Hi
Once in a while, I see an error when doing a "VACUUM" operation.
sqlite3_exec3(...) returns status=14 (unable to open database file).
I suppose that it fails to open a temporary database when doing
the VACUUM operation, but I don't see why.
sqlite3_extended_errcode(db) also returns extendedErrorCode=14
The code to vacuum looks simple, it does these operations:
==========================================================
sqlite3* db;
int status = sqlite3_open(dbName, &db);
if (status != SQLITE_OK) {
... no error happening here.
}
char* errMsg = NULL;
status = sqlite3_exec(db, "PRAGMA synchronous=OFF;", NULL, NULL, &errMsg);
if (status != SQLITE_OK) {
... no error happening here.
}
status = sqlite3_exec(db, "VACUUM;", NULL, NULL, &errMsg);
if (status != SQLITE_OK) {
... and here I get status is 14 once in a while?!
}
status = sqlite3_close(db);
if (status != SQLITE_OK) {
... no error happening here, even when above VACUUM failed.
}
==========================================================
I precise that:
- It's doing VACUUM of fairly large DBs (1 or a couple of Gb in general)
but the file system has far more free space. I realize that
VACUUM needs free space (>= 2 or 3 times the size of the DB?)
That should not be the problem. And if it was, I would expect
a different error code than 14.
- I'm doing several VACUUM in parallel of different DBs
in different processes. I'm not using threads.
Each process VACUUM a different database which is simple.
- The DB is opened just before doing the VACUUM (as in above code)
There is no other opened connection to it.
- It's not 100% reproducible. It happens maybe 1/10
of the times, which suggests that it could be a race condition.
Yet it's not using threads. Different processes uses
different databases, so it does not seem possible to have
race conditions in those conditions.
- Even though VACUUM fails, the DB looks fine.
- It's using SQLite-3.7.3 (actually, Spatialite-2.4.0) on Linux x86_64.
(OK, maybe time to upgrade SQLite)
- I've checked with Valgrind memory checker on tiny
databases: it sees no problem.
-> Any idea what could be wrong?
I wonder whether VACUUM of different databases happening
in parallel in different processes could use the same temporary
file names, causing conflicts.
Regards
-- Dominique
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