BuildTupleFromCStrings Memory Documentation?

Within the core codebase, BuildTupleFromCStrings is often called within a temporary memory context cleared after the call. In dblink.c, this is justified as being needed to “[clean up] not only the data we have direct access to, but any cruft the I/O functions might leak”.

I wrote a pretty minimal case to call BuildTupleFromCStrings in a loop (attached) and found that I was using 40GB of RAM in a few minutes, though I was not allocating any memory myself and immediately freed the tuple it returned.

Is the need to wrap this call in a protective context documented anywhere? Portions of the documentation use BuildTupleFromCStrings in examples without mentioning this precaution. Is it just well-known, or did I miss a README or comment somewhere?

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Jason Petersen
Software Engineer | Citus Data
303.736.9255
jason(at)citusdata(dot)com