g0del_was_wr0ng

4 ms·

1.
Zero Days and Cargo Cult Science(blog.hboeck.de)
1 points by g0del_was_wr0ng 10y ago|0 comments
2.
by g0del_was_wr0ng 10y ago
Well fair enough but that method of counting is not what everyone else does or assumes, so somebody just reading the title "120k writes per second" gets the wrong impression of whats going on. (An uninitiated reader would assume y
3.
by g0del_was_wr0ng 10y ago
By that logic a write to a postgres table would also count as N+1 writes, where N is the number of secondary indexes defined on that table? And also, by the same logic, replicating a write to three machines counts as three writes when the r
4.
by g0del_was_wr0ng 10y ago
It's doing 12k rows in 3k user-issued write operations/transaction per second. Counting any kind of "internal write effects" that result from a user write (i.e. write amplification) is obviously done to mislead in the be
5.
by g0del_was_wr0ng 10y ago
Well, you're missing that in Faunas case the writes are durably stored on N machines. I.e. their system provides fault tolerance in case a machine fails. You can't really do the same thing with postgres (without trading off ful
6.
by g0del_was_wr0ng 10y ago
Yeah it's a bit more complex than that... The disk "IOPS" number on the box doesn't translate 1:1 or even linearly to number of committed durable transactions per second. You should try this with postgres and see how it
7.
by g0del_was_wr0ng 10y ago
Including your 9x write amplification in the number of "consistent writes" doesn't count -- like at all. I'm amazed nobody called you out on this yet. You're doing 3k batches per second with 4 logical writes each, r
8.
by g0del_was_wr0ng 10y ago
I agree that your PG numbers don't sound likely/factual -- the reason for your confusion is probably that somebody gave you untrue performance numbers for postgres or you're not comparing the same things. Is the 1m+ TPS somet
9.
by g0del_was_wr0ng 10y ago
I think y0ghur7_xxx was talking about a usecase where you want to talk to the backend datastore from an application running outside of your datacenter in an untrusted environment (like an iOS/Android app, or a JS web frontend). In this
10.
by g0del_was_wr0ng 10y ago
>> The only way you can scale is to adopt a query-free architecture This is not really the case. There are database systems that can handle large scale and complex queries. Allthough usually at the price of providing reduced consisten
11.
by g0del_was_wr0ng 10y ago
So what do you do when the master for one of your shards fails? Do you drop all incoming writes for the shard on the floor? Or do you fail over to the shard's slave and promote the slave to the new master? Since you said you don't
12.
by g0del_was_wr0ng 10y ago
No, but when your requirement is to "never loose a write regardless of which server fails" you have to make sure the mutation was acknowledged by more than one server. So the least you have to do is to wait for a second server to