Client Applications

This section covers PostgreSQL client applications in contrib. They can be run from anywhere, independent of where the database server resides. See also PostgreSQL Client Applications for information about client applications that are part of the core PostgreSQL distribution.

oid2name

resolve OIDs and file nodes in a PostgreSQL data directory

Synopsis

oid2name [OPTION...]

Description

oid2name is a utility program that helps administrators to examine the file structure used by PostgreSQL. To make use of it, you need to be familiar with the database file structure, which is described in Database Physical Storage.

oid2name connects to a target database and extracts OID, filenode, and/or table name information. You can also have it show database OIDs or tablespace OIDs.

Options

oid2name accepts the following command-line arguments:

-f filenode, --filenode=filenode : show info for table with filenode filenode.

-i, --indexes : include indexes and sequences in the listing.

-o oid, --oid=oid : show info for table with OID oid.

-q, --quiet : omit headers (useful for scripting).

-s, --tablespaces : show tablespace OIDs.

-S, --system-objects : include system objects (those in information_schema, pg_toast and pg_catalog schemas).

-t tablename_pattern, --table=tablename_pattern : show info for table(s) matching tablename_pattern.

-V, --version : Print the oid2name version and exit.

-x, --extended : display more information about each object shown: tablespace name, schema name, OID and path.

-?, --help : Show help about oid2name command line arguments, and exit.

oid2name also accepts the following command-line arguments for connection parameters:

-d database, --dbname=database : database to connect to.

-h host, --host=host : database server's host.

-H host : database server's host. Use of this parameter is deprecated as of PostgreSQL 12.

-p port, --port=port : database server's port.

-U username, --username=username : user name to connect as.

To display specific tables, select which tables to show by using -o, -f and/or -t. -o takes an OID, -f takes a filenode, and -t takes a table name (actually, it's a LIKE pattern, so you can use things like foo%). You can use as many of these options as you like, and the listing will include all objects matched by any of the options. But note that these options can only show objects in the database given by -d.

If you don't give any of -o, -f or -t, but do give -d, it will list all tables in the database named by -d. In this mode, the -S and -i options control what gets listed.

If you don't give -d either, it will show a listing of database OIDs. Alternatively you can give -s to get a tablespace listing.

Environment

PGHOST, PGPORT, PGUSER : Default connection parameters.

This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Environment Variables).

The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values are always, auto and never.

Notes

oid2name requires a running database server with non-corrupt system catalogs. It is therefore of only limited use for recovering from catastrophic database corruption situations.

Examples

$ # what's in this database server, anyway?
$ oid2name
All databases:
    Oid  Database Name  Tablespace
----------------------------------
  17228       alvherre  pg_default
  17255     regression  pg_default
  17227      template0  pg_default
      1      template1  pg_default

$ oid2name -s
All tablespaces:
     Oid  Tablespace Name
-------------------------
    1663       pg_default
    1664        pg_global
  155151         fastdisk
  155152          bigdisk

$ # OK, let's look into database alvherre
$ cd $PGDATA/base/17228

$ # get top 10 db objects in the default tablespace, ordered by size
$ ls -lS * | head -10
-rw-------  1 alvherre alvherre 136536064 sep 14 09:51 155173
-rw-------  1 alvherre alvherre  17965056 sep 14 09:51 1155291
-rw-------  1 alvherre alvherre   1204224 sep 14 09:51 16717
-rw-------  1 alvherre alvherre    581632 sep  6 17:51 1255
-rw-------  1 alvherre alvherre    237568 sep 14 09:50 16674
-rw-------  1 alvherre alvherre    212992 sep 14 09:51 1249
-rw-------  1 alvherre alvherre    204800 sep 14 09:51 16684
-rw-------  1 alvherre alvherre    196608 sep 14 09:50 16700
-rw-------  1 alvherre alvherre    163840 sep 14 09:50 16699
-rw-------  1 alvherre alvherre    122880 sep  6 17:51 16751

$ # What file is 155173?
$ oid2name -d alvherre -f 155173
From database "alvherre":
  Filenode  Table Name
----------------------
    155173    accounts

$ # you can ask for more than one object
$ oid2name -d alvherre -f 155173 -f 1155291
From database "alvherre":
  Filenode     Table Name
-------------------------
    155173       accounts
   1155291  accounts_pkey

$ # you can mix the options, and get more details with -x
$ oid2name -d alvherre -t accounts -f 1155291 -x
From database "alvherre":
  Filenode     Table Name      Oid  Schema  Tablespace                Path
--------------------------------------------------------------------------
    155173       accounts   155173  public  pg_default   base/17228/155173
   1155291  accounts_pkey  1155291  public  pg_default  base/17228/1155291

$ # show disk space for every db object
$ du [0-9]* |
> while read SIZE FILENODE
> do
>   echo "$SIZE       `oid2name -q -d alvherre -i -f $FILENODE`"
> done
16            1155287  branches_pkey
16            1155289  tellers_pkey
17561            1155291  accounts_pkey
...

$ # same, but sort by size
$ du [0-9]* | sort -rn | while read SIZE FN
> do
>   echo "$SIZE   `oid2name -q -d alvherre -f $FN`"
> done
133466             155173    accounts
17561            1155291  accounts_pkey
1177              16717  pg_proc_proname_args_nsp_index
...

$ # If you want to see what's in tablespaces, use the pg_tblspc directory
$ cd $PGDATA/pg_tblspc
$ oid2name -s
All tablespaces:
     Oid  Tablespace Name
-------------------------
    1663       pg_default
    1664        pg_global
  155151         fastdisk
  155152          bigdisk

$ # what databases have objects in tablespace "fastdisk"?
$ ls -d 155151/*
155151/17228/  155151/PG_VERSION

$ # Oh, what was database 17228 again?
$ oid2name
All databases:
    Oid  Database Name  Tablespace
----------------------------------
  17228       alvherre  pg_default
  17255     regression  pg_default
  17227      template0  pg_default
      1      template1  pg_default

$ # Let's see what objects does this database have in the tablespace.
$ cd 155151/17228
$ ls -l
total 0
-rw-------  1 postgres postgres 0 sep 13 23:20 155156

$ # OK, this is a pretty small table ... but which one is it?
$ oid2name -d alvherre -f 155156
From database "alvherre":
  Filenode  Table Name
----------------------
    155156         foo

Author

B. Palmer [email protected]

vacuumlo

remove orphaned large objects from a PostgreSQL database

Synopsis

vacuumlo [OPTION...]DBNAME...

Description

vacuumlo is a simple utility program that will remove any “orphaned” large objects from a PostgreSQL database. An orphaned large object (LO) is considered to be any LO whose OID does not appear in any oid or lo data column of the database.

If you use this, you may also be interested in the lo_manage trigger in the lo module. lo_manage is useful to try to avoid creating orphaned LOs in the first place.

All databases named on the command line are processed.

Options

vacuumlo accepts the following command-line arguments:

-l limit, --limit=limit : Remove no more than limit large objects per transaction (default 1000). Since the server acquires a lock per LO removed, removing too many LOs in one transaction risks exceeding max_locks_per_transaction. Set the limit to zero if you want all removals done in a single transaction.

-n, --dry-run : Don't remove anything, just show what would be done.

-v, --verbose : Write a lot of progress messages.

-V, --version : Print the vacuumlo version and exit.

-?, --help : Show help about vacuumlo command line arguments, and exit.

vacuumlo also accepts the following command-line arguments for connection parameters:

-h host, --host=host : Database server's host.

-p port, --port=port : Database server's port.

-U username, --username=username : User name to connect as.

-w, --no-password : Never issue a password prompt. If the server requires password authentication and a password is not available by other means such as a .pgpass file, the connection attempt will fail. This option can be useful in batch jobs and scripts where no user is present to enter a password.

-W, --password : Force vacuumlo to prompt for a password before connecting to a database.

 This option is never essential, since vacuumlo will automatically prompt for a password if the server demands password authentication. However, vacuumlo will waste a connection attempt finding out that the server wants a password. In some cases it is worth typing `-W` to avoid the extra connection attempt.

Environment

PGHOST, PGPORT, PGUSER : Default connection parameters.

This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Environment Variables).

The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values are always, auto and never.

Notes

vacuumlo works by the following method: First, vacuumlo builds a temporary table which contains all of the OIDs of the large objects in the selected database. It then scans through all columns in the database that are of type oid or lo, and removes matching entries from the temporary table. (Note: Only types with these names are considered; in particular, domains over them are not considered.) The remaining entries in the temporary table identify orphaned LOs. These are removed.

Author

Peter Mount [email protected]