On 5/13/18 12:55 PM, Rowan Worth wrote:
> On 9 May 2018 at 08:56, Richard Hipp <d...@sqlite.org> wrote:
>>   But with
>> SQLite, there is no round-trip latency.  A "round-trip" to and
>> database is just a function call, and is very very cheap.
> I want to emphasise that Dr. Hipp's usage of "round-trip" only includes the
> latency of _communication_ between the app and database in this statement,
> and excludes any processing time required by the database.
> If you were to interpret "round-trip" from an app-centric perspective (as
> in "the time taken to retrieve/commit data") then the statement becomes
> misleading because handling the data involves i/o, possibly even
> synchronous i/o, which is not "very very cheap" by any standard I'm aware
> of :)
> -Rowan
Yes, if the request requires I/O, then that costs time, but then the
operation would likely use similar I/O in whatever way the application
needed to get that information, so that I/O shouldn't really be charged
to the use of a database, but to the information requested. One thing to
remember is SQLite is often compared as a better way to get information
then using simple disk i/o, so the 'cost' of using SQLite (compared to
the alternative) shouldn't include the base time to read the file, but
only any extra i/o above that.

Richard Damon

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