[R-Forge #5712] Error message for "allow.cartesian=TRUE"

[arunsrinivasan]

Submitted by: Arun ; Assigned to: Nobody; R-Forge link

The error message suggesting to use allow.cartesian=TRUE currently is:

# Error in vecseq(f__, len__, if (allow.cartesian) NULL else as.integer(max(nrow(x),  : 
#   Join results in 320342 rows; more than 160171 = max(nrow(x),nrow(i)). Check for duplicate key 
# values in i, each of which join to the same group in x over and over again. If that's ok, try including `j` 
# and dropping `by` (by-without-by) so that j runs for each group to avoid the large allocation. If you 
# are sure you wish to proceed, rerun with allow.cartesian=TRUE. Otherwise, please search for this 
# error message in the FAQ, Wiki, Stack Overflow and datatable-help for advice.

However, this also happens when x has duplicate values but not i. Check eddi's post here for an example.

So, it's a bit misleading to check for i having duplicate keys.. Not sure how to change it yet. Filing so that we don't miss it.

[arunsrinivasan]

This needs to be a FAQ as well. Will do before to close.

[mattdowle]

#742 was great fix, Arun! No need for FAQ.