mreiche / postgresql-first-last-aggregate

PostgreSQL first/last aggregate

This is a native PostgreSQL extension to support reading the first and last value of a group.

In comparison to partition's FIRST_VALUE() and LAST_VALUE() [1], it does only require groups.

The original snippet [2] has been modified to work with newer PostgreSQL versions.

Installation

Just run first_last_aggregegate.sql on your PostgreSQL console.

Example

select
    product,
    first(price) price_open,
    last(price) price_close,
    avg(price) price_avg,
    min(price) price_min,
    max(price) price_max
from products
    group by product

product	price_open	price_close	price_avg	price_min	price_max
Affe	9.272449	67.55699	52.32810068130493	9.272449	83.53931
Kuh	87.33832	20.83148	61.10811456044515	20.83148	97.54616
Katze	51.7085	50.019222	38.3283109664917	9.954079	51.7085

Note: Data was generated by test/test-data.sql

References

• [1] https://www.postgresqltutorial.com/postgresql-first_value-function/
• [2] https://wiki.postgresql.org/wiki/First/last_%28aggregate%29