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OCI Always Free - database keeps stopping. (APEX)

Mint-InnitNov 6 2019 — edited Dec 20 2019

Hi all, I appreciate that the correct space for this is probably the Oracle Cloud Customer Connect Community (I think - having gone round and round in circles trying to find where to discuss OCI issues). I haven't been able to set up an account there yet for various reasons but am in the process of doing so.

Anyway, seeing as OCI always free has had the hard sell as a good place for apex development, I'll ask here as well just in case anyone knows the answer.

I have created an Apex app on a free autonomous database. The app is used daily monday-friday. However every 7 days (I think) the DB suddenly stops, and I have to log into my tenancy and manually start it.

So it would appear that the "if you don't use it for 7 days it gets stopped" rule is being tripped. Fine, but I use it nearly every day! Do I in fact have to log into my cloud account AS WELL at least once a week to ensure everything keeps running? If so that is a real pain..

If anyone else is using the free tier for development and has any tips, that would be handy. (yes I tried the free 'chat' support - but I got as much help as expected, being a 'free' user ;-)

Cheers.

This post has been answered by Birch19 on Nov 13 2019
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Comments

715399
Answer
Hi,

It looks like incremental inference is indeed being used. Note that there is some overhead involved with doing incremental and non-incremental inference in general, so even with small models it might take a few seconds to finish. Some of the overhead is caused by the large number of rules in the OWLPRIME rulebase, so if you don't need all of them you can selectively disable some components using the GraphOracleSem.performInference(String components) procedure.

Also, it depends on your dataset. For instance, if you're adding only one triple, but that triple declares some heavily used property to be transitive, then that addition might trigger many additional inferences and updating the inferred graph will take more time.

Regarding OntModel APIs and incremental inference, depends on the loading method you use. Incremental inference works best with incremental loading. Please refer to Section 2.2.9 of the Semantic Technologies Developer's Guide for more details.

Cheers,
Vladimir
Marked as Answer by 696067 · Sep 27 2020
696067
That is very strange. I am basically inserting 'd' into a 5-level-deep tree of Transitive links. The tree has around 5300 nodes but 5000 of them are leaves.
It takes 5 seconds for the inference to be done whether I insert one leaf like 'd' or 100 of them.
By doing a performInference with only SCOH, SPOH, and TRANS it goes down to 3 seconds (further removing TRANS goes down to 2 seconds but I absolutely need to use TRANS).

How come it takes the same 3-5 seconds to infer 5 transitive links and 500 of them?
715399
Hi,

Can you let us know:
a) how large is the asserted dataset and how many triples are generated with inference (from scratch) ?
b) what is the performance target for the incremental inference calls?

Regarding b), if your inference performance target is on the order of milliseconds, you might want to try out PelletDB [1].

Cheers,
Vlad

[1] http://clarkparsia.com/pelletdb/
696067
Thanks Vlad, it looks like in-memory forward-chaining is more of what I am looking for in this regard.
As to your questions:
1) I basically have a 5 level deep tree where every node is transitive to the root, with 5000 leaves and nodes of 200,100,30,1 respectively which to my understanding is 15530 transitive links.
2) My performance target is indeed in the milliseconds but that's when it comes to adding 1-50 leaves.

Thank you for your answers.
Alexi
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Added on Nov 6 2019
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