On 11/03/2014 03:24 PM, Tom Lane wrote:
Andrew Dunstan <andrew@xxxxxxxxxxxx> writes:
andrew=# do $x$ declare r abc; begin for i in 1 .. 10000000 loop
select 'a','b',i into r.x,r.y,r.z; end loop; end; $x$;
DO
Time: 63731.434 ms
andrew=# do $x$ declare r abc; begin for i in 1 .. 10000000 loop r
:= ('a','b',i); end loop; end; $x$;
DO
Time: 18744.151 ms
Is it simply because the SELECT is in effect three assignments, so it
takes nearly 3 times as long?
I think it's more likely that the second example is treated as a "simple
expression" so it has less overhead than a SELECT.
Well, I accidetally left out this case:
andrew=# do $x$ declare r abc; begin for i in 1 .. 10000000 loop
select row('a','b',i) into r; end loop; end; $x$;
DO
Time: 81919.721 ms
which is slower still.
cheers
andrew
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