Hello,
If I delete records from a hashed file does that significantly influence the file's performance? Is it better to unload/reload the entire file, filtering out the records I do not need?
Thanks
Hashed files - delete recs vs reload
Moderators: chulett, rschirm, roy
-
- Premium Member
- Posts: 43
- Joined: Tue Sep 09, 2008 1:56 pm
Hashed files - delete recs vs reload
ASU Developer
While pure inserts are more efficient than delete/update on an existing table, the performance difference on a well hashed file (dynamic files are well-hashed) isn't great.
<a href=http://www.worldcommunitygrid.org/team/ ... TZ9H4CGVP1 target="WCGWin">
</a>
</a>
-
- Premium Member
- Posts: 43
- Joined: Tue Sep 09, 2008 1:56 pm
Hashed files don't suffer from fragmentation in that manner; but the default settings of 20% merge 80% split can cause overhead if you go past those limits. The hashed file uses a hashing algorithm on the key to decide into which group a record is placed, the number of groups is also seen as the MODulo of a file. Within these groups you have a linked list of values, so removing an element is not a big issue.
<a href=http://www.worldcommunitygrid.org/team/ ... TZ9H4CGVP1 target="WCGWin">
</a>
</a>
-
- Premium Member
- Posts: 43
- Joined: Tue Sep 09, 2008 1:56 pm
-
- Participant
- Posts: 54607
- Joined: Wed Oct 23, 2002 10:52 pm
- Location: Sydney, Australia
- Contact:
-
- Premium Member
- Posts: 43
- Joined: Tue Sep 09, 2008 1:56 pm