dr_strangelove

The architecture is described here:

https://youtu.be/Xa_fNuaSE_I?t=416

For german users a similar service is offered by 1&1 (iPayment, with "silent CGI"-mode). The form on the site is sent to the ipayement servers and those verify the transaction data, call a URL on your servers with the unique transaction token and success/error message, and only redirect the user back to your site after the callback is finished. Works pretty well, the credit card data never touches your server but the user doesn't notice that he left your site.

To open a terminal simply press cmd + return.

if you had an index on device_id there shouldn't be a difference in performance between the original table and the partioned one. the index is used to reduce the rows that need to be scanned so there wouldn't be a full table scan. btw, why do you use a table lock?

had this guy an index on "device_id" and "date_added", there is no way such a query would take 3-4 seconds.

To give you a background why vacuum is necessary: When you update a row in postgres, it is marked as deleted and a row with the updated contents is inserted. Likewise, when you delete a row, it is only marked as deleted but the space on disk will not automatically be reused. The vacuum process appends all these rows to the list of reusable rows.

If the autovacuum process is run too infrequently, the space used by the tables grows larger and there are many gaps between used rows. In addition to filling up more disk space than necessary this reduces sequencial scan performance. In this case you should run a vacuum full which packs the table and relases the unused space to the operating system (think of file system defragmentation). Unfortunately this is quite slow and uses table locks so you should not do it on a production system.

[EDIT:] From the awesome postgres documentation:

http://www.postgresql.org/docs/current/static/routine-vacuum...

You don't need VACUUM FULL. If you have problems with too much disk space used by your tables, increase the autovacuum frequency.

The language that fits this description best is Erlang, I would say ... (what, in this definition, is specific to objects compared to processes?)