Database Objects

The following table specifies the maximum size limitations for several database objects defined in Microsoft SQL Server 2005 Compact Edition (SQL Server Compact Edition) databases.

Category Object Maximum size limitations

Storage

Column name

128 characters

 

Columns in a table

1024

Row size

8060 bytes

 

Database password

40 characters

 

Database size

4 GB 1

 

Database size increase

1-page or 16-page increments, depending on table size

 

Page size

4 KB

 

Sessions

256

 

Size of BLOB (ntext and image) column

2 GB

 

Table name

128 characters

 

Table size

Unlimited

Queries

Characters in an SQL statement

Unlimited

 

Columns in a cursor

1024

 

Columns in an ORDER BY, GROUP BY, or DISTINCT clause

10242

 

Levels of nested subqueries

Unlimited

 

Named parameters

Supported

 

Operands in a query

Unlimited

 

Tables in a join

Unlimited

Indexes

BLOB columns

Cannot be indexed

 

Bytes in an index key

5123

 

Columns in an index

16

 

Indexes per table

249

Constraints

PRIMARY KEY, UNIQUE, Default constraints, and FOREIGN KEY

Supported 4

Constraints per table

249

1The default maximum size is 128 MB.

2This limit is applied only if a storage engine temporary table is used for implementing ORDER BY. If the Query Processor can leverage an existing index, there is no maximum column-number limit.

3 Longer keys are supported, but the data is truncated and a checksum is added at the end. For equivalence operations, this works fine (unless two checksums happen to be the same). This becomes a concern when using an ORDER BY clause. The ordering beyond the key length is returned based on the checksum and not the actual value.

4For every PRIMARY KEY and UNIQUE constraint defined on a table, an index is created on those columns. These indexes all count against the total number of indexes allowed for a table. Also, some data types (ntext, image) cannot be used as primary key columns because they cannot be indexed