simply about difficult
Suppose 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 MORESometimes you might want to see the active connections on a specific port, rather than just the status of the port. This can be done using netstat: Something like this will be output (for example for port 19356): Lines containing ESTABLISHED are active connections on the specified port. In our case, there are two of them.
READ MOREWhen using gRPC server-streaming call, you may need to interrupt the execution of the request on the server from the client side. We have a service on the server: And the sendRequest() method on the client: Suppose, that at some moment we need to send a message from the client to the server that the […]
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 MOREWhen using gRPC streaming or in some other cases, it may be necessary to compose one complete object from several others or from an iterator. Let’s take a look at an example. We have an iterator, received by gRPC stub: And we want to get one complete ProtoResult object, which will be the union of all […]
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
READ MOREWhen checking the quality of the code, you may encounter a problem that sounds like this: Or like this: This is not a bug in PMD. Here are some examples:
READ MORELet’s say you need to get the name of hdfs cluster in an application. To do this, you need to get the org.apache.hadoop.conf.Configuration object: In the place we need, we get the fs.defaultFS property value:
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