--On 1. Mai 2015 11:30:51 -0700 Tom Lane t...@sss.pgh.pa.us wrote:
No. The non-parameterized paths for a given relation must all have the
same rowcount estimates; otherwise the path comparison logic fails
fundamentally. Another way to look at it is that every correct path
will yield the
Bernd Helmle maili...@oopsware.de writes:
While looking into a customer performance problem, i saw this in
costsize.c, cost_index() (9.3.6, but it looks the same in HEAD):
...
What i'm wondering is the else branch, where the baserel row estimate is
assigned to the
IndexPath. However, it
While looking into a customer performance problem, i saw this in
costsize.c, cost_index() (9.3.6, but it looks the same in HEAD):
/* Mark the path with the correct row estimate */
if (path-path.param_info)
{
path-path.rows = path-path.param_info-ppi_rows;
Hi!
Some fragment of code (src/backend/optimizer/path/costsize.c, lineno ~400):
/*
* Normal case: apply the Mackert and Lohman formula, and then
* interpolate between that and the correlation-derived result.
*/
pages_fetched =
Teodor Sigaev teo...@sigaev.ru writes:
if (indexonly)
pages_fetched = ceil(pages_fetched * (1.0 -
baserel-allvisfrac));
As I understand the code, index_pages_fetched() returns summary of page's
read
for index and heap together.
No. Costs for touching the index
No. Costs for touching the index were computed by the amcostestimate
function; this code is solely about estimating costs for touching the
heap.
I see. Thank you.
--
Teodor Sigaev E-mail: teo...@sigaev.ru
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