Dynamic Loading Library! Extension using C Function

Dear PostgreSQL Community,

I just started learning PostgreSQL, and I am trying to develop a extension for postgre using SRF but I am stuck that how do I get the values by passing the constant integer value against a field/column without using the table name as argument. I already read the Xfunction document portion and successfully executed all most all the examples provided.

Suppose my query is

select get_all_greater_values(column_name, 2000) from table_name;

column_name
1000
2000
3000
4000

Result
3000
4000

Kindly help me for the above query and also suggest whether it is good to use the SRF or there is any other way to get results from this query. I want to implement extension code using C language as dynamic loading library. I really appreciate your concerns.

Regards

M. Bilal Sadiq