Creating Indexes

The default strategy for indexes in the automatically generated relational definition is to create:

• nonclustered index on _oid for primary tables;

• nonclustered index on ( _oid, _version) for primary version tables;

• nonclustered index on _oid for non-versioned auxiliary tables (for non-versioned set-valued or list-valued attributes); and

• nonclustered index on ( _oid, _version) for versioned auxiliary tables (for versioned set-valued or list-valued attributes); and

Users can define additional indexes by specifying a class or attribute domain specific property:

       "OPM_PD_Index[.number]" "(text)"

where (text) is an SQL create index command, and the optional [.number] is a suffix in order to make each property label distinct.

If the OPM_PD_Index property is specified as a class property for object class , then the additional index is created on the primary table for . If the OPM_PD_Index property is specified as an attribute property for a set-valued or list-valued simple or tuple attribute A, then the additional index is created on the auxiliary table representing A. This property has no effect if it is defined for a single-valued attribute, a derived attribute, or a derived class.

Users can also enable or disable the default index generated on a table by specifying the following domain specific property:

       "OPM_PD_DefIndex" "on/off"

The default mode is on. If OPM_PD_DefIndex property is specified for a class, then the primary table for this class is affected. If this property is specified for a set-valued or list-valued attribute, then the corresponding auxiliary table is affected.

One can also enable or disable the default index generated on a primary version table by specifying a similar domain specific property in class definition:

       "OPM_PD_DefIndex_V" "on/off"