Evaluating SQL expressions on dictionary encoded vectors
US11294816B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 3, 2017 |
| Grant date | Apr 5, 2022 |
| Priority date | — |
| Expiry date | Jul 11, 2039 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2212/60
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Techniques are described herein for reducing the number of redundant evaluations that occur when an expression is evaluated against an encoded column vector by caching results of expression evaluations. When executing a query that includes an expression that references columns for which dictionary-encoded column vectors exist, the database server performs a cost-based analysis to determine which expressions (or sub-expressions) would benefit from caching the expression's evaluation result. For each such expression, the database server performs the necessary computations and caches the results for each of the possible distinct input values. When evaluating an expression for a row with a particular set of input codes, a look-up is performed based on the input code combination to retrieve the pre-computed results of that evaluation from the cache.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.