Many databases and search engines allow you to customize your queries using your own so called “user defined functions” or UDF. Sphinx and Manticore are not exceptions. There’s a long section in the documentation about this - https://manual.manticoresearch.com/Extensions/UDFs_and_Plugins/UDF#UDF

Here I want to give just a quick example of how you can make a UDF which enables some fucntionality which can be really useful in some cases, but missing out of the box - sleep() function.

First of all create the code of your UDF in C:

[snikolaev@dev01 ~]$ cat sleep.c
#include </home/snikolaev/./manticore_gitlab/src/sphinxudf.h>

int sleep_ver() {
	return SPH_UDF_VERSION;
}

sphinx_int64_t sleep ( SPH_UDF_INIT * init, SPH_UDF_ARGS * args, char * error_flag ) {
	usleep(*args->arg_values[0] * 1000000);
}

As you can see it has only 2 functions:

• sleep_ver() returning just current SPH_UDF_VERSION from the included sphinxudf.h
• and sleep() which does the job - sleeps the number of seconds provided in argument #1

HINT: Make sure your file has extension “.c”, not “.cpp”, otherwise it may not work.

Next you need to build your library:

[snikolaev@dev01 ~]$ gcc sleep.c -shared -o sleep.so -g -fPIC
[snikolaev@dev01 ~]$

You now have sleep.so which includes your function:

[snikolaev@dev01 ~]$ ls -la sleep.so
-rwx--x--x 1 snikolaev snikolaev 8209 Sep 10 04:37 sleep.so

Next make sure you specify in your config where searchd should look for UDFs using plugin_dir directive:

common {
    plugin_dir = /home/snikolaev
}

Now start the searchd and create the function:

mysql> create function sleep returns int soname 'sleep.so';
Query OK, 0 rows affected (0.00 sec)

HINT: if you do not want to do it every time you start searchd you can put the command to a file:

[snikolaev@dev01 ~]$ cat state.sql
CREATE FUNCTION sleep RETURNS INT SONAME 'sleep.so';

and use

sphinxql_state = state.sql

in the searchd section of your config so it runs the command on start.

Once you have the function registered in the searchd you can use it:

mysql> select sleep(1);
+----------+
| sleep(1) |
+----------+
| 0 |
+----------+
1 row in set (1.00 sec)

If you have any questions about Sphinx UDFs don’t hesitate to ask us on our forum or in our public Slack channel.