Tarantool 3.7

Release date: 2026-04-12

Releases on GitHub: v. 3.7.0

The 3.7 release of Tarantool adds the following main product features and improvements for the Community and Enterprise editions:

Community Edition (CE)
- Multiple minor improvements and bug fixes.
Enterprise Edition (EE)
- Failover coordinator: safe SSL configuration.
- MemCS: dictionary encoding and lz4 compression.

[EE] Failover coordinator: safe SSL configuration

Tarantool failover coordinator now safely supports TLS-encrypted and mTLS-authenticated connections. SSL certificates and Certificate Authority can be configured via a dedicated failover-specific configuration section.

Previously, the coordinator relied on SSL parameters taken from instance URIs. In case of SSL + CA (mTLS), this approach might require the coordinator host to have access to private keys/certificates of the instances it connected to.

Now the failover.iproto.ssl configuration section is a source of SSL client parameters for outgoing net.box connections initiated by the coordinator. The parameters are injected into URI parameters passed to net.box.connect() only for URIs with params.transport: ssl, and do not affect non-SSL connections.

Example:

failover:
  mode: stateful
  iproto:
    listen:
      uri: '127.0.0.1:3302'
        params:
          transport: ssl
    ssl:
      ca_file: './certs/rootCA.pem'
      ssl_cert: './certs/coordinator.crt'
      ssl_key: './certs/coordinator.key'
      # Optional:
      # ssl_ciphers: 'ECDHE-RSA-AES256-GCM-SHA384:...'
      # ssl_password: 'secret'
      # ssl_password_file: './certs/key_passwords.txt'

[EE] MemCS: dictionary encoding and lz4 compression

This release brings two major memory utilization improvements in the MemCS engine:

Dictionary encoding for string columns (Arrow dictionary-encoded layout).
Column-level compression with the lz4 codec.

In typical workloads, using these features together provides an 8–13x reduction in memory footprint compared to uncompressed storage.

Dictionary encoding for string columns

MemCS can store string values in a dictionary-encoded form: unique strings are kept in a shared dictionary, while rows store integer IDs referencing dictionary entries. This is most effective for columns with many repeated values (for example, statuses, categories, event types).

Dictionary encoding is enabled via the layout option:

local s = box.schema.create_space('test', {
    engine = 'memcs', format = format, field_count = field_count,
})
local pk = s:create_index('pk', {layout = 'dict'})

Limitations and behavior

Only non-key string columns can use dictionary encoding. Other columns silently ignore layout = 'dict'.
Dictionary IDs are stored as uint16 (2 bytes per row).
The maximum number of unique values per dictionary-encoded column is UINT16_MAX (65536). When the dictionary is full, inserting a new unique value fails with an error.
Approximate memory usage for such a column is 2 * space_size + dict_size bytes.
Dictionary memory is included in space:bsize() statistics.
The implementation follows Apache Arrow dictionary-encoded layout, since Arrow is the standard interchange format for MemCS.

Важно

Currently the layout option can be specified only during the space creation. It’s not possible to change it for the existing space.

When reading via ArrowStream, MemCS always returns dictionary-encoded columns in Arrow dictionary-encoded layout:

the dictionary is returned as string-view
indices are uint16

Additional notes:

If no new unique values are inserted, all record batches share the same dictionary.
Dictionaries are returned by reference (no copying), so ArrowArray export has low overhead.
Dictionaries only grow (values are not removed), so after a dictionary update it remains compatible with batches produced with the previous dictionary.

LZ4 column compression

MemCS now supports column-level compression with lz4. Compression is applied to ranges of consecutive values, stored as compressed blocks.

Compression is configured per column in the space format using the compression attribute and can be enabled only at space creation time:

local format = {
    {'c1', 'uint64'},
    {'c2', 'string', is_nullable = true, compression = 'lz4'},
    {'c3', 'int32', compression = {type = 'lz4', acceleration = 1000}},
}
box.schema.create_space('test', {
    engine = 'memcs', field_count = #format, format = format,
})

Compression settings:

Algorithm: lz4
acceleration – LZ4-specific configuration parameter:
- allowed range: 1…65537
- recommended: 10…1000
- higher values improve compression and decompression speed, but reduce the compression ratio

Limitations

Only non-indexed columns can be compressed.
A column of any type supports compression, however «external» string values (strings longer than 12 characters) are currently not subject to compression.

Важно

Currently the compression attribute can be specified only during the space creation. It’s not possible to change it for the existing space.

Версия:

Tarantool 3.7

[EE] Failover coordinator: safe SSL configuration

[EE] MemCS: dictionary encoding and lz4 compression

Dictionary encoding for string columns

Limitations and behavior

LZ4 column compression

Limitations