So I tried and I got a very basic UDF working.
mysql> SELECT udf_fileexists_go("/etc/hosts"); +---------------------------------+ | udf_fileexists_go("/etc/hosts") | +---------------------------------+ | 1 | +---------------------------------+ 1 row in set (0.00 sec) mysql> SELECT udf_fileexists_go("/nonexistend"); +-----------------------------------+ | udf_fileexists_go("/nonexistend") | +-----------------------------------+ | 0 | +-----------------------------------+ 1 row in set (0.00 sec)
This is nowhere near production quality, so be careful.
The code is here:https://github.com/dveeden/udf_fileexists_go/blob/master/udf_fileexists_go.go.