Database Reference
In-Depth Information
How to do it...
pg_controldata <data-directory> | grep "system identifier"
Database system identifier: 5558338346489861223
Don't use
-D
in front of the data directory name. This is the only
PostgreSQL server application where you don't need to do that.
How it works...
pg_controldata
is a PostgreSQL server application that shows the contents of a server's
control file. The control file is located within the data directory of a server, and is created at
database initialization time. Some of the information within it is updated regularly, or when
certain major events occur.
The full output of
pg_controldata
looks like the following. (The bold values are ones
that may change over time as the server runs):
pg_control version number:
851
Catalog version number:
200911051
Database system identifier:
5408338346412861210
Database cluster state:
in production
pg_control last modified:
Thu 26 Nov 2009 09:39:23
GMT
Latest checkpoint location:
0/53D8E0
Prior checkpoint location:
0/53D840
Latest checkpoint's REDO location:
0/53D8E0
Latest checkpoint's TimeLineID:
1
Latest checkpoint's NextXID:
0/649
Latest checkpoint's NextOID:
11565
Latest checkpoint's NextMultiXactId:
1
Latest checkpoint's NextMultiOffset
0
Latest checkpoint's oldestXID:
641
Latest checkpoint's oldestXID's DB:
1
Time of latest checkpoint:
Thu 26 Nov 2009 09:15:02 GMT
Minimum recovery ending location:
0/0
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
