This utility allows administrators to examine the file structure used byPostgreSQL.  To make use of it, you need to be familiar with the filestructure, which is described in the "Database File Layout" chapter ofthe "Internals" section of the PostgreSQL documentation.Oid2name connects to the database and extracts OID, filenode, and tablename information.  You can also have it show database OIDs and tablespaceOIDs.When displaying specific tables, you can select which tables to show byusing -o, -f and -t.  The first switch takes an OID, the second takesa filenode, and the third takes a tablename (actually, it's a LIKEpattern, so you can use things like "foo%").  Note that you can use as manyof these switches as you like, and the listing will include all objectsmatched by any of the switches.  Also note that these switches can onlyshow objects in the database given in -d.If you don't give any of -o, -f or -t it will dump all the tables in thedatabase given in -d.  If you don't give -d, it will show a databaselisting.  Alternatively you can give -s to get a tablespace listing.Additional switches:	-i	include indexes and sequences in the database listing.	-x	display more information about each object shown:		tablespace name, schema name, OID.	-S	also show system objects		(those in information_schema, pg_toast and pg_catalog schemas)	-q	don't display headers		(useful for scripting)---------------------------------------------------------------------------Sample session:$ oid2nameAll databases:    Oid  Database Name  Tablespace----------------------------------  17228       alvherre  pg_default  17255     regression  pg_default  17227      template0  pg_default      1      template1  pg_default$ oid2name -sAll tablespaces:     Oid  Tablespace Name-------------------------    1663       pg_default    1664        pg_global  155151         fastdisk  155152          bigdisk$ cd $PGDATA/17228$ # 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$ oid2name -d alvherre -f 155173From database "alvherre":  Filenode  Table Name----------------------    155173    accounts$ # you can ask for more than one object$ oid2name -d alvherre -f 155173 -f 1155291From database "alvherre":  Filenode     Table Name-------------------------    155173       accounts   1155291  accounts_pkey$ # you can also mix the options, and have more details$ oid2name -d alvherre -t accounts -f 1155291 -xFrom database "alvherre":  Filenode     Table Name      Oid  Schema  Tablespace------------------------------------------------------    155173       accounts   155173  public  pg_default   1155291  accounts_pkey  1155291  public  pg_default$ # show disk space for every db object$ du [0-9]* |> while read SIZE FILENODE> do>   echo "$SIZE       `oid2name -q -d alvherre -i -f $FILENODE`"> done16 	   1155287  branches_pkey16 	   1155289  tellers_pkey17561 	   1155291  accounts_pkey...$ # same, but sort by size$ du [0-9]* | sort -rn | while read SIZE FN> do>   echo "$SIZE   `oid2name -q -d alvherre -f $FN`"> done133466 	    155173    accounts17561 	   1155291  accounts_pkey1177 	     16717  pg_proc_proname_args_nsp_index...$ # If you want to see what's in tablespaces, use the pg_tblspc directory$ cd $PGDATA/pg_tblspc$ oid2name -sAll 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 -ltotal 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 155156From database "alvherre":  Filenode  Table Name----------------------    155156         foo$ # end of sample session.---------------------------------------------------------------------------You can also get approximate size data for each object using psql.  Forexample,SELECT relpages, relfilenode, relname FROM pg_class ORDER BY relpages DESC;Each page is typically 8k.  Relpages is updated by VACUUM.---------------------------------------------------------------------------Mail me with any problems or additions you would like to see.  Clearing house for the code will be at:  http://www.crimelabs.netb. palmer, bpalmer@crimelabs.net