Thread: Question on Sort node's actual rows
Greetings.
--
Victor Y. Yegorov
I'm looking at a plan: http://explain.depesz.com/s/sPv
And I have a question. Why in the following snippet `Sort` node reports 128818 rows, although
child node returned only 352?
"-> Sort (cost=37.06..37.94 rows=352 width=20) (actual time=4.441..16.971 rows=128818 loops=1)
" Sort Key: ts.currency
" Sort Method: quicksort Memory: 52kB
" Buffers: shared hit=13
" -> Seq Scan on transaction_slip ts (cost=0.00..22.18 rows=352 width=20) (actual time=0.041..4.035 rows=352 loops=1)
" Filter: (account_id = 101)
" Rows Removed by Filter: 382
" Buffers: shared hit=13
This is:
PostgreSQL 9.3.1 on x86_64-apple-darwin12.5.0, compiled by i686-apple-darwin11-llvm-gcc-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00), 64-bit
Victor Y. Yegorov
Victor Yegorov <vyegorov@gmail.com> writes: > I'm looking at a plan: http://explain.depesz.com/s/sPv > And I have a question. Why in the following snippet `Sort` node > reports 128818 rows, although > child node returned only 352? It's under a mergejoin, which evidently is rescanning its right input a lot due to duplicate join keys in the left input. regards, tom lane