Causes Behind SQLite Corruption & How to Repair SQLite Databases

SQLite database shows resistant nature towards corruption. During execution of any transaction with SQLite database if you are facing any uncommon prospect then, it simply shows that your SQLite database moved to inaccessible state.

During any transaction if the process gets fail then, the actions automatically rolls back and users need to start from scratch when they get connected to the SQLite server. There are different conditions and situations due to which SQLite database moves to inaccessible manner afterwards SQLite users look for a best remedy for SQLite database revival.

Within this article you will get a frequent view of reasons due to which SQLite database moves to non-accessible state:

File Overwriting Operations -> Overwriting of SQLite files is possible as these files are ordinary disk files, not any way is there to defend the database from such actions.

• Running File Descriptor:  Closing and reopening a file Decryptor may overwrite the thread managed on SQLite log files, in this case the data should go on to the Server gets replaced and it shows corruption afterwards
• Restore While Transaction Is In Running Mode:  Backup processes running at the backend of system may try to create backup of SQLite files while the transaction is not completed. The backup will save some logs of previous state and some logs of earlier transactions, at the end transactions id will not match and user will see the corruption issue.
• Hot Journal Deletion:  For recovery of database SQLite use auxiliary journal files with the same name of the database, only the suffix -journal or -wal gets added. During SQLite database repair, if the Server will not find journal file due to renaming, deletion, or file move then there will be no hope for automatic database recovery.

File Locking Issues: For coordinating concurrent processes, SQLite uses locking database facility and the reason behind it is avoiding changes done by two different processes for a single database that explores data corruption.

• Missing Lock Details: File systems those are treated as reliable sources for locking databases may have some un-resolvable bugs along with and when any database thread is locked but such kind of system then chances of data corruption increase.
• Posix Advisory Lock Cancellation: This facility is important to be settled into all UNIX system running SQLite for default locking, The Close () system call oftentimes interrupt this action and it further generates SQLite thread corruption. The main cause behind this kind of corruption may be linking of SQLite database multiple copies
• Contradiction Of Two Locking Protocols: SQLite3 vfs and SQLite3 open v2(), these two protocols are well known for SQLite database handling, in a system working with SQLite with both of these protocols then contradiction will surely take place
• Rename Or Unlink Database: Once you rename a file of SQLite database that is actually not present at the same location then, it may a result of unlink or rename the SQLite database or file, it is also not a good practice as it will be responsible to corrupt SQLite database
• Numerous Links For A File: If you have linked up a SQLite database to multiple links with network connectivity then, it will again show corruption situations.

Database Syncing Failure: If sync command of SQLite Server playing the role of I/O barrier instead of a true sync, then any failure may come across to you that further rollback actions, you can say it violation of ACID property. In this case database will be in resistant mode.

• Disk Drives Not Honoring Sync Requests:  for out-of-order disk requests SQLite does not have any built-in method, Commit roll back may affect the durability of database but, it does not corrupt the database actually. To defense the database against failed sync operation, users should use SQLite WAL mode.
• PRAGMAs For Restricting Data Syncing: By setting PRAGMA synchronous setting to the OFF state, all sync operations are omitted. This setting helps to improve the performance of SQLite databases but unfortunately it shows corruption as OS reorders all the actions.

Flash And Disk Drive Failures: The changes in content of hard drives and disk drives may be quite annoying for SQLite users.

• Unsafe Flash Memory Controllers: Converting or writing database content from one file format to other while your hard drive is not power protected is another known cause for generating interruption into SQLite databases.
• No More Data Storage Capability: When disk has no space for data storage and you are trying to write something into it then SQLite corruption may take place.

Memory corruption, other problems in operating systems, and SQLite bugs are also enlisted within the crucial causes due to which SQLite files and databases move to inaccessible mode.

For instant and assured recovery of SQLite databases, you can use SQLite Recovery tool availed under the brand name SysTools.