What does database query and insert speed depend on?

Question

At my work we have a small database (as in two hundred tables and maybe a total of a million of rows or so).

I\'ve always expected it to be quite fast in the order of se

Answer 1

"I've always expected it to be quite fast in the order of several ten of thousands insertion per second and with querys taking milliseconds once the connection is established."

(a) Database performance depends for 99% on the amount of physical I/O (unless you are in some small site using an in-memory database, which can harmlessly afford to postpone all physical I/O until after the day is done). (b) Database I/O involves not only the actual physical I/O to the data files, but also the physical I/O to persist the journals/logs/... (and journaling is often even done in dual mode (i.e. twice) since say about two decades or so). (c) In what way the "amount of inserts" corresponds to the "amount of physical I/O", is completely determined by how much options the database designer has available for optimising the physical design. Only one thing can be said in general about this : SQL systems mostly fail (to provide the options necessary to transform "tens of thousands of inserts" to just maybe "a couple of hundreds" of physical I/O). Meaning that "tens of thousands of inserts" usually also implies "thousands of physical I/O", which usually implies "tens of seconds".

That said, your message seems to express an expectation that somehow "inserts are extremely fast ("tens of thousands per second")" while "queries are slower" ("milliseconds per query", implying "less than 1000 queries per second"). That expectation is absurd.