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: In some examples, formatting semi-structured data in a database includes obtaining semi-structured data in a column store database, assigning the semi-structured data to a semi-structured column with a key and value format, and formatting the semi-structured data with an optimal search format.

Abstract: In an example, a flexible schema table may be schematized. Records from the flexible schema table may be queried and, for keys in the records, a data type is estimated for each key. View columns may then be selected from the keys based on a predetermined condition. A view of the flexible schema table may be created from the selected view columns, wherein the view includes the view columns and the data types for the view columns.

Abstract: A non-transitory machine-readable storage medium stores instructions that upon execution cause a processor to, in response to a receipt of a query, communicate, via a first encrypted channel using a first key, first encrypted data between a plurality of nodes of a distributed database system, the first encrypted data comprising query metadata and a second key; communicate, via a second encrypted channel, second encrypted data between the plurality of nodes of the distributed database system, the second encrypted channel using the second key included in the first encrypted data, the second encrypted data comprising query data; and generate, by the plurality of nodes of the distributed database system, results for the query based on the query data in the second encrypted data.

Abstract: A technique includes modeling assignments of a plurality of nodes to a plurality of shards associated with a database operation based on a target throughput for the plurality of nodes. The modeling includes constraining the assignments based on an aggregate outflow from the plurality of nodes. The technique includes initializing the aggregate outflow to be less than the target throughput; and determining the assignments based on the modeling.

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 applying a first mapping to associate a plurality of data records for a plurality of database nodes with a plurality of segments of a storage that is shared by the database nodes; and applying a many-to-many second mapping to associate the segments with the database nodes.

Abstract: A non-transitory machine-readable storage medium stores instructions that upon execution cause a processor to, in response to a receipt of a query, communicate, via a first encrypted channel using a first key, first encrypted data between a plurality of nodes of a distributed database system, the first encrypted data comprising query metadata and a second key; communicate, via a second encrypted channel, second encrypted data between the plurality of nodes of the distributed database system, the second encrypted channel using the second key included in the first encrypted data, the second encrypted data comprising query data and generate, by the plurality of nodes of the distributed database system, results for the query based on the query data in the second encrypted data.

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 applying a first mapping to associate a plurality of data records for a plurality of database nodes with a plurality of segments of a storage that is shared by the database nodes; and applying a many-to-many second mapping to associate the segments with the database nodes.

Abstract: A technique includes modeling assignments of a plurality of nodes to a plurality of shards associated with a database operation based on a target throughput for the plurality of nodes. The modeling includes constraining the assignments based on an aggregate outflow from the plurality of nodes. The technique includes initializing the aggregate outflow to be less than the target throughput; and determining the assignments based on the modeling.

Abstract: A technique includes determining an earliest query start time associated with a plurality of queries currently being processed by a node; and based on the identified earliest query start time, selecting a version of a global catalog existing at the earliest start time. The global catalog represents objects stored in a storage shared by the node and at least one other node. The technique includes communicating the selected version of the global catalog to an object garbage collector for the storage.

Abstract: In an example, a flexible schema table may be schematized. Records from the flexible schema table may be queried and, for keys in the records, a data type is estimated for each key. View columns may then be selected from the keys based on a predetermined condition. A view of the flexible schema table may be created from the selected view columns, wherein the view includes the view columns and the data types for the view columns.

Abstract: In some examples, formatting semi-structured data in a database includes obtaining semi-structured data in a column store database, assigning the semi-structured data to a semi-structured column with a key and value format, and formatting the semi-structured data with an optimal search format.

Abstract: Updating statistics in distributed databases includes storing global statistics about at least one distributed table column distributed across multiple database nodes, where the global statistics have sensitive data for a query plan optimization process and insensitive data for the query plan optimization process, and updating the sensitive data of the global statistics more frequently than the insensitive data.

Abstract: A method for object dependency management for historical access includes assigning versions to states of a structure for storing objects, and assigning the versions to dependency changes between the objects. The method further includes managing historical access to the objects based on an analysis of the versions and the dependency changes between the objects.