postgresql shared buffers

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От Praveen Kumar N
Тема postgresql shared buffers
Дата
Msg-id Pine.LNX.4.61.0609081438590.7141@students.iiit.ac.in
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Ответы Re: postgresql shared buffers  (Heikki Linnakangas <heikki@enterprisedb.com>)
Re: postgresql shared buffers  (Gregory Stark <stark@enterprisedb.com>)
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hai...
        I have installed postgresql from sourcecode.I would like to know
how pages are replaced in the bufferpool when we join two relations.I 
tried to trace it by editing files 
pgsql/src/backend/storage/buffer/(bufmgr.c,freelist.c).But i feel still I
am missing some information after observing extracted information abt 
buffer replacement.My input datasize is 10times more than main memory/RAM 
size.When I joined two relations,postgresql accessed both relations 
sequentially one by one and that too only once.Then how is it joining two 
relations by accessing only once? Is it storing that accessed relations 
some where other than main memory/bufferpool(Becos they cant fit into main 
memory).

So can anybdy tell me is there is ne thing I am 
missing? Is there any concept like postgresql cache similar to kernel 
cache otherthan sharedbuffers.If so how can we figure it out.

Is there any way by which postgresql is accessing database 
relations through,other than rotines in bufmgr.c nd freelist.c(I 
mean any other routines like ReadBuffer,StrategyGet etc.)

thanks in anticipation.

--  N Praveen Kumar Btech-IV CSE IIIT,Hyd AP,India
    Imagination is more important than knowledge...                                --Albert Einstein


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