Specifies whether to perform WHERE processing optimization by subsetting the data in the Hadoop cluster with MapReduce.
| Valid in: | spdsserv.parm file |
| Default: | Data subsetting is performed on the SPD Server host. |
| Interactions: | The HADOOPACCELWH parameter option affects only domains that specify HADOOP=YES or domains that specify any other Hadoop option. |
| Requesting that data subsetting be performed in the Hadoop cluste might improve performance by taking advantage of the filtering and ordering capabilities of the MapReduce framework. As a result, only the subset of the data is returned to the SPD Server client. Performance is often improved with large tables when the WHERE expression qualifies only a relatively small subset. |
specifies that data subsetting is performed in the Hadoop cluster with a MapReduce program. Here is an example:
hadoopaccelwh;
| Requirements | To perform data subsetting in the Hadoop cluster, there are requirements. See WHERE Processing Optimization with MapReduce. |
| To submit the MapReduce program to the Hadoop cluster, the Hadoop configuration file must include the properties to run MapReduce (MR1) or MapReduce 2 (MR2) and YARN. | |
| Interaction | With HADOOPACCELWH specified in the spdsserv.parm file, you can use the SPDSACWH= macro variable or the ACCELWHERE= table option to turn off WHERE processing optimization. |
specifies that WHERE processing optimization with MapReduce cannot be requested.
| Interaction | With NOHADOOPACCELWH specified in the spdsserv.parm file, you cannot use the SPDSACWH= macro variable or the ACCELWHERE= table option to request WHERE processing optimization. |