[
https://issues.apache.org/jira/browse/KYLIN-4810?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17231077#comment-17231077
]
ASF GitHub Bot commented on KYLIN-4810:
---------------------------------------
hit-lacus commented on pull request #1477:
URL: https://github.com/apache/kylin/pull/1477#issuecomment-726453109
+1
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
> TrieDictionary is not correctly build
> -------------------------------------
>
> Key: KYLIN-4810
> URL: https://issues.apache.org/jira/browse/KYLIN-4810
> Project: Kylin
> Issue Type: Bug
> Components: Job Engine
> Affects Versions: v2.3.2
> Reporter: ShengJun Zheng
> Priority: Critical
> Fix For: Future
>
>
> Hi, recently, I've met a problem in our product environment: Segments failed
> to merge because TrieDictionaryForest was disordered
> {code:java}
> java.lang.IllegalStateException: Invalid input data. Unordered data cannot be
> split into multi trees
> at
> org.apache.kylin.dict.TrieDictionaryForestBuilder.addValue(TrieDictionaryForestBuilder.java:92)
> at
> org.apache.kylin.dict.TrieDictionaryForestBuilder.addValue(TrieDictionaryForestBuilder.java:78)
> at
> org.apache.kylin.dict.DictionaryGenerator$StringTrieDictForestBuilder.addValue(DictionaryGenerator.java:214)
> at
> org.apache.kylin.dict.DictionaryGenerator.buildDictionary(DictionaryGenerator.java:81)
> at
> org.apache.kylin.dict.DictionaryGenerator.buildDictionary(DictionaryGenerator.java:65)
> at
> org.apache.kylin.dict.DictionaryGenerator.mergeDictionaries(DictionaryGenerator.java:106)
> {code}
> After some analysis, we found out when there is large values in a
> dict-encoded column, iterating over a single TrieDictionaryTree will get
> unordered data.
>
> Digging into the source code, the root cause is as described:
> # Kylin will split a TrieTree Node into two parts when a single nodes's
> value length is more than 255 bytes
> # Then, these tow parts of value will be added to build the TrieTree. In
> fact the splitted two parts should not be used as new values to add to the
> TrieTree.
> # Step 2 will cause the TrieDictionaryTree build more leave nodes，and the
> extra leaf nodes will be 'end-value' of dictionary tree;
> # It has no impact to the correctness of the dict tree itself, except for
> adding some additional nodes .
> # But If you spit a UTF-8 word, you will get unordered data when iterating
> over the tree ( Something todo with Java UTF-8 String Serialize/Deserialize
> implementations. Please Refer to JDK sun.nio.cs.UTF_8.class)
> How to re-produce ? Run test code :
> {code:java}
> TrieDictionaryForestBuilder builder = new TrieDictionaryForestBuilder(new
> StringBytesConverter());
> String longUrl =
> "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好~~~";
> builder.addValue(longUrl);
> TrieDictionaryForest<String> dict = builder.build();
> TrieDictionaryForestBuilder mergeBuild = new TrieDictionaryForestBuilder(new
> StringBytesConverter());
> for (int i = dict.getMinId(); i <= dict.getMaxId(); i++) {
> String str = dict.getValueFromId(i);
> System.out.println("add value into merge tree");
> mergeBuild.addValue(str);
> }
> The log output of this test code is:
> add value into merge tree
> add value into merge tree
> 16:59:36 [main] INFO
> org.apache.kylin.dict.TrieDictionaryForestBuilder.addValue(TrieDictionaryForestBuilder.java:127)
> values not in ascending order, previous
> 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\xEF\xBF\xBD',
> current
> 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\xE4\xBD\xA0\xE5\xA5\xBD~~~'
> {code}
> We can see from the test code's output：
> # We only add 1 value but the tire dictionary tree turn out to have 2 end
> vlaues
> # Iterating over the TrieDictionary Tree got unordered data
> We address this problem by
> # classify values which is a whole column value, which is splitted value,
> # not mark splitted value as end-value of a TrieTree Node.
> I wonder if there is something wrong, thanks.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
