Re: Creating an indexing policy on long columns error

The gruesome details of the LONG Datatype :-)

LONG columns store variable length character strings containing up to 2 gigabytes, or 231-1 bytes. LONG columns have many of the characteristics of VARCHAR2 columns. You can use LONG columns to store long text strings. Oracle uses LONG columns in the data dictionary to store the text of view definitions. The length of LONG values may be limited by the memory available on your computer.

You can reference LONG columns in SQL statements in these places:

SELECT lists
SET clauses of UPDATE statements
VALUES clauses of INSERT statements
The use of LONG values are subject to some restrictions:

A table cannot contain more than one LONG column. LONG columns cannot appear in integrity constraints (except for NULL and NOT NULL constraints).
LONG columns cannot be indexed.
A stored function cannot return a LONG value. Within a single SQL statement, all LONG columns, updated tables, and locked tables must be located on the same database. LONG columns cannot appear in certain parts of SQL statements:

WHERE, GROUP BY, ORDER BY, or CONNECT BY clauses or with the DISTINCT operator in SELECT statements
the UNIQUE clause of a SELECT statement the column list of a CREATE CLUSTER statement the CLUSTER clause of a CREATE SNAPSHOT statement SQL functions (such as SUBSTR or INSTR) expressions or conditions
SELECT lists of queries containing GROUP BY clauses SELECT lists of subqueries or queries combined by set operators SELECT lists of CREATE TABLE ... AS SELECT statements SELECT lists in subqueries in INSERT statements Triggers can use the LONG datatype in the following manner:

A SQL statement within a trigger can insert data into a LONG column. If data from a LONG column can be converted to a constrained datatype (such as CHAR and VARCHAR2), a LONG column can be referenced in a SQL statement within a trigger. Note that the maximum length for these datatypes is 32K. Variables in triggers cannot be declared using the LONG datatype. :NEW and :OLD cannot be used with LONG columns. You can use the Oracle Call Interface functions to retrieve a portion of a LONG value from the database. See Oracle Call Interface Programmer's Guide.

Paul in VT Received on Thu Jun 24 1999 - 14:18:12 CDT