Method to accelerate queries using dynamically generated alternate data formats in flash cache

Patent metadata

Field	Value
Publication number	US-10296462-B2
Application number	US-201313840811-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Mar 15, 2013
Publication date	May 21, 2019
Grant date	May 21, 2019

Abstract

A method for accelerating queries using dynamically generated columnar data in a flash cache is provided. In an embodiment, a method comprises a storage device receiving a first request for data that is stored in the storage device in a base major format in one or more primary storage devices. The storage device comprises a cache. The base major format is any one of: a row-major format, a column-major format and a hybrid-columnar format. Based on first one or more criteria, it is determined whether to rewrite the data into rewritten data in a rewritten major format. In response to determining to rewrite the data into rewritten data in a rewritten major format, the storage device rewrites at least a portion of the data into particular rewritten data in the rewritten major format. The rewritten data is stored in the cache.

First claim

What is claimed is:

1. A method comprising steps of:
a storage device, which cooperates with a database server, but which is separate from the database server, receiving a first request for data stored in said storage device, said storage device storing said data in a base major format in one or more primary storage devices, said storage device comprising a cache;
wherein said base major format is any one of: a row-major format, a column-major format and a hybrid-columnar format;
in response to receiving the first request for said data stored in said storage device:
said storage device determining, based on first one or more criteria, to rewrite said data into rewritten data in a rewritten major format;
in response to determining to rewrite said data into rewritten data in a rewritten major format:
said storage device rewriting at least a portion of said data in a particular major format, of said base major format, into particular rewritten data in said rewritten major format;
wherein said rewritten major format is different than said particular major format;
said storage device storing said particular rewritten data in said cache; and
said storage device returning at least a portion of the data requested by said first request to said database server;
said storage device receiving a second request for said data stored in said storage device;
in response to receiving said second request, said storage device determining to access said particular rewritten data to satisfy said second request; and
 in response to determining to access said particular rewritten data to satisfy said second request, said storage device accessing said particular rewritten data stored in said cache.

2. The method of claim 1 , wherein determining to access said particular rewritten data to satisfy said second request is performed based on second one or more criteria.
said second request, said storage device accessing said particular rewritten data.

3. A method comprising steps of:
a storage device, which cooperates with a database server, but which is separate from the database server, receiving a first request for data blocks stored in said storage device, said storage device storing rows in said data blocks in a base major format in one or more primary storage devices, said storage device comprising a cache;
wherein said base major format is any one of: a row-major format, a column-major format and a hybrid-columnar format;
in response to receiving the first request for said data blocks stored in said storage device:
said storage device determining, based on first one or more criteria, to rewrite said data blocks into rewritten data in a rewritten major format;
in response to determining to rewrite said data blocks into rewritten data in a rewritten major format:
said storage device rewriting at least a portion of said data blocks in a particular major format, of said base major format, into particular rewritten data in said rewritten major format;
wherein said rewritten major format is different than said particular major format;
said storage device generating metadata describing at least said rewritten data;
said storage device storing said particular rewritten data in said cache; and
said storage device returning at least a portion of the data blocks requested by said first request to said database server;
said storage device receiving a second request for said data stored in said storage device;
in response to receiving said second request, said storage device determining to access said particular rewritten data to satisfy said second request; and
 in response to determining to access said particular rewritten data to satisfy said second request, said storage device accessing said particular rewritten data stored in said cache.

4. The method of claim 3 , wherein determining, to access said particular rewritten data to satisfy said second request is performed based on second one or more criteria.

5. The method of claim 3 , wherein the first one or more criteria are based on at least one of:
a number of columns in a database table; and
a database container that contains at least said portion of said data blocks requested by said first request.

6. The method of claim 4 , wherein the second one or more criteria is based on at least one of:
a number of columns requested in said second request; and
a number of rows accessed to service said second request.

7. The method of claim 3 , wherein said at least said portion of said data blocks includes columns, where said metadata specifies a location of each column within said cache.

8. An apparatus comprising:
one or more processors;
a storage device, which cooperates with a database server, but which is separate from the database server, configured to perform:
receiving a first request for data stored in said storage device, said storage device storing said data in a base major format in one or more primary storage devices, said storage device comprising a cache;
wherein said base major format is any one of: a row-major format, a column-major format and a hybrid-columnar format;
in response to receiving the first request for said data stored in said storage device:
said storage device determining, based on first one or more criteria, to rewrite said data into rewritten data in a rewritten major format;
in response to determining to rewrite said data into rewritten data in a rewritten major format:
said storage device rewriting at least a portion of said data in a particular major format, of said base major format, into particular rewritten data in said rewritten major format;
wherein said rewritten major format is different than said particular major format;

said storage device storing said particular rewritten data in said cache; and
said storage device returning at least a portion of the data requested by said first request to said database server;
said storage device receiving a second request for said data stored in said storage device;
in response to receiving said second request, said storage device determining to access said particular rewritten data to satisfy said second request; and
 in response to determining to access said particular rewritten data to satisfy said second request, said storage device accessing said particular rewritten data stored in said cache.

9. The apparatus of claim 8 , wherein determining, to access said particular rewritten data to satisfy said second request is performed based on second one or more criteria.

10. An apparatus comprising:
one or more processors;
a storage device, which cooperates with a database server, but which is separate from the database server, configured to perform:
receiving a first request for data blocks stored in said storage device, said storage device storing rows in said data blocks in a base major format in one or more primary storage devices, said storage device comprising a cache;
wherein said base major format is any one of: a row-major format, a column-major format and a hybrid-columnar format;
in response to receiving the first request for said data blocks stored in said storage device:
based on first one or more criteria, determining to rewrite said data blocks into rewritten data in a rewritten major format;
in response to determining to rewrite said data blocks into rewritten data in a rewritten major format:
said storage device rewriting at least a portion of said data blocks in a particular major format, of said base major format, into particular rewritten data in said rewritten major format;
wherein said rewritten major format is different than said particular major format;
said storage device generating metadata describing at least said re

Assignees

• Oracle Int Corp

Inventors

• Loaiza Juan
• Ganesh Amit
• Macnicol Roger
• Kamp Jesse
• Holloway Allison
• Ng Adrian
• Marwah Vineet

Classifications

• G06F16/22 Primary

  Indexing; Data structures therefor; Storage structures · CPC title

• G06F16/24552

  Database cache management · CPC title

• G06F12/0875 Primary

  with dedicated cache, e.g. instruction or stack · CPC title