Kill ROracle query from Shiny

[Karim Chikh]

Hi everyone,

I built a Shiny app where the users can fetch data from and Oracle DB (using ROracle package).

However we want to give the users the possibility to kill the Oracle query that is taking too long and was wondering if anyone knows a trick to kill the query from Shiny?

So far, what the end users do is simply log out from shiny, and this does not sounds like a good solution as I don't even know if it really kills the query...

On top of that, it seems like the app sometimes crashes when the query is too big (anyone trying to access it gets an "Page not found" error) but not sure if that is the only cause as the app is new and need further testing.

Many Thanks,

Karim

[Joe Cheng]

(I'm very surprised that you would get "Page not found" sometimes but not others on the same URL. If this behavior persists let me know.)

Are you using Shiny Server Open Source or Pro?

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[Karim Chikh]

Hi, Yes I am using the Pro version and yes so far it seems like the user who runs the big query still sees the app's page but anyone else trying to do anything on it gets "Page not Found" but I will run further test to confirm.

[Karim Chikh]

Hi,

Since my previous message we did check again the "Page not found" error and it still happens when someone runs a "too big" query: so while the query runs, the user just doesn't realise it but he's query is preventing anyone else from accessing the app.

So we thought about adding a kill query button but the solutions we found online such as the stackoverflow one below did not always work.

https://stackoverflow.com/questions/15482179/roracle-hanging-how-can-i-cancel-the-query

So by the end we still used the parallel processing and added a time limit to kill it (if the query runs for more than X minutes then kill).

I hope this helps those who get into same challenge.

/Kx

[Joe Cheng]

For the life of me, I can't imagine why you would get "Page not found" (instead of some other kind of error). If you're still in a position to easily repro that, can you send me a screenshot? Seeing the fonts, etc. will help identify where the error is coming from (the browser, Shiny, or Shiny Server).

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