I see that only table documentos has a unique index. Is it really soI thougth that a primary key would create a unique index implictly.
that none of the other tables has a key to uniquely identify a record?
Perhaps the others have a unique attribute but it was never declared
when forming the index?
Sure, my pgsql is version 7.3.4 (I was obviosly mistaken when I wrote 7.4.3 in a previous email) I used to do clustering in some tables, but is a expensive operation as said...I do not remember which version of PostgreSQL you are using, but there is now a CLUSTER command. Now, I am speaking with my experience in other database systems, and so perhaps the PostgreSQL group may find it necessary to correct me. I have only recently began working with PostgreSQL versions beyond 7.1.3 which had no cluster command (or at least I was not aware of one). In other database systems, a clustered index is incredibly valuable. In fact, a unique, clustered index is always a silver bullet to marvelous performance. Perhaps some of the experts can give measurements as to the effectiveness of clustering in PostgreSQL. Here is the link for the cluster documentation: http://www.postgresql.org/docs/current/static/sql-cluster.html
From the description, clustering is expensive and your tables are large.So it should be an infrequent operation.
-- Diogo Biazus diogo@ikono.com.br http://www.ikono.com.br
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