ArangoDB：Foxx服务中的事务限制

Question

I'm trying to find documentation describing restrictions on what can be safely accessed from within a transaction running within a javascript Foxx micro-service. I had read somewhere (can't find it now) that you can't access anything except what is passed via the transaction parameters array, and you must re-import all node modules that are used within the transaction. I'm curious what I can safely pass into a transaction - such as the ArangoDB database object itself (instead or re-importing it), why these restrictions exist, and what the performance implications are (object marshaling?). In my testing on a single-node server, it seems that accessing externally defined variables does work, so I assume these restrictions have to do with more complex configurations of the database server/cluster.

Thanks!

Answer 1

I had read somewhere (can't find it now) that you can't access anything except what is passed via the transaction parameters array

This applies to UDFs (user-defined functions), not Foxx micro-services.

I believe that all the cautions about Foxx are in the manual:

https://docs.arangodb.com/3.3/Manual/Foxx/

In particular:

• "you should not rely on server-side state (other than the database itself) between different requests as there is no way of making sure consecutive requests will be handled in the same context."

• "Because the JavaScript code is running inside the database ... all Foxx and ArangoDB APIs are purely synchronous and should be considered blocking."