Hi all,
we have a little problem with the locking of sqlite connections in
combination with the shared cache model.
We are using sqlite 3.6.10 (on Ubuntu 9.04) or later. Same problem
occurs on the latest ubuntu version with sqlite 3.7.4.
Problem:
We have a multi threaded application that connects from different
threads to a common sqlite database that contains just one large table
(kind of log).
We have enabled shared cache globaly and open the database connections
for read/write from the main thread and read only / multi threading
enabled (SQLITE_OPEN_READONLY | SQLITE_OPEN_NOMUTEX) from the other
threads.
After opening the database connection "Read-Uncommitted Isolation Mode"
is directly enabled using
if (sqlite3_exec(log_database_local, "PRAGMA read_uncommitted=True;",
NULL, 0, &err) != SQLITE_OK) {...
If the log table is well filled (~ 5.000.000 entries) we do different
requests on this table from different threads. They are read-only right
now.
One request takes very long time to complete (select distinct xyz
from ... where ...).
While this request is processed, opening the same database from another
thread blocks until the sqlite3_prepare for the first thread is
completed, even if shared cache model is enabled.
Is there any chance to open the same database from different threads to
do read-only requests _without_ blocking the requests at any place?
We need to be able to read the contents from the table in parallel from
different threads even if one single database requests takes very long
time.
Any help or short hint would be very appreciated!
Thanks in advance,
Ole Reinhardt
--
Thermotemp GmbH, Embedded-IT
Embedded Hard-/ Software and Open Source Development,
Integration and Consulting
http://www.embedded-it.de
Geschäftsstelle Siegen - Steinstraße 67 - D-57072 Siegen -
tel +49 (0)271 5513597, +49 (0)271-73681 - fax +49 (0)271 736 97
Hauptsitz - Hademarscher Weg 7 - 13503 Berlin
Tel +49 (0)30 4315205 - Fax +49 (0)30 43665002
Geschäftsführer: Jörg Friedrichs, Ole Reinhardt
Handelsregister Berlin Charlottenburg HRB 45978 UstID DE 156329280
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
