Difference between revisions of "Database backends"

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Minetest supports serveral database backends. This page provides a comparison of all three backends.
+
{{Languages}}
 +
Luanti supports several database backends. This page provides a comparison of all backends.
  
−
The database backend is set using the <code>backend</code> setting in ''world.mt''.
+
There are four database backends in Luanti (since 5.6.0):
  
−
If you want to migrate a world to a new backend use <code>minetestserver --migrate [name of new backend] --world [path to your world directory]</code>
+
* Map
−
= Comparison table =
+
* Players
 +
* Authentication
 +
* Mod Storage
  
−
{| class="wikitable sortable" style="text-align: left; font-size: smaller"
+
== Map backend ==
 +
 
 +
The database backend is set using the <code>backend</code> setting in ''world.mt''. Put the name of the backend in lowercase as the value of the setting (e.g. <code>backend=sqlite3</code> for SQLite3).
 +
 
 +
If you want to migrate a world map to a new backend, use <code>minetestserver --migrate <name of new backend> --world <path to your world directory></code>. It will automatically update world.mt to reflect the new backend.
 +
 
 +
If using a client build, server instructions can be given using "<code>minetest --server</code>", e.g. <code>minetest --server --migrate <name of new backend> --world <path to your world directory></code>.
 +
 
 +
== Player backend ==
 +
 
 +
The database backend is set using the <code>player_backend</code> setting in ''world.mt''. If it doesn't exist, the default is ''files''.
 +
 
 +
If you want to migrate players to a new backend, use <code>minetestserver --migrate-players <name of new backend> --world <path to your world directory></code>. It will automatically update world.mt to reflect the new backend.
 +
 
 +
== Authentication backend ==
 +
 
 +
The database backend is set using the <code>auth_backend</code> setting in ''world.mt''. If it doesn't exist, the default is ''files''.
 +
 
 +
If you want to migrate the authentication data to a new backend, use <code>minetestserver --migrate-auth <name of new backend> --world <path to your world directory></code>. It will automatically update world.mt to reflect the new backend.
 +
 
 +
== Mod Storage backend ==
 +
The database backend is set using the <code>mod_storage_backend</code> setting in ''world.mt''. If it doesn't exist, the default is ''files''.
 +
 
 +
If you want to migrate mod storage to a new backend, use <code>minetestserver --migrate-mod-storage <name of new backend> --world <path to your world directory></code>. It will automatically update world.mt to reflect the new backend.
 +
 
 +
 
 +
== Comparison table ==
 +
This table is a rough estimate of what you may expect from each database backend in terms of speed, reliability and compatibility. It is elaborated on in each section, and your mileage may vary.
 +
 
 +
{| class="wikitable" style="text-align: left; font-size: smaller"
 
|-
 
|-
 
! Backend
 
! Backend
Line 12: Line 44:
 
! Reliability
 
! Reliability
 
! Compatibility with builds
 
! Compatibility with builds
 +
! Map
 +
! Players
 +
! Authentication
 +
! Mod Storage
 
|-
 
|-
 
| SQLite3
 
| SQLite3
−
| style="background-color: #F99;" |
 
−
'''Acceptable'''
 
−
| style="background-color: #FFB;" |
 
−
'''Acceptable''' ''(db can corrupt if accessed while open)''
 
 
| style="background-color: #9F9;" |
 
| style="background-color: #9F9;" |
−
'''Very good''' ''(supported by any Minetest version)''
+
'''Good'''
 +
| style="background-color: #9F9;" |
 +
'''Good'''
 +
| style="background-color: #9EF;" |
 +
'''Very good''' ''(always supported)''
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔ (5.5.0+)
 
|-
 
|-
 
| LevelDB
 
| LevelDB
−
| style="background-color: #FFB;" |
 
−
'''Good'''
 
 
| style="background-color: #9F9;" |
 
| style="background-color: #9F9;" |
 
'''Good'''
 
'''Good'''
 +
| style="background-color: #FAA;" |
 +
'''Bad'''
 
| style="background-color: #FFB;" |
 
| style="background-color: #FFB;" |
−
'''Usually supported'''
+
'''Mostly supported'''
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| |
 
|-
 
|-
 
| Redis
 
| Redis
−
| style="background-color: #9F9;" |
+
| style="background-color: #9EF;" |
−
'''Very good''' ''(data always kept in RAM)''
+
'''Very good''' ''(data kept in RAM)''
 
| style="background-color: #9F9;" |
 
| style="background-color: #9F9;" |
 
'''Good'''
 
'''Good'''
−
| style="background-color: #F99;" |
+
| style="background-color: #FFB;" |
−
'''None''' ''(needs redis server)''
+
'''Inconvenient''' ''(Redis server required)''
 +
| style="text-align: center" | ✔
 +
| |
 +
| |
 +
| |
 +
|-
 +
| PostgreSQL
 +
| style="background-color: #9EF;" |
 +
'''Very good''' ''(most used data are in memory, others from disk)''
 +
| style="background-color: #9EF;" |
 +
'''Very good'''
 +
| style="background-color: #FFB;" |
 +
'''Inconvenient''' ''(PostgreSQL server required)''
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔ (5.7.0+) ''([https://niklp.net/posts/minetest-postgresql-benchmark/ very slow])``
 
|-
 
|-
 
| Dummy
 
| Dummy
−
| style="background-color: #9F9;" |
+
|  |
−
'''Very good''' ''(data always kept in RAM)''
+
'''N/A'''
−
| style="background-color: #F99;" |
+
|  |
−
'''None''' ''(nothing is actually saved)''
+
'''N/A'''
−
| style="background-color: #F99;" |
+
|  |
−
'''None''' ''(nothing is actually saved)''
+
'''N/A'''
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| |
 +
| |
 +
|-
 +
| Files (deprecated)
 +
| style="background-color: #FAA;" |
 +
'''Bad'''
 +
| style="background-color: #FAA;" |
 +
'''Bad'''
 +
| style="background-color: #FDA;" |
 +
'''Deprecated''' ''(support may be removed)''
 +
| style="text-align: center" |
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
| style="text-align: center" | ✔
 +
|}
 +
 
 +
The ''Compatibility with builds'' column is only relevant if you want to distribute the worlds.
 +
 
 +
=== SQLite3 ===
 +
SQLite3 is the default backend for all Luanti backends, it is supported by every Luanti build and is therefore the standard database format that is used to distribute worlds.
 +
 
 +
It has decent speeds, good reliability and works out of the box without configuration making it perfect for singleplayer worlds and small servers.
 +
 
 +
=== LevelDB ===
 +
LevelDB offers better speeds and also compression for smaller filesizes compared to SQLite, but LevelDB as a database suffers from serious reliability issues that are well known both inside and outside of Luanti <ref>[https://lazyjminetest.blogspot.com/2014/09/avoiding-leveldb-in-minetest-for-now.html Avoiding LevelDB in Minetest for now]</ref><ref>[https://github.com/google/leveldb/issues?utf8=%E2%9C%93&q=corrupt+is%3Aissue Issues · google/leveldb · GitHub]</ref><ref>[https://bugs.chromium.org/p/chromium/issues/detail?id=261623 Unrecoverable corruption in Chromium]</ref><ref>[https://forum.syncthing.net/t/panic-leveldb-table-corruption-on-data-block/2526/23 Corruption in syncthing]</ref><ref>[https://github.com/google/leveldb/issues/333 Corruption after power loss]</ref><ref>[http://ethereum.stackexchange.com/questions/1159/corruption-on-data-block-while-synchronising Corruption in Ethereum]</ref><ref>[https://bitcointalk.org/index.php?topic=1394020.0 LevelDB reliability?]</ref><ref>[https://stackoverflow.com/questions/40675204/does-leveldb-still-corrupt-data Does LevelDB still corrupt data?]</ref>. Random corruption may occur including to but not limited to during powerloss or any other unexpected shutdown where the database is not safely closed. It should be used with caution.
 +
 
 +
LevelDB support is included in the official Windows builds and most Linux builds.
 +
 
 +
=== Redis ===
 +
Redis support for the map backend was added to Luanti in April 2014, Redis is mainly useful for servers as it allows multiple worlds to be stored in one Redis instance. You need to install it additionally (''libhiredis'' library) and Luanti needs to compiled with support for it.
 +
 
 +
Information about setting up a Redis server can be found here: https://redis.io/topics/quickstart
 +
 
 +
==== world.mt settings for Redis ====
 +
* <code>redis_address</code> '''--''' The IP or hostname of the redis server.
 +
* <code>redis_port</code> '''--''' The port of the redis server. ''Optional, default: 6379''
 +
* <code>redis_hash</code> '''--''' Hash where the MapBlocks are stored in, if you want multiple worlds in one redis instance this needs to be different for each world. If you don't need that you can use e.g. <code>IGNORED</code>.
 +
 
 +
=== PostgreSQL ===
 +
PostgreSQL support was added to Luanti in May 2016, it's mainly useful for servers as it allows multiple worlds in a single instance, in multiple databases.
 +
 
 +
PostgreSQL is an excellent alternative to Redis. It doesn't store all data in memory, only recent and frequent data is loaded into memory. All data is on disk storage and data storage is very robust. You can also easily interface a website in front of your database to offer a frontend to your users.
 +
 
 +
While we support older versions, it is recommended to use PostgreSQL 9.5 at least for UPSERT functionality.
 +
 
 +
To improve PostgreSQL's performance with Luanti servers, please configure <code>postgresql.conf</code> with a minimum <code>shared_buffer</code> of 512MB, with a maximum of 50% of your server's available RAM.
 +
 
 +
==== world.mt for PostgreSQL ====
 +
* <code>pgsql_connection</code> '''--''' PostgreSQL connection string for world map | ''host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>''
 +
* <code>pgsql_player_connection</code> '''--''' PostgreSQL connection string for players | ''host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>''
 +
* <code>pgsql_auth_connection</code> '''--''' PostgreSQL connection string for auth | ''host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>''
 +
* <code>pgsql_mod_storage_connection</code> '''--''' PostgreSQL connection string for mod storage | ''host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>''
 +
 
 +
=== MariaDB ===
 +
MariaDB support is currently pending [https://github.com/minetest/minetest/pull/13266 (see PR #13266)]. It allows about the same capabilities as PostgreSQL.
 +
 
 +
To use the MariaDB database backend, the MariaDB C++ connector is required which usually is not part of the MariaDB package. You can find the [https://github.com/mariadb-corporation/mariadb-connector-cpp source code for it here].
 +
 
 +
=== Dummy ===
 +
A dummy database backend, which stores all MapBlocks in RAM without saving them. This means, as soon the server shuts down or you leave in singleplayer, all changes made to the world are lost. When you re-join, the world will be re-generated from scratch.
 +
 
 +
This backend is used by servers which don't need a persistent map, such as Capture the Flag. It can also be useful for development when testing map generation capabilities.
  
−
|}
+
=== Files ===
 +
A legacy backend for player and authentification data. Everything is stored in plaintext files. It's slow, unreliable and clunky. Use of this backend is discouraged now and it's possible this backend will be removed in the future.
  
−
== SQLite3 ==
+
For mod storage, Files uses the legacy JSON-based storage method as opposed to a regular database system. It is slower and will keep the entire mod storage data in memory.
−
SQLite3 is the default backend for all Minetest worlds, it is supported by every Minetest builds and is therefore the standard database format that is used to distribute worlds.  
 
−
== LevelDB ==
 
−
LevelDB is mostly used on servers because of it's improved reliability and the ability to use more than 4GB space.
 
−
== Redis ==
 
−
Redis support was added to Minetest in April 2014, redis is mainly useful for servers as it allows multiple worlds to be stored in one redis instance:
 
−
=== world.mt settings for redis ===
 
−
<code>redis_address</code> '''--''' The IP or hostname of the redis server.
 
  
−
<code>redis_port</code> '''--''' The port of the redis server. ''Optional, default: 6379''
+
== References ==
  
−
<code>redis_hash</code> '''--''' Hash where the MapBlocks are stored in, if you want multiple worlds in one redis instance this needs to be different for each world.
+
[[Category:Server]]
−
== Dummy ==
+
[[Category:Map]]
−
A dummy database backend.
 

Latest revision as of 23:40, 22 October 2024

Languages Language: English • français

Luanti supports several database backends. This page provides a comparison of all backends.

There are four database backends in Luanti (since 5.6.0):

  • Map
  • Players
  • Authentication
  • Mod Storage

Map backend

The database backend is set using the backend setting in world.mt. Put the name of the backend in lowercase as the value of the setting (e.g. backend=sqlite3 for SQLite3).

If you want to migrate a world map to a new backend, use minetestserver --migrate <name of new backend> --world <path to your world directory>. It will automatically update world.mt to reflect the new backend.

If using a client build, server instructions can be given using "minetest --server", e.g. minetest --server --migrate <name of new backend> --world <path to your world directory>.

Player backend

The database backend is set using the player_backend setting in world.mt. If it doesn't exist, the default is files.

If you want to migrate players to a new backend, use minetestserver --migrate-players <name of new backend> --world <path to your world directory>. It will automatically update world.mt to reflect the new backend.

Authentication backend

The database backend is set using the auth_backend setting in world.mt. If it doesn't exist, the default is files.

If you want to migrate the authentication data to a new backend, use minetestserver --migrate-auth <name of new backend> --world <path to your world directory>. It will automatically update world.mt to reflect the new backend.

Mod Storage backend

The database backend is set using the mod_storage_backend setting in world.mt. If it doesn't exist, the default is files.

If you want to migrate mod storage to a new backend, use minetestserver --migrate-mod-storage <name of new backend> --world <path to your world directory>. It will automatically update world.mt to reflect the new backend.


Comparison table

This table is a rough estimate of what you may expect from each database backend in terms of speed, reliability and compatibility. It is elaborated on in each section, and your mileage may vary.

Backend Speed Reliability Compatibility with builds Map Players Authentication Mod Storage
SQLite3

Good

Good

Very good (always supported)

✔ ✔ ✔ ✔ (5.5.0+)
LevelDB

Good

Bad

Mostly supported

✔ ✔ ✔
Redis

Very good (data kept in RAM)

Good

Inconvenient (Redis server required)

✔
PostgreSQL

Very good (most used data are in memory, others from disk)

Very good

Inconvenient (PostgreSQL server required)

✔ ✔ ✔ ✔ (5.7.0+) (very slow)``
Dummy

N/A

N/A

N/A

✔ ✔
Files (deprecated)

Bad

Bad

Deprecated (support may be removed)

✔ ✔ ✔

The Compatibility with builds column is only relevant if you want to distribute the worlds.

SQLite3

SQLite3 is the default backend for all Luanti backends, it is supported by every Luanti build and is therefore the standard database format that is used to distribute worlds.

It has decent speeds, good reliability and works out of the box without configuration making it perfect for singleplayer worlds and small servers.

LevelDB

LevelDB offers better speeds and also compression for smaller filesizes compared to SQLite, but LevelDB as a database suffers from serious reliability issues that are well known both inside and outside of Luanti [1][2][3][4][5][6][7][8]. Random corruption may occur including to but not limited to during powerloss or any other unexpected shutdown where the database is not safely closed. It should be used with caution.

LevelDB support is included in the official Windows builds and most Linux builds.

Redis

Redis support for the map backend was added to Luanti in April 2014, Redis is mainly useful for servers as it allows multiple worlds to be stored in one Redis instance. You need to install it additionally (libhiredis library) and Luanti needs to compiled with support for it.

Information about setting up a Redis server can be found here: https://redis.io/topics/quickstart

world.mt settings for Redis

  • redis_address -- The IP or hostname of the redis server.
  • redis_port -- The port of the redis server. Optional, default: 6379
  • redis_hash -- Hash where the MapBlocks are stored in, if you want multiple worlds in one redis instance this needs to be different for each world. If you don't need that you can use e.g. IGNORED.

PostgreSQL

PostgreSQL support was added to Luanti in May 2016, it's mainly useful for servers as it allows multiple worlds in a single instance, in multiple databases.

PostgreSQL is an excellent alternative to Redis. It doesn't store all data in memory, only recent and frequent data is loaded into memory. All data is on disk storage and data storage is very robust. You can also easily interface a website in front of your database to offer a frontend to your users.

While we support older versions, it is recommended to use PostgreSQL 9.5 at least for UPSERT functionality.

To improve PostgreSQL's performance with Luanti servers, please configure postgresql.conf with a minimum shared_buffer of 512MB, with a maximum of 50% of your server's available RAM.

world.mt for PostgreSQL

  • pgsql_connection -- PostgreSQL connection string for world map | host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>
  • pgsql_player_connection -- PostgreSQL connection string for players | host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>
  • pgsql_auth_connection -- PostgreSQL connection string for auth | host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>
  • pgsql_mod_storage_connection -- PostgreSQL connection string for mod storage | host=<db_host> user=<db_user> password=<db_password> dbname=<db_name>

MariaDB

MariaDB support is currently pending (see PR #13266). It allows about the same capabilities as PostgreSQL.

To use the MariaDB database backend, the MariaDB C++ connector is required which usually is not part of the MariaDB package. You can find the source code for it here.

Dummy

A dummy database backend, which stores all MapBlocks in RAM without saving them. This means, as soon the server shuts down or you leave in singleplayer, all changes made to the world are lost. When you re-join, the world will be re-generated from scratch.

This backend is used by servers which don't need a persistent map, such as Capture the Flag. It can also be useful for development when testing map generation capabilities.

Files

A legacy backend for player and authentification data. Everything is stored in plaintext files. It's slow, unreliable and clunky. Use of this backend is discouraged now and it's possible this backend will be removed in the future.

For mod storage, Files uses the legacy JSON-based storage method as opposed to a regular database system. It is slower and will keep the entire mod storage data in memory.

References

  1. ↑ Avoiding LevelDB in Minetest for now
  2. ↑ Issues · google/leveldb · GitHub
  3. ↑ Unrecoverable corruption in Chromium
  4. ↑ Corruption in syncthing
  5. ↑ Corruption after power loss
  6. ↑ Corruption in Ethereum
  7. ↑ LevelDB reliability?
  8. ↑ Does LevelDB still corrupt data?
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