Flexible in-memory column store placement

Patent metadata

Field	Value
Publication number	US-2018096010-A1
Application number	US-201615281718-A
Country	US
Kind code	A1
Filing date	Sep 30, 2016
Priority date	Sep 30, 2016
Publication date	Apr 5, 2018
Grant date	—

Abstract

Techniques are described herein for distributing distinct portions of a database object across volatile memories of selected nodes of a plurality of nodes in a clustered database system. The techniques involve storing a unit-to-service mapping that associates a unit (a database object or portion thereof) to one or more database services. The one or more database services are mapped to one or more nodes. The nodes to which a service is mapped may include nodes in disjoint database systems, so long as those database systems have access to a replica of the unit. The database object is treated as in-memory enabled by nodes that are associated with the service, and are treated as not in-memory enabled by nodes that are not associated with the service.

First claim

What is claimed is:

1 . A method comprising:
storing, in a database that is accessible to a plurality of nodes, a unit-to-service mapping that maps a particular unit in the database to a particular database service; storing, in the database, a service-to-node mapping that maps the particular database service to one or more nodes; wherein less than all of the plurality of nodes are included in the one or more nodes; based on both the unit-to-service mapping and the service-to-node mapping, the one or more nodes treating the particular unit as in-memory enabled and nodes, of the plurality of nodes, other than the one or more nodes treating the particular unit as not in-memory enabled; and wherein, each node of the one or more nodes treats the particular unit as in-memory enabled by loading at least a portion of the in-memory object into local volatile memory in response to a load-triggering event.

2 . The method of claim 1 wherein the particular unit is an entire database object.

3 . The method of claim 1 wherein the particular unit is one or more chunks of a database object but less than all of the database object.

4 . The method of claim 1 further comprising, as part of loading the copy of the particular unit into local volatile memory, converting the particular unit from a persistent-format to a mirror-format.

5 . The method of claim 1 wherein:
the particular unit is a first object in the database;
the database includes a second object;
the second object is not mapped to any service; and
the method further comprising storing data that indicates that the second object is to be treated as memory-enabled by one of:
all of the plurality of nodes, or
none of the plurality of nodes.

6 . The method of claim 1 wherein the one or more nodes includes a first node that has loaded a copy of the particular unit into volatile memory, the method further comprising:
detecting that the particular database service has stopped on the first node; and
responsive to detecting that the particular database service has stopped on the first node, deallocating the copy of the particular unit from local volatile memory of the first node.

7 . The method of claim 1 wherein the one or more nodes includes a first node that has loaded a copy of the particular unit into volatile memory, the method further comprising:
receiving a request at the first node that requires the particular unit;
determining that the first node has loaded a copy of the particular unit into volatile memory; and
reading the copy of the particular unit.

8 . The method of claim 1 wherein the one or more nodes includes a first node that has loaded a copy of the particular unit into volatile memory, the method further comprising:
receiving a request at a second node that requires the particular unit;
determining that the first node has loaded a copy of the particular unit into volatile memory; and
sending the request to the first node.

9 . The method of claim 1 further comprising:
receiving a request that requires the particular unit;
determining that no node of the one or more nodes has loaded a copy of the particular unit into volatile memory; and
in response to determining that no node has loaded a copy of the particular unit into volatile memory, at least one node of the one or more nodes loading at least a portion of the particular unit into local volatile memory.

10 . The method of claim 1 wherein the plurality of nodes belong to a first database system and the one or more nodes include at least one node that belongs to a second database system that is disjoint relative to the first database system.

11 . The method of claim 10 wherein the one or more nodes include a node in the first database system and a node in the second database system.

12 . The method of claim 10 wherein the one or more nodes include only nodes in the second database system.

13 . The method of claim 10 wherein:
the particular unit is a first object in the database;
the database includes a second object that is a portion of the first object;
the second object is mapped to one or more nodes of the first database system; and
the particular unit is mapped to one or more nodes of the second database system.

14 . The method of claim 1 wherein the particular unit comprises a plurality of chunks and each node of the one or more nodes hosts one or more chunks of the plurality of chunks.

15 . One or more non-transitory computer-readable media storing instructions, wherein the instructions include:
instructions which, when executed by one or more hardware processors, cause storing, in a database that is accessible to a plurality of nodes, a unit-to-service mapping that maps a particular unit in the database to a particular database service; instructions which, when executed by one or more hardware processors, cause storing, in the database, a service-to-node mapping that maps the particular database service to one or more nodes; wherein less than all of the plurality of nodes are included in the one or more nodes; instructions which, when executed by one or more hardware processors, cause based on both the unit-to-service mapping and the service-to-node mapping, the one or more nodes treating the particular unit as in-memory enabled and nodes, of the plurality of nodes, other than the one or more nodes treating the particular unit as not in-memory enabled; and wherein, each node of the one or more nodes treats the particular unit as in-memory enabled by loading at least a portion of the in-memory object into local volatile memory in response to a load-triggering event.

16 . The one or more non-transitory computer-readable media of claim 15 , wherein the particular unit is an entire database object.

17 . The one or more non-transitory computer-readable media of claim 15 , wherein the particular unit is one or more chunks of a database object but less than all of the database object.

18 . The one or more non-transitory computer-readable media of claim 15 , the instructions further comprising:
instructions which, when executed by one or more hardware processors, cause as part of loading the copy of the particular unit into local volatile memory, converting the particular unit from a persistent-format to a mirror-format.

19 . The one or more non-transitory computer-readable media of claim 15 wherein:
the particular unit is a first object in the database;
the database includes a second object;
the second object is not mapped to any service; and
the instructions further including instructions which, when executed by one or more hardware processors, cause storing data that indicates that the second object is to be treated as memory-enabled by one of:
all of the plurality of nodes, or
none of the plurality of nodes.

20 . The one or more non-transitory computer-readable media of claim 15 wherein the one or more nodes includes a first node that has loaded a copy of the particular unit into volatile memory, the instructions further comprising:
instructions which, when executed by one or more hardware processors, cause detecting that the particular database service has stopped on the first node; and
instructions which, when executed by one or more hardware processors, cause responsive to detecting that the particular database service has stopped on the first node, deallocating the copy of the particular unit from local volatile memory of the first node.

21 . The one or more non-transit

Assignees

• Oracle Int Corp

Inventors

• Mukherjee Niloy
• Kamp Jesse
• Lahiri Tirthankar
• Colgan Maria
• Raja Vivekanandhan
• Krishnaswamy Vasudha
• Gupta Aditi
• Kulkarni Kartik

Classifications

• G06F16/24552

  Database cache management · CPC title

• G06F16/221 Primary

  Column-oriented storage; Management thereof · CPC title

• G06F3/064

  Management of blocks · CPC title

• G06F16/2282

  Tablespace storage structures; Management thereof · CPC title

• G06F3/0604

  Improving or facilitating administration, e.g. storage management · CPC title