I'm storing UUID v4 values in a PostgreSQL v9.4 table, under column "id".
When I create the table, is there any difference in following write or read performance whether I define the "id" column as VARCHAR(36), CHAR(36), or UUID data …
As the title suggests, I'd like to select the first row of each set of rows grouped with a GROUP BY.
Specifically, if I've got a purchases table that looks like this:
SELECT * FROM purchases;
My Output:
id | customer | total
…
I need to retrieve all rows from a table where 2 columns combined are all different. So I want all the sales that do not have any other sales that happened on the same day for the same price. The sales …