Caching data between a database server and a storage system

• US 8,868,831 B2
• Filed: 12/07/2009
• Issued: 10/21/2014
• Est. Priority Date: 09/14/2009
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Goyal, Kiran Badrinarain, Macnaughton, Neil J. S., Ho, Eugene, Lee, Adam Y., Gokhale, Vipin, Hu, Wei-Ming, Loaiza, Juan R., Umamageswaran, Kothanda, Baddepudi, Bharat C. V., Erlikhman, Boris, Tsukerman, Alexander, Aya, Selcuk, Hansen, Roger, Ng, Adrian
• Primary Examiner(s): Farrokh, Hashem
• Application Number:
  US12/631,985
• Publication Number:
  US 20110066791A1
• Time in Patent Office: 1,779 Days
• Field of Search: 711/118, 711/122, 707/E17.12
• US Class Current: 711/118
• CPC Class Codes: G06F 12/084 with a shared cache
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/0888 using selective caching, e.g. bypass
• CPC Class Codes: G06F 12/0897 with two or more cache hierarchy levels with multilevel cache hierarchies G06F12/0811
• CPC Class Codes: G06F 16/22 Indexing; Data structures therefor; Storage structures
• CPC Class Codes: G06F 16/24552 Database cache management
• CPC Class Codes: G06F 2212/283 Plural cache memories
• CPC Class Codes: G06F 2212/311 In host system
• CPC Class Codes: G06F 2212/312 In storage controller
• CPC Class Codes: G06F 2212/465 Structured object, e.g. database record

Abstract

Techniques are provided for using an intermediate cache between the shared cache of a database server and the non-volatile storage of a storage system. The intermediate cache may be local to the machine upon which the database server is executing, or may be implemented within the storage system. In one embodiment, the database system includes both a DB server-side intermediate cache, and a storage-side intermediate cache. The caching policies used to populate the intermediate cache are intelligent, taking into account factors that may include which database object an item belongs to, the item type of the item, a characteristic of the item; or the database operation in which the item is involved.

Claims

1. A method comprising:

receiving, from an application that performs operations on a plurality of objects, one or more indications of which objects, of the plurality of objects, have a particular designation;

wherein the plurality of objects is persistently stored outside of an intermediate cache in data from disk blocks on one or more non-volatile storage devices;

caching, in the intermediate cache, disk blocks that are transferred between (a) a volatile memory used by the application and (b) the one or more non-volatile storage devices;

for a particular disk block that is transferred between the volatile memory and the one or more non-volatile storage devices, determining for which particular object, of the plurality of objects, the particular disk block stores data;

wherein data representative of the particular object is persistently stored on a particular plurality of disk blocks on the one or more non-volatile storage devices;

wherein caching the data includes using the intermediate cache, with respect to the particular disk block, in a manner that is based, at least in part, on whether the particular object for which the particular disk block stores data has said particular designation;

wherein the method is performed by one or more computing devices.

2. The method of claim 1 wherein:

the particular designation is a KEEP designation; and

the step of using the intermediate cache includes;

storing the particular disk block in a reserved area of the intermediate cache if the particular disk block belongs to an object with the KEEP designation; and

storing the particular disk block in an unreserved area of the intermediate cache if the particular disk block belongs to an object that does not have the KEEP designation.

3. The method of claim 2 wherein:

the particular disk block belongs to an object that has the KEEP designation; and

storing the particular disk block in a reserved area includes;

within the intermediate cache, replacing another disk block with the particular disk block, wherein the other disk block stores data that belongs to an object that does not have a KEEP designation; and

in response to replacing the other disk block with the particular disk block, increasing the size of the reserved area and decreasing the size of the unreserved area.

4. The method of claim 1 wherein:

the particular designation is a NONE designation; and

the step of using the intermediate cache includes caching the particular disk block in the intermediate cache only if the particular disk block belongs to an object that does not have a NONE designation.

5. The method of claim 1, wherein the plurality of objects include one or more of:

database objects, files, or collections, and wherein the disk blocks correspond to one or more of table rows, data blocks, index entries, or file portions.

6. A method comprising:

caching, in an intermediate cache, data that is transferred between a volatile memory used by a database server and a non-volatile storage device that is used to persistently store the data;

wherein the step of caching the data includes using the intermediate cache, with respect to an item of the data that is transferred between the volatile memory and the non-volatile storage, in a manner that is based, at least in part, on one or more of;

whether the item is a disk block of an index block type;

whether the item is a disk block of a data block type;

whether the item is a disk block of an undo block type;

whether the item is encrypted;

whether the item is a secondary copy of a mirrored item;

or

whether the item is involved in a table scan operation;

wherein the method is performed by one or more computing devices.

7. The method of claim 6 wherein using the intermediate cache includes determining whether or not to store the item in the intermediate cache based, at least in part, on whether the item is a disk block of an index block type.

8. The method of claim 6 further comprising determining not to store the item in the intermediate cache based on the item being a disk block of an undo block type.

9. The method of claim 6 wherein using the intermediate cache includes determining whether or not to store the data item in the intermediate cache based, at least in part, on whether the item is a disk block of a data block type.

10. The method of claim 6 further comprising determining not to store the item in the intermediate cache based on the item being a secondary copy of a mirrored item.

11. The method of claim 6 further comprising determining not to store the item in the intermediate cache based on the item being encrypted.

12. The method of claim 6 further comprising determining not to store the item in the intermediate cache based on the item being involved in a table scan operation.

13. The method of claim 6 wherein the intermediate cache is implemented by FLASH memory.

14. The method of claim 6 wherein the intermediate cache is local to a server machine on which the database server is executing.

15. The method of claim 14 wherein items are loaded into intermediate cache based on a load-on-replace policy.

16. The method of claim 6 wherein the intermediate cache is managed by a storage system to which the non-volatile storage device belongs.

17. The method of claim 16 wherein the database server is one of a plurality of database servers for which the storage system stores items in the intermediate cache.

18. The method of claim 16 wherein items are loaded into the intermediate cache on a load-on-read and load-on-write policy.

19. The method of claim 16 wherein:

the step of using the intermediate cache is performed by the storage system; and

the method further comprises the storage system receiving, from the database server,

information that indicates at least one of;

whether the item is a disk block of an index block type;

whether the item is a disk block of a data block type;

whether the item is a disk block of an undo block type;

whether the item is encrypted;

whether the item is a secondary copy of a mirrored item;

or

a type of database operation in which the item is involved.

20. A method comprising:

caching, in an intermediate cache, data that is transferred between a volatile memory used by a database server and a non-volatile storage device that is used to persistently store the data, the database server configured to execute a plurality of distinct types of database operations with respect to the data;

wherein the step of caching the data includes using the intermediate cache, with respect to an item of the data that is transferred between the volatile memory and the non-volatile storage, in a manner that is base, at least in part on;

for which type of database operation, of the plurality of distinct types of database operations, the database server is using the item;

wherein using the intermediate cache includes determining whether or not to store the data item in the intermediate cache based, at least in part, on the type of database operation in which the item is involved.

21. A non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause:

receiving, from an application that performs operations on a plurality of objects, one or more indications of which objects, of the plurality of objects, have a particular designation;

wherein the plurality of objects is persistently stored outside of an intermediate cache in data from disk blocks on one or more non-volatile storage devices;

caching, in the intermediate cache, disk blocks that are transferred between (a) a volatile memory used by the application and (b) the one or more non-volatile storage devices;

for a particular disk block that is transferred between the volatile memory and the one or more non-volatile storage devices, determining for which particular object, of the plurality of objects, the particular disk block stores data;

wherein data for the particular object is persistently stored on a particular plurality of disk blocks on the one or more non-volatile storage devices;

wherein caching the data includes using the intermediate cache, with respect to the particular disk block, in a manner that is based, at least in part, on whether the particular object for which the particular disk block stores data has said particular designation.

22. The non-transitory computer-readable media of claim 21 wherein:

the particular designation is a KEEP designation; and

the step of using the intermediate cache includes;

storing the particular disk block in a reserved area of the intermediate cache if the particular disk block belongs to an object with the KEEP designation; and

storing the particular disk block in an unreserved area of the intermediate cache if the particular disk block belongs to an object that does not have the KEEP designation.

23. The non-transitory computer-readable media of claim 22 wherein:

the particular disk block belongs to an object that has the KEEP designation; and

storing the particular disk block in a reserved area includes;

within the intermediate cache, replacing another disk block with the particular disk block, wherein the other disk block stores data that belongs to an object that does not have a KEEP designation; and

in response to replacing the other disk block with the particular disk block, increasing the size of the reserved area and decreasing the size of the unreserved area.

24. The non-transitory computer-readable media of claim 21 wherein:

the particular designation is a NONE designation; and

the step of using the intermediate cache includes caching the particular disk block in the intermediate cache only if the particular disk block belongs to an object that does not have a NONE designation.

25. The non-transitory computer-readable media of claim 21, wherein the plurality of objects include one or more of:

database objects, files, or collections, and wherein the disk blocks correspond to one or more of table rows, data blocks, index entries, or file portions.

26. A non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause:

caching, in an intermediate cache, data that is transferred between a volatile memory used by a database server and a non-volatile storage device that is used to persistently store the data;

wherein the step of caching the data includes using the intermediate cache, with respect to an item of the data that is transferred between the volatile memory and the non-volatile storage, in a manner that is based, at least in part, on one or more of;

whether the item is a disk block of an index block type;

whether the item is a disk block of a data block type;

whether the item is a disk block of an undo block type;

whether the item is encrypted;

whether the item is a secondary copy of a mirrored item;

or

whether the item is involved in a table scan operation.

27. The non-transitory computer-readable media of claim 26 wherein using the intermediate cache includes determining whether or not to store the item in the intermediate cache based, at least in part, on whether the item is a disk block of an index block type.

28. The non-transitory computer-readable media of claim 26 further comprising determining not to store the item in the intermediate cache based on the item being disk block of an undo block type.

29. The non-transitory computer-readable media of claim 26 wherein using the intermediate cache includes determining whether or not to store the data item in the intermediate cache based, at least in part, on whether the item is a disk block of a data block type.

30. The non-transitory computer-readable media of claim 26 further comprising instructions for determining not to store the item in the intermediate cache based on the item being a secondary copy of a mirrored item.

31. The non-transitory computer-readable media of claim 26 further comprising instructions for determining not to store the item in the intermediate cache based on the item being encrypted.

32. The non-transitory computer-readable media of claim 26 further comprising instructions for determining not to store the item in the intermediate cache based on the item being involved in a table scan operation.

33. The non-transitory computer-readable media of claim 26 wherein the intermediate cache is implemented by FLASH memory.

34. The non-transitory computer-readable media of claim 26 wherein the intermediate cache is local to a server machine on which the database server is executing.

35. The non-transitory computer-readable media of claim 34 wherein items are loaded into intermediate cache based on a load-on-replace policy.

36. The non-transitory computer-readable media of claim 26 wherein the intermediate cache is managed by a storage system to which the non-volatile storage device belongs.

37. The non-transitory computer-readable media of claim 36 wherein the database server is one of a plurality of database servers for which the storage system stores items in the intermediate cache.

38. The non-transitory computer-readable media of claim 36 wherein items are loaded into the intermediate cache on a load-on-read and load-on-write policy.

39. The non-transitory computer-readable media of claim 36 wherein:

using the intermediate cache is performed by the storage system; and

the computer-readable media further comprises instructions for the storage system receiving, from the database server, information that indicates at least one of;

whether the item is a disk block of an index block type;

whether the item is a disk block of a data block type;

whether the item is a disk block of an undo block type;

whether the item is encrypted;

whether the item is a secondary copy of a mirrored item;

or

a type of database operation in which the item is involved.

40. A non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause:

caching, in an intermediate cache, data that is transferred between a volatile memory used by a database server and a non-volatile storage device that is used to persistently store the data, the database server configured to execute a plurality of distinct types of database operations with respect to the data;

wherein the step of caching the data includes using the intermediate cache, with respect to an item of the data that is transferred between the volatile memory and the non-volatile storage, in a manner that is based at least in part on;

for which type of database operation, of the plurality of distinct types of database operations, the database server is using the item;

wherein using the intermediate cache includes determining whether or not to store the data item in the intermediate cache based, at least in part, on the type of database operation in which the item is involved.

41. A method comprising:

caching, in an intermediate cache, disk blocks that are transferred between a volatile memory used by a database server and a non-volatile storage device that is used to persistently store the disk blocks, the database server configured to perform database operations with respect to a plurality of database objects, the disk blocks storing data that belong to the plurality of database objects;

wherein the step of caching the disk blocks includes using the intermediate cache, with respect to a particular disk block that is transferred between the volatile memory and the non-volatile storage, in a manner that is based, at least in part, on;

whether the particular disk block is one of a plurality of disk blocks that stores data belonging to a particular database object, of the plurality of database objects, that has a particular designation, the particular database object being one of;

a table, index, or tablespace;

wherein the method is performed by one or more computing devices.

42. The method of claim 41 further comprising:

receiving data that indicates that the particular database object to which the data in the disk block belongs is designated as a NONE object; and

determining not store the particular disk block in the intermediate cache because the data in the particular disk block belongs to an object that is designated as a NONE object.

43. The method of claim 41 further comprising:

receiving data that designates the particular database object as a KEEP object;

storing the particular disk block in a reserved area of the intermediate cache because the particular database object is designated as a KEEP object;

storing a second data block in an unreserved area of the of the intermediate cache in response to determining that the second data block belongs to a different database object that has not been designated as a KEEP object.

44. The method of claim 43 further comprising preventing disk blocks that do not belong to KEEP objects from replacing, within the intermediate cache, disk blocks that belong to KEEP objects, while allowing disk blocks that belong to KEEP objects to replace, within the intermediate cache, disk blocks that do not belong to KEEP objects.

45. The method of claim 41, further comprising:

receiving, from the database server, one or more indications of which database objects of the plurality of database objects have the particular designation;

based on information received in an input/output request from the database server for the particular disk block, identifying to which database object, of the plurality of database objects, the data within the particular disk block belongs.

46. A non-transitory computer-readable media storing instructions which, when executed by one or more processors, cause:

caching, in an intermediate cache, disk blocks that are transferred between a volatile memory used by a database server and a non-volatile storage device that is used to persistently store the disk blocks, the database server configured to perform database operations with respect to a plurality of database objects, the disk blocks storing data that belong to the plurality of database objects;

wherein the step of caching the disk blocks includes using the intermediate cache, with respect to a particular disk block that is transferred between the volatile memory and the non-volatile storage, in a manner that is based, at least in part, on;

whether the particular disk block is one of a plurality of disk blocks that stores data belonging to a particular database object, of the plurality of database objects, that has a particular designation, the particular database object being one of;

a table, index, or tablespace;

wherein the method is performed by one or more computing devices.

47. The non-transitory computer-readable media of claim 46 further comprising instructions for:

receiving data that indicates that the particular database object to which the data in the disk block belongs is designated as a NONE object; and

determining not store the particular disk block in the intermediate cache because the data in the particular disk block belongs to an object that is designated as a NONE object.

48. The non-transitory computer-readable media of claim 46 further comprising instructions for:

receiving data that designates the particular database object as a KEEP object;

storing the particular disk block in a reserved area of the intermediate cache because the particular database object is designated as a KEEP object;

storing a second data block in an unreserved area of the of the intermediate cache in response to determining that the second data block belongs to a different database object that has not been designated as a KEEP object.

49. The non-transitory computer-readable media of claim 48 further comprising instructions for preventing disk blocks that do not belong to KEEP objects from replacing, within the intermediate cache, disk blocks that belong to KEEP objects, while allowing disk blocks that belong to KEEP objects to replace, within the intermediate cache, disk blocks that do not belong to KEEP objects.

50. The non-transitory computer-readable media of claim 46, further comprising instructions for:

receiving, from the database server, one or more indications of which database objects of the plurality of database objects have the particular designation;

based on information received in an input/output request from the database server for the particular disk block, identifying to which database object, of the plurality of database objects, the data within the particular disk block belongs.