Adaptive Server configuration allows page sizes of 2K, 4K, 8K, or 16K bytes. Also, the limit of 255 bytes for char/binary columns has been removed. Adaptive Server supports extended sizes of char, varchar, binary, and varbinary datatypes. The new limit depends on the page size of the server. For various page sizes, the new limits are as follows:
Page size |
Maximum column size |
|---|---|
2048 |
2048 |
4096 |
4096 |
8192 |
8192 |
16384 |
16384 |
These sizes are 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 allpages 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 – as many as 1024 columns per table are allowed, as long as the columns can still fit on a page. 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 version 12.5 can be larger than in earlier version, depending on server page size. In Table 2-2, maximum index width is shown according to page size:
Page size |
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 is unchanged in version 12.5.
