[ACCUMULO-3646] Duplicate entries when iterator emits entries past seek() range

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.6.1
• Fix Version/s: 1.7.0
• Component/s: docs

Environment

Ubuntu 14.04, Accumulo 1.6.1, Hadoop 2.6.0, Zookeeper 3.4.6

• Assignee: Shana Hutchison
• Reporter: Shana Hutchison
• Created: 05/Mar/15 15:06
• Updated: 03/Jun/16 18:07
• Resolved: 28/Apr/15 03:51

Description

The SortedKeyValueIterator's seek() method documents that an iterator may return keys past the range passed to seek(). However, an iterator set at scan-time that returns values past the range passed to seek() will return those keys multiple times if the client uses a BatchScanner. This does not occur when the client uses a Scanner. This has nothing to do with the VersioningIterator. This has nothing to do with the entries actually in the table. Also affects MiniAccumulo.

If this is intended, we should update the SortedKeyValueIterator seek() documentation with a warning that returning keys past the seek() range may result in a client seeing duplicate keys. If this is not intended, then it is a bug.

Test code: See InjectTest

• method testInjectOnScan_Empty fails because it uses a BatchScanner
• method testInjectOnScan_Empty_Reg passes because it uses a Scanner

In these methods, the InjectIterator emits entries that go beyond the seek() range. We confirm what is going on by placing a DebugIterator right after.

Logs when using the BatchScanner:
notice that the "m1" row is returned twice:

015-03-05 06:05:34,768 [graphulo.BranchIterator] INFO : class edu.mit.ll.graphulo.InjectIterator: init on scope scan
2015-03-05 06:05:34,768 [graphulo.BranchIterator] INFO : class edu.mit.ll.graphulo.InjectIterator: init on scope scan
2015-03-05 06:05:34,770 [iterators.DebugIterator] DEBUG: init(edu.mit.ll.graphulo.InjectIterator@e9fe846, {}, org.apache.accumulo.tserver.TabletIteratorEnvironment@b99fd03)
2015-03-05 06:05:34,771 [iterators.DebugIterator] DEBUG: 0x516E9F1F seek((-inf,f%00; : [] 9223372036854775807 false), [], false)
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> a1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> a1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopValue() --> 1
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F next()
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> c1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> c1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> c1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopValue() --> 1
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F next()
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> m1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> m1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> true
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopKey() --> m1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F getTopValue() --> 1
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F next()
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> false
2015-03-05 06:05:34,772 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> false
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x516E9F1F hasTop() --> false
2015-03-05 06:05:34,770 [iterators.DebugIterator] DEBUG: init(edu.mit.ll.graphulo.InjectIterator@2528a1f1, {}, org.apache.accumulo.tserver.TabletIteratorEnvironment@244a532a)
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA seek([f%00; : [] 9223372036854775807 false,+inf), [], false)
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA hasTop() --> true
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA getTopKey() --> m1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA hasTop() --> true
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA getTopKey() --> m1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA hasTop() --> true
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA getTopKey() --> m1 colF3:colQ3 [] 1425553534769 false
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA getTopValue() --> 1
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA next()
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA hasTop() --> false
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA hasTop() --> false
2015-03-05 06:05:34,773 [iterators.DebugIterator] DEBUG: 0x5DBB88BA hasTop() --> false

Issue Links

• relates to: ACCUMULO-3633 Please provide information on implementing custom iterators in the documentation
• links to: GitHub Pull Request #33