Re: R-Trees.
От | Tsirkin Evgeny |
---|---|
Тема | Re: R-Trees. |
Дата | |
Msg-id | 42105ADD.8090700@mail.jct.ac.il обсуждение исходный текст |
Ответ на | R-Trees. (Michael Wray <mwray@hecomm.org>) |
Список | pgsql-admin |
I don't think this is a postgres question it is perl one ,so you are in the wrong place .just as a hint look for a perl module that do what you want *i think perl::Text os something).Any way this is a wrong list . Evgeny Michael Wray wrote: >(Please CC me, if you reply as I am out of pocket now and not able to be on >mailing lists at this time...); > >I'm not sure which list I was reading, but I've been looking for info about >R-Trees, and stumbled across my favourite DB backend's mailing lists... > >I've used RTREE based db engines before (Informix) but was unaware of PostGres >and MySQL implementing RTREE capability until tonight. > >While I understand the basic concept of an RTREE. I would like to be pointed >someplace to get more info on the algorithms of RTREES and how they work, as >I'd like to implement something that uses RTREE algorithms, and be able to >represent a whole record w/ items with values,subvalues,subsubvalues, >etc...in an object type format. > >(Something that can get a whole record for a customer and break it out into >all the pieces automagically.. as an example.) > > >I'm used to doing code like this for parsing data for a customer from an >RTREE: >(Mixed Pseudocode and perl): >$customer=GETDATA; >$MultivalueMarker="~"; >$SubvalueMarker=0007; >$valuemarker=0008; > >foreach $customer (@recordlist) { > @carray=split ($ValueMarker,$customer,10); > @phonearray=split($SubValueMarker,@carray[7]); > foreach $phoneitem (@phonearray) { > my ($phone,$number)= split($MultiValueMarker,$phoneitem); > $phonehash{$phone}=$number; > } > @domainarray=split ($SubValueMarker,@carray[8]); > @emailarray=split ($MultiValueMarker,@domainarray[2]); > >} > >And at some point the data is packed and unpacked.... >I'd like to hide all that using objects and make it so one could say read in a >template, and then make access to the data based on names defined in the >template. > >As for an SQL database using Rtrees: >This doesn't seem like good practice for use if one is using SQL to do queries >with as it isn't structured around this kind of datatype, is there black >magic going on here that autoguesses joins, etc based on relationship of data >in the tree? > >(When PG first announced Multidimensional support for the db, I didn't believe >it to be an rtree because of the slowness at which queries occurred, when >using multivalued data, even in a small database.) I would hope that pgsql >would have other ways of handling queries on an rtree. And it may well do >that now.) > > > > >---------------------------(end of broadcast)--------------------------- >TIP 5: Have you checked our extensive FAQ? > > http://www.postgresql.org/docs/faq > >
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