Oracle International Corporation

Alexander C Ho

Jeffrey Ira Cohen

Cetin Ozbutun

Hakan Jakobsson

Michael Charles Depledge

Quoc Tai Tran

Mark Kremer

Juan R Loaiza

William Havinden Bridge, Jr

Graham Wood

Gianfranco Putzolu

Ashok M Joshi

Julian Hyde

Jonathan D Klein

Boris Klots

Wei Huang

Dinesh Das

Larry Stevens

Rafael E Caicedo

Khaled Abdel-Motagaly

Christopher D Dallara

Paul C Strefling

Kioumars Najmabadi

Tze L Siu

Hisako Yamashiro

Described herein are approaches for partitioning a buffer cache for dynamically selecting buffers in the buffer cache to store data items, such as data blocks in a DBMS. The selection is based on data access and/or usage patterns. A buffer cache includes multiple buffer pools. A buffer pool is selected from among the multiple buffer pools to store a data item. The selection of a buffer pool is based on various factors, including the likelihood that storing the data item will produce future cache hits, and properties of buffer pools that vary between the buffer pools. Properties of a buffer pool include not only how the buffer pools are organized, both logically and physically, but also how the buffer pool is managed. Examples of a buffer pool property include buffer pool size, size of a buffer in the buffer pool, and the replacement strategy used for a buffer pool (e.g. LRU).

Managing partitioned cache

The present invention provides a method and apparatus for partitioning a buffer cache for dynamically mapping data blocks with a particular replacement strategy based on the associated table's access and/or usage patterns. According to the method, a buffer cache in a computer system is managed by dividing the buffer cache into multiple buffer pools. In managing the buffer cache, when a data item is requested, it is first determined whether the requested data item is stored in a buffer within the buffer cache. If the requested data item is not stored in a buffer in the buffer cache, then a particular buffer pool in the buffer cache is dynamically selected for storing the requested data item. Once the particular buffer pool is selected, the requested data item is stored into a buffer in the particular buffer pool.

A method and apparatus for segmenting bitmaps in a bitmap index is provided. A segmented bitmap includes a plurality of bitmap segments that are used to indicate which records in a body of records that is associated with the segmented bitmap satisfy a particular criteria. Each bitmap segment contains a string of bits that correspond to a corresponding range of records in the body of records. There may be gaps between the ranges represented by the bitmap segments when, for example, the body of records does not contain records in a particular range. For the purposes of retrieval, compression, de-compression, locking and logging, the database system treats each bitmap segment as a distinct data item.

Bitmap segmentation

A method and apparatus for generating and using bitmaps in a database system that employs multi-level identifiers is provided. The generated bitmaps include bits that correspond to the identifiers that have been assigned to existing records, as well as bits that correspond to all intervening multi-level identifiers that have not yet been assigned. Therefore, when new rows are inserted into the table associated with the bitmap, new bits do not have to be inserted into the existing bitmap. When existing rows are deleted, the bits that correspond to the deleted rows are not themselves deleted, but are simply set to a value that indicates that the corresponding row does not satisfy the criteria associated with the bitmap.

Creating bitmaps from multi-level identifiers

A method and apparatus for inserting sorted data into an indexed table is provided. Two or more nodes are used to insert the data into the indexed table. Before an entry for each inserted row is stored in the index associated with the table, the key values in the index entry are transformed using an operation that affects the order of the key values. For example, the order of the bytes used to represent the key values in the index entry may be reversed. The index entries are stored in the portion of the index that corresponds to the transformed key values. As a result, the entries for consecutive key values will not necessarily be stored in the same portion of the index. Consequently, the nodes will not have to compete for a 'hot' portion of an index if the nodes are inserting data with key values that fall into the same approximate range. The inverse of the transformation operation is performed on the transformed key values read from the index before the key values are supplied to the user.

Reverse-byte indexing

A method and apparatus provide bitmapped indexing with high granularity locking. Whenever a change is made to a data table upon which a bitmapped index is based, two differential entries are generated and stored as index entries in the bitmapped index. Each differential entry identifies a bit to be flipped in the corresponding bitmap index entry. When applied to corresponding bitmap index entry, the changes are reflected in the appropriate bitmaps. Whenever a bitmap is read from the bitmapped index, any corresponding differential entries are applied so that the resulting bitmap reflects the change made to the data table.

Bitmapped indexing with high granularity locking

An improved method and apparatus for creating an index is disclosed. All data repositories containing the data necessary to create the index are identified, and one of these data repositories is then selected based on a predetermined criteria. The predetermined criteria includes the size of the possible data repositories, or a determination of which data repository will require the least amount of sorting. The selected data repository is then used to create an index.

Selecting a qualified data repository to create an index

Growing community of inventors

Belmont, CA, United States of America

Alexander C Ho