simply about difficult
In the previous article, we already figured out how to terminate a container with a specific exit code. To begin with, the return value must be smaller then 256. You can notice that: If you terminate the container with a code of 0 or some other positive number, then the same code will be sent […]
READ MOREYou need to mark container’s start class using the @YarnComponent and mark method with the @OnContainerStart annotations: Despite the fact that the description of the annotation says that it cannot return anything, the return value works. We make the return value of type int. 0 – means successful shutdown of the container, non-zero values – […]
READ MORESuppose that we have an SBY application, which includes AppMaster and Container. When the container falls due to an exception, we need to send exception text to the AppMaster. When the container falls, the AppMaster’s onContainerFailed() method is automatically called: The method is in the StaticEventingAppmaster class. Your AppMaster must be inherited from it. We […]
READ MOREIf you get an exception like this: Check this two things first: Is the path to the keytab correct? Does the process have permission to read the keyab? In my case it turned out that there was no keytab read permission in hdfs. Thanks Xavier Portebois.
READ MORELet’s imagine that you need to know the actual distribution of keys by regions of the HBase table. There is no direct way to find it. But you can use this workaround: you need to send scan queries with region boundaries: This code will display line by line the number of keys in each region of the […]
READ MORESuppose you need to run HBase utility class from Java code. Such a class will have a main() method, which we will use. For demonstrating, we will use RowSplitter class. Firstly, we need to add the hbase-server module (for example, version 1.2.3) to pom.xml: In some our own class, let’s call RegionSplitter’s main(): If you […]
READ MORESuppose, that you need to create an HBase table with a certain preliminary created number of regions. You can use RegionSplitter tool to do this. Running RegionSplitter from command line / shell An example of a call from the command line / shell: The pattern is: SPLITALGORITHM is a java class name of a class […]
READ MORELet’s say you need to create an HBase table with a certain constant number of regions. Regions pre-creation First, you need to create a table with a certain pre-created number of regions. You can use one of the createTable() method overloads for that: You can make the byte[][] splitKeys array as follows: We need to add […]
READ MOREYou may encounter an exception like this: Most likely, you have a versioning problem: you are using hbase-client version 2.x.x with the server version 1.x.x. Also, you are trying to call HBase Admin API functions. The fact is that the hbase-client version 2.x.x can send only regular get, scan, put, delete requests to the hbase […]
READ MOREIf you are looking for default scan request parameters, here they are: Parameter Default value startRow HConstants.EMPTY_START_ROW stopRow HConstants.EMPTY_END_ROW maxVersions 1 batch -1 allowPartialResults false storeLimit -1 storeOffset 0 caching -1 maxResultSize -1L cacheBlocks true reversed false timeRange TimeRange.allTime() asyncPrefetch null small false mvccReadPoint -1L limit -1 readType Scan.ReadType.DEFAULT needCursorResult false
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