Techniques for evaluating query predicates during in-memory table scans
US10216794B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 4, 2018 |
| Grant date | Feb 26, 2019 |
| Priority date | — |
| Expiry date | Apr 4, 2038 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2212/401
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Techniques are described herein for filtering data from a table during an in-memory scan. Predicates are pushed to in-memory scan to avoid scanning unnecessary columnar units and reduce the overhead of decompressing, row stitching and distributing data during evaluation. Techniques are described herein for generating implied predicates that have conditions on single columns from complex predicates that have multiple conditions on the same column, which can be evaluated during an in-memory scan. Techniques are also described herein to reduce the overhead of a table scan for processing a join query. When redistributing a first table for performing a hash-join, the nodes performing an in-memory scan of the first table may create a filter that tracks unique values from the join key. Data from the second table is only processed and transferred to other nodes in the cluster if the values from the join key pass through the filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.