BigQuery UDF memory exceeded error on multiple rows but works fine on single row

Question

I\'m writing a UDF to process Google Analytics data, and getting the \"UDF out of memory\" error message when I try to process multiple rows. I downloaded the raw data and f

Answer 1

A UDF will fail on anything but very small datasets if it has a lot of if/then levels, such as:
if () {
.... if() {
.........if () {
etc

We had to track down and remove the deepest if/then statement.

But, that is not enough. In addition, when you pass the data into the UDF run a "GROUP EACH BY" on all the variables. This will force BQ to send the output to multiple "workers". Otherwise it will also fail.

I've wasted 3 days of my life on this annoying bug. Argh.