On Wed, Apr 16, 2014 at 7:38 PM, Bruce Momjian br...@momjian.us wrote:
On Thu, Apr 10, 2014 at 06:03:15PM +0100, Simon Riggs wrote:
On 6 February 2014 18:21, Jeff Janes jeff.ja...@gmail.com wrote:
On Tue, Feb 4, 2014 at 2:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch
On Thu, Apr 10, 2014 at 06:03:15PM +0100, Simon Riggs wrote:
On 6 February 2014 18:21, Jeff Janes jeff.ja...@gmail.com wrote:
On Tue, Feb 4, 2014 at 2:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method.
On 6 February 2014 18:21, Jeff Janes jeff.ja...@gmail.com wrote:
On Tue, Feb 4, 2014 at 2:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random integers it does 18% fewer
compares and takes
On 26/02/14 03:08, Robert Haas wrote:
On Tue, Feb 25, 2014 at 2:55 PM, Jeremy Harris j...@wizmail.org wrote:
On 24/02/14 17:38, Robert Haas wrote:
On Thu, Feb 20, 2014 at 7:27 PM, Jeremy Harris j...@wizmail.org wrote:
Run under cachegrind, it takes about N/10 last-level cache misses,
all
On 24/02/14 17:38, Robert Haas wrote:
On Thu, Feb 20, 2014 at 7:27 PM, Jeremy Harris j...@wizmail.org wrote:
Run under cachegrind, it takes about N/10 last-level cache misses,
all for the new item being introduced to the heap. The existing
code takes none at all.
Can you explain this
On Tue, Feb 25, 2014 at 2:55 PM, Jeremy Harris j...@wizmail.org wrote:
On 24/02/14 17:38, Robert Haas wrote:
On Thu, Feb 20, 2014 at 7:27 PM, Jeremy Harris j...@wizmail.org wrote:
Run under cachegrind, it takes about N/10 last-level cache misses,
all for the new item being introduced to the
On Thu, Feb 20, 2014 at 7:27 PM, Jeremy Harris j...@wizmail.org wrote:
On 09/02/14 17:11, Jeremy Harris wrote:
On 06/02/14 18:21, Jeff Janes wrote:
Did you try sorting already-sorted, reverse
sorted, or pipe-organ shaped data sets? We will also need to test it on
strings. I usually use
On 09/02/14 17:11, Jeremy Harris wrote:
On 06/02/14 18:21, Jeff Janes wrote:
Did you try sorting already-sorted, reverse
sorted, or pipe-organ shaped data sets? We will also need to test it on
strings. I usually use md5(random()::text) to generate strings for such
purposes, at least for a
On Fri, Feb 7, 2014 at 4:28 PM, Jeremy Harris j...@wizmail.org wrote:
On 06/02/14 22:12, Jeremy Harris wrote:
Did you try sorting already-sorted, reverse
sorted, or pipe-organ shaped data sets?
Summary (low numbers better):
Random ints: 83% compares, level on time.
Sorted ints:
On 06/02/14 22:12, Jeremy Harris wrote:
Did you try sorting already-sorted, reverse
sorted, or pipe-organ shaped data sets?
Summary (low numbers better):
Random ints: 83% compares, level on time.
Sorted ints: level compares, 70% time.
Reverse-sorted ints: 10% compares, 15%
On 05/02/14 21:56, Robert Haas wrote:
On Tue, Feb 4, 2014 at 5:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random integers it does 18% fewer
compares and takes 10% less time for the heapify,
On Thu, Feb 6, 2014 at 4:22 AM, Jeremy Harris j...@wizmail.org wrote:
On 05/02/14 21:56, Robert Haas wrote:
On Tue, Feb 4, 2014 at 5:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random
On Tue, Feb 4, 2014 at 2:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random integers it does 18% fewer
compares and takes 10% less time for the heapify, over the work_mem
range 1024 to
On 06/02/14 18:21, Jeff Janes wrote:
How big of
sets were you sorting in each case?
Big enough to go external. The timings and compare-counts given are
purely for the heapify stage not the total for the sort, so are
constrained by the work_mem not by the sort size per se.
I'm limited to
On 06/02/14 14:22, Robert Haas wrote:
On Thu, Feb 6, 2014 at 4:22 AM, Jeremy Harris j...@wizmail.org wrote:
On 05/02/14 21:56, Robert Haas wrote:
On Tue, Feb 4, 2014 at 5:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a
On Tue, Feb 4, 2014 at 5:22 PM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random integers it does 18% fewer
compares and takes 10% less time for the heapify, over the work_mem
range 1024 to
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random integers it does 18% fewer
compares and takes 10% less time for the heapify, over the work_mem
range 1024 to 1048576.
Both algorithms appear to be O(n) (contradicting Wikipedia's claim
On Wed, Feb 5, 2014 at 7:22 AM, Jeremy Harris j...@wizmail.org wrote:
The attached patch replaces the existing siftup method for heapify with
a siftdown method. Tested with random integers it does 18% fewer
compares and takes 10% less time for the heapify, over the work_mem
range 1024 to
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