public inbox for pgsql-novice@postgresql.org  
help / color / mirror / Atom feed
Why only some files have  fsm and vm extensions
2+ messages / 2 participants
[nested] [flat]

* Why only some files have  fsm and vm extensions
@ 2026-05-20 09:48 Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
  2026-05-20 12:51 ` Re: Why only some files have  fsm and vm extensions Laurenz Albe <laurenz.albe@cybertec.at>
  0 siblings, 1 reply; 2+ messages in thread

From: Subramanian,Ramachandran @ 2026-05-20 09:48 UTC (permalink / raw)
  To: pgsql-novice@lists.postgresql.org <pgsql-novice@lists.postgresql.org>

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


Freundliche Grüße

i. A. Ramachandran Subramanian
Zentralbereich Informationstechnologie

Alte Leipziger Lebensversicherung a.G.


Hallesche Krankenversicherung a.G.





Alte Leipziger Lebensversicherung a.G., Alte Leipziger-Platz 1, 61440 Oberursel
Vors. des Aufsichtsrats: Dr. Walter Botermann · Vorstand: Christoph Bohn (Vors.), Dr. Jürgen Bierbaum (stv. Vors.), Frank Kettnaker, Dr. Jochen Kriegmeier, Alexander Mayer, Christian Pape, Wiltrud Pekarek, Udo Wilcsek
Sitz Oberursel (Taunus) · Rechtsform VVaG · Amtsgericht Bad Homburg v. d. H. HRB 1583 · USt.-IdNr. DE 114106814





 
Hallesche Krankenversicherung a.G.,  Löffelstraße 34-38, 70597 Stuttgart
Vors. des Aufsichtsrats: Dr. Walter Botermann · Vorstand: Christoph Bohn (Vors.), Dr. Jürgen Bierbaum (stv. Vors.), Frank Kettnaker, Dr. Jochen Kriegmeier, Alexander Mayer, Christian Pape,
Wiltrud Pekarek, Udo Wilcsek
Sitz Stuttgart · Rechtsform VVaG · Amtsgericht Stuttgart HRB 2686 · USt.-IdNr. DE 147802285
Beiträge zu privaten Kranken- und Pflegekrankenversicherungen unterliegen nicht der Versicherungsteuer (§ 4 Nr. 5 VersStG) · Versicherungsleistungen sowie Umsätze aus Versicherungsvertreter-/Maklertätigkeiten sind umsatzsteuerfrei
 



 
Die Pflichtangaben der ALH Gruppe gemäß § 35a GmbHG bzw. § 80 AktG finden Sie hier: https://www.alte-leipziger.de/impressum 





______________________

ALH Gruppe
Alte Leipziger-Platz 1, 61440 Oberursel
Tel.: +49 (6171) 66-4882
Fax: +49 (6171) 66-800-4882
E-Mail: ramachandran.subramanian@alte-leipziger.de
www.alte-leipziger.de
www.hallesche.de



^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: Why only some files have  fsm and vm extensions
  2026-05-20 09:48 Why only some files have  fsm and vm extensions Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
@ 2026-05-20 12:51 ` Laurenz Albe <laurenz.albe@cybertec.at>
  0 siblings, 0 replies; 2+ messages in thread

From: Laurenz Albe @ 2026-05-20 12:51 UTC (permalink / raw)
  To: Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>; pgsql-novice@lists.postgresql.org <pgsql-novice@lists.postgresql.org>

On Wed, 2026-05-20 at 09:48 +0000, Subramanian,Ramachandran wrote:
> 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?

The ones that don't have these files have never been processed by VACUUM.

>    2. Why for some tables fsm is bigger than the table itself?

Because the tables are very small.

Yours,
Laurenz Albe






^ permalink  raw  reply  [nested|flat] 2+ messages in thread


end of thread, other threads:[~2026-05-20 12:51 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2026-05-20 09:48 Why only some files have  fsm and vm extensions Subramanian,Ramachandran <ramachandran.subramanian@alte-leipziger.de>
2026-05-20 12:51 ` Laurenz Albe <laurenz.albe@cybertec.at>

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox