Re: [GENERAL] searching oid's
От | Adriaan Joubert |
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Тема | Re: [GENERAL] searching oid's |
Дата | |
Msg-id | 387E2319.2A11D310@albourne.com обсуждение исходный текст |
Ответ на | searching oid's (admin <admin@wtbwts.com>) |
Ответы |
Re: [GENERAL] searching oid's
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Список | pgsql-general |
> First, I tried searching tables by their oid, but explain returned > sequential scans. Second, I tried specifing the oid as the primary key in > a table, but the oid column wasn't found. Finally, I created an index for > oid which worked fine. In the end, I feel I'm back to square one having to > use the same index as with my char(32) id's. It seems my only gain would > be 28 bytes per row and no speed gain, apart perhaps for building the > index which should be a bit slower for a char(32) datatype rather than an > integer. Using oid's is not a good idea, as they don't automatically get dumped with pg_dump. And once your referential integrity gets screwed up and you are using oid's you are really in a mess, as you cannot change oids. Use a serial field to generate a key for every row, which generates you a sequence of integers. It is much better than oids at a cost of 4 bytes. As far as i have understood you need an index if you want to avoid a sequential scan as tuples are not stored in a hierarchy in the table. Only in indexes do you get b-trees etc. So define your serial field as a primary key and you are done. And comparing 4-byte ints is much faster than comparing 32-byte text fields, that's for sure. Adriaan
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