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From: oysteing@idt.unit.no (Oystein Groevlen)
Newsgroups: comp.databases
Subject: Size of ORACLE Temporary Segments
Message-ID: <1990Dec10.101707.14149@idt.unit.no>
Date: 10 Dec 90 10:17:07 GMT
Sender: news@idt.unit.no (Usenet news admin)
Reply-To: oysteing@idt.unit.no (Oystein Groevlen)
Organization: Div. of CS & Telematics, Norwegian Institute of Technology
Lines: 26

I tried posting this last week, but it seems like it never left my terminal.


We are using ORACLE version 6.0.27 on an 386-machine with ISC Unix.

The Database Administrator's Guide says that temporary segments are used for
unindexed joins (among other things). We are thinking of making a separate
tablespace for temporary segments. 

My question is how to estimate how large the database file for this tablespace needs to be. I guess this depends on the size of the RAM, so maybe the question should be how much virtual memory is needed. 

Is there a general formula for estimating the space needed for an unindexed join
based on the size of the tables involved?

In our case we have two tables. Table A has 86415 rows of 50 byte each and table B has 345660 rows of 57 bytes. How big a temporary segment is needed for an unindexed join of A and B? What about a unindexed join of four B (selfjoin)?

Any advice and/or comments are appreciated.

-- 
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Oystein Groevlen 
Division of Computer Systems and Telematics
The Norwegian Institute of Technology
The University of Trondheim
Email: oysteing@idt.unit.no
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