I was doing some testing with temporary tables using this sql:
begin;
select pg_sleep(30);
create temporary TABLE foo (a int, b int, c int, d text);
insert into foo SELECT (x%1000) AS a,(x%1001) AS b, (x % 650) as c, ''
as d FROM generate_series( 1, 1000000 ) AS x;
-- create temporary TABLE foo AS SELECT (x%1000) AS a,(x%1001) AS b,
(x % 650) as c, '' as d FROM generate_series( 1, 1000000 ) AS x;
select count(1) from foo;
While it was in pg_sleep, I would attach to the backend process with strace.
I observed a few things that I don't yet understand, but one thing I
did notice was an I/O pattern (following the count(1)) that seemed to
suggest that the table was getting its hint bits set. I thought hint
bits were just for the mvcc side of things? If this is a temporary
table, is there any need or benefit to setting hint bits?
--
Jon
