On 28.03.2013 13:09, Jeff Archer wrote:
On Wed, Mar 27, 2013 at 6:35 PM, Simon Slavin <slav...@bigfraud.org> wrote:
Reasonable figures. With 5764 writes to the disk in separates transactions you
have quite a lot of reading of data plus 5764 attempts to update the database
file. The updates have to be done in the right order, and each update has to
wait for the disk to be rotated into the right position, though each update
changes only a small amount of data (probably two sectors).
But my most basic question remains. Why is single transaction faster
than PRAGMA journal_mode = off?
Seems to me that with no journal there should only be single set of
writes to the actual db and that journaling would double the number of
writes because data has to be written to journal file as well.
2.5 sec with journal
5.5 sec without journal <= seems like this sould be the smaller number
You should read the sections 3 forward.
http://www.sqlite.org/atomiccommit.html
A single transaction happens mostly in memory then is flushed to the OS
Cache in one step. The Journal file (the amount of pages that will be
changed) is small while inserting new data into a database and the OS
File Cache is usually large enough ...
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
