Some thoughts on replication
От | Dirk Heinrichs |
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Тема | Some thoughts on replication |
Дата | |
Msg-id | 01012518451100.12641@linux обсуждение исходный текст |
Ответы |
Re: Some thoughts on replication
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Список | pgsql-admin |
Hi folks, Maybe this belongs to the developers mailing list, but I'm not subscribed to that list, so I post it here. I've read through todo list on the website, especially the planned replication feature. It seems to me that implementing replication into postgresql is a rather hard and longterm task. I want to show two possible alternatives, used in a real world application (a billing system based on Informix) I was involved in a few years ago. In our case we didn't need (or want) to replicate the whole database, but only a few tables. The first thing was to use synonym tables. In Infomix one can just type something like create synonym mysynonym for table mytable:somedb@somehost; where the somedb and somehost values are optional. It was then possible to work on the synonym as if it where a normal table. Later, we also did table replication based on triggers, a daemon and a configuration table. The tables which had to be replicated where entered in the config table, together with their destination. Then a little script was used to setup the apprpriate insert, update and delete triggers for those tables. When one of the triggers fired, the daemon contacted its friend on the other host and did the same action on the remote database. I think there was also a timestamp in the config table which had to be updated. I don't know more details anymore, but that was roughly the concept. Maybe one of those two (or both) is easier and faster to realise than database replication. Any comments? Bye... Dirk
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