> 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.
