Why only some files have fsm and vm extensions - Mailing list pgsql-novice

Hallo,

  I am beginning to read the internals of Postgres , got curious and looked at the actual files .

I learnt that FSM contains the Space map and vm the visibility map for a given table.

1. Why only some tables have it and others do not?
2. Why for some tables fsm is bigger than the table itself?

Not all the tables without fsm and vm are 0 bytes . There are tables that are non zero but do not have fsm and vm.

Thank you in advance for your time.

LG

Ram

-rw-------. 1 postgres postgres 24576 May 18 09:40 1261_fsm

-rw-------. 1 postgres postgres  8192 May 18 09:40 1261_vm

-rw-------. 1 postgres postgres  8192 May 18 09:40 1262

-rw-------. 1 postgres postgres 24576 May 18 09:40 1262_fsm

-rw-------. 1 postgres postgres  8192 May 18 09:40 1262_vm

-rw-------. 1 postgres postgres  8192 May 18 09:40 2396

-rw-------. 1 postgres postgres 24576 May 18 09:40 2396_fsm

-rw-------. 1 postgres postgres  8192 May 18 09:40 2396_vm

postgres@lx90177:/var/lib/pgsql/AUFGABEN-VERWAL/data/global$ ls

1213      1214_fsm  1260      1261_fsm  1262_vm   2397  2677  2698  2965  3593  4176  4182  4186  6100  6244  6302             pg_internal.init

1213_fsm  1214_vm   1260_fsm  1261_vm   2396      2671  2694  2846  2966  4060  4177  4183  6000  6114  6245  6303

1213_vm   1232      1260_vm   1262      2396_fsm  2672  2695  2847  2967  4061  4178  4184  6001  6115  6246  pg_control

1214      1233      1261      1262_fsm  2396_vm   2676  2697  2964  3592  4175  4181  4185  6002  6243  6247  pg_filenode.map