On 28/09/18 11:56, Vladimir Ryabtsev wrote:
>
> > It could affect space storage, for the smaller blocks.
> But at which extent? As I understand it is not something about "alignment" to
> block size for rows? Is it only low-level IO thing with datafiles?
>
Maybe 'for the smaller blocks' was not very meaningful.
What i mean is 'in terms of wasted disk space: '
In an example:
create table test_space (i int);
empty table:
select pg_total_relation_size('test_space');
pg_total_relation_size
------------------------
0
(1 row)
insert one single record:
insert into test_space values (1);
select pg_total_relation_size('test_space');
pg_total_relation_size
------------------------
8192
select pg_relation_filepath('test_space');
pg_relation_filepath
----------------------
base/16384/179329
ls -alh base/16384/179329
-rw------- 1 postgres postgres 8.0K Sep 28 16:09 base/16384/179329
That means, if your block size was bigger, then you would have bigger space
allocated for one single record.
regards,
fabio aprdi
