Hi All,

(1)I am Amit Kumar Khare, I am doing MCS from UIUC USA offcampus from India.

(2) We have been asked to enhance postgreSQL in one of our assignments. So I 
have chosen to pick "Add free-behind capability for large sequential scans" 
from TODO list. Many thanks to Mr. Bruce Momjian who helped me out and 
suggested to make a patch for this problem.

(3)As explained to me by Mr. Bruce, the problem description is that if say 
cache size is 1 mb and a sequential scan is done through a 2mb file over and 
over again the cache becomes useless.Because by the time the second read of 
the table happens the first 1mb has been forced out of the cache already.Thus 
the idea is not to cache very large sequential scans, but to cache index scans 
small sequential scans.

(4)what I think the problem arises because of default LRU page replacement 
policy. So I think we have to make use of MRU or LRU-K page replacement 
policies.

(5)But I am not sure and I wish more input into the problem description from 
you all. I have started reading the buffer manager code and I found that 
freelist.c may be needed to be modified and may be some other too since we 
have to identify the large sequential scans.

Please help me out

Regards
Amit Kumar Khare



Tue, 12 Feb 2002 01:12:57 -0600
khare <khare@students.uiuc.edu>
Add free-behind capability for large sequential scans