I have an Adobe Air SQLite db in my application. I was wondering if there was anyway for me to test for corruption provided the db opens ? PRAGMA statements aren't allowed, so that is out of the question.
PRAGMA integrity_check is the only reasonable method.
You could try to read all data from the DB, but this will not find all errors.
Related
I want to upgrade my inserts velocity and I read about modifying the journal mode. How can I do it on TCL code? Thanks!
Assuming db is your SQLite database handle, you just issue a PRAGMA like this:
db eval {
PRAGMA journal_mode = WAL;
}
If you care a lot about speed and not much about integrity (I have one application where this is the case) then you're probably sufficiently well served by just turning off synchronization while you're doing all the inserts.
db eval {
PRAGMA synchronous = OFF;
}
Doing this makes writing to an SQLite database about as fast as just writing directly to your own binary file, but it is only a good idea in some cases. (My case alluded to above is where the writing process is what made the database and where anything other than total success is not useful to users. It's definitely not a normal database use-case!)
Note that pragmas are per DB handle/connection.
The goal is to complete an online backup while other processes write to the database.
I connect to the sqlite database via the command line, and run
.backup mydatabase.db
During the backup, another process writes to the database and I immediately receive the message
Error: database is locked
and the backup disappears (reverts to a size of 0).
During the backup process there is a journal file, although it never gets very large. I checked that the journal_size_limit pragma is set to -1, which I believe means its unlimited. My understanding is that writes to the database should go to the journal during the backup process, but maybe I'm wrong. I'm new to sqlite and databases in general.
Am I going about this the wrong way?
If the sqlite3 backup writes "Error: database is locked", then you should use
sqlite3 source.db ".timeout 10000" ".backup backup.db"
See also Increase the lock timeout with sqlite, and what is the default values? about default timeouts (spoiler: it's zero) and now with backups solved you can switch SQLite to WAL mode (it supports multiple writers!).
//writing this as an answer so it would be easier to google this, thanks guys!
I'm using System.Data.SQLite to create an encrypted SQLite database in a WPF project. The encryption is done by providing a password in the connection string just like this one:
new SQLiteConnection("Data Source=database.sqlite;Password=123456;Version=3;New=false;Compress=True;);
This works well but since the database is encrypted now I'm not able to open it anymore with tools like DB Browser for SQLite or SQLiteStudio. SQLite Studio offers the possibility to open a database of type SQLCipher but I'm struggling to provide the correct settings for my database to open.
Does anybody know how to open an encrypted SQLite database, so I can inspect the data in it?
I was the same problem with SQLiteStudio, in my case, I resolved using the following configuration for SQLChiper:
PRAGMA kdf_iter = '64000';
PRAGMA cipher_page_size = 1024;
PRAGMA cipher_hmac_algorithm = HMAC_SHA1;
PRAGMA cipher_default_kdf_algorithm = PBKDF2_HMAC_SHA1;
On the SQLiteStudio would be like:
For extra configuration or other possible parameters, you could visit the following link https://www.zetetic.net/sqlcipher/sqlcipher-api/
I have a sqlite database in my UWP app. On the very first launch of my app, I create the database and set it up with all the tables and stuff. I play around with the app and generate some data just fine. But when I close and relaunch the app, it starts giving me 'file is encrypted or is not a database' error while trying to execute any query.
I am using sqlite3.dll v3.12.0 and here is my pragma key statement (with an example encryption key):
"PRAGMA key='aes256:66zk4rsKBIfSJ4vhF1XkzFxzrznOhjjnotuHRdKADIg='"
I verified, on second launch, the encryption key is being used to run the pragma key statement.
Edit: It looks like the encryption went just fine. Because, when I use a tool like SQLite Manager and provide the same key, it opens the db just fine.
I think what might be happening to you Is that you use to have a previous library of SQLite working with encryption working properly like I did.
<SDKReference Include="SQLite.UAP.2015, Version=3.10.2">
<Name>SQLite for Universal App Platform</Name>
</SDKReference>
And since you updated the library to v3.12.0 the PRAGMA key in this version did not work hence not being able to enter to the previous encrypted DB.
I'm trying to rebuild the link to that version but is hard: "SQLite.UAP.2015, Version=3.10.2"
I have a sqlite database that I want to open using sqlite3.exe. Now I get an error when I try to make queries, saying "file is encrypted or is not a database". This may seem stupid but I've been looking around on internet and I just don't find how to supply a password (or key) to sqlite3.exe to decrypt the database. The -help option or .help command of sqlite3.exe don't show anything to do that... Is it possible to do that, and if so how can I do it?
It is unlikely that the database would be encrypted, unless you have a reason to believe it is. Are you able to open the database at all, or are you getting this error once you issue some SQL query? If it's the former, your file is probably either not an sqlite db to begin with, or it is corrupted; if it's the latter, please check the integrity of your db with:
pragma integrity_check;
See http://www.sqlite.org/pragma.html#pragma_integrity_check for more info about this pragma.
In any case, unless your db is really encrypted (which sqlite does not support natively), your db is probably unusable.
SQLite reports that error when you pass it a file which is either not actually a SQLite database, or alternatively has been corrupted. There are several SQLite addons to support encryption, but other than that SQLite doesn't have encryption.
It can also happen when you try and open a SQLite v3 database with SQLite v2 (and possibly for other version mismatches).
Assuming you have experienced corruption (and not just passing the wrong file, or using the wrong version of SQLite), you may want to check the PRAGMA synchronous settings you're using, and also review the list of fixed data-corrupting bugs.
Checkout this this forum here. The guy had the same question as you. The thing is that there is not any form of protection offered as a standard package in sqlite3 API, but you can try System.Data.SQLite. These are the codes posted on the forum:
#include <SQLite.au3> don't include sqlite.dll.au3 !!!
_SQLite_Startup ("System.Data.SQLite.dll")
ConsoleWrite(_SQLite_LibVersion() & #LF)
_SQLite_Open("testcrypt.db")
_SQLite_Exec(-1, "pragma key = 'Radu is happy!';create table if not exists test (id integer, val text);" & _
"insert into test values (1, 'abc');")
Local $row
_SQLite_QuerySingleRow(-1, "select * from test;", $row)
ConsoleWrite($row[1] & #LF)
_SQLite_Close()
_SQLite_Shutdown()
hope that helps.