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DRILL-5137 - Optimize count(*) queries on MapR-DB Binary Tables #700

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DRILL-5137 - Optimize count(*) queries on MapR-DB Binary Tables #700

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5 changes: 5 additions & 0 deletions contrib/storage-hbase/src/main/java/org/apache/drill/exec/store/hbase/HBaseRecordReader.java
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Expand Up @@ -124,6 +124,11 @@ protected Collection<SchemaPath> transformColumns(Collection<SchemaPath> columns
} else {
rowKeyOnly = false;
transformed.add(ROW_KEY_PATH);
/* DRILL-5137 - optimize count(*) queries on MapR-DB Binary tables */
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@adityakishore adityakishore Dec 21, 2016

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This branches into the else part of
if (!isStarQuery()) {

Can you verify if a query can be both Star and Skip query at the same time when count(*) has been requested?

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@spanchamiamapr spanchamiamapr Dec 22, 2016

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Yes, I verified this in my testing.

if (isSkipQuery()) {
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@adityakishore adityakishore Dec 21, 2016

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Further optimization can be name by returning only a count vector in the next() call, similar to this.

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@spanchamiamapr spanchamiamapr Dec 22, 2016

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I thought of this, however I got stuck because there is no vectorContainerWriter in HBaseRecordReader class. If you can send a diff of how to do this, I can include that too. Thanks!

hbaseScan.setFilter(
HBaseUtils.andFilterAtIndex(hbaseScan.getFilter(), HBaseUtils.LAST_FILTER, new FirstKeyOnlyFilter()));
}
}


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