On 12/17/2013 12:49 AM, Heikki Linnakangas wrote:
On 12/17/2013 12:22 AM, Alexander Korotkov wrote:On Mon, Dec 16, 2013 at 3:30 PM, Heikki Linnakangas <hlinnakan...@vmware.comwrote:On 12/12/2013 06:44 PM, Alexander Korotkov wrote: When values are packed into small groups, we have to either insertinefficiently encoded value or re-encode whole right part of values.It would probably be simplest to store newly inserted items uncompressed, in a separate area in the page. For example, grow the list of uncompressed items downwards from pg_upper, and the compressed items upwards from pg_lower. When the page fills up, re-encode the whole page.I hacked together an implementation of a variant of Simple9, to see how it performs. Insertions are handled per the above scheme.
Here's an updated version of that, using the page layout without item-indexes that I described in the other post. This is much less buggy than that earlier crude version I posted - and unfortunately it doesn't compress as well. The earlier version lost some items :-(.
Nevertheless, I think this page layout and code formatting is better, even if we switch the encoding back to the varbyte encoding in the end.
I haven't tested WAL replay or VACUUM with this version yet, so those are likely broken.
- Heikki
gin-packed-postinglists-simple8-segments-1.patch.gz
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