On Fri, May 19, 2006 at 09:03:31AM -0400, Tom Lane wrote: > Martijn van Oosterhout <kleptog@svana.org> writes: > > I'm seeing 250,000 blocks being cut down to 9,500 blocks. That's almost > > unbeleiveable. What's in the table? > > Yeah, I'd tend to question the test data being used. gzip does not do > that well on typical text (especially not at the lower settings we'd > likely want to use).
However, postgres tables are very highly compressable, 10-to-1 is not that uncommon. pg_proc and pg_index compress by that for example. Indexes compress even more (a few on my system compress 25-to-1 but that could just be slack space, the record being 37-to-1 (pg_constraint_conname_nsp_index)). The only table on my test system over 32KB that doesn't reach 2-to-1 compression with gzip -3 is one of the toast tables. So getting 25-to-1 is a lot, but possibly not that extreme. pg_statistic, which is about as close to random data as you're going to get on a postgres system, compresses 5-to-1. Have a nice day, -- Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/ > From each according to his ability. To each according to his ability to > litigate.
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