How to use editdist3 in sqlite

Question

According to an answer to another question, in sqlite the Levenshtein distance is implemented in a SQL function called editdist3. (Compare also the documentatio

Answer 1

It turns out editdist3 is contained in an sqlite extension that has to be loaded explicitly. As I didn’t find it in the Gentoo sqlite package, I also had to build it myself. As the documentation says:

The spellfix1 virtual table is not included in the SQLite amalgamation and is not a part of any standard SQLite build. It is a loadable extension.

First I fetched the source code

wget https://sqlite.org/2016/sqlite-src-3110100.zip
unzip sqlite-src-3110100.zip

then it has to be compiled

gcc -shared -fPIC -Wall -Isqlite-src-3110100 sqlite-src-3110100/ext/misc/spellfix.c -o spellfix.so

and finally it can be loaded with

.load ./spellfix

Note that sqlite automatically appends the extension .so.

To use it in python – which was my original intention – the following needs to be done:

db = sqlite3.connect(':memory:')

db.enable_load_extension(True)
db.load_extension('./spellfix')
db.enable_load_extension(False)