A.3 Logical Database Limits

This table describes limit types and limit values for logical database items.

Item Type of Limit Limit Value

Columns

Maximum per table

1000

Columns

Maximum per index (or clustered index)

32

Columns

Maximum per bitmapped index

30

Constraints

Maximum per column

Unlimited

Constraints

Maximum per database

4,294,967,293

Database users

Maximum per database

4,294,967,293

Dictionary-managed database objects

Maximum per database

4,254,950,911 - overhead

Indexes

Maximum per table

Unlimited

Indexes

Total size of indexed column

75% of the database block size minus some overhead

Partitions

Maximum length of linear partitioning key

4 KB - overhead

Partitions

Maximum number of columns in partition key

16 columns

Partitions

Maximum number of partitions allowed per table or index

1024K - 1

Rows

Maximum number per table

Unlimited

Stored Packages

Maximum size

Approximately 6,000,000 lines of code.

See Also: Oracle Database PL/SQL Language Reference for details

Subpartitions

Maximum number of subpartitions in a composite partitioned table

1024K - 1

Subqueries

Maximum levels of subqueries in a SQL statement

Unlimited in the FROM clause of the top-level query

255 subqueries in the WHERE clause

System Change Numbers (SCNs)

Maximum

281,474,976,710,656, which is 281 trillion SCNs

Tables

Maximum per clustered table

32 tables

Tables

Maximum per database

Unlimited

Oracle does not define a limit on the number of tables per database. However, tables are subject to the limit on the maximum number of dictionary-managed database objects allowed per database. See the entry for "Dictionary-managed database objects" in this table.

Trigger Cascade Limit

Maximum value

Operating system-dependent, typically 32

Users and Roles

Maximum

2,147,483,638

Note:

The limit on how long a SQL statement can be depends on many factors, including database configuration, disk space, and memory

Note:

When an object instance exists in memory, there is no fixed limit on the number of attributes in the object. But the maximum total amount of memory consumed by an object instance is 4 GB. When an object instance is inserted into a table, the attributes are exploded into separate columns in the table, and the Oracle 1000-column limit applies.