How to use % operator from the extension pg_trgm?

问题

I have my pg_trgm module installed.

pg_trgm | 1.0     | extensions | text similarity measurement and index ...

The schema set is extensions. To use it I have to run something like this select:

extensions.similarity('hello','hallo');

I'm trying to run a statement using the % operator and got the following message.

mydb=# select * from rssdata where description % 'Brazil';
ERROR:  operator does not exist: character varying % unknown
LINE 1: select * from rssdata where description % 'Brazil';
                                            ^
HINT:  No operator matches the given name and argument type(s).
You might need to add explicit type casts. 

What is necessary to run % or <-> operators?

回答1:

Most probably this is a problem with the search_path. Run:

SHOW search_path;

Is the schema where you installed pg_trgm included? If not, include it.

Alternatively, you can schema-qualify functions - and even operators using the OPERATOR() construct:

SELECT * FROM rssdata WHERE extensions.similarity(description, 'Brazil') > .8;
SELECT * FROM rssdata WHERE description OPERATOR(extensions.%) 'Brazil';

Makes it independent from the search_path.

来源：https://stackoverflow.com/questions/22975599/how-to-use-operator-from-the-extension-pg-trgm