Oracle International Corporation

Harmeek Singh Bedi

Ashish Thusoo

Richard Yu Gu

Subhransu Basu

Thierry Cruanes

Ananth Raghavan

Bhaskar Ghosh

Susan M Kotsovolos

Geeta Arora

Yujie Cao

Tugrul Bingol

A method for performing multiple merge operations with a source data structure and a plurality of destination data structures, in which the source data structure is scanned one time in order to obtain source data that is then used for multiple merge operations. The source data is then used consecutively in order to merge the source data into the one or more destination data structures. Each merge is performed using the same scan of the source data structure and within the same execution of a database command.

Pipleline merge operations using source data and multiple destination data structures

Techniques are described herein for partitioning a database table using a virtual column as the partitioning key. A virtual column is defined by the database to contain results of a defining expression. Partitioning can be performed using a variety of partitioning schemes, such as range partitioning and hash partitioning. The partitions are automatically updated to reflect changes to the values in the base columns upon which the virtual column depends. Partition pruning and parallel-wise partition joins can be performed on database tables which have been partitioned on virtual columns.

Partitioning in virtual columns

Techniques are described herein for performing column functions on virtual columns in database tables. A virtual column is defined by the database to contain results of a defining expression. Statistics are collected and maintained for virtual columns. Indexing is performed on virtual columns. Referential integrity is maintained between two tables using virtual columns as keys. Join predicate push-down operations are also performed using virtual columns.

Virtual columns

Techniques are described herein for replacing a part of an expression in a query to a database with a virtual column. A virtual column is defined by the database to contain results of a defining expression. A part of an expression in a query is replaced with a virtual column whose defining expression is equal to the part of the expression in the query. The part of an expression in a query can be the entire expression. When an expression in a query can be replaced with more than one replacement expression involving virtual columns, the replacement expression with the least cost of query processing is selected.

Expression replacement in virtual columns

Techniques are described herein for supporting pipelining operations involving DML (Data manipulation Language) and query. In an embodiment, a DML operation is performed for the purpose of changing data in a database system from a first state to a second state. Before the data in the database system is changed by the DML operation, the DML operation has an in-memory representation of such data. In an embodiment, a subsequent query operation that logically depends on the data in the database system in the second state is granted access to the in-memory representation of such data in the second state before the data in the database system is changed by the DML operation to the second state. As a result, operations may be executed in a pipelined fashion with minimum blocking.

Pipelining operations involving DML and query

Method and apparatus for performing multi-table merge operations in a database environment

A technique for migrating (e.g., 'copying' or 'moving') temporary data from one session to another session is provided. While executing a workload associated with a particular session, session state is created. A subset of the session state comprises large objects that are referred to as &#x201c;temporary data.&#x201d; Thus, temporary data is stored in a database (instead of in the database server) and is normally deleted when the particular session is deleted. To avoid this deletion when the session state is migrated to a different session, the temporary data, in one embodiment, is saved in an external storage that is separate from the database. An external table is created in the external storage and stores the temporary data. Location information to access the external table is provided to the other session.

Migrating temporary data of a session

Provided herein are techniques that may be used to dramatically increase parallism for distributed DML operations. The work of distributed DML operations are distributed in a way that avoids self-dead locks, by ensuring that, for a given data block, no more than one slave is assigned to modify a row that is wholly contained by the data block or whose head row piece is contained by the data block. Assigning slaves in this way not only allows more slaves to be assigned to modify a partition, but allows for greater flexibility in load balancing.

TQ distribution that increases parallism by distributing one slave to a particular data block

Technique for using a current lookup for performing multiple merge operations using source data that is modified in between the merge operations

Method and apparatus for performing multiple merge operations using source data that is modified in between the merge operations

The present invention provides the ability to alternatively update or insert a row into a table. This functionality is accomplished by merging a source table with a destination table such that the rows in the combined table are classified as an update row or an insert row. An identifier is inserted into each row to indicate its class. Examination of the identifier allows the row to be correctly inserted into the destination table or correctly updated in the destination table.

Method for conditionally updating or inserting a row into a table

Conditional functionality is provided for database merge operations. A merge operation, for merging data from a source to a destination, involves performing a default operation for each source record. Default operations associated with a MERGE statement include UPDATE and INSERT operations. Which default operation is performed depends on whether any destination record corresponds to a given source record. In an embodiment, whether a specified condition is satisfied is determined. If the condition is satisfied, then the default operation that is appropriate for a given source record is performed. If the condition is not satisfied, then the given source record is processed without performing the appropriate default operation. In one aspect, the UPDATE clause of the MERGE statement is extended to include a conditional DELETE clause. Hence, records are deleted as appropriate based on a temporary updated state, as part of the same process as the update operation, without an additional table scan and without having to first update the record in shared memory or in persistent storage.

Growing community of inventors

Foster City, CA, United States of America

Harmeek Singh Bedi