diff options
author | Pierre Schmitz <pierre@archlinux.de> | 2011-06-22 11:28:20 +0200 |
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committer | Pierre Schmitz <pierre@archlinux.de> | 2011-06-22 11:28:20 +0200 |
commit | 9db190c7e736ec8d063187d4241b59feaf7dc2d1 (patch) | |
tree | 46d1a0dee7febef5c2d57a9f7b972be16a163b3d /docs/databases | |
parent | 78677c7bbdcc9739f6c10c75935898a20e1acd9e (diff) |
update to MediaWiki 1.17.0
Diffstat (limited to 'docs/databases')
-rw-r--r-- | docs/databases/ibm_db2.txt | 3 | ||||
-rw-r--r-- | docs/databases/postgres.txt | 100 | ||||
-rw-r--r-- | docs/databases/sqlite.txt | 12 |
3 files changed, 115 insertions, 0 deletions
diff --git a/docs/databases/ibm_db2.txt b/docs/databases/ibm_db2.txt new file mode 100644 index 00000000..3c3f381c --- /dev/null +++ b/docs/databases/ibm_db2.txt @@ -0,0 +1,3 @@ +== See also == +*[http://www.mediawiki.org/wiki/Manual:IBM_DB2 Installation instructions] +*[http://ca.php.net/manual/en/function.db2-connect.php PHP Manual for DB2 functions]
\ No newline at end of file diff --git a/docs/databases/postgres.txt b/docs/databases/postgres.txt new file mode 100644 index 00000000..cec51861 --- /dev/null +++ b/docs/databases/postgres.txt @@ -0,0 +1,100 @@ +This document describes the state of Postgres support in MediaWiki. + + +== Overview == + +Support for PostgreSQL has been available since version 1.7 +of MediaWiki, and is fairly well maintained. The main code +is very well integrated, while extensions are very hit and miss. +Still, it is probably the most supported database after MySQL. +Much of the work in making MediaWiki database-agnostic came +about through the work of creating Postgres support. + + +== Required versions == + +The current minimum version of PostgreSQL for MediaWiki is 8.1. +It is expected that this will be raised to 8.3 at some point, +as 8.1 and 8.2 are nearing end of life. + + + +== Database schema == + +Postgres has its own schema file at maintenance/postgres/tables.sql. + +The goal is to keep this file as close as possible to the canonical +schema at maintenance/tables.sql, but without copying over +all the usage comments. General notes on the conversion: + +* The use of a true TIMESTAMP rather than the text string that +MySQL uses is highly encouraged. There are still places in the +code (especially extensions) which make assumptions about the +textual nature of timestamp fields, but these can almost always +be programmed around. + +* Although Postgres has a true BOOLEAN type, boolean columns +are always mapped to SMALLINT, as the code does not always treat +the column as a boolean (which is limited to accepting true, +false, 0, 1, t, or f) + +* The default data type for all VARCHAR, CHAR, and VARBINARY +columns should simply be TEXT. The only exception is +when VARBINARY is used to store true binary data, such as +the math_inputhash column, in which case BYTEA should be used. + +* All integer variants should generally be mapped to INTEGER. +There is small-to-no advantage in using SMALLINT versus +INTEGER in Postgres, and the possibility of running out of +room outweighs such concerns. The columns that are BIGINT +in other schemas should be INTEGER as well, as none of them +so far are even remotely likely to reach the 32 billion +limit of an INTEGER. + +* Blobs (blob, tinyblog, mediumblob) should be mapped to TEXT +whenever possible, and to BYTEA if they are known to contain +binary data. + +* All length modifiers on data types should be removed. If +they are on an INTEGER, it's probably an error, and if on +any text-based field, simply using TEXT is preferred. + +* Sequences should be explicitly named rather than using +SERIAL, as the code can depend on having a specific name. + +* Foreign keys should be used when possible. This makes things +both easier and harder in the code, but most of the major +problems have now been overcome. Always add an explicit ON DELETE +clause, and consider carefully what choice to use (all things +considered, prefer CASCADE). + +* The use of CIDR should be done very carefully, because the code +will sometimes want to store things such as an empty string or +other non-IP value in the column. When in doubt, use TEXT. + +* Indexes should be created using the original MySQL tables.sql +as a guide, but keeping in mind the ability of Postgres to use +partial indexes, functional indexes, and bitmaps. The index names +should be logical but are not too important, as they are never +referenced directly by the code (unlike sequence names). Most of +the indexes in the file as of this writing are there due to production +testing of expensive queries on a busy wiki. + + +== Keeping in sync with tables.sql == + +The script maintenance/postgres/compare_schemas.pl should be +periodically run. It will parse both "tables.sql" files and +produce any differences found. Such differences should be fixed +or exceptions specifically carved out by editing the script +itself. This script has also been very useful in finding problems +in maintenance/tables.sql itself, as it is very strict in the +format it expects things to be in. :) + + +== Getting help == + +In addition to the normal venues (MediaWiki mailing lists +and IRC channels), the #postgresql channel on irc.freenode.net +is a friendly and expert resource if you should encounter a +problem with your Postgres-enabled MediaWiki. diff --git a/docs/databases/sqlite.txt b/docs/databases/sqlite.txt new file mode 100644 index 00000000..b8a45553 --- /dev/null +++ b/docs/databases/sqlite.txt @@ -0,0 +1,12 @@ +SQLite shares the MySQL schema file at maintenance/tables.sql, with a set of +compatibility regexes to convert MySQL syntax to SQLite syntax: + +* BINARY() and VARBINARY() fields are converted to BLOB +* the UNSIGNED modifier is removed +* "INT" fields are converted to "INTEGER" +* ENUM is converted to BLOB +* the BINARY collation modifier is removed +* AUTO_INCREMENT is converted to AUTOINCREMENT +* Any table options are removed +* Truncated indexes are upgraded to full-width indexes +* FULLTEXT indexes are converted to ordinary indexes |