We can see a second logging message init ok without having called the initialization function a second time. Testing pattern 'at' WITHOUT capture group, expecting empty return Testing pattern 'at' WITHOUT capture group Testing pattern 'g(oog)+le' WITH capture group = 1 Testing pattern 'g(oog)+le' WITHOUT capture group Testing pattern 'x(ab)' WITH capture group = 0 Testing pattern 'x(ab)' WITH capture group = 1 Testing pattern 'x(ab)' WITHOUT capture group We can test it by adding the following at the end of our testing script, we will get an error: If we open a new DB connection, the functions will not be available. It seems to work! We just need to fix one more problem. execute ( "SELECT regex_extract('at', 'hello')" ). fetchone () assert row = "cat", row print ( "Testing pattern 'at' WITHOUT capture group, expecting empty return" ) row = conn.
execute ( "SELECT regex_extract('at', 'cat')" ). fetchone () assert row = "oog", row print ( "Testing pattern 'at' WITHOUT capture group" ) row = conn. execute ( "SELECT regex_extract('g(oog)+le', 'googoogoogle', 1)" ). fetchone () assert row = "googoogoogle", row print ( "Testing pattern 'g(oog)+le' WITH capture group = 1" ) row = conn. execute ( "SELECT regex_extract('g(oog)+le', 'googoogoogle')" ). fetchone () assert row = "xab", row print ( "Testing pattern 'g(oog)+le' WITHOUT capture group" ) row = conn. execute ( "SELECT regex_extract('x(ab)', 'xxabaa', 0)" ). fetchone () assert row = "ab", row print ( "Testing pattern 'x(ab)' WITH capture group = 0" ) row = conn. execute ( "SELECT regex_extract('x(ab)', 'xxabaa', 1)" ). fetchone () assert row = "xab", row print ( "Testing pattern 'x(ab)' WITH capture group = 1" ) row = conn. execute ( "SELECT regex_extract('x(ab)', 'xxabaa')" ). enable_load_extension ( False ) print ( "Running tests." ) print ( "Testing pattern 'x(ab)' WITHOUT capture group" ) row = conn. execute ( "SELECT load_extension('target/release/libsqlite_regex.dylib', 'sqlite3_regex_init') " ) conn. #! use crate:: ffi:: loadable_extension_init use anyhow:: Context as ACtxt use log:: LevelFilter use regex:: bytes:: Regex use rusqlite:: ffi use rusqlite:: functions:: " ) conn. This will tell the rust compiler that we are building a shared library. UPDATE: I’ve created a new fork which merges the changes in that PR with the current latest rusqlite release (v0.27.0) here.For more context why this is needed, see #910. Using this rusqlite fork from Genomicsplc.The most important details to note here are: That is an SQLite extension that enables zstd compression on SQLite, I highly recommend checking it out if you want to look at more advanced examples than this post. This post is a simplified version of some techniques I learned from phiresky/sqlite-zstd. In this post, we’ll see how we can use Rust to write an SQLite loadable extension. Then you can just share the compiled object and load them from any application or programming language. Loadable extensions can be written in any programming language that can be compiled to a shared library/DLL. This is where loadable extensions come in. That means that you need to have the function available in the same scope as your application. They have to be defined in your program.They’re local to an SQLite connection, not shared for every process connected to the DB.SQLite has a powerful extension mechanism: loadable extensions.īeing an in-process database, SQLite has other extensions mechanisms like application-defined functions (UDF for short).
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