Specific DirectConnect servers support text and image data to varying degrees. See the DirectConnect documentation for information on text, unitext, and image support.
The server uses the length defined in the global variable @@textsize for the column length. Before issuing create table, the client application should set @@textsize to the required length by invoking set textsize.
For DirectConnect servers that support text, unitext, and image datatypes but do not support text pointers, the following restrictions apply:
The writetext command is not supported.
The readtext command is not supported.
Client-Library functions that use text pointers are not supported.
DB-Library functions that use text pointers are not supported.
For DirectConnect servers that support text, unitext, and image datatypes but do not support text pointers, some additional processing is performed to allow the following functions to be used:
patindex
char_length
datalength
If text pointers are supported, the server performs these functions by issuing an RPC to the DirectConnect server.
For DirectConnect servers that do not support text pointers, the server stores data in the sysattributes system table. Data pages are preallocated on a per column per row basis. The column size is determined by @@textsize. If this value is not sufficient an error is returned.
Specific DirectConnect servers may or may not support pattern matching against the text datatype. If a DirectConnect server does not support this pattern matching, the server copies the text value to internal data pages and performs the pattern matching internally. The best performance is seen when pattern matching is performed by the DirectConnect server.
You must use writetext, select into, or insert...select to enter text, unitext, or image values that exceed 450 bytes.
You can use select into and insert...select to insert text, unitext, or image values, but the table must have a unique index.
