NON-BLOCKING PARALLEL MEMORY MECHANISMS

摘要

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.

主权项

1. A computer implemented method to delete obsolete versions from memory, the method comprising:
receiving a transaction descriptor associated with a vertical chain of row versions from a plurality of vertical chains of row versions, wherein the plurality of vertical chains of row versions is intersected with a plurality of horizontal chains of row versions to form a grid structure; terminating a link to a current row version in the vertical chain, wherein the vertical chain comprises row versions of multiple rows, and wherein the link to the current row version is included in the transaction descriptor; upon determining that the current row version is not a rollback version, terminating a link from the current row version to an older row version in a horizontal chain and terminating a link from the current row version to a next row version in the vertical chain, wherein the horizontal chain comprises row versions of a row; upon determining that the older row version is set as ready for garbage collection, deleting the older row version from memory; and upon determining that the current row version is set as ready for garbage collection, deleting the current row version from memory.