New server limits

Limits on length of char, varchar, binary and varbinary datatypes - In version 12.5 as in prior releases of Adaptive Server Enterprise, a row cannot span page boundaries, therefore column size has been limited by row size. However, in version 12.5 of Adaptive Server Enterprise, configuration allows page sizes of 2K, 4K, 8K or 16K bytes. Also, the arbitrary limit of 255 bytes for char/binary columns has been removed. The version 12.5 supports extended sizes of char, varchar, binary and varbinary data types. The new limit depends on the page size of the server. For various page sizes, the new limits are as follows:

**Table 2-1: New Limits**
Pagesize	Max. Column Size
2048	2048
4096	4096
8192	8192
16384	16384

Note that these sizes are still approximate. The basic rule specifies that the limit is the maximum size that still allows a single row to fit on a page. These limits also vary depending on the locking scheme specified when the table is created. It is assumed that the bulk of proxy tables are created with the default locking scheme, which is all page locking.

Limits on length of Transact-SQL variables and parameters - the size of char, varchar, binary and varbinary variables are extended to equal the maximum size of columns of the same datatype for a given server. This allows variables to be passed to stored procedures (or RPCs) whose length exceeds the current limit of 255 bytes.
Limits on number of columns per table- the old limit of 250 are removed, and up to 1024 columns per table are allowed, as long as the columns can still fit on a page. Note that there is a limit of 254 variable length columns (null columns are also considered variable length).
Limits on the width of an index - the total width of an index within Adaptive Server Enterprise can be larger than in prior releases, depending on server page size. In the following table, maximum index width is shown according to pagesize:

**Table 2-2: Maximum Index Width**
Pagesize	Index Width
2048	600
4096	1250
8192	2600
16384	5300

Limits on the number of columns per index - the current limit of 31 columns per index are unchanged in version 12.5.

What these changes mean to CIS and remote servers CIS connects to is described in the following sections.