Re: column size too large, is this a bug?
От | Andrew Rawnsley |
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Тема | Re: column size too large, is this a bug? |
Дата | |
Msg-id | 1692C8F2-81A6-11D8-B278-000393A47FCC@ravensfield.com обсуждение исходный текст |
Ответ на | Re: column size too large, is this a bug? ("Jaime Casanova" <el_vigia_ec@hotmail.com>) |
Ответы |
Re: column size too large, is this a bug?
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Список | pgsql-performance |
Its a way of representing a tree with right-left pointers in each record (basically re-inventing a hierarchical database in a relational model...). A good description is in Joe Celko's SQL For Smarties book. Selection is very fast because any node's children have node ID's between the right and left nodes of said node, so there's no mucking about with connect by and what not. There's a synopsis linked at the PG Cookbook pages (http://www.brasileiro.net/postgres/cookbook), but the cookbook seems to off-line (I think I'll offer to mirror it - this happens frequently). There's another description at http://www.intelligententerprise.com/001020/celko.jhtml? _requestid=65750. Insertion takes a fair amount of work, as you generally have to re-arrange the node IDs when you add a record. On Mar 29, 2004, at 12:05 PM, Jaime Casanova wrote: > >> Andrew, > >> > I used to use the connect-by patch, but have since rewritten >> everything >> > to use a nested set model. > >> Cool! You're probably the only person I know other than me using >> nested sets >> in a production environment. > > > can you explain me what is a nested set? > > _________________________________________________________________ > Add photos to your messages with MSN 8. Get 2 months FREE*. > http://join.msn.com/?page=features/featuredemail > > > ---------------------------(end of > broadcast)--------------------------- > TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faqs/FAQ.html > -------------------- Andrew Rawnsley President The Ravensfield Digital Resource Group, Ltd. (740) 587-0114 www.ravensfield.com
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