Re: Add visibility map information to pg_freespace.

Hello, I've brought visibilitymap extentions for pg_freespacemap
and pgstattuple.

At Mon, 08 Jul 2013 16:59:05 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote in <20130708(dot)165905(dot)118860769(dot)horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>
> I'll come again with the first implementation of it. And as for
> pg_freespacemap, I'll keep the current direction - adding column
> to present output records format of pg_freespace(). And
> documentation, if possible.

pg_freespace_vm_v2.patch:

Interface has been changed from the first patch. The version of
pg_freespace() provided with vm information is named
pg_freespace_with_vminfo() and shows output like following.

| postgres=# select * from pg_freespace_with_vminfo('t'::regclass) limit 10;
| blkno | avail | is_all_visible
| -------+-------+----------------
| 0 | 64 | t
| 1 | 32 | t
| 2 | 96 | t
| 3 | 64 | t
| 4 | 96 | t
| 5 | 96 | t
| 6 | 128 | t
| 7 | 32 | t
| 8 | 96 | t

pgstattuple_vm_v1.patch:

The first version of VM extension for pgstattuple. According to
the previous discussion, the added column is named
'all_visible_percent'.

| postgres=# select * from pgstattuple('t');
| -[ RECORD 1 ]-------+---------
| table_len | 71770112
| tuple_count | 989859
| tuple_len | 31675488
| tuple_percent | 44.13
| dead_tuple_count | 99
| dead_tuple_len | 3168
| dead_tuple_percent | 0
| free_space | 31886052
| free_percent | 44.43
| all_visible_percent | 99.98

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center