pg_language registers call interfaces or languages in which you can write functions or stored procedures. See under CREATE LANGUAGE and in the Programmer's Guide for more information about language handlers.
Table 3-11. pg_language Columns
|lanname||name||Name of the language (to be specified when creating a function)|
|lanispl||bool||This is false for internal languages (such as SQL) and true for dynamically loaded language handler modules. It essentially means that, if it is true, the language may be dropped.|
|lanpltrusted||bool||This is a trusted language. See under CREATE LANGUAGE what this means. If this is an internal language (lanispl is false) then this field is meaningless.|
|lanplcallfoid||oid||pg_proc.oid||For non-internal languages this references the language handler, which is a special function that is responsible for executing all functions that are written in the particular language.|
|lancompiler||text||not currently used|