International Business Machines Corporation

Couchbase, Inc.

Marco Greco

Raghupathi Keshava Murthy

Bingjie Miao

Prathibha Bisarahalli Prabhakar

Sitaram Vemulapalli

John Frederic Miller

Nita Dembla

Lynette D Adayilamuriyil

Srinath Duvuru

Jeffrey A McMahon

A document-oriented database system generates an optimal query execution plan for database queries on an untyped field included in a collection of documents. Each untyped field is configured to store one or more scalar data values. The system generates histograms for scalar data values stored in untyped fields. Responsive to receiving a query statement for fetching or updating data value stored in one of the untyped fields, the system assigns a cost to each operator associated with the query statement based on the histogram, compares the costs assigned to the operators, and generates a query execution plan based on the comparison, and query the database using the query execution plan.

Cost-based query optimization for untyped fields in database systems

A document-oriented database system generates an optimal query execution plan for database queries on an untyped data field included in a collection of documents. The system generates histograms for multiple types of data stored by the untyped data field and uses the histograms to assign costs to operators usable to execute the database query. The system generates the optimal query execution plan by selecting operators based on the assigned costs. In various embodiments, the untyped data field stores scalars, arrays, and objects.

Cost-based query optimization for array fields in database systems

Cost-based optimization for document-oriented database queries on arrays

Cost-based optimization for document-oriented database queries

Embodiments for an approach to managing a relational database. The relational database comprises a first table defining a primary key, and at least one other table with a foreign key constraint referencing the primary key. The data of the first table and at least one other table is divided into a plurality of partitions, each containing data associated with a subset of primary key values. Receiving a partition management policy, defining one or more conditions for the first table and at least one other table and an operation performed on the partitions of the first table and at least one other table. Determining if the first table and at least one other table satisfy the one or more conditions of the partition management policy, if not, performing the operation.

Managing relational databases

An approach to managing a relational database. The relational database comprises a first table defining a primary key, and at least one other table with a foreign key constraint referencing the primary key. The data of the first table and at least one other table is divided into a plurality of partitions, each containing data associated with a subset of primary key values. Receiving a partition management policy, defining one or more conditions for the first table and at least one other table and an operation performed on the partitions of the first table and at least one other table. Determining if the first table and at least one other table satisfy the one or more conditions of the partition management policy, if not, performing the operation.

In a method for table statistics update, in response to a request to modify a row in a target table, a database management system inspects a log record for the modified row in the target table, determines that the target table is configured for continuous statistics evaluation, and determines whether a mini-bin related to the modified row exists. When the mini-bin related to the modified row does not exist, the database management system creates the mini-bin. When the mini-bin related to the modified row exists, the database management system aggregates the modified row into the mini-bin, and when the mini-bin is determined to have reached a threshold size, stores the mini-bin to a disk. The database management system then consolidates a plurality of mini-bins stored in the disk and corresponding to the target table into a set of bins.

Continuous automatic update statistics evaluation using change data capture techniques

The present invention provides a method, a system, and a computer program product of preventing thread monitoring preemptions in an almost fair busy lock. In an exemplary embodiment, the method, the system, and the computer program product include (1) publishing a current state of a lock and a claim non-atomically to the lock by a next owning thread, the claim comprising a structure capable of being read and written only in a single memory access, (2) obtaining a ticket, where the claim comprises an identifier of a ticket obtained by the next owning thread, and an indication that the next owning thread is claiming the lock; (3) comparing the ticket obtained by the next owning thread with a current ticket; (4) preventing thread monitoring preemptions; and (5) responsive to a match between the ticket obtained by the next owning thread and the current ticket, non-atomically acquiring the lock.

Almost fair busy lock

Embodiments relate to managing exclusive control of a shareable resource between a plurality of concurrently executing threads. An aspect includes determining the number of concurrently executing threads waiting for exclusive control of the shareable resource. Another aspect includes, responsive to a determination that the number of concurrently executing threads waiting for exclusive control of the shareable resource exceeds a pre-determined value, one or more of said concurrently executing threads terminating its wait for exclusive control of the shareable resource. Another aspect includes, responsive to a determination that the number of concurrently executing threads waiting for exclusive control of the shareable resource is less than a pre-determined value, one or more of said one or more concurrently executing threads which terminated its wait for exclusive control of the shareable resource, restarting a wait for exclusive control of the shareable resource.

Busy lock and a passive lock for embedded load management

Provided are techniques for cyclic based data partitioning policy with automatic physical schema management. A data partitioning policy for data is received, wherein the data partitioning policy identifies a condition for automatically implementing the data partitioning policy and criteria for modifying a set of partitions. In response to the condition occurring, the data partitioning policy is automatically applied to select at least one partition from the set of partitions based on the criteria. An operation is performed on the at least one partition to modify the set of partitions.

Policy based automatic physical schema management

Managing exclusive control of a shareable resource includes publishing a claim non atomically to a lock by a thread that is next to own the lock in an ordered set of threads that have requested to own the lock. The claim includes a structure capable of being read and written only in a single memory access. A determination is made of whether the next owning thread has been pre-empted. Responsive to the determination, the next owning thread of the lock acquires the lock if the next owning thread has not been pre-empted and retries acquisition of the lock if the next owning thread has been pre-empted. Responsive to the next owning thread being pre-empted, a subsequent owning thread acquires the lock unfairly and atomically, consistently modifies the lock such that a next lock owner can determine that the next lock owner has been preempted.

Access to a shareable resource between threads is controlled by a lock having shared, optimistic and exclusive modes and maintaining a list of threads requesting ownership of said lock. A shared optimistic mode is provided. A lock state descriptor is provided for each desired change of mode comprising a current mode in which a thread has already acquired the lock. When a thread acquires the lock in shared optimistic mode, other threads are allowed to acquire the lock in shared or optimistic mode. When a thread which acquired the lock in shared optimistic mode wants to acquire the lock in exclusive mode, other threads which have acquired the lock in shared or optimistic mode are prevented from acquiring the lock in exclusive mode until the thread which acquired the lock in shared optimistic mode and requested to acquire the lock in exclusive mode releases the lock.

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Staines, United Kingdom

Marco Greco