Oracle provides a plethora of tools for monitoring user activity, including tracing, monitoring wait events, as well as ASH. However, sometimes I want a quick (literally) overview of a session. To do this, I query the gv$sesstat view. However, the…
Category: Database
HBase JMX metrics
HBase exposes several metrics via JMX beans, some of which are similar to the Oracle performance counters recorded by AWR. Actually, they aren’t even *close* to what Oracle provides, but one can hope 🙂 Below is a simple example of…
Printing hadoop properties
The hadoop Configuration class implements the Iterable interface, so you can simply create a default configuration and list all properties, or pass a custom XML configuration file and print the properties from that. Below is a simple example. import java.util.*;…
ipcrm not removing SGA shared memory segment
Today, I had an issue I had seen before, but I can never remember how I fix it. As such, I wanted to document it here. Although rare, periodically an abnormally terminated instance will leave behind a shared memory segment.…
Flashback ability with HBase
Oracle has a great feature called flashback query. This allows a user to (try to) query a row as it existed at some point in the past. It provides this functionality by trying to find the necessary UNDO to reconstruct…
Printing all property values in an HBase configuration
I’m sure there is an easier (perhaps built-in) way to do this, but for now, I wanted to document how you can print all properties for a given configuration that you load into a JVM. import java.util.*; import org.apache.hadoop.hbase.*; import…
Simple HBase stress tester
What is below is a simple class to read a random set of records from a table. This should be a good start if you are looking for a simple one class test case, that may also be useful for…
Simple HBase class to load data
What is below is a simple java class to load the customers table we created in a previous post import java.util.*; import org.apache.hadoop.hbase.client.*; import org.apache.hadoop.hbase.util.*; public class putHbase { public static void main(String[] args) throws Exception { HTable hTable =…
Bridging the gap…from SQL to No SQL
For any DBA’s that have had someone call them and ask “What do you know about NoSQL?”, this post is specifically intended. Before you have a conniption fit and began quoting Tom Kyte-ism’s (an exceptionally smart guy, if you do…
How to change LOB parameter on an XMLTYPE column
I couldn’t find this in the documentation, so I thought I would post it in case someone else has the same question. If you have an XMLTYPE datatpe column stored as a CLOB, you can modify attributes using the example…