Sap Se

Sap Ag

Sangyong Hwang

Sang Kyun Cha

Sung Heun Wi

Chanho Jeong

Lars Fricke

Kihong Kim

Keunjoo Kwon

Juchang Lee

Ki Hong Kim

Joo Young Yoon

Frank Renkes

Jane Jung Lee

Devices, methods and systems for processing database queries formatted differently than the database storage model being queried are disclosed. Processing database queries independent of the storage model of the queried database may be performed by receiving a query for one or more data items stored in a database, determining whether to use at least one query operator that uses data having a format different from the storage model format of at least one of one or more data items stored in the database and converting the format of the data used by the at least one query operator to a format that matches the storage model format of at least one of one or more data items stored in the database. Related systems, methods, and articles of manufacture are also described.

Processing database queries using format conversion

A system includes reception of a database query, determination of a first logical query execution plan to execute the database query, determination of a second logical query execution plan to execute the database query, determination of a first plurality of resource usage estimates associated with the first logical query execution plan, determination of a second plurality of resource usage estimates associated with the second logical query execution plan, and determination, based on the first plurality of resource usage estimates and the second plurality of resource usage estimates, whether it is determinable to a suitable degree of certainty that one of the first logical query execution plan and the second logical query execution plan will be associated with a smaller amount of resource usage than the other one of the first logical query execution plan and the second logical query execution plan.

Uncertainty-aware selection of query execution plan

Total global minimum costs can be determined for multiple sub-plans for completing a multi-operation database process to be performed in a distributed database management system that includes a plurality of nodes. The multiple sub-plans can include different distributions of node locations of a plurality of operators among the plurality of nodes. An optimal plan having a lowest total minimum global cost can be selected from the multiple sub-plans.

Optimal operator placement for distributed query processing

An estimation algorithm can generate a uniqueness metric representative of data in a database table column that is split across a plurality of data partitions. The column can be classified as categorical if the uniqueness metric is below a threshold and as non-categorical if the uniqueness metric is above the threshold. A first estimation factor can be assigned to the column if the column is classified as categorical or a larger second estimation factor can be assigned if the column is non-categorical. A cost estimate for system resources required to perform a database operation on the database table can be calculated. The cost estimate can include an estimated total number of distinct values in the column across all of the plurality of data partitions determined using the assigned first estimation factor or second estimation factor and a number of rows in the table as inputs to an estimation function.

Unique value calculation in partitioned table

An optimistic, latch-free index traversal ('OLFIT') concurrency control scheme is disclosed for an index structure for managing a database system. In each node of an index tree, the OLFIT scheme maintains a latch, a version number, and a link to the next node at the same level of the index tree. Index traversal involves consistent node read operations starting from the root. To ensure the consistency of node read operations without latching, every node update operation first obtains a latch and increments the version number after update of the node contents. Every node read operation begins with reading the version number into a register and ends with verifying if the current version number is consistent with the register-stored version number. If they are the same, the read operation is consistent. Otherwise, the node read is retried until the verification succeeds. The concurrency control scheme of the present invention is applicable to many index structures such as the B+-tree and the CSB+-tree.

Cache-conscious concurrency control scheme for database systems

A system, method and computer product for accelerating parallel database transactions. One or more data processors execute a first transaction on a database. The first transaction includes a transactional lock associated with each of one or more records to update the one or more records during the first transaction, and a pre-commit command to request acknowledgement of committing the updating of the one or more records during the first transaction. The one or more data processors execute a second transaction on the database in parallel with the first transaction. The second transaction includes a transactional lock associated with each of one or more records to update the one or more records during the second transaction, and a pre-commit command to request acknowledgement of committing the updating of the one or more records during the second transaction. The transactional locks of the first and second transactions are released before flushing log records associated with the first and second transactions.

Growing community of inventors

Leimen, Germany

Sangyong Hwang