On 26.06.2013 16:37, Amit Kapila wrote:
On Wednesday, June 26, 2013 2:15 AM Heikki Linnakangas wrote:
Can you also try the attached patch, please? It's the same as before,
but in this version, I didn't replace the prev and next pointers in
PGLZ_HistEntry struct with int16s. That avoids some table lookups, at
the expense of using more memory. It's closer to what we have without
the patch, so maybe that helps on your system.
Yes it helped a lot on my system.
Ok, good. Strange, I did not expect such a big difference.
There was minor problem in you patch, in one of experiments it crashed.
Fix is not to access 0th history entry in function pglz_find_match(),
modified patch is attached.
Thanks, good catch! I thought that a pointer to the 0th entry would
never make it into the prev/next fields, but it does. In fact, we never
store a NULL there anymore, a pointer to the 0th entry is now always
used to mean 'invalid'. I adjusted the patch to remove the NULL check,
and only check for the 0th entry.
Committed.
- Heikki
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