Abstract: Distributed database systems including a plurality of SQL compute nodes are described herein that enable such nodes to operate with versioned metadata despite the fact that SQL is only single-version aware. The distributed database system further includes a global logical metadata server to store and manage versions of metadata, to determine which of such versions should be visible at any given point in time, and enable creation of a virtual database that includes the proper versions of metadata. In an aspect, a central transaction manager manages global transaction identifiers and their associated start times, abort times and/or commit times that enables determination of transaction and metadata version visibility for any point in time. In an aspect, the visible metadata is included in a virtual database that logically overlays a physical database and provides the correct version of metadata in lieu of the current metadata version stored in the physical database.

Abstract: Distributed database systems including a plurality of SQL compute nodes are described herein that enable such nodes to operate with versioned metadata despite the fact that SQL is only single-version aware. The distributed database system further includes a global logical metadata server to store and manage versions of metadata, to determine which of such versions should be visible at any given point in time, and enable creation of a virtual database that includes the proper versions of metadata. In an aspect, a central transaction manager manages global transaction identifiers and their associated start times, abort times and/or commit times that enables determination of transaction and metadata version visibility for any point in time. In an aspect, the visible metadata is included in a virtual database that logically overlays a physical database and provides the correct version of metadata in lieu of the current metadata version stored in the physical database.