@InterfaceAudience.Private public class RegionSplitter extends Object
RegionSplitterclass provides several utilities to help in the administration lifecycle for developers who choose to manually split regions instead of having HBase handle that automatically. The most useful utilities are:
Both operations can be safely done on a live server.
Question: How do I turn off automatic splitting?
Answer: Automatic splitting is determined by the configuration value HConstants.HREGION_MAX_FILESIZE. It is not recommended that you set this to Long.MAX_VALUE in case you forget about manual splits. A suggested setting is 100GB, which would result in > 1hr major compactions if reached.
Question: Why did the original authors decide to manually split?
Answer: Specific workload characteristics of our use case allowed us to benefit from a manual split system.
Question: Why is manual splitting good for this workload?
Answer: Although automated splitting is not a bad option, there are benefits to manual splitting.
Question: What's the optimal number of pre-split regions to create?
Answer: Mileage will vary depending upon your application.
The short answer for our application is that we started with 10 pre-split regions / server and watched our data growth over time. It's better to err on the side of too little regions and rolling split later.
The more complicated answer is that this depends upon the largest storefile
in your region. With a growing data size, this will get larger over time. You
want the largest region to be just big enough that the
selection algorithm only compacts it due to a timed major. If you don't, your
cluster can be prone to compaction storms as the algorithm decides to run
major compactions on a large series of regions all at once. Note that
compaction storms are due to the uniform data growth, not the manual split
If you pre-split your regions too thin, you can increase the major compaction interval by configuring HConstants.MAJOR_COMPACTION_PERIOD. If your data size grows too large, use this script to perform a network IO safe rolling split of all regions.
|Modifier and Type||Class and Description|
HexStringSplit is a well-known
A generic interface for the RegionSplitter code to use for all it's functionality.
A SplitAlgorithm that divides the space of possible keys evenly.
|Constructor and Description|
|Modifier and Type||Method and Description|
The main function for the RegionSplitter application.
public static void main(String args) throws IOException, InterruptedException, org.apache.commons.cli.ParseException
args- Usage: RegionSplitter <TABLE> <SPLITALGORITHM> <-c <# regions> -f <family:family:...> | -r [-o <# outstanding splits>]> [-D <conf.param=value>]
IOException- HBase IO problem
InterruptedException- user requested exit
org.apache.commons.cli.ParseException- problem parsing user input
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