PostgreSQL: VACUUM FULL or CLUSTER?

I'm nearly out of disk space because of a query that tried to update every row in a huge table. I don't have enough space for CLUSTER (though it would barely fit if I dropped indexes first and recreated them afterwards).

How can I estimate how long VACUUM will take? How about VACUUM FULL? How do the three (with CLUSTER) compare in terms of开发者_StackOverflow社区 running time and disk usage?

It's PostgreSQL 8.3.

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use cluster, until 8.4 vacuum full is broke. if it takes to long you might as well dump and reload the table.