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'''Tavi on !PostgreSQL 7.4''' ''Converting a Tavi 0.26 Wiki from !MySQL 4.1 to !PostgreSQL 7.4'' ---- This page documents the process of comverting a Tavi 0.26 Wiki running on !MySQL 4.1, to run on !PostgreSQL 7.4. It provides references to the previous works this process is based on, and to sources for the software required. ''Abstract'' Tavi is a PHP Wiki implementation running on a webserver. VEMS has been using Tavi for several years, however there have been ongoing problems with the !MySQL database backend that Tavi requires. The problems appear to be index related, and have not been repeatable (therefore fixable) but have been addressed by regular dump and reloads. This should not be necessary, so an alternative was sought. Tavi does not support databases other than !MySQL by default so conversion to another Wiki rather than another database was initially considered. It is important not to lose data in the process, so either conversion may have been difficult. Fortunately, there is a patch to provide !PostgreSQL support for Tavi 0.25, written by Juha-Mikko Ahonen and available from his website. Less fortunately, the performance when searching the database is not adequate (!PostgreSQL does not support text indexes by default) and it has not been updated to the current version of Tavi. The work by Ahonen was however a good place to start, so full credit must be given to him for the inspiration and initial patch. The work described below extends Ahonens patch, updating it for 0.26 compatibility, refining the queries, and increasing search speed by an order of magnitude by using the TSearch2 functionality by Oleg Bartunov and Teodor Sigaev. The stable release of TSearch2 is provided with the !PostgreSQL distribution. Links to the software mentioned above are at the end of this document. ''Aims'' * Provide a high performance alternative to the !MySQL 4.1 database. * Document the process of converting version 0.26 of Tavi to !PostgreSQL 7.4. * Document the process of converting the default Tavi installation to the customised VEMS Tavi installation. ''Prerequisites'' * Apache webserver (any version). * PHP 4 or 5 with !MySQL and !PostgreSQL support. * Tavi 0.26 sources. * !MySQL 4.1 database with Tavi data (if conversion of existing data is required). * !PostgreSQL 7.4 installation with TSearch2 available. * Shell access to run the conversion scripts. * Perl support may be required if no existing Tavi config.php is available. ---- ''The Conversion Process'' As VEMS is using Tavi 0.26 with Captcha, the first step is to update Juha-Mikko Ahonens !PostgreSQL port of Tavi from 0.25 to 0.26. Tavi 0.26 !MySQL to !PostgreSQL patch (un-optimised): [http://www.vems.hu/files/MembersPage/RichardBarrington/TaviPostgreSQL/tavi-0.26-postgresql.diff.gz tavi-0.26-postgresql.diff.gz] The next logical step is optimisation of the !PostgreSQL database queries, however to do this we need some test data loaded. So we'll change course and figure out how script the data transfer from !MySQL Tavi to !PostgreSQL Tavi. Fortunately, we're using !MySQL v4.1 which supports some useful options. To get a !PostgreSQL compatible data dump, we can run: {{```mysqldump -t --compatible=postgresql --skip-add-locks --skip-disable-keys --skip-extended-insert --default-character-set=latin1 -u$USERNAME -p$PASSWORD $DATABASE $TABLES >data.sql```}} This gives us an SQL data (only) script which can be run after we have created the Tavi schema in !PostgreSQL. Creating the basic Tavi schema is straight forward, and is again based on Juha-Mikko Ahonens work. The only change being to add a CHECK constraint to the mutable field of the pages table. Sample schema (VEMS efi_ table prefixes): [http://www.vems.hu/files/MembersPage/RichardBarrington/TaviPostgreSQL/tavi-postgresql-schema.sql.gz tavi-postgresql-schema.sql.gz] The !PostgeSQL user and database must be created, then we can import the data dumped from !MySQL: {{createuser -D -A -U $DBA -P $USERNAME}} {{createdb -U $DBA -O $USERNAME -E LATIN1 $DATABASE}} {{psql -q -U $USERNAME -f data.sql $DATABASE}} We can then apply the patch and copy Juha-Mikko Ahonens {{dbpg.php}} file into {{wiki/lib/}} path, and ensure that the line {{DBClass = 'dbpg';}} is in the Tavi {{config.php}} file. We now have a working Tavi 0.26 !PostgreSQL system, but there is still much work to be done! Text searching is ''extremely'' slow, as is retrieving the list of recent updates and orphaned pages, etc. ---- ''Software:'' Tavi Wiki: * http://tavi.sourceforge.net/ Apache HTTP server: * http://httpd.apache.org/ PHP engine: * http://www.php.net/ !MySQL database: * http://www.postgresql.org/ !PostgreSQL database: * http://www.postgresql.org/ Initial !PostgreSQL patch for Tavi: * http://tavi.sourceforge.net/TaviPatches/PostgreSQLSupport * http://jmz.iki.fi/download.php/en/Tavi+Patches TSearch2 full-text-index search engine for !PostgreSQL: * http://www.sai.msu.su/~megera/postgres/gist/tsearch/V2/
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