Difference between revisions of "Database backends"
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| − | + | Luanti supports several database backends. This page provides a comparison of all backends. | |
| − | There are four database backends in | + | There are four database backends in Luanti (since 5.6.0): |
* Map | * Map | ||
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=== SQLite3 === | === SQLite3 === | ||
| − | SQLite3 is the default backend for all | + | 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. | 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 === | ||
| − | 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 | + | 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. | LevelDB support is included in the official Windows builds and most Linux builds. | ||
=== Redis === | === Redis === | ||
| − | Redis support for the map backend was added to | + | 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 | Information about setting up a Redis server can be found here: https://redis.io/topics/quickstart | ||
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=== PostgreSQL === | === PostgreSQL === | ||
| − | PostgreSQL support was added to | + | 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. | 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. | ||
| Line 151: | Line 151: | ||
While we support older versions, it is recommended to use PostgreSQL 9.5 at least for UPSERT functionality. | While we support older versions, it is recommended to use PostgreSQL 9.5 at least for UPSERT functionality. | ||
| − | To improve PostgreSQL's performance with | + | 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 ==== | ==== world.mt for PostgreSQL ==== | ||
Revision as of 23:40, 22 October 2024
 Language: |
English • français |
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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: 6379redis_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.