Oracle Sequences are commonly used to generate unique numeric identifiers for database records. However, generating sequence values can be a performance constraint for high-concurrency applications. One way to improve performance is to cache Oracle Sequences by reducing the number of dictionary accesses required to generate sequence values.
This guide will explain how to cache Oracle Sequence to improve data dictionary resources.
How to Cache Oracle Sequence to Improve/Enhance Data Dictionary Resources?
The following options can be used to cache Oracle sequence to improve data dictionary resources:
Before starting with the improvement, log in to the Oracle database as a System Administrator by typing the below-given command:
In the above command, “root1234” is the database password.
Output
The output showed the successful login to an Oracle database.
After the successful login, let’s confirm the cache size and maximum value of the sequence.
Check Cache Size
To check the cache size, the SELECT statement can be used with the CACHE_SIZE as given below:
WHERE SEQUENCE_OWNER = 'C##MD'
AND SEQUENCE_NAME = 'DBOBJECTID_SEQUENCE';
In the above command, the cache size of a sequence named “DBOBJECTID_SEQUENCE” is selected from the ALL_SEQUENCES view.
Output
The output showed that the Cache size is 50.
Check Max Value
The “MAX_VALUE” can be used with the SELECT statement to fetch the maximum value from the sequence, as shown below:
WHERE SEQUENCE_OWNER = 'C##MD'
AND SEQUENCE_NAME = 'DBOBJECTID_SEQUENCE';
Output
The output displayed the Max value from the sequence.
How to Cache Oracle Sequence Using the CACHE Option?
The “CACHE” option is used to pre-allocate a specified number of sequence values in memory, which are then used by the database without the need for dictionary accesses. To cache an Oracle Sequence, you can use the CACHE option when creating or altering the sequence.
The example is given below:
In the above example:
-
- The “C##MD” is the sequence owner.
- The “DBOBJECTID_SEQUENCE” is the sequence name.
- “70” is the new cache size.
Output
The output displayed that the cache size has been altered.
Let’s confirm the cache size by typing the given command:
WHERE SEQUENCE_OWNER = 'C##MD'
AND SEQUENCE_NAME = 'DBOBJECTID_SEQUENCE';
Output
The output displayed that the cache size has been changed to 70.
How to Cache Oracle Sequence Using the NOORDER Option?
The “NOORDER” option is used to pre-allocate a specified number of sequence values in memory without ordering the values in any specific order. Without this option, Oracle will need to lock the sequence before generating a new value that may decrease performance.
By using the “NOORDER” option, Oracle can cache the sequence values and improve the utilization of data dictionary resources. Here is an example:
Output
The output “Sequence altered” showed that the changes have been made.
How to Cache Oracle Sequence Using the KEEP Option?
The “KEEP” option is used to retain sequence values that have been generated and not yet used, even if the database crashes or is shut down unexpectedly. It also decreases the chance of sequence gaps. The KEEP option can be useful for sequences that are frequently accessed or for sequences that are used in highly concurrent environments.
Type the given below command to cache Oracle Sequence to improve data dictionary resources using the KEEP option:
Output
The output demonstrated that the sequence has been altered:
This is how to cache Oracle Sequence to improve data dictionary resources.
Conclusion
Caching Oracle Sequences using the “CACHE”, “NOORDER”, and “KEEP” options can improve data dictionary resources by reducing the number of dictionary access required to generate sequence values. The CACHE option pre-allocates a specified number of sequence values in memory. This guide has explained various options to cache Oracle sequences to improve/enhance data dictionary resources.
