The latest regular update to SQLite, the widely used embeddable SQL database library that is found in many memory constrained gadgets such as cellphones, PDAs, and MP3 players, has been released with performance improvements and an SHA1 extension.
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 new version achieves a performance improvement of around 25 percent when using the R-Tree extension. This improvement was achieved by using more compiler built-ins and other optimizations.
More generally, there's a performance improvement of around 1.5 percent due to an increase in the default size of the lookaside memory buffer allocated for each database connection. This has been increased from 64,000 bytes to 120,000 bytes. While this only adds 56KB of extra memory per connection, If you have applications that are more sensitive to memory utilization than performance, you can reverse this change at compile-time, at start-time, or at run-time.
The new SHA1 extension implements two functions that compute SHA1 hashes. The new sha1(X) function computes the SHA1 hash of the input X, or NULL if X is NULL, while the sha1_query(Y) function evalutes all queries in the SQL statements of Y and returns a hash of their results. SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function designed by the US National Security Agency. It produces a 160-bit hash value known as a message digest.
Other improvements include an enhanced LEMON parser generator so that it can store the parser object as a stack variable rather than allocating space from the heap and make use of that enhancement in the amalgamation. Lemon is an LALR(1) parser generator for C that does the same job as bison and yacc.
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