Levenshtein-Distance-for-IBM-Informix

Edit distance function (based on Levenshtein distance) for IBM Informix Server.

in levenshtein.sql:

• levenshtein() - returns integer which is Levenshtein edit distance between two strings.

• hexstr_to_bigint() and hexval() are taken from this StackOverflow question - https://stackoverflow.com/questions/31295620/how-to-process-bitand-operation-in-informix-with-column-in-hex-string-format

In java section:

• ls_dst.java - java source code for Levenshtein distance (https://en.wikibooks.org/wiki/Algorithm_Implementation/Strings/Levenshtein_distance#Java)

how to set it up in Informix IDS:

1. Determine which version of java your IDS uses:

• look at your JVPHOME var.
• do JVPHOME/bin/java -version

2. Compile udr for your informix java version. For example like this:

javac -target 1.6 -source 1.6 -bootclasspath /path to jre/jre1.6.0_45/lib/rt.jar ls_dst.java

3. Create jar from it:

jar cf ls_dst.jar ls_dst.class

4. Copy it to directory where informix has read-write rights
5. Execute statments:

EXECUTE PROCEDURE
  sqlj.install_jar("file://path to jar/ls_dst.jar", "lsdst_jar");

here:

• ls_dst.jar - your jar
• lsdst_jar - name of the jar, which will be used by informix

6. Create function:

create function ls_dst(CHAR(50), CHAR(50))
returns integer
external name 'YOUR_DATABASE_NAME.YOUR_USER_NAME.lsdst_jar:ls_dst.ls_dst()'
language java;

Be careful in this part. It take a lot of time for me to figure out how i must set parameters. if you have database named "testdb" with user "dummy" on it, your call will be:

create function ls_dst(CHAR(50), CHAR(50))
returns integer
external name 'testdb.dummy.lsdst_jar:ls_dst.ls_dst()'
language java;

lsdst_jar in this path is jar name used in a call above and ls_dst.ls_dst() - is a call of ls_dst function in ls_dst class (see java code)

Now you can use it like:

select ls_dst("smy", "Smyth") from some_table;