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MAINTAINING CROSS-NODE COHERENCE OF AN IN-MEMORY DATABASE OBJECT IN A MULTI-NODE DATABASE CLUSTER

  • US 20160350352A1
  • Filed: 12/29/2015
  • Published: 12/01/2016
  • Est. Priority Date: 05/29/2015
  • Status: Active Grant
First Claim
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1. A method comprising:

  • maintaining, in a persistent storage, a database that is accessible to a plurality of database server instances;

    wherein the database includes a table that is physically organized in a plurality of units, wherein each unit of the plurality of units is stored in persistent storage and comprises one or more contiguous rows of the table stored in row-major format;

    generating, in a first volatile memory local to a first database server instance of the plurality of database server instances, a first in-memory copy of a first chunk of the table;

    wherein the first in-memory copy of the first chunk of the table comprises one or more columns from one or more units of the plurality of units in column-major format;

    acquiring, by the first database server instance, a first lock that covers a particular unit of the plurality of units;

    receiving, at the first database server instance, a first request to release the first lock;

    in response to receiving the first request, releasing the first lock, andin response to releasing the first lock, storing, in the first volatile memory, a first indication that each row in the first in-memory copy of the first chunk that is also generated from the particular unit is invalid;

    wherein the first database server instance responds to requests to read data from the first chunk by;

    obtaining data items, that belong to the first chunk and that have not been invalidated in the first in-memory copy, from the first in-memory copy; and

    obtaining data items, that belong to the first chunk and have been invalidated in the first in-memory copy, from a source other than the first in-memory copy;

    wherein the method is performed by one or more computing devices.

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