[HBASE-15398] Cells loss or disorder when using family essential filter and partial scanning protocol

• Type: Bug
• Status: Patch Available
• Priority: Critical
• Resolution: Unresolved
• Affects Version/s: 1.2.0, 1.1.3
• Component/s: dataloss, Scanners
• Assignee: Phil Yang
• Reporter: Phil Yang
• Created: 04/Mar/16 17:05
• Updated: 22/Mar/16 19:13

Description

In RegionScannerImpl, we have two heaps, storeHeap and joinedHeap. If we have a filter and it doesn't apply to all cf, the stores whose families needn't be filtered will be in joinedHeap. We scan storeHeap first, then joinedHeap, and merge the results and sort and return to client. We need sort because the order of Cell is rowkey/cf/cq/ts and a smaller cf may be in the joinedHeap.

However, after HBASE-11544 we may transfer partial results when we get SIZE_LIMIT_REACHED_MID_ROW or other similar states. We may return a larger cf first because it is in storeHeap and then a smaller cf because it is in joinedHeap. Server won't hold all cells in a row and client doesn't have a sorting logic. The order of cf in Result for user is wrong.

And a more critical bug is, if we get a LIMIT_REACHED_MID_ROW on the last cell of a row in storeHeap, we will break scanning in RegionScannerImpl and in populateResult we will change the state to SIZE_LIMIT_REACHED because next peeked cell is next row. But this is only the last cell of one and we have two... And SIZE_LIMIT_REACHED means this Result is not partial (by ScannerContext.partialResultFormed), client will see it and merge them and return to user with losing data of joinedHeap. On next scan we will read next row of storeHeap and joinedHeap is forgotten and never be read...

Issue Links

• relates to: HBASE-11544 [Ergonomics] hbase.client.scanner.caching is dogged and will try to return batch even if it means OOME
• links to: review board