After much code reading, testing, and using the extremely handy pageinspect
contrib to look at pages, here's what I believe is happening. I am not
attempting to describe every possible scenario, only this one test path.
Following my short test scenario above...
- Inserted rows get line pointers
I think this simple test highlights the question well.
--
create temporary table t(x int) with (autovacuum_enabled=off);
insert into t select x from generate_series(1,1,1)x;
vacuum verbose t;
select dead_tuple_count from pgstattuple('t');-- 0
delete from t where x = 100;
This is an expansion of the question I posed in this thread:
http://postgresql.1045698.n5.nabble.com/Need-help-understanding-vacuum-verbose-output-tp2265895p2266912.html
I am framing the question here in relation to pgstattuple. Running 8.4.4 on
Centos.
I have a table T with 5,063,463 rows.
Robert Haas wrote:
My thought would be is autovacuum running in the background in
between these commands?.
That's a good thought, but no, autovacuum_vacuum_scale_factor is set to 0.2,
meaning that over 1 million dead tuples are necessary for autovacuum.
Besides, if autovacuum had run, I
