Addresses CodeRabbit review on #3221, "Check the output size before
with_subtotals builds subtotal lines": the size limit was checked only
after every subtotal line existed. A row with 4000 key columns at total
depth 4000 nested with_subtotals 4000 levels deep and overflowed the
stack (the process aborted) before the late check could refuse it.
with_subtotals now works without recursion: each line gets an id for its
key prefix at every level, a stable sort by those ids keeps each group
together in first-appearance order, and one walk adds the subtotals.
The output size (with the header and total lines when present) is
checked while the groups are counted, before any subtotal line is built.
Test: groupby_subtotals_past_the_size_limit_are_refused_before_they_are_built.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
GROUPBY's total_depth only ever added one Total line. In Excel a depth
of N adds a subtotal line for each group of the first N - 1 key columns
(after the group, or before it when the depth is negative) and labels
the last line "Grand Total"; a depth greater than the number of key
columns, or above 1 with field_relationship 1 (a flat table), is
#VALUE!. The subtotals aggregate the group's source rows, so AVERAGE and
COUNT subtotals are right too.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
