On Thu, Feb 13, 2014 at 2:42 AM, Kohei KaiGai <kai...@kaigai.gr.jp> wrote:
> 2014-02-12 14:59 GMT+09:00 Haribabu Kommi <kommi.harib...@gmail.com>: > > 7. In ccache_find_tuple function this Assert(i_min + 1 < cchunk->ntups); > can > > go wrong when only one tuple present in the block > > with the equal item pointer what we are searching in the forward scan > > direction. > > > It shouldn't happen, because the first or second ItemPointerCompare will > handle the condition. Please assume the cchunk->ntups == 1. In this case, > any given ctid shall match either of them, because any ctid is less, equal > or > larger to the tuple being only cached, thus, it moves to the right or left > node > according to the scan direction. yes you are correct. sorry for the noise. > > 8. I am not able to find a protection mechanism in insert/delete and > etc of > > a tuple in Ttree. As this is a shared memory it can cause problems. > > > For design simplification, I put a giant lock per columnar-cache. > So, routines in cscan.c acquires exclusive lwlock prior to invocation of > ccache_insert_tuple / ccache_delete_tuple. Correct. But this lock can be a bottleneck for the concurrency. Better to analyze the same once we have the performance report. Regards, Hari Babu Fujitsu Australia
