felixge

12 ms·

121.
by felixge 9y ago
> But when you get locked into Oracle and it makes it nearly impossible to move because of the features your relying on, has a big effect on shaping your perspective on this. I hear you. Picking a database is major decision and shouldn&#
122.
by felixge 9y ago
Yeah, this doesn't actually work. You'll get this error: ERROR: ALTER TYPE ... ADD cannot run inside a transaction block
123.
by felixge 9y ago
Yeah, maybe I'll update the post and mention ENUMs. I like the type safety of ENUMs, and I'm actually using them in my application, but they can cause a lot of problems. E.g. it's currently almost impossible to remove an ENUM
124.
by felixge 9y ago
Author here. > If ever you decide you want to migrate away from Postgres, you'll need to rewrite all the business logic into some other out of process language. Yeah, but I don't consider this a bad thing. IMO migrating between
125.
Implementing State Machines in PostgreSQL(felixge.de)
8 points by felixge 9y ago|1 comments
126.
by felixge 9y ago
I've looked into creating a flame graph visualization for PostgreSQL EXPLAIN output before, but CTEs that are scanned multiple times complicate things a bit. That's because the first scan on a CTE node will cause the CTE query to
127.
by felixge 9y ago
Do you have an example of "traditional (inverted-)back-trace"?
128.
by felixge 9y ago
Maybe I'm missing something, but the final query in the article seems complicated/inefficient for no apparent reason. IMO this one should be better: SELECT DISTINCT ON (message_id) message_id, status FROM emails OR
129.
by felixge 9y ago
You can use user defined aggregates in postgres to model state machines. I'm using this technique quite successfully and have been meaning to write a blog post about it.
130.
by felixge 9y ago
Running your tests against a different DB than what you're using is an anti-pattern IMO. You'll not be able to trust the results, and you'll be limited to the lowest common denominator of the databases your using.
131.
by felixge 9y ago
:). Thank you, this is definitely helping my motivation to write more of these posts! If you haven't seen it before, I think you'll also like this post (not by me): http://patshaughnessy.net/2014/10/13&#x
132.
PostgreSQL operations that you can't EXPLAIN(felixge.de)
4 points by felixge 9y ago|2 comments
133.
by felixge 9y ago
AFAIK the best way to access German bank accounts programmatically is AqBanking, which is used by e.g. GNUCash. It also comes with a CLI: https://www.aquamaniac.de/sites/aqbanking/cli.php
134.
by felixge 10y ago
We're currently experimenting with logical decoding in 9.6, so I'd be curious to hear what problems you've been running into.
135.
by felixge 10y ago
I don't think it's that simple. Imagine a simple add(int32, int32) int32 function. Unless you write a test for all 2^32 * 2^32 possible inputs and their expected outputs, how could you guarantee that the AI will come up with the &
136.
by felixge 10y ago
I think there is plenty of evidence that the EO order was designed to be a "muslim ban" [1]. Fortunately it was done poorly, and didn't hold up in court so far. https://www.youtube.com/watch?v=aGOwEOTYfuE&
137.
by felixge 10y ago
> In two years, your average consumer probably doesn't care if their device is still receiving software updates. They'll jump onto a new phone plan, with a fresh, cool new mobile, with a better screen, newer software (features!
138.
by felixge 10y ago
Thanks. > I know a count of the whole table takes about a minute tho. But the filter > group by was ~1s as the grouping was done on about < 50 rows of the filtered result. Yeah, that makes sense. I'm running some queries in pr
139.
by felixge 10y ago
Cool. I'm not familiar with it, that's why I ask :). Anyway, is the performance you mentioned for a scan over the entire table? E.g. to do an aggregate?
140.
by felixge 10y ago
And that's for a sequential scan over all of those tuples? That'd be very impressive. Does SQLServer support parallel execution? Or how come it be so fast?
141.
by felixge 10y ago
I completely missed that. So yeah, your comment is spot on. The default cost settings seem way too low. I'll certainly try tuning them for our postgres servers :). Thanks!
142.
by felixge 10y ago
Interesting. Are you sure that the limit is shared by all workers? > When the accumulated cost reaches a limit (specified by vacuum_cost_limit), the process performing the operation will sleep for a short period of time, as specified by
143.
by felixge 11y ago
Sure, but after the connection is established, and "memory pressure" [1] is gone, shouldn't the tcp implementation grow the window again? [1] I'm putting this in quotes, because the machines in questions have ridiculous
144.
by felixge 11y ago
I don't know if it was a kernel issue, but I was able to reproduce the problem in another DC by setting somaxconn artificially low (to 2 IIRC) in order to artificially force Linux into SYN cookie mode, and that reproduced this issue as
145.
by felixge 11y ago
There was definitely packet loss and retransmission due to it, so the packets were not the same on both sides of the router. But this doesn't explain why TCP connections would be stuck with small windows for their entire lifetime after
146.
by felixge 11y ago
Here is another Linux TCP horror story: An application I'm working on was experiencing slow database query performance under "load" [1]. Restarting the database temporarily "fixed" the issue, only to reappear again
147.
by felixge 11y ago
I guess that's arguably better than accepting corrupted data, but still a step backwards from the abstraction TCP is intended to provide in regards to checksums ...
148.
by felixge 11y ago
Does TLS support transparent retransmits of corrupted packets?
149.
by felixge 12y ago
Author here. I'd like to clarify that my use case involves talking to devices inside a factory (i.e. LAN) that are expected to be physically connected/disconnected on occasion. The devices are speaking a text protocol, and my goal
150.
GoDrone - A Parrot AR Drone 2.0 Firmware written in Go(felixge.de)
3 points by felixge 13y ago|0 comments

More ›