7. Configuring and Managing VectorH : Performance Tips : Create Indexes
Share this page                  
Create Indexes
Primary (clustered) indexes can be created for Vector tables.
Note:  VectorH does not support secondary indexes.
A clustered index (also known as a primary index in Vector) is a table organized as an index.
Use a primary index only if the table is predominantly accessed through the indexed columns. If the table is often filtered or joined only on non-indexed columns then the index will likely slow down rather than improve query performance.
Restrictions are as follows:
Create a primary index after creating the table.
Only one primary index is allowed per table.
An initial bulk load into the table is directly and efficiently written to disk. Subsequent updates are always loaded into memory first, unless the COMBINE operation (see  MODIFY...TO COMBINE Statement--Merge and Update Data) is used.
To create a primary index
Enter your CREATE INDEX statement at the terminal monitor prompt. The following example creates an index named l_idx on the l_shipdate column of the lineitem table:
CREATE INDEX l_idx ON lineitem(l_shipdate);