From: | Mark Kirkwood <markir(at)i4free(dot)co(dot)nz> |
---|---|
To: | reedstrm(at)rice(dot)edu, pgsql-general(at)postgresql(dot)org |
Subject: | Re: Unimpletmented features |
Date: | 2000-08-19 02:13:10 |
Message-ID: | 399DED36.FCDABB43@i4free.co.nz |
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Lists: | pgsql-general |
Ross,
I am not so sure that ALTER <object> family is used for development
purposes only...
Consider data warehousing where typically each day the administrator
would :
1 Extract data from source database(s) - usually in ascii file
format, as these dbs may be connection unfriendly, not controlled by us
etc etc etc
2 Modify relevant tables in the target database and disable all
constraints ( primary keys too usually )
3 Drop all remaining indexes
4 Bulk load the source data.
5 Enable all constraints
6 Create any remaining indexes
These tables tend to have a very large number of rows ( >100,000,000 )
and are often corrospondingly large ( >10GB ) and thus it is important
to remove indexes and constraints to load the data in a sensible time
frame ( a few hours or less).
Postgresql is good at the "star" type queries that are common in such
warehouse applications, and thus is well suited to move into that area -
but the unimplemented ALTER features hinder this
regards
Mark
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