Thanks for your responses.
Actually we have two problems:
a) "database is locked" which in majority comes from sqlite3_step doing
BEGIN IMMEDIATE which indeed is obtaining a write lock
Basically we have just one connection per one datafile except one case
when we have two connections for one datafile (one is read/write and the
other is read only).
Now I see that all "database is locked" problems comes from these shared
datafile connections. So maybe this problem is actually somewhere inside
our application.
We have WAL but I don't understand how WAL introduces opportunity for
"database is locked" errors.
We have no busy timeout set because we use System.Data.SQlite library
which has its own waiting mechanism (repeating the
sqlite3_reset/sqlite3_step within 30 secons).
b) "database disk image is malformed", which is sometimes really caused
by AV software. Our application is an email client, so the antivirus
could theoretically found a virus signature inside datafile (but why
would it just modify the file instead of moving to the quarantine as
whole?).
We also have many reports with "database schema has changed" errors.
I have implemented locking_mode=exclusive (along with shared cache) and
will check if this makes difference.
Best regards,
Jiri
On 24.11.2017 20:08:34, "Keith Medcalf" <kmedc...@dessus.com> wrote:
No.
The Windows Search Indexer or Windows Defender only processes files
when they are "closed" (that is, the act of closing a file adds it to
the queue of files to be processed). As long as they are "open" they
are not enqueued for processing. There are a few exceptions, but they
all require "application support" to behave in the non-default "do not
fiddle-faddle with open files".
To do otherwise would be completely foolish (or more correctly,
brain-dead).
Of course, if the software in question is a third-party thing such as
from Slimeytech, McCrappy, or another brain dead vendor, then it is
possible that it fiddle-faddles with files that are "in use" because it
requires a certain minimum (but very low) wattage to realize what a
really truly bad idea (ie, completely and utterly brain-dead) that is.
---
The fact that there's a Highway to Hell but only a Stairway to Heaven
says a lot about anticipated traffic volume.
-----Original Message-----
From: sqlite-users [mailto:sqlite-users-
boun...@mailinglists.sqlite.org] On Behalf Of Nelson, Erik - 2
Sent: Friday, 24 November, 2017 10:20
To: SQLite mailing list
Subject: Re: [sqlite] Need SQLite datafiles to be locked on OS level
(Windows)
Jirí Matejka Sent on Friday, November 24, 2017 3:45 AM
but this does not prevent reading and modifying the file from other
processes while they are open by SQLite in our process.
Does antivirus or Windows randomly modify other applications' files?
It seems like no program could reliably execute under such
circumstances.
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