Le 25/04/2022 à 22:19, Wes McKinney a écrit :
I was going to reply to this e-mail thread on user@ but thought I would start a new thread on dev@. Executing user-defined functions in memory, especially untrusted functions, in general is unsafe. For "trusted" functions, having an in-memory API for writing them in user languages is very useful. I remember tinkering with adding UDFs in Impala with LLVM IR, which would allow UDFs to have performance consistent with built-ins (because built-in functions are all inlined into code-generated expressions), but segfaults would bring down the server, so only admins could be trusted to add new UDFs. However, I wonder if we should eventually define an "external UDF" protocol and an example UDF "harness", using Flight to do RPC across the process boundaries. So the idea is that an external local UDF Flight execution service is spun up, and then data is sent to the UDF in a DoExchange call. As Jacques pointed out in an interview 1], a compelling solution to the UDF sandboxing problem is WASM. This allows "untrusted" WASM functions to be run safely in-process.
How does the sandboxing work in this case? Is it simply executing in a separate process with restricted capabilities, or are other mechanisms put in place?
