PostgreSQL: Merge rows with the same date and time but different numeric values in one row with average of the values
|1|2|2012-01-01|12:00:00|1.3459|1.3645|

SELECT col1, col2, col3, col4, AVG(col5) col5, AVG(col6) col6
FROM table_name
GROUP BY col1, col2, col3, col4;