The cego database stores the most relevant configuration information in a single XML file. Before creating any tablesets for the database, this file must be setup.

Please note : The novice user never should edit the xml file manually, rather it is modified via database console or admin console client commands. Later on, specific database parameters can be configured manually by the advanced user. This requires an understanding of the file structure, so this chapter gives an introduction to it.

3.1   General attributes

The xml file starts with the standard header version declaration and is defined with the document type CEGO_DB_CONFIG

<?xml version="1.0"?>
<!DOCTYPE CEGO_DB_CONFIG>

This declaration is followed by a root element tag called DATABASE. Several attributes for the database tag are used to define general tableset independent database parameters. In the following, a table is given for the description of the available parameters.

For example, a configuration file might look like

<?xml version="1.0"?>
<!DOCTYPE CEGO_DB_CONFIG>
<DATABASE NAME="cegodb" PAGESIZE="4096" ADMINPORT="2000" LOGPORT="3000" DBPORT="2200">
...
</DATABASE>

3.2   User entries

All database users are also stored in the configuration file. Database users are described with the following attributes.

Here we give a sample user entry

...
<USER NAME="lemke" PASSWD="da00df214a29217555a08a7cf890d1b8" TRACE="OFF" ROLE="ALL"></USER>
...

3.3   Role entries

Roles are used by the database to restrict data access for the users. Database roles can be created and assigned by the database administrator. See the role management section for a more detailed description.

Roles are identified by its unique name.

Any access right of a role are described with permission entries. Permission entries are subtags inside the role tag with the following attributes

A sample role entry can look like

...
<ROLE NAME="ALL">  <PERM TABLESET="lit" FILTER="ALL" PERM="ALL" PERMID="lit_P"></PERM>
</ROLE>
...

3.4   Date format entries

For date scanning, a list of formats can be specified using the DATETIMEFORMAT tag. Setting up the VALUE attribute for each element specifies the format. Several dateformat entries can be defined.

Sample:

...
<DATETIMEFORMAT VALUE="%d.%m.%Y %H:%M:%S"/>
<DATETIMEFORMAT VALUE="%d.%m.%Y"/>
<DATETIMEFORMAT VALUE="%Y%m%d"/>
 ...

3.5   Node entries

If cego operates in distributed mode, all known hosts are registered in the xml file. Since for each node a health checking is performed, the status of the corresponding host is stored to the status attribute. The xml tag has the following form

...
 <NODE HOSTNAME="dude.local" STATUS="ONLINE"> </NODE>
 ...

3.6   Tableset entries

A cego database can contain several tableset configurations. A tableset is a set of database objects with a dedicated transaction and log management.

As subtags of the DATABASE tag, several XML tags of name TABLESET can be used to specify tablesets. A Cego tableset contains all required information to ensure a transaction based query handling. So each of these components must be described in the tableset section

Sample:

...
<TABLESET NAME="TS1" TSROOT="/usr/local/cegodb" TSID="1" TMPFID="10" SYSSIZE="200" TMPSIZE="200" LSN="26"
PRIMARY="geek" SECONDARY="geek" MEDIATOR="geek">
...
<TABLESET>

3.6.1   System files

Each tablesets object information is stored in a tableset dictionary. For this, the tableset system file is used.

Temporary information is stored the the tableset temp space. This space is mainly used for transaction rollback information and sort areas.

Please note, that the size attribute for system and temp space is based on database page units.

3.6.2   Data files

Depending on the size of the database, an appropriate number of datafiles should be defined. Once a datafile is created, it can not be resized. To increase the database, a new database must be added. After initial creation of the database, datafiles are added using one of the the Cego administration utilities. See the corresponding datafile expansion section for more information.

At creation time, any number of datafiles can be defined. Using the DATAFILE subtag entries beyond the TABLESET tag, datafiles are described.

Tag attributes for datafiles are

Sample:

...
<DATAFILE TYPE="APP" FILEID="11" NAME="./data11.dbf" SIZE="1000"> </DATAFILE>
...

3.6.3   Log files

Database logfiles are used to store query information for any modification queries ( create, insert, update, delete ). Logfiles have fixed sizes and they are written sequentially in a cyclic way. This means, if the end of one logfile has reached a logfile switch to the next defined logfile is done. At this time, the bufferpool is synched to the datafiles and the current written log entry number is written as LSN value to the XML-file Furthermore, if a logfile is completely written and archive mode is enabled, the logfile is released for backup in the offline log area. See section Archive log mode for more information how to enable log mode. At creation time, the number of ( online ) redolog files must be defined. Tag attributes for logfiles are

Sample:

...
<LOGFILE NAME="./redolog11.log" SIZE="300000" STATUS="ACTIVE"> </LOGFILE>
...

3.6.4   Counters

Tableset counters can be used to manage any kind of unique identifiers, which are used for the data tables. For performance reasons, counters are also stored to the database xml file in the following manner

Sample:

...
<COUNTER NAME="userid" VALUE="4711" </COUNTER>
...