Change the schema that stores test names to be more efficient

Currently in the postgres database I store "test_names" in the following table:

CREATE TABLE IF NOT EXISTS test_names
(
    test_name_n     integer  PRIMARY KEY  NOT NULL  GENERATED BY DEFAULT AS IDENTITY,
    test_executable text NOT NULL,
    test_function   text,
    test_datatag    text,
    UNIQUE NULLS NOT DISTINCT (test_executable, test_function, test_datatag)
);

Note the "UNIQUE" constraint, which adds an index on the three components of a test_name (test_executable,test_function,test_datatag).
This is based on the facts that the combination of these components is mostly stable, does not grow.

I now see that this is not true, there are data tags that are generated randomly and the list grows a lot with each integration. Thus this table gets too long and becomes a bottleneck after the index outgrows the memory.

I also see indexing (automatically by the UNIQUE constraint) on a combination of many text fields is expensive. The size of the index has grown larger than the size of the data.

Rethink and re-design the schema to perform better.