Administration: Omnidex Indexing

Indexing Types and Options

Index Types

Omnidex supports four types of indexes. These types of indexes provide support for handling Omnidex criteria, table joins, aggregations, and ordering. They also support both textual data and non-textual data. Most databases use a combination of these index types to meet their indexing needs.

Omnidex Indexes

Omnidex Indexes provide the bulk of Omnidex functionality. These indexes are placed on columns that are involved in Omnidex criteria, table joins, aggregations, and ordering. Omnidex indexes can also be used to retrieve data without having to access the database.

Typically, administrators place Omnidex Indexes on all columns that are involved in the SQL statement. The Omnidex SQL Engine will use each index in different ways depending on how the corresponding column is used in the SQL statement. In a given query, some indexes will satisfy criteria or support table joins, while other indexes will fulfill aggregations or ordering. In a subsequent query, those same indexes may get used for a different purpose.

An Omnidex Index can also be created with multiple columns. These indexes are valuable for optimizing SQL statements with multiple columns in the GROUP BY clause, ORDER BY clauses, or the aggregation functions (COUNT, SUM, MIN, MAX and AVERAGE).

Omnidex Bitmap Index - A common variation

An Omnidex Bitmap Index uses a bitmap storage format to reduce disk space usage and speed performance. Omnidex Bitmap Indexes are appropriate for non-textual columns with thirty or less distinct values.

QuickText Indexes

QuickText Indexes are designed for small blocks of text, such as names, addresses, descriptions, and general text. QuickText Indexes parse the contents of the column so that each word is indexed separately. Queries can then mention just a few of the words in that column rather than having to mention the whole column. For example, a column containing the name “John Q. Doe” can be located by just asking for “John” or “John Doe”. QuickText Indexes provide basic text searches at the same speed as Omnidex Indexes.

FullText Indexes

FullText Indexes are designed for large blocks of text, such as abstracts, articles, and text documents. FullText Indexes parse the contents of the column so that each word is indexed separately. FullText Indexes also track the position of each word in the field to aid in providing relevancy scores. Queries can use special syntax to require that one word be a certain distance from another word, or adjacent as a phrase. FullText Indexes necessarily have more overhead than QuickText Indexes.

Custom Indexes

Custom Indexes allow more granular control over the options used on an index. A Custom Index is also used in special situations such as pre-joined indexes or partial-column indexes.

Additional Resources

See also:

 
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admin/indexing/indexes/types.txt · Last modified: 2016/06/28 22:38 (external edit)
 
 
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