Managing data records

Patent metadata

Field	Value
Publication number	US-9916338-B2
Application number	US-201514695771-A
Country	US
Kind code	B2
Filing date	Apr 24, 2015
Priority date	Apr 24, 2015
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

Data records may be managed in a relational database by monitoring, a record length for a first data record in a page of memory, an amount of free space in the page, and a page length. In response to receiving an operator command to replace the first data record with a second data record, a database management system may determine whether an estimated record length of a compressed second data record is outside of the amount of free space in the page. In response to determining the estimated record length of a compressed second data record is outside of the amount of free space in the page, the database management system may determine whether an estimated length of a compressed page is outside of the page length. In response to determining the estimated length of a compressed page is within the page length, the page may be compressed.

First claim

What is claimed is:

1. A computer implemented method for managing data records in a relational database, the method comprising:
monitoring, by a processor, a record length for a first data record of the relational database stored in a page of memory, an amount of free space in the page, and a page length of the page;
receiving an operator command to replace the first data record with a second data record in the relational database;
determining, based upon receiving the operator command, whether an estimated record length of an compressed second data record is outside of the amount of free space in the page;
in response to determining that the estimated record length of the compressed second data record is outside of the amount of free space in the page, determining whether an estimated length of a compressed page that includes the second data record is outside of the page length; and
in response to determining that the estimated length of the compressed page is within the page length, compressing the page including the second data record in the relational database.

2. The method of claim 1 , wherein receiving the operator command includes comparing the record length of the second data record with the amount of free space in the page.

3. The method of claim 2 , further comprising:
determining, based on comparing the record length of the second data record with the amount of free space in the page, the record length of the second data record to be within the amount of free space in the page; and
replacing the first data record with the second data record.

4. The method of claim 1 , wherein determining whether an estimated record length of a compressed second data record is outside of the amount of free space in the page further comprises:
comparing the record length of the second data record with the amount of free space in the page;
estimating, in response to comparing, a record length of a compressed second data record; and
comparing, in response to estimating, the estimated record length of the compressed second data record with the amount of free space in the page.

5. The method of claim 4 , further comprising:
determining, based upon the comparing, the estimated record length of the compressed second data record is within the amount of free space in the page;
compressing the second data record; and
replacing the first data record with the compressed second data record.

6. The method of claim 1 , wherein determining whether the estimated length of a compressed page that includes the second data record is outside of the page length further comprises:
estimating a length of a compressed page; and
comparing, in response to estimating, the estimated length of the compressed page with the page length.

7. The method of claim 6 , wherein in response to determining that the estimated length of the compressed page is within the page length, the method further comprises:
compressing the page; and
replacing the page with a compressed page.

8. The method of claim 6 , wherein comparing the estimated length of the compressed page with the page length further comprises:
determining the estimated length of the compressed page is outside of the page length; and
creating an overflow record for the second data record.

9. The method of claim 1 , wherein the operator command corresponds with modifier commands, the modifier commands including update operators.

10. The method of claim 1 , wherein the amount of free space in the page includes reserved or unused space in the page in the relational database.

11. A computer program product for managing data records in a relational database, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, wherein the computer readable storage medium is not a transitory signal per se, the program instructions executable by a processor to cause the processor to perform a method comprising:
monitoring, by the processor, a record length for a first variable data record of the relational database stored in a page of memory, an amount of free space in the page, and a page length of the page;
receiving an operator command to replace the first variable data record with a second variable data record in the relational database;
determining, by the processor, based upon receiving the operator command, whether an estimated record length of a compressed variable second data record is outside of the amount of free space in the page;
in response to determining that the estimated record length of the compressed variable second data record is outside of the amount of free space in the page, determining whether an estimated length of a compressed page that includes the variable second data record is outside of the page length; and
in response to determining that the estimated length of the compressed page is within the page length, compressing the page including the second data record in the relational database.

12. The computer program product of claim 11 , wherein determining whether the estimated length of a compressed page that includes the variable second data record is outside of the page length further comprises:
estimating a length of a compressed page; and
comparing, in response to estimating, the estimated length of the compressed page with the page length.

13. The computer program product of claim 12 , wherein in response to determining that the estimated length of the compressed page is within the page length, the method further comprises:
compressing the page; and
replacing the page with a compressed page.

14. The computer program product of claim 12 , wherein comparing the estimated length of the compressed page with the page length further comprises:
determining the estimated length of the compressed page is outside of the page length; and
creating an overflow record for the second variable data record.

15. The computer program product of claim 11 , wherein the operator command corresponds with modifier commands, the modifier commands including update operators.

16. A computer system for managing data records in a relational database, the computer system comprising:
a memory; and
a processor in communication with the memory, wherein the processor is configured to perform a method, the method comprising:
monitoring, by the processor, a record length for a first data record of the relational database stored in a page of memory, an amount of free space in the page, and a page length of the page;
receiving an operator command to replace the first data record with a second data record in the relational database;
determining, by the processor, based upon receiving the operator command, whether an estimated record length of a compressed second data record is outside of the amount of free space in the page;
in response to determining that the estimated record length of the compressed second data record is outside of the amount of free space in the page, determining whether an estimated length of a compressed page that includes the second data record is outside of the page length; and
in response to determining that the estimated length of the compressed page is within the page length, compressing the page including the second data record in the relational database.

17. The computer system of claim 16 , wherein receiving the operator command includes comparing the record length of the second data record with the amount of free space in the page.

18. The computer system of claim 17 , further comprising:
determining, based on compar

Assignees

• IBM

Inventors

• Fang Min
• Jin Di
• Shi zhen yu
• Slinger Nigel G
• Wang Shu
• Zheng li fei
• Zhu wen jie

Classifications

• G06F17/30371

  Physics · mapped topic

• G06F17/30982

  Physics · mapped topic

• H03M7/6058

  Saving memory space in the encoder or decoder · CPC title

• H03M7/3084

  using adaptive string matching, e.g. the Lempel-Ziv method · CPC title

• G06F17/30339 Primary

  Physics · mapped topic