Disk-based hash join process
US9275110B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 2013 |
| Grant date | Mar 1, 2016 |
| Priority date | — |
| Expiry date | Sep 5, 2033 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/284
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A database system performs hash join process for processing queries that join an inner and an outer database table. The hash join processes builds a hash table in memory for the inner table. The database system receives a limit on the memory for storing the hash table. The database system maximizes the number of partitions stored in memory for the hash table. If the hash table exceeds the limit of the memory while adding rows from the inner table, the database system selects a partition for spilling to a persistent storage. The partition selected for spilling to may be the largest partition or a partition larger than most of the partitions. The database system initializes the hash table to a number of partitions that is substantially equal to half of the total number of blocks that can be stored within the specified limit of memory for the hash table.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.