On Dec 1, 4:55 am, Eric Rannaud <eric.rann...@gmail.com> wrote: > Athttp://www.911pagers.org/, a relatively simple query such > ashttp://www.911pagers.org/#rangeId0-128, which does: > > SELECT * FROM MessageS where id >= 0 && id < 128 order by id > > and fetches 128 entities, takes anywhere between 1s and 4s, usually > around +2.5s, measured on the server, in wall-clock time, with the > following code: > > Calendar c = Calendar.getInstance(); > long t0 = c.getTimeInMillis(); > qmsgr = (List<MessageS>) qmsg.execute(lo, hi); > System.err.println("getCMIdRange:qmsg: " + (c.getTimeInMillis() - t0)); > > id is not the primary key of MessageS, but a 'long' field, _unique_ in > each entity (so it maps 1-to-1 with the entities). Note: such a query > doesn't require a specific index.
Why "such a query doesn't require a specific index"? There's no such thing as unique constraint on google data store. > > There are about 500,000 MessageS entities in the datastore, for a > total of 140 MB, excluding metadata (of which there are about 85 MB). > > Repeating the same request several times in a row doesn't improve > response time. The delay has been pretty consistent over several days. > Note again that the delay is measured on the server, the latency of my > connection is not a factor. > > I am aware App Engine is a preview and all, but 2.5s, really? > > I can find the data faster in a text file split across 4 machines over > a shared Ethernet 10Mb with a bunch of Python for loops running on > OLPC XOs, for $DEITY's sake. > > Eric. -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to google-appeng...@googlegroups.com. To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
