On 29.06.2013 11:56, Heikki Linnakangas wrote:
On 25.06.2013 01:03, Alexander Korotkov wrote:
New revision of patch is attached. Now it includes some docs.
Thanks! I'm looking into this in detail now.
First, this patch actually contains two major things:
1. Pack item pointers more tightly on posting data leaf pages.
2. Allow opclass implementation to attach "additional information" to
each item pointer.
These are two very distinct features, so this patch needs to be split
into two. I extracted the 1st part into a separate patch, attached, and
am going to focus on that now.
I made one significant change: I removed the 'freespace' field you added
to GinpageOpaque. Instead, on data leaf pages the offset from the
beginning of the page where the packed items end is stored in place of
the 'maxoff' field. This allows for quick calculation of the free space,
but there is no count of item pointers stored on the page anymore, so
some code that looped through all the item pointers relying on 'maxoff'
had to be changed to work with the end offset instead. I'm not 100%
wedded on this, but I'd like to avoid adding the redundant freespace
field on pages that don't need it, because it's confusing and you have
to remember to keep them in sync.
Ah, crap, looks like I sent the wrong patch, and now I can't find the
correct one anymore. The patch I sent didn't include the changes store
end offset instead of freespace. I'll rewrite that part..
- Heikki
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
