A PCRE internal error occured. This might be caused by a faulty plugin

* [[topbar |Table of Contents]] * [[intro:overview:what|Introduction]] * [[install:home|Installation]] * [[install:editions|Product Editions]] * [[install:requirements|System Requirements]] * [[install:platforms|Supported Platforms]] * [[install:guides:home|Installation Guides]] * [[install:licensing:home|Licensing]] * [[install:releases:home|Release Notes]] * [[admin:home|Administration]] * [[admin:admin:home|Administration Basics]] * [[admin:admin:architecture:home|Omnidex Architecture]] * [[admin:admin:applications:home|Building Applications]] * [[admin:basics:home|Omnidex Fundamentals]] * [[admin:basics:environments:home|Omnidex Environments]] * [[admin:basics:sqlengine:home|Omnidex SQL Engine]] * [[admin:basics:updates:home|Omnidex Updates]] * [[admin:basics:network:home|Network Services]] * [[admin:indexing:home|Omnidex Indexing]] * [[admin:indexing:concepts:home|Indexing Concepts]] * [[admin:indexing:indexes:home|Indexing Options]] * [[admin:indexing:creation:home|Index Creation]] * [[admin:indexing:strategies:home|Indexing Strategies]] * [[admin:indexing:activecounts:home|ActiveCounts]] * [[admin:indexing:powersearch:home|PowerSearch]] * [[admin:indexing:autocomplete:home|AutoComplete]] * [[admin:indexing:text:home|Omnidex Text]] * [[admin:features:home|Omnidex Features]] * [[admin:features:snapshots:home|Omnidex Snapshots]] * [[admin:features:grids:home|Omnidex Grids]] * [[admin:features:rollups:home|Rollup Tables]] * [[admin:features:geo:home|Geographic Searches]] * [[admin:features:expressioncols:home|Expression Columns]] * [[admin:features:segments:home|Omnidex Segments]] * [[admin:features:attach:home|Attaching Data]] * [[admin:features:export:home|Exporting Data]] * [[admin:optimization:home|Optimizing Queries]] * [[admin:optimization:plans:home|Query Plans]] * [[admin:optimization:caches:home|Dynamic Caches]] * [[admin:optimization:config:home|Configuring Omnidex]] * [[integration:home|Integration]] * [[integration:rdbms:home|Relational Databases]] * [[integration:rdbms:oracle:home|Oracle]] * [[integration:rdbms:sqlserver:home|SQL Server]] * [[integration:rdbms:mysql:home|MySQL]] * [[integration:rdbms:odbc:home|Generic ODBC]] * [[integration:rawdata:home|Raw Data Files]] * [[integration:rawdata:fixed:home|Fixed-length Files]] * [[integration:rawdata:delimited:home|Delimited Files]] * [[integration:rawdata:ost:home|Standalone Tables]] * [[dev:home|Development]] * [[dev:sql:home|Omnidex SQL]] * [[dev:sql:overview|Overview]] * [[dev:sql:statements:home|Statements]] * [[dev:sql:functions:home|Functions]] * [[dev:sql:examples:home|Examples]] * [[dev:connections:home|Connection Strings]] * [[dev:odbc:home|ODBC Interface]] * [[dev:jdbc:home|JDBC Interface]] * [[dev:debugging:home|Logging/Debugging]] * [[programs:home|Programs]] * [[programs:odxsql:home|OdxSQL]] * [[programs:odxnet:home|OdxNet]] * [[appendix:home|Appendix]] * [[dev:sql:home|Omnidex SQL]] * [[dev:sql:statements:home|Statements]] * [[dev:sql:functions:home|Functions]] * [[dev:sql:examples:home|Examples]] * [[http://www.omnidex.com/download/|Downloads]] * [[support:home|Support]]

~~NOTOC~~ {{page>:top_add&nofooter&noeditbtn}} ====== Administration: Omnidex Indexing ====== ===== Indexing Concepts ===== [[admin:indexing:concepts:home|Overview]] | [[admin:indexing:concepts:criteria|Criteria]] | [[admin:indexing:concepts:joins|Joins]] | [[admin:indexing:concepts:aggregations|Aggregations]] | [[admin:indexing:concepts:ordering|Ordering]] | **[[admin:indexing:concepts:retrieval|Retrievals]]** ---- ==== Retrievals ==== As Omnidex optimizes a query, it looks for ways to use indexes to process criteria, table joins, aggregations and ordering. It may also find that the data to be returned to the user can be obtained from the indexes. This can allow an entire query to be processed without ever accessing the database. This technique provides exceptional performance. The simplest example of this is queries that request counts. Omnidex always maintains a count of the rows that have been qualified. If the query requests a count, Omnidex can simply return it from the indexes. Other queries may perform aggregations and use GROUP BY clauses. These can be returned from the indexes as well. Other queries may request primary keys, or even data from other columns. If these columns are found in the indexes, they will be returned from the index in order to minimize retrieval from the database. Omnidex will automatically perform this optimization. Using these techniques, it is possible to optimize complex queries without ever accessing the database. A query may access dozens of tables, applying a wide variety of criteria and performing aggregations and ordering. If Omnidex can, it will attempt to satisfy all of these aspects in the indexes, providing the best performance possible. ===== ===== **[[admin:indexing:concepts:ordering|Prev]]** ====== Additional Resources ====== See also: {{page>:admin:indexing:see_also&nofooter&noeditbtn}} {{page>:bottom_add&nofooter&noeditbtn}}

 
Back to top
admin/indexing/concepts/retrieval.txt ยท Last modified: 2016/06/28 22:38 (external edit)
 
 
chimeric.de = chi`s home Valid CSS Driven by DokuWiki do yourself a favour and use a real browser - get firefox!! Recent changes RSS feed Valid XHTML 1.0