systabnames & partnum

Posted in 2006

in4mixDBA — 26 Jul 2006 11:28:45 -0700 — source: Usenet: comp.databases.informix

Hello... I am new to this group... as well as a new informix DBA... I was wondering if there is anyway for me to know is the partnum column from table systabnames in the sysmaster database is a unique column. I checked my database and it is unique. Is there any documentation on this so that I can be assured that it will always be unique? Thank you, Any help would be great, --in4mixDBA

↪ replying to in4mixDBA

bozon — 26 Jul 2006 13:26:59 -0700 — source: Usenet: comp.databases.informix

It will be unique in systabnames but if a table is fragmented then in the systables table in the user databases will be 0 and you will have to look at the sysfragments table. So, in systabnames the same table name (different parts of the fragmented table) will have different part numbers. in4mixDBA wrote: > Hello... I am new to this group... as well as a new informix DBA... > > I was wondering if there is anyway for me to know is the partnum column > from table systabnames in the sysmaster database is a unique column. > > I checked my database and it is unique. Is there any documentation on > this so that I can be assured that it will always be unique? > > Thank you, > > Any help would be great, > > --in4mixDBA

↪ replying to in4mixDBA

Art S. Kagel — Wed, 26 Jul 2006 17:13:05 -0400 — source: Usenet: comp.databases.informix

in4mixDBA wrote: > Hello... I am new to this group... as well as a new informix DBA... > > I was wondering if there is anyway for me to know is the partnum column > from table systabnames in the sysmaster database is a unique column. > > I checked my database and it is unique. Is there any documentation on > this so that I can be assured that it will always be unique? In order to understand the partnum, you have to understand what the partnum in systabnames represents. Each entry in systabnames is a table, index, or a fragment of a table or index in some database (there are exceptions, representing smart large objects independent of a database, but the rest of the discussion holds for these server objects as well). These objects are cumulatively known as partitions. Every partition has a single on-disk data structure known as it Tablespace Tablespace or partition header page. No two objects can share a partition header page. The physical address of that page is the partition's partnum, literally its "partition number". So, naturally, this is a unique address. Art S. Kagel