Use the image datatype to store larger blocks of binary data on external data pages. An image column can store up to 2,147,483,647 bytes of data on linked lists of data pages separate from other data storage for the table.
When you initialize an image column with a non-null insert or update, Adaptive Server assigns a text pointer and allocates an entire 2K data page to hold the value. Each page stores a maximum of 1800 bytes.
To save storage space, define image columns as NULL. To add image data without saving large blocks of binary data in your transaction log, use writetext. See the Reference Manual for details on writetext.
You cannot use the image datatype:
For parameters to stored procedures, as values passed to these parameters, or for local variables
For parameters to remote procedure calls (RPCs)
In order by, compute, group by, or union clauses
In an index
In subqueries or joins
In a where clause, except with the keyword like
With the + concatenation operator
In the if update clause of a trigger
If you are using databases connected with Component Integration Services, there are several differences in the way image datatypes are handled. See the Component Integration Services User’s Guide for more information.
For more information about the image datatype, see “Changing text, unitext, and image data”.
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