Abstract: A technique includes performing optimistic concurrency control to process a request associated with a transaction to change a schema of an object. Performing the optimistic concurrency control includes locally modifying the object to change the schema of the object based on the request; after locally modifying the object, locking a global catalog to block the object from being globally modified; validating the locally modified object based on the global catalog; and committing the modified object to a globally shared storage in response to the modified object being validated.

Abstract: A technique includes storing, by a computer, a composite metadata object in a catalog. The composite metadata object represents information about a plurality of database objects of a table structure; the table structure includes a plurality of rows and a plurality of columns; the plurality of database objects is associated with a subset of rows of the plurality of rows; and the plurality of database objects is associated with a plurality of files corresponding to the columns. The technique includes processing, by the computer, a database transaction based on the based on composite metadata object.

Abstract: A database management system includes a cluster of nodes over which a columnar database has been sharded into shards to which the nodes are subscribed. Source nodes of the cluster store up-to-date metadata objects for the shards, and target nodes of the cluster storing out-of-date metadata objects for the shards. A coordinator node initiates a parallel batch metadata transfer update process in which the out-of-date metadata objects at the target nodes are updated in parallel from the up-to-date metadata objects at the source nodes. The coordinator node can determine pairs of source nodes and target nodes; the source node and the target node of each pair respectively store an up-to-date metadata object and an out-of-date metadata object for a same shard.

Abstract: A database management system includes a cluster of nodes over which a columnar database has been sharded into shards to which the nodes are subscribed. Source nodes of the cluster store up-to-date metadata objects for the shards, and target nodes of the cluster storing out-of-date metadata objects for the shards. A coordinator node initiates a parallel batch metadata transfer update process in which the out-of-date metadata objects at the target nodes are updated in parallel from the up-to-date metadata objects at the source nodes. The coordinator node can determine pairs of source nodes and target nodes; the source node and the target node of each pair respectively store an up-to-date metadata object and an out-of-date metadata object for a same shard.

Abstract: A technique includes storing, by a computer, a composite metadata object in a catalog. The composite metadata object represents information about a plurality of database objects of a table structure; the table structure includes a plurality of rows and a plurality of columns; the plurality of database objects is associated with a subset of rows of the plurality of rows; and the plurality of database objects is associated with a plurality of files corresponding to the columns. The technique includes processing, by the computer, a database transaction based on the based on composite metadata object.

Abstract: A technique includes performing optimistic concurrency control to process a request associated with a transaction to change a schema of an object. Performing the optimistic concurrency control includes locally modifying the object to change the schema of the object based on the request; after locally modifying the object, locking a global catalog to block the object from being globally modified; validating the locally modified object based on the global catalog; and committing the modified object to a globally shared storage in response to the modified object being validated.