| From: | "Roberts, Jon" <Jon(dot)Roberts(at)asurion(dot)com> |
|---|---|
| To: | "Alvaro Herrera" <alvherre(at)commandprompt(dot)com> |
| Cc: | "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>, "Richard Broersma" <richard(dot)broersma(at)gmail(dot)com>, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, <lists(at)stringsutils(dot)com>, "Pgsql General list" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Default fill factor for tables? |
| Date: | 2008-07-11 20:55:11 |
| Message-ID: | 1A6E6D554222284AB25ABE3229A92762E9A74C@nrtexcus702.int.asurion.com |
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| Lists: | pgsql-general |
> Roberts, Jon escribió:
>
> > Why would you set the fillfactor to anything other than 100 for a
> > PostgreSQL table?
>
> To favor HOT updates.
>
> --
I can find very little information on hot updates but I found this: http://archives.postgresql.org/pgsql-patches/2006-11/msg00059.php
It states, "This design optimizies the updates when none of the index columns are modified and length of the tuple remains the same after update."
How can a row's length change? I think it must mean the size (in bytes) of the row remains the same.
If this is the constraint, then I still don't see the benefit. If the size can vary, I can see the benefit because the new column value may be larger than the old value thus needing the space.
Why isn't the hot update documented in these locations?
http://www.postgresql.org/docs/8.3/interactive/sql-createtable.html
http://www.postgresql.org/docs/8.3/interactive/sql-update.html
http://www.postgresql.org/docs/8.3/interactive/sql-altertable.html
Jon
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