Optimizing single-value database read operations using a single value cache

Patent metadata

Field	Value
Publication number	US-10360210-B2
Application number	US-201414274973-A
Country	US
Kind code	B2
Filing date	May 12, 2014
Priority date	May 12, 2014
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

The present disclosure describes methods, systems, and computer program products for optimizing single-value database read operations. One computer-implemented method includes initializing, by a computer, a single value cache associated with a created database table where a column of the database table contains a single or unique data value, verifying that the created database table is in a useable state, performing an operation on the database table, and retrieving the data value from the single value cache without locking the column containing the single or unique data value.

First claim

What is claimed is:

1. A computer-implemented method comprising:
initializing, by a computer, a single value cache associated with a column of a database table containing a single or unique data value, wherein each column of the database table is associated with a particular main storage and a particular delta storage, wherein the single value cache is initialized and marked for caching based on a computed finding of identical single or unique data values in both the particular main storage and the particular delta storage associated with the column of the database table, and wherein the particular delta storage contains changes from data in the particular main storage;
verifying that the created database table is in a useable state;
performing a database operation on the database table; and
retrieving the data value from the single value cache without locking the column containing the cached single or unique data value.

2. The method of claim 1 , wherein the single value cache is part of metadata associated with the database table.

3. The method of claim 1 , wherein both the particular main storage and the particular delta storage are scanned individually for the single or unique values.

4. The method of claim 3 , wherein data stored in the single value cache is stored as a raw data value.

5. The method of claim 3 , wherein the particular main storage and the particular delta storage each has a data dictionary used to combine values in the particular main storage and the particular delta storage to determine if the single value cache should be persisted for the database table.

6. The method of claim 1 , wherein in operations where the database table is exclusively locked, all table columns are scanned for single or unique values using a value dictionary associated with each column to determine how many distinct values are being used in each column.

7. The method of claim 1 , wherein the single value cache is marked as dirty until an exclusively lock phase occurs for the database table.

8. The method of claim 1 , wherein NULL values are treated as normal values.

9. A non-transitory, computer-readable medium storing computer-readable instructions executable by a computer and configured to:
initialize a single value cache associated with a column of a database table containing a single or unique data value, wherein each column of the database table is associated with a particular main storage and a particular delta storage, wherein the single value cache is initialized and marked for caching based on a computed finding of identical single or unique data values in both the particular main storage and the particular delta storage associated with the column of the database table, and wherein the particular delta storage contains changes from data in the particular main storage;
verify that the created database table is in a useable state;
perform a database operation on the database table; and
retrieve the data value from the single value cache without locking the column containing the cached single or unique data value.

10. The medium of claim 9 , wherein the single value cache is part of metadata associated with the database table.

11. The medium of claim 9 , wherein both the particular main storage and the particular delta storage are scanned individually for the single or unique values.

12. The medium of claim 11 , wherein data stored in the single value cache is stored as a raw data value.

13. The medium of claim 11 , wherein the particular main storage and the particular delta storage each has a data dictionary used to combine values in the particular main storage and the particular delta storage to determine if the single value cache should be persisted for the database table.

14. The medium of claim 9 , wherein in operations where the database table is exclusively locked, all table columns are scanned for single or unique values using a value dictionary associated with each column to determine how many distinct values are being used in each column.

15. The medium of claim 9 , wherein the single value cache is marked as dirty until an exclusively lock phase occurs for the database table.

16. The medium of claim 9 , wherein NULL values are treated as normal values.

17. A system, comprising:
a memory;
at least one hardware processor interoperably coupled with the memory and configured to:
initialize a single value cache associated with a column of a database table containing a single or unique data value, wherein each column of the database table is associated with a particular main storage and a particular delta storage, wherein the single value cache is initialized and marked for caching based on a computed finding of identical single or unique data values in both the particular main storage and the particular delta storage associated with the column of the database table, and wherein the particular delta storage contains changes from data in the particular main storage;
verify that the created database table is in a useable state;
perform a database operation on the database table; and
retrieve the data value from the single value cache without locking the column containing the cached single or unique data value.

18. The system of claim 17 , wherein the single value cache is part of metadata associated with the database table, both the particular main storage and the particular delta storage are scanned individually for the single or unique values, and data stored in the single value cache is stored as a raw data value.

19. The system of claim 18 , wherein the particular main storage and the particular delta storage each has a data dictionary used to combine values in the particular main storage and the particular delta storage to determine if the single value cache should be persisted for the database table.

20. The system of claim 17 , wherein in operations where the database table is exclusively locked:
all table columns are scanned for single or unique values using a value dictionary associated with each column to determine how many distinct values are being used in each column; and
a single value cache marked as dirty is unmarked.

Assignees

• Seufert Thomas
• Geissinger Steffen
• Sap Se

Inventors

• Seufert Thomas
• Geissinger Steffen

Classifications

• G06F16/2282

  Tablespace storage structures; Management thereof · CPC title

• G06F16/951

  Indexing; Web crawling techniques · CPC title

• G06F16/172

  Caching, prefetching or hoarding of files · CPC title

• G06F16/2453 Primary

  Query optimisation · CPC title

• G06F16/14

  Details of searching files based on file metadata · CPC title