Query performance in PostgreSQL using 'similar to'

Question

I need to retrieve certain rows from a table depending on certain values in a specific column, named columnX in the example:

select *
from t         


        

Answer 1

If you are only going to search lists of one-character values, then split each string into an array of characters and index the array:

CREATE INDEX
        ix_tablename_columnxlist
ON      tableName
USING   GIN((REGEXP_SPLIT_TO_ARRAY(columnX, '')))

then search against the index:

SELECT  *
FROM    tableName
WHERE   REGEXP_SPLIT_TO_ARRAY(columnX, '') && ARRAY['A', 'B', 'C', '1', '2', '3']