Database Variable Size Entry Container Free Space Handling Based on Use Patterns

• US 20180335949A1
• Filed: 05/19/2017
• Published: 11/22/2018
• Est. Priority Date: 05/19/2017
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP SE
• Inventors: Thomsen, Dirk
• Granted Patent: US 10,642,756 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 12/123 with age lists, e.g. queue, most recently used [MRU] list or least recently used [LRU] list
• CPC Class Codes: G06F 16/22 Indexing; Data structures therefor; Storage structures

Abstract

Allocation of an entry in a variable size entry container is initiated in an in-memory database system. The variable size entry container includes a plurality of pages forming a chain. Thereafter, it is determined whether free space is found within the pre-existing pages. If free space is found, the entry is allocated in the free space. Otherwise, a new page is created and appended to the chain so that the entry can be allocated on such new page.

Claims

1. A computer-implemented method comprising:

initiating, in an in-memory database system, allocation of an entry in a variable size entry container, the variable size entry container comprising a plurality of pages forming a chain;

determining whether free space is found within the pre-existing pages;

allocating the entry in free space if free space is found;

or

creating a new page and appending it to the chain and allocating the entry on the new page.

2. The method of claim 1 further comprising:

deleting a page in the page chain when all entries on such page are de-allocated.

3. The method of claim 1, wherein the determining comprises measuring an amount of fragmentation within the page.

4. The method of claim 1, wherein the determining is based on whether a pattern of using the container is configured such that new entries are added and oldest entries are deleted when space is needed.

5. The method of claim 1, further comprising loading at least a portion of the page chain into memory of the in-memory database system.

6. The method of claim 1, wherein the entry is allocated to the new page prior to the page being appended to the chain.

7. The method of claim 1, wherein the entry is allocated to the new page subsequent to the page being appended to the chain.

8. A system comprising:

at least one data processor; and

memory storing instructions which, when executed by the at least one data processor, result in operations comprising;

initiating allocation of an entry in a variable size entry container, the variable size entry container comprising a plurality of pages forming a chain;

determining whether free space is found within the pre-existing pages;

allocating the entry in free space if free space is found;

or

creating a new page and appending it to the chain and allocating the entry on the new page.

9. The system of claim 8, wherein the at least one data processor and memory form part of an in-memory database system.

10. The system of claim 8, wherein the operations further comprise:

deleting a page in the page chain when all entries on such page are de-allocated.

11. The system of claim 8, wherein the determining comprises measuring an amount of fragmentation within the page.

12. The system of claim 8, wherein the determining is based on whether a pattern of using the container is configured such that new entries are added and oldest entries are deleted when space is needed.

13. The system of claim 8, wherein the operations further comprise:

loading at least a portion of the page chain into memory of the in-memory database system.

14. The system of claim 8, wherein the entry is allocated to the new page prior to the page being appended to the chain.

15. The system of claim 8, wherein the entry is allocated to the new page subsequent to the page being appended to the chain.

16. A non-transitory computer program product storing instructions which, when executed by at least one data processor forming part of at least one computing device, result in operations comprising:

initiating allocation of an entry in a variable size entry container, the variable size entry container comprising a plurality of pages forming a chain;

determining whether free space is found within the pre-existing pages;

allocating the entry in free space if free space is found;

or

creating a new page and appending it to the chain and allocating the entry on the new page.

17. The computer program product of claim 16, wherein the operations further comprise:

deleting a page in the page chain when all entries on such page are de-allocated.

18. The computer program product of claim 16, wherein the determining comprises measuring an amount of fragmentation within the pagebased on whether a pattern of using the container is configured such that new entries are added and oldest entries are deleted when space is needed.

19. The computer program product of claim 16, wherein the entry is allocated to the new page prior to the page being appended to the chain.

20. The computer program product of claim 16, wherein the entry is allocated to the new page subsequent to the page being appended to the chain.