On 2020-10-30 02:43, Masahiko Sawada wrote:
Using the integer set is very memory efficient (5MB vs. 114MB in the
base case) and there is no 1GB limitation. Looking at the execution
time, I had expected that using the integer set is slower on recording
TIDs than using the simple array but in this experiment, there is no
big difference among methods. Perhaps the result will vary if vacuum
needs to record much more dead tuple TIDs. From the results, I can see
a good improvement in the integer set case and probably a good start
but if we want to use it also for lazy vacuum, we will need to improve
it so that it can be used on DSA for the parallel vacuum.
I've attached the patch I used for the experiment that adds xx_vacuum
GUC parameter that controls the method of recording TIDs. Please note
that it doesn't support parallel vacuum.
How do you want to proceed here? The approach of writing a wrapper for
bsearch with bound check sounded like a good start. All the other ideas
discussed here seem larger projects and would probably be out of scope
of this commit fest.
