Is there a size limit for a text variable in a flow?

Question

Is there an upper size limit for a text variable in a flow? We are told there's a 4000 character limit for input variables, but I want to know about ordinary variables that are not being used for input or output.

I believe that Apex imposes no limit other than heap size (6MB) on string variables. Are flows relying on Apex strings?

I have a test flow where I have demonstrated that flow text variables can hold at least 8k. I can continue adjusting the test to get some idea of what the limit might be in practice, but I'm interesting in knowing if there are any published limits. I have not found any thus far.

Answer 1

The max size for a flow is apparently 4,194,304 characters. Once I got rid of that error, I found that the UI really doesn't like strings over about 1,000,000 characters for a default value. I finally found the maximum size for a default value, which is a paltry 65,535 characters, after which you get:

Text: data value too large: "my beautifully long string... (max length=65535)

I ran a doubler algorithm and found out that at 128MB of data, I would get an internal server error. It did get up to 64MB of data without crashing though...

So, it doesn't appear there's a programmed limit, but there is a hard limit before things break.