Heikki Linnakangas wrote:
One complaint we've heard from clients trying out EDB or PostgreSQL is
that loading data is slower than on other DBMSs.
I ran oprofile on a COPY FROM to get an overview of where the CPU time
is spent. To my amazement, the function at the top of the list was
PageAddItem with 16% of samples.
On every row, PageAddItem will scan all the line pointers on the
target page, just to see that they're all in use, and create a new
line pointer. That adds up, especially with narrow tuples like what I
used in the test.
Attached is a fix for that. It adds a flag to each heap page that
indicates that "there isn't any free line pointers on this page, so
don't bother trying". Heap pages haven't had any heap-specific
per-page data before, so this patch adds a HeapPageOpaqueData-struct
that's stored in the special space.
My simple test case of a COPY FROM of 10000000 tuples took 19.6 s
without the patch, and 17.7 s with the patch applied. Your mileage may
vary.
What is the speedup with less narrow tuples? 10% improvement is good but
not stellar.
cheers
andrew
---------------------------(end of broadcast)---------------------------
TIP 1: if posting/reading through Usenet, please send an appropriate
subscribe-nomail command to [EMAIL PROTECTED] so that your
message can get through to the mailing list cleanly
