NO_OUTPUT_ROWS
this row. Matches the
corresponding value
of SORT_RS_ID in the my_stats.SYSXPLAIN_RESULTSETS
row for the result set
which required this sort
to be performed.
type of sort that was
performed. The code
values include 'IN' for
an internal sort, and
'EX' for an external
sort. An internal sort is
one which was entirely
performed in-memory
and did not overflow
to any temporary files,
while an external sort
used one or more
external files.
were provided to the
sorter.
were returned by the
sorter. Note that this
may be fewer rows than
were input, for example
when the sorter is
performing GROUP
BY processing or is
eliminating duplicates.
which were provided.
This value will be NULL
for an internal sort, but
for an external sort it
indicates how many
times the intermediate
sort files were merged
together. External sorts
are far more expensive
than internal sorts, and
each additional merge
run that an external
sort must perform adds
considerably more to
the overhead of the
sort.