When files in pg_multixact/{members,offsets} get recycled?

Hello,

Running latest 9.3.9. Database was never pg_upgraded. I list
pg_multixact/offsets and pg_multixact/members and I see many files
with dates more than one year old. Is that ok?

# ls -1 members/[0-9A-F]* | wc -l
     894

# ls -la members | head
total 127064
drwx------  2 pgsql  pgsql     896 Mar 31  2014 .
drwx------  4 pgsql  pgsql       4 Dec 11  2013 ..
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0000
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0001
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0002
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0003
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0004
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0005
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0006

# ls -la members | tail
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 0374
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 0375
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 0376
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 0377
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 0378
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 0379
-rw-------  1 pgsql  pgsql  262144 Mar 31  2014 037A
-rw-------  1 pgsql  pgsql  262144 Mar 31  2014 037B
-rw-------  1 pgsql  pgsql  262144 Mar 31  2014 037C
-rw-------  1 pgsql  pgsql  253952 Jun 24 01:58 037D

As shown, only file 037D in members was recently changed.

The same in offsets:

# ls -1 offsets/[0-9A-F]* | wc -l
      60

# ls -la offsets | head
total 15795
drwx------  2 pgsql  pgsql      62 Mar 30  2014 .
drwx------  4 pgsql  pgsql       4 Dec 11  2013 ..
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0000
-rw-------  1 pgsql  pgsql  262144 Dec 11  2013 0001
-rw-------  1 pgsql  pgsql  262144 Dec 21  2013 0002
-rw-------  1 pgsql  pgsql  262144 Jan 12  2014 0003
-rw-------  1 pgsql  pgsql  262144 Jan 29  2014 0004
-rw-------  1 pgsql  pgsql  262144 Feb  6  2014 0005
-rw-------  1 pgsql  pgsql  262144 Feb  9  2014 0006

# ls -la offsets | tail
-rw-------  1 pgsql  pgsql  262144 Mar 24  2014 0032
-rw-------  1 pgsql  pgsql  262144 Mar 24  2014 0033
-rw-------  1 pgsql  pgsql  262144 Mar 25  2014 0034
-rw-------  1 pgsql  pgsql  262144 Mar 26  2014 0035
-rw-------  1 pgsql  pgsql  262144 Mar 27  2014 0036
-rw-------  1 pgsql  pgsql  262144 Mar 28  2014 0037
-rw-------  1 pgsql  pgsql  262144 Mar 28  2014 0038
-rw-------  1 pgsql  pgsql  262144 Mar 29  2014 0039
-rw-------  1 pgsql  pgsql  262144 Mar 30  2014 003A
-rw-------  1 pgsql  pgsql  172032 Jun 24 01:58 003B

As shown, only file 003B in members was recently changed.

# pg_controldata /usr/local/pgsql/logs/data

pg_control version number:            937
Catalog version number:               201306121
Database system identifier:           5896471202307701721
Database cluster state:               in production
pg_control last modified:             Thu Jun 25 14:42:42 2015
Latest checkpoint location:           26FF/685373F0
Prior checkpoint location:            26FF/680609E0
Latest checkpoint's REDO location:    26FF/680658A0
Latest checkpoint's REDO WAL file:    00000005000026FF00000068
Latest checkpoint's TimeLineID:       5
Latest checkpoint's PrevTimeLineID:   5
Latest checkpoint's full_page_writes: on
Latest checkpoint's NextXID:          1/3898164439
Latest checkpoint's NextOID:          23515628
Latest checkpoint's NextMultiXactId:  3908584
Latest checkpoint's NextMultiOffset:  46799749
Latest checkpoint's oldestXID:        3698648295
Latest checkpoint's oldestXID's DB:   131438
Latest checkpoint's oldestActiveXID:  3898164439
Latest checkpoint's oldestMultiXid:   1
Latest checkpoint's oldestMulti's DB: 131438
Time of latest checkpoint:            Thu Jun 25 14:42:39 2015
Fake LSN counter for unlogged rels:   0/1
Minimum recovery ending location:     0/0
Min recovery ending loc's timeline:   0
Backup start location:                0/0
Backup end location:                  0/0
End-of-backup record required:        no
Current wal_level setting:            hot_standby
Current max_connections setting:      500
Current max_prepared_xacts setting:   0
Current max_locks_per_xact setting:   64
Maximum data alignment:               8
Database block size:                  8192
Blocks per segment of large relation: 131072
WAL block size:                       8192
Bytes per WAL segment:                16777216
Maximum length of identifiers:        64
Maximum columns in an index:          32
Maximum size of a TOAST chunk:        1996
Date/time type storage:               64-bit integers
Float4 argument passing:              by value
Float8 argument passing:              by value
Data page checksum version:           0

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Piotr Gasidło