Pavan Lanka created ORC-743:
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Summary: Conversion of SArg into Filters, to take advantage of
LazyIO
Key: ORC-743
URL: https://issues.apache.org/jira/browse/ORC-743
Project: ORC
Issue Type: New Feature
Components: Reader
Reporter: Pavan Lanka
Assignee: Pavan Lanka
ORC-742 introduces lazy evaluation of the non-filter columns in the presence of
filters. This builds further on that to convert SArg into filters.
h3. SArg to Filter
SArg to Filter converts the passed SArg into a filter. This enables automatic
compatibility with both Spark and Hive as they already push down Search
Arguments down to ORC.
The SArg is automatically converted into a [Vector
Filter|https://github.pie.apple.com/planka/orc/blob/4_optimize_filter/java/core/src/java/org/apache/orc/filter/VectorFilter.java].
Which is applied during the read process.
The builder for search argument should allow skipping normalization during the
[build|https://github.com/apache/hive/blob/storage-branch-2.7/storage-api/src/java/org/apache/hadoop/hive/ql/io/sarg/SearchArgumentImpl.java#L491].
This has already been proposed as part of HIVE-24458.
Normalization is very poor in performance in the presence of multilevel
predicates.
||Benchmark||(fSize)||(fType)||(normalize)||Mode||Cnt||Score||Error||Units||
|ComplexFilterBench.filter|2|vector|true|avgt|20|74.321|± 0.156|us/op|
|ComplexFilterBench.filter|2|vector|false|avgt|20|78.119|± 0.351|us/op|
|ComplexFilterBench.filter|4|vector|true|avgt|20|267.405|± 1.202|us/op|
|ComplexFilterBench.filter|4|vector|false|avgt|20|136.284|± 0.637|us/op|
|ComplexFilterBench.filter|8|vector|true|avgt|20|9907.765|± 49.208|us/op|
|ComplexFilterBench.filter|8|vector|false|avgt|20|247.714|± 0.651|us/op|
Explanation:
* *fSize* identifies the size of the OR clause that will be normalized.
* *normalize* identifies whether normalize was carried out on the Search
Argument.
Observations:
* Normalizing the search argument results in a significant performance penalty
given the explosion of the operator tree
** In case where an AND includes 8 ORs, the unnormalized version is faster by
*97.32%*
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