SQLite briefing for Linux kernel hackers

same heap and stack.An SQLite database is a single ordinary file on disk.An additional transient journal file may appear from time There is no configuration file available to tell SQLite about the database file that are currently unused and that the filesystem for the F2FS filesystem on Linux.Each database file is either in rollback-mode or in WAL-mode. All pages in the same database file are the same size. atomically as follows:Creating a rollback journal file in the Drop the exclusive lockNotes:On step (1), the rollback journal and the database file are kept in operations (unlink, truncate, or header-overwrite) are atomic.All writes to the database file are an integer number of pages and If not found → Done.Play back the rollback journal into the database file.Call fdatasync() on the database file.Barrier - All of the above must complete before any of the following.Disable the rollback journal using one of the following: The WAL file is a file in the same directory as the database and with the same name as the database but with "-wal" appended.Append a "commit mark"Call fdatasync() on the WAL file to commit the transactionNotes:Step 3 can be omitted with the consequence that transactions are no next process to open the database.Call fdatasync() on the "-wal" file.Wait for all concurrent readers to stop using pages in the main database that have changes in the WAL file.Barrier - All of the writes to the WAL file must complete before any subsequent writes to the database file.Write the most recent change for every page in the WAL file back descriptor to the state it was in prior to F2FS-BEGIN.The F2FS atomic write capability is only useful for databases that would for WAL-mode databases.Transactions using F2FS atomic write proceed as follows:Start a new transaction by invoking F2FS-BEGIN. If that ioctl() fails, fallback to using a rollback journal.Write changes directly into the database file. using a traditional rollback journal.Notes:Writes issued on a file descriptor for which a transaction has been write(), ftruncate(), and unlink().When an application deletes content from an SQLite database, SQLite does it overwrites deleted content with zeros when you clear your search history.)SQLite could tell the filesystem about regions of the file that are unused