Objectivity/DB: Difference between revisions

Revision as of 10:14, 3 December 2014

Revision as of 21:05, 3 December 2014

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|date= January 2000

|publisher= Academic Press

|isbn= 1-55860-647-51558606475

|accessdate= December 1, 2014

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</ref> The OIDs are also used in support of scalable collections (tree, list, set etc.), indices and [[hash table]]s. Eliminating the relational [[Join]] operations inherent in a relational database gives Objectivity/DB a marked performance advantage, in orders of magnitude.

<ref>

{{Citation

| author = Suzanne W. Dietrich, Susan D. Urban

| year = 2011

| title = Fundamentals of Object Databases

| publisher = Morgan & Claypool Publishers

| page = 2

| isbn = 9781608454761

| url = http://books.google.com/books?id=x_8myOrO1dgC&printsec=frontcover&dq=Fundamentals+of+Object+Databases&hl=en&sa=X&ei=1XV_VIqeDIWoogS4kYKwCQ&ved=0CC0Q6AEwAA#v=onepage&q=Fundamentals%20of%20Object%20Databases&f=false

| accessdate = December 3, 2014

}}

</ref>

<ref>

{{Citation

| editor = Alan Dearle, Roberto V. Zicari

| year = 2010

| title = Objects and Databases, Third International Conference Proceedings, ICOODB

| publisher = Springer

| page = 34

| isbn = 3642160913

| url = http://books.google.com/books?id=AHHE015TBrIC&printsec=frontcover#v=onepage&q&f=false

| accessdate = December 3, 2014

}}

</ref>

<ref>

{{Citation

| author = C.S.R Prabhu

| year = 2011

| title = Object-Oriented Database Systems - Approaches and Architecture, Third Edition

| publisher = Asoke K. Ghosh, PHI Learning Private Limited

| page = 67

| isbn = 9788120340930

| url = http://books.google.com/books?id=aRdl1j31MfoC&printsec=frontcover#v=onepage&q&f=false

| accessdate = December 3, 2014

}}

</ref>

Objectivity/DB is also different from [[RDBMS]]s in the way in which it handles queries. The application declares and initializes an iterator that locates and returns qualified objects as soon as they are located. Many RDBMSs manifest a view of the results before returning any of them. The Objectivity/DB Parallel Query Engine splits queries into subtasks directed at individual databases or containers. Remote query agents service each subtask and return results to the iterator. The Parallel Query Engine has two replaceable components: a splitter that can determine how to best subdivide the task and a filter in the query agent that can further refine a query. A query involving cities in Europe might be split into forty nine subtasks, one for each country. The filter might access an external data source before qualifying or disqualifying the objects that the Query Agent has found in the Objectivity/DB database or container.

Databases and system data (catalogs and [[Database schema|schema]]) can be replicated to multiple locations using a quorum based synchronous replication mechanism. Replicas that are temporarily separated from the quorum are transparently resynchronized when they are reconnected to the network that services them and their peers. Individual databases and lock servers can be allocated votes that are used to determine whether or not a client can update a replica.