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HBase >> mail # dev >> Scanner with explicit columns list is very slow

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Scanner with explicit columns list is very slow
Its 0.94.6 and there is chance that the issue has been fixed already

Simple table: one column + one qualifier

Two type of scans:

1. Scan.addFamily(CF)

2. Scan.addColumn(CF, CQ)

Both run on block cache (all data in memory)

Tested on StoreScanner directly.

1. 4.2M KVs per sec per one thread
2. 1.5M KVs per second per one thread.

The difference? First scanner's ScanQueryMatcher returns INCLUDE, DONE, second - INCLUDE_NEXT_ROW, DONE
The cost of Row's reseek is huge.

Best regards,
Vladimir Rodionov
Principal Platform Engineer
Carrier IQ, www.carrieriq.com
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