MVCC
(Multi-Version Concurrency Control), serialized isolation levels, row-level
locking, and XA. *TokuDB* scales with high number of client connections, even
for large tables.

Lock Diagnostics

*TokuDB* provides users with the tools to diagnose locking and
deadlock issues. For more information, see [Lock Visualization in TokuDB](

Progress Tracking

Running `SHOW PROCESSLIST` when adding indexes provides
status on how many rows have been processed. Running `SHOW PROCESSLIST`
also shows progress on queries, as well as insertions, deletions and
updates. This information is helpful for estimating how long operations will
take to complete.

Fast Recovery

*TokuDB* supports very fast recovery, typically less than a minute.

Get expert help

If you need assistance, visit the community forum for comprehensive and free database knowledge, or contact our Percona Database Experts for professional support and services.

Last update: 2024-03-22