Upgrading a database from a first version to a second version

1. A method for upgrading a database from a first version to a second version, the method comprising:

operating, by a first processor, a first version of a database management system of the database;

operating, by a second processor, a second version of the database management system of the database;

receiving, by the second processor and from the first processor, a copy of a database application schema;

producing, by the second processor and using the second version of the database management system and the copy of the database application schema, an original version of a database catalog for the second version of the database management system;

receiving, by the first processor and from the second processor, a copy of the original version of the database catalog for the second version of the database management system;

producing, by the first processor, a catalog for an upgrade of the database, the catalog for the upgrade having tables and indices that are identical to tables and indices included in the copy of the original version of the database catalog for the second version of the database management system;

saving, by the first processor and in the catalog for the upgrade, the copy of the original version of the database catalog for the second version of the database management system; and

causing, by the first processor and for information in the catalog for the upgrade, a change in references to locations of data in the database from being with respect to an organization of the database according to the first version of the database management system to being with respect to an organization of the database according to the second version of the database management system.

2. The method of claim 1 , wherein the first processor is different from the second processor.

3. The method of claim 2 , wherein a processing speed of the second processor is less than a processing speed of the first processor.

4. The method of claim 1 , wherein a duration of time of an event in which, during the upgrade of the database, the database is unresponsive to a request is a short duration of time.

5. The method of claim 4 , wherein the short duration of time is less than or equal to thirty seconds.

6. The method of claim 1 , wherein an upgrade of the database application schema is suspended during the upgrade of the database.

7. The method of claim 1 , further comprising ceasing, by the first processor and in response to a completion of the change in references, an operation of the first version of the database management system by the first processor.

8. The method of claim 7 , further comprising starting, by the first processor and in response to the completion of the change in references, an operation of the second version of the database management system by the first processor, wherein the operation of the second version of the database management system by the first processor uses the catalog for the upgrade as a working version of the database catalog for the second version of the database management system.

9. The method of claim 8 , wherein the working version of the database catalog for the second version of the database management system is configured to store metadata related to the database application schema and related to the database management system.

10. The method of claim 8 , further comprising causing, by the first processor, the second version of the database management system to interact with data stored in a storage of the database.

11. The method of claim 10 , wherein the causing the second version of the database management system to interact with the data stored in the storage of the database is performed on a portion of the data in response to a request to access the portion of the data.

12. The method of claim 11 , wherein the upgrade of the database is performed in a manner that is imperceptible to a user of the database.

13. The method of claim 8 , further comprising:

ceasing, by a third processor and in response to the completion of the change in references, an operation of the first version of the database management system by the third processor; and

starting, by the third processor and in response to the completion of the change in references, an operation of the second version of the database management system by the third processor.

14. The method of claim 13 , wherein the ceasing by the third processor and the starting by the third processor occur after the ceasing by the first processor and the starting by the first processor.

15. The method of claim 14 , wherein the first processor and the third processor are associated with a same cluster of the database.

16. The method of claim 14 , wherein:

the first processor is associated with a primary cluster of the database; and

the third processor is associated with a disaster recovery cluster of the database.

17. A non-transitory computer-readable medium storing computer code for upgrading a database from a first version to a second version, the computer code including instructions to cause:

a second processor to:

operate a second version of a database management system of the database;

receive, from a first processor, a copy of a database application schema; and

produce, using the second version of the database management system and the copy of the database application schema, an original version of a database catalog for the second version of the database management system; and

the first processor to:

operate a first version of the database management system of the database;

receive, from the second processor, a copy of the original version of the database catalog for the second version of the database management system;

produce a catalog for an upgrade of the database, the catalog for the upgrade having tables and indices that are identical to tables and indices included in the copy of the original version of the database catalog for the second version of the database management system;

save, in the catalog for the upgrade, the copy of the original version of the database catalog for the second version of the database management system; and

cause, for information in the catalog for the upgrade, a change in references to locations of data in the database from being with respect to an organization of the database according to the first version of the database management system to being with respect to an organization of the database according to the second version of the database management system.

18. A system for upgrading a database from a first version to a second version, the system comprising:

a second processor configured:

operate a second version of a database management system of the database;

receive, from a first processor, a copy of a database application schema; and

produce, using the second version of the database management system and the copy of the database application schema, an original version of a database catalog for the second version of the database management system; and

the first processor configured to:

operate a first version of the database management system of the database;

receive, from the second processor, a copy of the original version of the database catalog for the second version of the database management system;

produce a catalog for an upgrade of the database, the catalog for the upgrade having tables and indices that are identical to tables and indices included in the copy of the original version of the database catalog for the second version of the database management system;

save, in the catalog for the upgrade, the copy of the original version of the database catalog for the second version of the database management system; and

cause, for information in the catalog for the upgrade, a change in references to locations of data in the database from being with respect to an organization of the database according to the first version of the database management system to being with respect to an organization of the database according to the second version of the database management system.

19. The system of claim 18 , wherein:

the first processor is further configured to:

cease, in response to a completion of the change in references, an operation of the first version of the database management system by the first processor; and

start, in response to the completion of the change in references, an operation of the second version of the database management system by the first processor, the operation of the second version of the database management system by the first processor using the catalog for the upgrade as a working version of the database catalog for the second version of the database management system; and

the system further comprises a third processor, the third processor configured to:

cease, in response to the completion of the change in references, an operation of the first version of the database management system by the third processor; and

start, in response to the completion of the change in references, an operation of the second version of the database management system by the third processor.

20. The system of claim 19 , wherein the first processor is located at a first site, the third processor is located at a second site, and the second site is remote from the first site.