On 23 February 2018 at 04:00, Bill Moran <wmoran@xxxxxxxxxxxxxxxxx> wrote: > 2) The negative impact of an unused index is tiny compared to the negative > impact of a missing index. I'd say that would entirely depend on the workload of the table and the entire cluster. Disk space and I/O to write WAL and index pages to is surely a finite resource. Not to mention the possibility of disallowing HOT-Updates in the heap. It would seem to me that anyone using the "shotgun" indexing method may end up having to learn more about indexing the hard way. Learning the hard way is something I like to try to avoid, personally. Probably it all has to come down to how important it is that your app actually can handle the load vs devs/dba experience level divided by time, both of the latter two are also a finite resource. So, it probably all has to be carefully balanced and quite possibly a person's opinion strongly relates to their experience. If you were in the air traffic control business, perhaps your opinion might not be the same!? ... Sorry, the aeroplane crashed because the replica instance lagged and the plane's location wasn't updated... Analysis shows that the DBA indexed every column in the table and the WAL volume was more than the network's bandwidth could handle over the holiday period. (Note: I know nothing about air traffic control, but it does seem like something you'd want to make stable systems for, games on the internet, probably less so...). -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
