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 |
If If See Also: "MAX_COLUMNS" initialization parameter for additional details |
Columns |
Maximum per index (or clustered index) |
32 |
Columns |
Maximum per bitmapped index |
30 |
Constraints |
Maximum per column |
Not defined Oracle does not define a limit on the number of constraints per column. However, constraints are subject to the limit on the maximum number of constraints in the database. See the entry for "Constraints - Maximum per database" in this table. |
Constraints |
Maximum per database |
4,294,967,293 Constraints are numbered internally from 1 to 4,294,967,294. The internal number is incremented each time a constraint is created. One number is always consumed by a special internal user called You can view constraint numbers by querying the |
Dictionary-managed database objects |
Maximum per database |
4,254,950,911 - overhead
|
Indexes |
Maximum per table |
Not defined Oracle does not define a limit on the number of indexes per table. However, indexes 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. |
Indexes |
Total size of indexed column(s) |
Approximately 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 |
Not defined |
Stored Packages |
Maximum size |
Approximately 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 |
A limit is not defined for subqueries in the |
System Change Numbers (SCNs) |
Maximum |
263 - 248 = 9,223,090,561,878,065,152 SCNs |
Tables |
Maximum per clustered table |
32 tables |
Tables |
Maximum per database |
Not defined 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. |
Users and Roles |
Maximum |
2,147,483,638 Users and roles are numbered internally from 0 to 2,147,483,638. The internal number is incremented each time a user or role is created, and numbers are never recycled. One number is always consumed by a special internal user called You can view user and role numbers by querying the |
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 these columns count toward the limit on the maximum number of columns per table.