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https://issues.apache.org/jira/browse/PARQUET-2237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17691650#comment-17691650
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ASF GitHub Bot commented on PARQUET-2237:
-----------------------------------------
yabola commented on code in PR #1023:
URL: https://github.com/apache/parquet-mr/pull/1023#discussion_r1113173851
##########
parquet-hadoop/src/main/java/org/apache/parquet/filter2/statisticslevel/StatisticsFilter.java:
##########
@@ -289,8 +320,14 @@ public <T extends Comparable<T>> Boolean visit(Lt<T> lt) {
T value = lt.getValue();
- // drop if value <= min
- return stats.compareMinToValue(value) >= 0;
+ // we are looking for records where v < someValue
+ if (stats.compareMinToValue(value) >= 0) {
+ // drop if value <= min
+ return BLOCK_CANNOT_MATCH;
+ } else {
+ // if value > min, we must take it
+ return BLOCK_MUST_MATCH;
Review Comment:
@gszadovszky Thank you for your reply!
In the original implementation, `BLOCK_MUST_MATCH` can be judged using
minMax.
So if we follow the specification, can we using minMax as the data result of
an enlarged range. So we can accurately judge that when the data is not in this
range.
> Improve performance when filters in RowGroupFilter can match exactly
> --------------------------------------------------------------------
>
> Key: PARQUET-2237
> URL: https://issues.apache.org/jira/browse/PARQUET-2237
> Project: Parquet
> Issue Type: Improvement
> Reporter: Mars
> Priority: Major
>
> If we can accurately judge by the minMax status, we don’t need to load the
> dictionary from filesystem and compare one by one anymore.
> Similarly , Bloomfilter needs to load from filesystem, it may costs time and
> memory. If we can exactly determine the existence/nonexistence of the value
> from minMax or dictionary filters , then we can avoid using Bloomfilter to
> Improve performance.
> For example,
> # read data greater than {{x1}} in the block, if minMax in status is all
> greater than {{{}x1{}}}, then we don't need to read dictionary and compare
> one by one.
> # If we already have page dictionaries and have compared one by one, we
> don't need to read BloomFilter and compare.
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