Sap Se

Sybase, Inc.

Rahul Mittal

Amit Pathak

Jay Gorakhnath Sudrik

Simhachala Sasikanth Gottapu

Swati Sharma

Aditya Gurajada

Paresh Manhar Rathod

A system for an in-memory row storage architecture can be provided. In some implementations, the system performs operations including processing a database statement comprising a first database transaction affecting one or more rows in an in-memory row store, registering the database statement at a start of execution of the database statement, the start of execution occurring at a first time, unregistering the registered database statement at an end of execution of the database statement, determining a second time at which execution of an oldest currently registered database statement was started, assigning a garbage collection thread to a second database transaction committed at a third time and affecting at least one row of the plurality of rows, and activating the garbage collection thread to reclaim memory within the in-memory row store when the third time is less than the second time. Related systems, methods, and articles of manufacture are also described.

Garbage collection for in-memory row storage

A system for an in-memory row storage architecture can be provided. In some implementations, the system performs operations comprising determining that data stored at a first location in a persistent page store is active, copying the data to a second location in an in-memory row store in response to determining that the data is active, indexing the data in an index table in response to determining that the data is active, accessing the data at the second location in the in-memory row store based on the index table, and performing an update of the data in the in-memory row store. Related systems, methods, and articles of manufacture are also described.

In-memory row storage architecture

Example embodiments of a database employing an efficient form of multi-version concurrency control (MVCC) are described. In an example embodiment, in response to receiving an update command for a first row of a plurality of rows of a database, an image of the first row stored in a first memory area is stored in a second memory area. In a third memory area storing a first database structure and associated pointer corresponding to the image of the first row stored in the first memory area, a second data structure and associated pointer corresponding to the image of the first row in the second memory area are stored. The second data structure is linked to the first data structure. The image of the first row in the first memory area is overwritten with an image of a new version of the first row provided in the update command.

Efficient database multi-version concurrency control

A multi-layer data structure is configured to access rows, pages, and locks stored in memory of a database. The multi-layer data structure may include a row mapping table configured to convert a row identifier of a row in the database into a row address of the row to be accessed stored in a cache memory. The row mapping table may be used to compare bits of the row identifier with corresponding bits of the row address in the cache memory. Each layer of multi-layer row mapping table can be configured to store certain of the bits oldie row address and the row address can be determined by comparing the bits of the row address with the corresponding bits of the row identifier at each layer of the data structure.

Multi-layered row mapping data structure in a database system

A transaction descriptor associated with a vertical chain of row versions is received. The vertical chain of row versions is traversed. The vertical chain is part of a grid structure formed by a number of vertical chains intersected with a number of horizontal chains. A link to a current row version is terminated. A link from the current row version to an older row version in a horizontal chain is locally stored and terminated. The older row version is set as ready for garbage collection. The current row version is set as ready for garbage collection. A link from the current row version to a next row version in the horizontal chain is locally stored and terminated. The next row version is appointed as current.

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Pune, India

Rahul Mittal