Glossary

• A legacy Omnidex datatype name that is now referred to “String”. A datatype in Omnidex that refers to a string terminated with a null just like strings in the C language. C Strings are used as a return data type from many Omnidex SQL Functions. C Strings are recommended over the Varchar datatype because of internal performance.

• A term indicating the number of unique values in a column or the number of rows in a table.

• With respect to databases, there are two distinct types of cardinality: table cardinality and column cardinality.

• Table cardinality is the number of rows in a table.
• Column cardinality is the number of unique values in a column.

• Omnidex uses these values to determine the best method to use to process a query against multiple tables.

The products table is a parent table with a primary key that has a column cardinality of 10,000. This means it has 10,000 unique product codes.

The orders table is a child table with 10,000,000 rows. This means it has a table cardinality of 10,000,000.

  SELECT O.PRODUCT_CODE, O.CUSTOMER_NO, O.STATUS 
      FROM PRODUCTS P, ORDERS O 
      WHERE P.PRODUCT_CODE=O.PRODUCT_CODE 
      AND P.PRODUCT_NAME = 'PRINTER'

• A dataset consisting of every possible combination of rows from mulitple tables.

For example: Customers is the parent table and activity and orders are the child tables. Selecting from both the activity and orders table for a particular customer will produce a cartesian product. Meaning, every row in the activity table will be qualified with every row in the orders table. If activity has 10 rows for one customer and orders has 10 rows for the same customer, the cartesian product is 100 rows. table1 (t1) contains 2 rows (r1, r2) and table2 (t2) contains 3 rows (r1, r2, r3). The cartesian product or these tables contains 6 rows: t1r1-t2r1, t1r1-t2r1, t1r1-t2r3, t1r2-t2r1, t1r2-t2r2, t1r2-t2r3.

• A list containing data elements where each data element has a pointer to the previous and successive data element. See also: linked list

• A child table or detail data set.

• A column or field in a child table that identifies rows in the table containing the same values; also known as a repeating key. See also: key

• A table subordinate to a parent table or master data set.
• A table where several rows may share the same identifying value for any given column.

• Child rows are not usually uniquely identifiable by the contents of a single field.

There is a one-to-many relationship between the parent table and the child table.

• The user interface aspect of a client/server system, usually a personal computer or small computer workstation dedicated to immediate, local user interactions, such as system navigation and help, rather than widely accessed or centralized computational activity, such as data processing.

• A distributed technology approach, or system, where computer processing is divided by function to take advantage of processing on multiple computer units, dividing tasks between client activities and server activities. See client and server.

• Data represented by codes instead of actual data values, used by data warehouses to conserve data storage space, e.g., income ranges represented by a single character.

• A logical representation of a field in individual rows for a given table or view. A column defines a set of fields that share the same data and the same position (offset and length) for any given row in a table.

• The number of unique values in a column. See also: cardinality, table cardinality

• A type of Omnidex index that lets you index data from either a part or a combination of parts of columns, or entire columns (one or more items from a field). You can create composite indexes in DBINSTAL during Omnidex installation. See also: composite keys

• A logical MDK or ASK field comprised of several fields or parts of fields. See also: composite index

• A direct link between the application and an environment catalog.

• A computer program, typically ODBC-compliant, that processes data extracted from a database.

• Generic applications such as Microsoft Excel, Seagate's Crystal Reports and Brio's BrioQuery, that make generic calls through ODBC to a database.

• Applications that work with a database through an ODBC driver.

• A count of the number of rows qualified for the current set of criteria. This count differs from the qualifying count which returns the total number of rows qualified when the rows found in the current search are merged with the rows in the qualified subset. This applies to oaqualify and the SQL extended command, QUALIFY.

• A working area that defines the current position of a process in an open environment.

• In OmniAccess, cursors are established by a call to oaopencursor, and closed by a call to oaclosecursor. They are referenced through the cursor option as an integer value in calls to OmniAccess routines.

• In ODBC and JDBC, cursors are created with statement objects.

• See Also $CONTAINS