%META:TOPICINFO{author="ChrisBartram" date="1170468925" format="1.1" version="1.2"}%
%META:TOPICPARENT{name="Hp3000ImageSql"}%
---+ What are these new files that appear on my (MPE/iX or XL) system related to my database? (basenameGB and basenameTC)

  {basename}GB - Created when the database is opened in batch or online. Some concern because the file is released.

  {basename}TC - Permanent file.

The {basename}GB file is in actual fact the MPE/iX replacement for the DBB and DBG buffers of yore (MPE/V and IMAGE/V on MPE/XL) It is created when the first user accesses the database and purged when the last user closes the database. The buffer settings in DBUTIL have no effect on the size of this file. 

The {basename}TC is a file that is created at ATTACH time. It is a small file and each record contains the name of the DBE to which the DB is attached. When the last DETACH is performed for that base, the TC file disappears. 

There is also an ATCINFO file associated with the DBE that gets created at ATTACH time. 

  --[[DenysBeauchemin]]

<pre>
Note about Allbase (IMAGE/SQL) files      
------------------------------------

I hope this clears up the confusion concerning
DBECon,DBEFiles,DBEFileSets etc..

An Allbase DBE consists of three types of file:

   DBECon   One only. This contains Allbase
            startup parms such as logging
            and other various controls

   DBEFiles From one to thousands
            User data is kept here

   DBELogs  For logging activity for recovery
            and auditing
</pre>

!DBEFiles are collected together to form "!DBEFileSets" There is no IMAGE counterpart to the "!DBEFileSet", and is best imagined as a bunch of OSFiles grouped under a single heading. It is a "Set of D!BEFiles", or !DBEFileSet. 

There may be many !DBEFileSets created in an Allbase DBE. Remenber, a !DBEFileSet is a logical thing, not physical 

When an "Allbase native" table is created, its storage is allocated to a !DBEFileSet, and not a single OS file which is the case when allocating a dataset to a file under turboimage. (IMAGE/SQL tables do not have any storage allocated to them out of ALLBASE !DBEFileSet space, just a few rows in the Allbase system catalog used to describe it) 

The Allbase Table may then grow to fill all !DBEFiles in a !DBEFileSet, at which point you may wish to increase the space you want made available to it by "increasing the capacity of the !DBEFileSet". You do this simply by creating another !DBEFile, then adding it to that !DBEFileSet. Additionally, you do not have to allocate all the storage up front; you are able to create a !DBFile with an initial allocation, an increment size and max size, Allbase will expand the file, by increment, when required. 

A !DBEFileSet may have just one or many tables assigned to it. 

The Allbase system catalog (where image "table" and view definitions are kept) resides in a !DBEFileSet called the SYSTEM !DBEFileSet, and always includes the first !DBEFile ever created (when the DBE is created in fact). The first file is called "DBEFLE0"....the same file as mentioned in previous postings to this thread. 

The DBA would normally (and is recommended to) create other !DBEFileSets having DBFiles to contain "user" data. This is because the SYSTEM !DBEFileSet is the default location for temp tables used for results and sorting, etc. It is therefore important to keep contention on SYSTEM !DBFiles as low as possible. There are other methods of controlling the allocation of, and contention for "SYSTEM" space such as defining tempspaces and moving stored sections etc, but are beyond this thread. 


  --[[MikeWhitely]]


-- Main.ChrisBartram - 18 May 2006