Move zero-size safeguard into cache_score function

Author: jc-harrison

flowdb/bin/build/0030_utilities.sql

@@ -247,7 +247,7 @@ $$
           cache_score_multiplier+POWER(1 + ln(2) / cache_half_life(), nextval('cache.cache_touches') - 2)
         END
         WHERE query_id=cached_query_id
-        RETURNING cache_score(cache_score_multiplier, compute_time, greatest(table_size(tablename, schema), 0.00001)) INTO score;
+        RETURNING cache_score(cache_score_multiplier, compute_time, table_size(tablename, schema), 0.00001) INTO score;
         IF NOT FOUND THEN RAISE EXCEPTION 'Cache record % not found', cached_query_id;
         END IF;
   RETURN score;
@@ -267,7 +267,7 @@ CREATE OR REPLACE FUNCTION cache_score(IN cache_score_multiplier numeric, IN com
 	RETURNS float AS
 $$
   BEGIN
-  RETURN cache_score_multiplier*((compute_time/1000)/tablesize);
+  RETURN cache_score_multiplier*((compute_time/1000)/greatest(tablesize, 0.00001));
   END
 $$ LANGUAGE plpgsql
 SECURITY DEFINER