Administration: Omnidex Fundamentals

Omnidex Updates

Online Updates

Some applications require that databases are updated online. Omnidex supports online updates using the INSERT, DELETE and UPDATE statement, though there are restrictions that should be considered by the administrator and the application designer. When Omnidex processes an INSERT, DELETE or UPDATE statement, it updates the indexes for all affected columns before the operation is completed. Omnidex supports online updates on both relational databases and raw data files.

Omnidex processes online updates at a rate of approximately 2.5 million index entries an hour per table1. This means that rows can be inserted into a table with 25 indexes at a rate of approximately 100,000 per hour. For heavily indexed tables or larger numbers of updates, administrators should consider Offline Updates which process index updates at a rate that is 200 times faster.

Omnidex has many features that are designed for read-only databases. This is in keeping with Omnidex's design as a “NoSQL” database that favors performance on large database. The NoSQL movement is a loose term describing databases that search data outside of the traditional relational database. NoSQL databases are designed to improve performance by not adhering to the ACID requirements for databases governing Atomicity, Consistency, Isolation and Durability.

When choosing whether to use online updates, the following restrictions should be considered:

  • Omnidex does not support database transactions.
  • Omnidex does not support the relational ACID requirements (Atomicity, Consistency, Isolation and Durability).
  • Most Omnidex applications will place tens or hundreds of indexes on a table, and this makes online updates impractical.
  • Omnidex Bitmap indexes are not updated on INSERT, DELETE or UPDATE statements. Omnidex Bitmap indexes are used to improve queries that reference low-cardinality data, and are heavily used on tables containing millions of rows.
  • Omnidex Grids do not support INSERT, DELETE or UPDATE statements.
  • Omnidex Rollup Tables are not updated on INSERT, DELETE or UPDATE statements.
  • Omnidex Text Dictionaries are not updated on INSERT, DELETE or UPDATE statements.
  • Omnidex cannot use Cached Qualification Optimizations on tables when tables are updated using INSERT, DELETE or UPDATE statements.
  • Omnidex UPDATE statements do not allow SET commands to values other than literals or constants.

1 An "index entry" represents an indexed column in a single row. If the column contains textual data that is indexed with QuickText or FullText indexes, then an "index entry"" represents a single word or number in an indexed column in a single row. Indexing rates are affected by machine performance, database performance, indexing options and concurrency.

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admin/basics/updates/online.txt · Last modified: 2016/06/28 22:38 (external edit)