(
  SELECT Example_id
  FROM   Table.Example
  WHERE  TRANSLATE(LTRIM(PLCY_NBR, '0'), '-~', '') like'35243'
)
UNION
(
  SELECT EXAMPLE
  FROM   TABLE.EXAMPLE
  WHERE  EXAMPLE.SRC_SYS_ID = 14 
    AND TRANSLATE(LTRIM(PLAN_NBR, '0'), '-~', '') like'34123'
);

I set the parameters:

Set random_page_cost = 1.0;
Set seq_page_cost = 1.0;

Even after creating a GIN index for like, the planning time is reduced, but the execution time is the same. I need to optimise the query.