This gives a solution to the common limitation of maximum file size of 2 Gb in most 32-bit UNIX systems. From here, we'll refer to ``the table'' as the set of physical files that are necessary for data storage plus their associated indexes.
The default type of table is packed. To change the type of table used, see ``Changing Table Types'' .
sche.tab<tab>definition sche.tab<tab>definition . . .where
The syntax for the PACKED definition is the following:
The following is an example of how the table layout of a given schema
can be specified:
schema.$*<tab>PACKED<tab>/usr/tabsdsc
If the `.sv' file has the following line for schema definition
If the schema whose table types are going to be changed is no empty, you will
have to export its data first, and then make a clear table opration before
the shutdown. Then, after the startup, you will have to perform an
import operation to restore the data.
The steps necessary to change a table's type, the steps can be summarized as
follows:
Example
aurus.$*<tab>PACKED<tab>/disk1/dbess/
aurus.cbtes<tab>RANGED<tab>/disk2/dbess/:1M,/disk3/dbess/
aurus.astos<tab>roundrobin<tab>2k<tab>/disk2/dbess,disk3/dbess/
aurus.*<tab>PACKED<tab>/disk1/dbess/
The contents of this file mean the following:
where schema identifies the desired schema of the server, and $*
identifies all the schema description tables of the schema.
NOTE: if a table type is defined twice, Essentia will consider
only the first definition.Compatibility with Previous Versions
When a table of Essentia 3.3 or lower is used with Ess
entia 3.3.1, Essentia will automatically create a layout description file using
the information in the `.sv' file. For this conversion to happen automatically,
the DiskConfiguration entry will have to be set correctly in the configuration file.
Example
Schemas<tab>sch1:dir_sch1:id_sch1,sch2,dir_sch2:id_sch2
The physical layout file Essentia will generate will be:
sch1.$*<tab>PACKED<tab>dir_sch1
sch1.*<tab>PACKED<tab>dir_sch1
sch2.$*<tab>PACKED<tab>dir_sch2
sch2.*<tab>PACKED<tab>dir_sch2
and the Schemas line will be converted to the Essentia 3.3.1 format,
as follows:
Schemas<tab>sch1:id_sch1,sch2:id_sch2
Creating New Schemas
For the creation of a new schema, Essentia still uses the contents of the
Dbase line of the `.sv' file. When a new schema apepars in this line,
Essentia will automatically generate new entries in the physical layout
file and in the Schemas line.
Changing Table Types
If you want to change a table type especification, you have to shutdown
the server before making any change. Then you can modify the physical layout
file to the desired configuration.