On Sep 19, 2007, at 10:30 AM, Richard Broersma Jr wrote:
Not quite. Once a page has reached it's fill factor percentage full,
no more inserts will happen on that page, only updates. Also, I
think you have large/small backwards wrt fill factor. If you have a
fill factor of, say, 40% then once a page has reached 40% full no
more inserts will happen (unless some space is reclaimed by vacuum).
So, smaller fill factors == bigger holes. The bigger the fill
factor, the smaller the whole: if you have a fill factor of 90%,
only 10% is reserved for updates of rows on that page.
So (just to reiterate), fill factor can be applied to both a table
and/or an index(es). But the
"holes" built into the page of a table or index can only be filled
by UPDATE Statements.
Thanks for the clarification!
Yep. Although, to be strictly honest, I guess the term UPDATE isn't
the best term to use for indexes. My description works best for
tables, see the section on FILLFACTOR in http://www.postgresql.org/
docs/8.2/interactive/sql-createindex.html for a better description of
what happens for indexes -- slightly different semantics, but the
same general effect.
Also, note that once we have HOT, figuring out fill factor for
indexes will be a whole different ball game. Currently, an update to
any tuple in a table, results in a new index entry. With hot, index
entries will only happen if the indexed column is changed in the update.
Erik Jones
Software Developer | Emma®
erik@xxxxxxxxxx
800.595.4401 or 615.292.5888
615.292.0777 (fax)
Emma helps organizations everywhere communicate & market in style.
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