|SQLite Introduces Vacuum Into|
|Written by Kay Ewbank|
|Tuesday, 12 February 2019|
The team at SQLite has added a Vacuum Into command that lets you back up a database atomically so that the backup is as small as possible and contains no forensic traces of deleted content.
SQLite is an in-process library that implements a self-contained, serverless, transactional SQL database engine. The entire SQL database with multiple tables, indexes, triggers, and views, is contained in a single disk file. The developers say SQLite is the most used database engine in the world, as it is built into all mobile phones and most computers and is often used by other applications.
SQLite already had a Vacuum command that rebuilds the database file, repacking it into a minimal amount of disk space. Using Vacuum with an Into clause means that the original database file is unchanged and a new database is created in the filename given by the argument to the Into clause. The new database will contain the same logical content as the original database, fully vacuumed. Vacuum Into provides an alternative to the backup API for generating backup copies of a live database. The advantage it offers is that the resulting backup database is as small as it can be.
The other improvements to this release, SQLite 3.27. are to the command-line interface, mostly to support testing and debugging; and to the Deserialize API. This has a new control for setting an upper bound on the size of the in-memory database it creates; and it now honors its own read-only flag, which until now was ignored. Elsewhere, there are general improvements to the robustness of SQLite when it is reading and writing maliciously corrupted database files.
The developers have also fixed a bug in the query optimizer that caused an adverse interaction between the OR optimization and the optimization that tries to use values read directly from an expression index instead of recomputing the expression.
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|Last Updated ( Tuesday, 12 February 2019 )|