We are running this perfectly fine. for us the smaller table changes
rather infrequent say. only a few times per day. The performance of the
flush is way lower than the computing power you need to bring to the
table to account for all the records beeing emmited after the one single
update.
On 16.11.2017 18:02, Trevor Huey wrote:
Ah, I think I see the problem now. Thanks for the explanation. That is
tricky. As you said, it seems the easiest solution would just be to
flush the cache. I wonder how big of a performance hit that'd be...
On Thu, Nov 16, 2017 at 9:07 AM Jan Filipiak <jan.filip...@trivago.com
<mailto:jan.filip...@trivago.com>> wrote:
Hi Trevor,
I am leaning towards the less intrusive approach myself. Infact
that is how we implemented our Internal API for this and how we
run it in production.
getting more voices towards this solution makes me really happy.
The reason its a problem for Prefix and not for Range is the
following. Imagine the intrusive approach. They key of the RockDB
would be CombinedKey<A,B> and the prefix scan would take an A, and
the range scan would take an CombinedKey<A,B> still. As you can
see with the intrusive approach the keys are actually different
types for different queries. With the less intrusive apporach we
use the same type and rely on Serde Invariances. For us this works
nice (protobuf) might bite some JSON users.
Hope it makes it clear
Best Jan
On 16.11.2017 16:39, Trevor Huey wrote:
1. Going over KIP-213, I am leaning toward the "less intrusive"
approach. In my use case, I am planning on performing a sequence
of several oneToMany joins, From my understanding, the more
intrusive approach would result in several nested levels of
CombinedKey's. For example, consider Tables A, B, C, D with
corresponding keys KA, KB, KC. Joining A and B would produce
CombinedKey<KA, KB>. Then joining that result on C would produce
CombinedKey<KC, CombinedKey<KA, KB>>. My "keyOtherSerde" in this
case would need to be capable of deserializing CombinedKey<KA,
KB>. This would just get worse the more tables I join. I realize
that it's easier to shoot yourself in the foot with the less
intrusive approach, but as you said, " the user can stick with
his default serde or his standard way of serializing". In the
simplest case where the keys are just strings, they can do simple
string concatenation and Serdes.String(). It also allows the user
to create and use their own version of CombinedKey if they feel
so inclined.
2. Why is there a problem for prefix, but not for range?
https://github.com/apache/kafka/pull/3720/files#diff-8f863b74c3c5a0b989e89d00c149aef1L162
On Thu, Nov 16, 2017 at 2:57 AM Jan Filipiak
<jan.filip...@trivago.com <mailto:jan.filip...@trivago.com>> wrote:
Hi Trevor,
thank you very much for your interested. Too keep discussion
mailing list focused and not Jira or Confluence I decided to
reply here.
1. its tricky activity is indeed very low. In the KIP-213
there are 2 proposals about the return type of the join. I
would like to settle on one.
Unfortunatly its controversal and I don't want to have the
discussion after I settled on one way and implemented it. But
noone is really interested.
So discussing with YOU, what your preferred return type would
look would be very helpfull already.
2.
The most difficult part is implementing
this
https://github.com/apache/kafka/pull/3720/files#diff-ac41b4dfb9fc6bb707d966477317783cR68
here
https://github.com/apache/kafka/pull/3720/files#diff-8f863b74c3c5a0b989e89d00c149aef1R244
and here
https://github.com/apache/kafka/pull/3720/files#diff-b1a1281dce5219fd0cb5afad380d9438R207
One can get an easy shot by just flushing the underlying
rocks and using Rocks for range scan.
But as you can see the implementation depends on the API. For
wich way the API discussion goes
I would implement this differently.
3.
I only have so and so much time to work on this. I filed the
KIP because I want to pull it through and I am pretty
confident that I can do it.
But I am still waiting for the full discussion to happen on
this. To get the discussion forward it seems to be that I
need to fill out the table in
the KIP entirly (the one describing the events, change
modifications and output). Feel free to continue the
discussion w/o the table. I want
to finish the table during next week.
Best Jan thank you for your interest!
_____ Jira Quote ______
Jan Filipiak
<https://issues.apache.org/jira/secure/ViewProfile.jspa?name=jfilipiak>
Please bear with me while I try to get caught up. I'm not yet
familiar with the Kafka code base. I have a few questions to
try to figure out how I can get involved:
1. It seems like we need to get buy-in on your KIP-213? It
doesn't seem like there's been much activity on it besides
yourself in a while. What's your current plan of attack for
getting that approved?
2. I know you said that the most difficult part is yet to be
done. Is there some code you can point me toward so I can
start digging in and better understand why this is so difficult?
3. This issue has been open since May '16. How far out do you
think we are from getting this implemented?
