How to stream through query results ?

[jbtrystram]

Hi,

Result

I am using the java remote hot rod client to query entries in a cache then delete the result. However, I expect the number of results to be quite large and that may cause memory issues in my application. Setting a `maxResults` value on the query could help, but then I'd have to execute it multiple times, which isn't optimal.

The documentation mention that streaming through the results is possible [1] but i can't find how to do that. I've looked at the various documentation and could not find a way to retrieve a Stream of objects ?

Also, just to be sure : there is no way to directly delete the results of a query ? It's a bit cumbersome at the moment since I get back the values, needs to constructs the corresponding keys and use them for the deletion operation.

I don't need to get the results in my application, it's just a blind deletion. Is there a more efficient way to do it ?

Thanks !

[1] : Indexing and Querying with Infinispan 10.0

[zhurlik]

Hi,

I guess this can help you

Streams Tutorial - Infinispan

Thanks,

Vlad

[jbtrystram]

Thanks !

But this won't change any thing : doing query.list() will still load all the results in memory..

[zhurlik]

I didn't check how it works inside, but what I can see that this sample uses a reference to cache and then goes through keys using stream... Probably I am wrong and didn't catch what did you mean

[william.burns]

Unfortunately Indexing itself doesn't have a way to delete entries that map to a specific index, without iterating as you have done. If your query returns too many results, you have to use `maxResults` and retrieve them in batches.

The other option is if you can do it is to use distributed streams that Vladimir is referencing. Unfortunately, what you need to do isn't supported as a direct API in a remote cache. Instead you need to use a ServerTask that invokes distributed streams. Once you are in a ServerTask you can do something like I mentioned in How to delete all entries whose values satisfy certain condition

If you need more information on ServerTask you can take a look at Infinispan 9.4 User Guide