GT.M databases consist of one or more UNIX files. Most database files have a UNIX file structure externally and a GT.M Database Structure (GDS) internally. Management of the GDS files by the GT.M run-time system assures high performance and integrity. GT.M database files are coordinated by a Global Directory. The Global Directory identifies which global names belong in which files, and specifies the creation characteristics for each file. To specify access to a database, each M process must define the gtmgbldir environment variable to point to the associated Global Directory.
To define and maintain a Global Directory, use the Global Directory Editor (GDE) utility. The GDE utility automatically upgrades existing global directories to the current format. The MUPIP command CREATE uses the characteristics as defined in the Global Directory to create the associated database. In a production environment, the system manager typically maintains Global Directories.
For more information on GDE and MUPIP refer to the "Global Directory Editor" and "MUPIP" chapters in the GT.M Administration and Operations Guide.
Example:
This example is a sequence of events that illustrate steps you might typically perform in creating a new global directory, in our example PAYROLL.GLD. To assist you in following the sequence, each actual step appears in typewriter font, as you might see on your terminal screen, followed by an explanation in normal text font.
$ ls payroll.gld payroll.gld not found
The ls command verifies that there are no existing files with the name payroll.gld.
$ gtmgbldir=payroll.gld $ export gtmgbldir
This establishes the current value of the environment variable gtmgbldir as payroll.gld. GT.M uses gtmgbldir to identify the current Global Directory. When defined at the shell prompt, gtmgbldir maintains the defined value only for the current login session. The next time you log into UNIX, you must again define the value of gtmgbldir as payroll.gld to use it as the current Global Directory.
This example defines gtmgbldir without a full pathname. The environment variable points to the payroll.gld file in the current working directory. Therefore if the default directory changes, GT.M attempts to locate the Global Directory in the new default directory and cannot use the original file. If you intend for the Global Directory to consistently point to this file, even if the default directory changes, use a full file-specification for gtmgbldir.
$ /usr/lib/fis-gtm/V6.0-0001_x86/gtm
GTM>do ^GDE
%GDE-I-LOADGD, Loading Global Directory file
/home/jdoe/.fis-gtm/V6.0-001_x86/g/payroll.gld
%GDE-I-VERIFY, Verification OK
GDE>
This invokes the Global Directory Editor by entering GDE from the GT.M prompt and produces an informational message.
GDE> show -all
*** TEMPLATES ***
Def Rec Key Null Standard
Region Coll Size Size Subs NullColl Journaling
--------------------------------------------------------------------------------------------
<default> 0 4080 255 NEVER Y Y
Jnl File (def ext: .mjl) Before Buff Alloc Exten
------------------------------------------------------------------------------
<default> <based on DB file-spec> Y 128 2048 2048
Segment Active Acc Typ Block Alloc Exten Options
------------------------------------------------------------------------------
<default> * BG DYN 4096 5000 10000 GLOB =1000
LOCK = 40
RES = 0
ENCR = OFF
<default> MM DYN 4096 5000 10000 DEFER
LOCK = 40
*** NAMES ***
Global Region
------------------------------------------------------------------------------
* DEFAULT
*** REGIONS ***
Dynamic Def Rec Key Null Standard
Region Segment Coll Size Size Subs NullColl Journaling
------------------------------------------------------------------------------------------------------------------
DEFAULT DEFAULT 0 4080 255 NEVER Y Y
*** JOURNALING INFORMATION ***
Region Jnl File (def ext: .mjl) Before Buff Alloc Exten
---------------------------------------------------------------------------------------
DEFAULT $gtmdir/$gtmver/g/payroll.mjl
Y 128 2048 2048
*** SEGMENTS ***
Segment File (def ext: .dat)Acc Typ Block Alloc Exten Options
-------------------------------------------------------------------------------------------
DEFAULT $gtmdir/$gtmver/g/dayroll.dat
BG DYN 4096 5000 10000 GLOB=1000
LOCK= 40
RES = 0
ENCR=OFF
*** MAP ***
- - - - - - - - - - Names - - - - - - - - - -
From Up to Region / Segment / File(def ext: .dat)
-----------------------------------------------------------------------------------------------------------------------------------
% ... REG = DEFAULT
SEG = DEFAULT
FILE = $gtmdir/$gtmver/g/payroll.dat
LOCAL LOCKS REG = DEFAULT
SEG = DEFAULT
FILE = $gtmdir/$gtmver/g/payroll.dat
The GDE SHOW command displays the default Global Directory.
GDE> change -segment default -allocation=1000 file=payroll.dat
The GDE CHANGE command sets the database file name to payroll.dat, and specifies a file size of 1000 blocks (of 1024 bytes).
GDE>exit %GDE-I-VERIFY, Verification OK %GDE-I-GDCREATE, Creating Global Directory file /usr/lib/fis-gtm/V6.0-001_x86/payroll.gld %GDE-I-GDEIS, Global Directory
The GDE EXIT command terminates GDE. The Global Directory Editor creates a default Global Directory and displays a confirmation message.
$ ls payroll.gld payroll.gld
This ls command shows the new Global Directory has been created.
In the simplest case, running the Global Directory Editor and immediately EXITing creates a Global Directory with a default single file database.
To create the database file payroll.dat, use the GT.M MUPIP CREATE utility.
Example:
$ mupip create Created file payroll.dat
The MUPIP CREATE command generates the database file. Notice that the MUPIP CREATE syntax does not include the file name. MUPIP uses the environment variable gtmgbldir to find the Global Directory payroll.dat and obtains the file name from that Global Directory. MUPIP then checks to make sure that payroll.dat does not already exist and creates payroll.dat with the characteristics described in payroll.dat.
Example:
$ mupip load payroll.gld GT.M MUPIP EXTRACT 02-MAY-2013 22:21:37 ZWR Beginning LOAD at record number: 3 LOAD TOTAL Key Cnt: 279 Max Subsc Len: 28 Max Data Len: 222 Last LOAD record number: 281
This uses the MUPIP LOAD command to load a sequential file into the database.
Because MUPIP uses the environment variable gtmgbldir to locate a Global Directory, which identifies the database file(s), the LOAD command does not require any information about the target database. With few exceptions, the GT.M utilities work in the same way.