Update. This method is not called in MemStoreScanner, but direct call to :
readPoint = MultiVersionConsistencyControl.getThreadReadPoint(); on every next, seek etc which is basically the same. All these calls become very expensive when you try to achieve 10s of millions RPS in scan operations. Best regards, Vladimir Rodionov Principal Platform Engineer Carrier IQ, www.carrieriq.com e-mail: [email protected] ________________________________________ From: Vladimir Rodionov Sent: Friday, October 11, 2013 2:18 PM To: [email protected] Subject: skipKVsNewerThanReadpoint in StoreFileScanner and MemStoreScanner >From HRegion: synchronized(scannerReadPoints) { if (isolationLevel == IsolationLevel.READ_UNCOMMITTED) { // This scan can read even uncommitted transactions this.readPt = Long.MAX_VALUE; MultiVersionConsistencyControl.setThreadReadPoint(this.readPt); } else { this.readPt = MultiVersionConsistencyControl.resetThreadReadPoint(mvcc); } If isolation level is READ_UNCOMMITTED than this method should never be called in both StoreFileScanner and MemStoreScanner If isolation level is READ_COMMITTED than this method must be called only in MemStoreScanner, because HFiles are immutable no new KV's can be added to HFile after StoreFileScanner was created. Correct? Best regards, Vladimir Rodionov Principal Platform Engineer Carrier IQ, www.carrieriq.com e-mail: [email protected] Confidentiality Notice: The information contained in this message, including any attachments hereto, may be confidential and is intended to be read only by the individual or entity to whom this message is addressed. If the reader of this message is not the intended recipient or an agent or designee of the intended recipient, please note that any review, use, disclosure or distribution of this message or its attachments, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and/or [email protected] and delete or destroy any copy of this message and its attachments.
