create or replace function realtime.build_prepared_statement_sql(
    prepared_statement_name text,
    entity regclass,
    columns realtime.wal_column[]
)
    returns text
    language sql
as $$
/*
Builds a sql string that, if executed, creates a prepared statement to
tests retrive a row from *entity* by its primary key columns.
Example
    select realtime.build_prepared_statement_sql('public.notes', '{"id"}'::text[], '{"bigint"}'::text[])
*/
    select
'prepare ' || prepared_statement_name || ' as
    select
        exists(
            select
                1
            from
                ' || entity || '
            where
                ' || string_agg(quote_ident(pkc.name) || '=' || quote_nullable(pkc.value #>> '{}') , ' and ') || '
        )'
    from
        unnest(columns) pkc
    where
        pkc.is_pkey
    group by
        entity
$$;