Sqlite is a single file shared between users just like a word processing
file shared between multiple users. It is not a DBMS server and just
uses the regular fcntl type file locks.
[EMAIL PROTECTED] wrote:
-------- Original-Nachricht --------
Datum: Tue, 04 Jul 2006 12:01:25 -0500
Von: John Stanton <[EMAIL PROTECTED]>
An: sqlite-users@sqlite.org
Betreff: Re: [sqlite] Multiple Users
Hello Gerrry, Aristotle and John
Many thanks for your answers. I'm very glad about your help.
Yes, I found this Page (File Locking And Concurrency In SQLite
Version 3) at last weekend and read it more than one times....
but there a some things, they finally I dont understand and
results to the questions in my first posting
I know, that my question is a question like "how many users can
share a file", but thats not my intention.
Citation
{
2.0 Overview
Locking and concurrency control are handled by the the pager
module. The pager module is responsible for making SQLite
"ACID" (Atomic, Consistent, Isolated, and Durable). The pager
module makes sure changes happen all at once, that either all
changes occur or none of them do, that two or more processes
do not try to access the database in incompatible ways at the
same time, and that once changes have been written they persist
until explicitly deleted. The pager also provides an memory
cache of some of the contents of the disk file.
}
Does this mean, that the Pager drive the (File-)Lockings during
the multiple writings to disk? Thats the thing, what I only
need (I think so *hmmm*): The Shared-Dos-File-Locking near to
operating system. The logical locking to the edited records I
do myself.
Does it mean, if multiple processes in a Network try to
write to the same DB, to the same Table, but every process in
its own (logical-locked) record, I don't get Problems, because
the Pager himself do the File-Write-Locking to the shared File
(as a DOS-File, not a DB)?
If your application observes the locking rules or provides its own
synchronization you can have very many concurrent users. If your
application doesn't observe locking you can only have one user.
I do only a logical Record-Locking, not a locking to the Filesystem,
that makes sure, that not more than one User can edit the same record
and its related record's in other tables. I know, that SQLite-DB is a
File-Based-DB opened by the User as a Shared-File for Read and Write.
But if I understand yours all right, that is not the think, I have to
look at this. Thats the Pagers's Job. Is it so?
Greetings from a very hot Germany
Anne
