TopMiniSite
-
8 min readTo decrease the heartbeat time of slave nodes in Hadoop, you can adjust the dfs.heartbeat.interval and dfs.namenode.heartbeat.recheck-interval properties in the hdfs-site.xml configuration file. By decreasing these values, you can make the slave nodes report their status to the NameNode more frequently, resulting in a faster heartbeat time.
-
5 min readTo replace the first three characters of a string in Oracle, you can use the SUBSTR function along with the CONCAT function. You can extract the rest of the string starting from the fourth character using SUBSTR and then concatenate it with the new characters you want to insert.
-
3 min readTo convert a date from the format 'dd-mm-yyyy' to 'dd-mmm-yyyy' in PostgreSQL, you can use the TO_CHAR function with the appropriate format specifier.
-
4 min readTo load native libraries in Hadoop, you need to set the proper environment variables for the native library path. First, you need to compile the native library specifically for the Hadoop version you are using. Then, you can use the HADOOP_OPTS environment variable to specify the path to the native library. Additionally, you can also set the java.library.path property in the Hadoop configuration to point to the directory containing the native library.
-
4 min readTo use a for loop for inserting data in Oracle, you can write a PL/SQL block that iterates over a specific range of values using the FOR loop construct. Within the loop, you can execute an INSERT statement to add records to a table. The syntax for a simple FOR loop in PL/SQL looks like this: BEGIN FOR i IN 1..
-
4 min readTo increase the stack size for Julia in Windows, you can set the --stack-size option when launching Julia. This can be done by running Julia from the command line with the following syntax:julia --stack-size=[desired_stack_size] [optional_arguments]Replace [desired_stack_size] with the size in bytes that you want to allocate for the stack. You can increase or decrease this value as needed to optimize performance.
-
6 min readAfter using the row_number() function in PostgreSQL to assign a unique row number to each row in a result set, you can filter and select specific rows based on their row numbers by using a subquery. One way to achieve this is by wrapping the initial query with the row_number() function in a subquery, and then selecting the desired rows based on their assigned row numbers in the outer query. For example, you can use a WHERE clause in the outer query to filter rows based on their row numbers.
-
9 min readTo change the task scheduler in Hadoop, you can modify the configuration settings in the mapred-site.xml file. The task scheduler in Hadoop determines how tasks are scheduled and allocated to nodes in the cluster. The default task scheduler in Hadoop is the Capacity Scheduler.You can change the task scheduler by setting the mapreduce.jobtracker.taskScheduler property in the mapred-site.xml configuration file.
-
3 min readTo extract the year from a date in Oracle, you can use the EXTRACT function with the YEAR keyword. For example, you can write a query like this:SELECT EXTRACT(YEAR FROM your_date_column) AS year FROM your_table_name;This will extract the year from the date stored in the specified column in your table and return it as a result. You can replace "your_date_column" with the name of the column containing the date and "your_table_name" with the name of your table.
-
4 min readIn Julia, you can define a function within another function by simply writing one function inside the body of another function. This is known as nested functions. Nested functions can be useful for encapsulating functionality that is only needed within the scope of the outer function.When defining a nested function, it has access to all the variables in the outer function's scope, including its arguments and local variables. This can be helpful for creating more modular and reusable code.
-
5 min readTo disable the native zlib compression library in Hadoop, you can modify the Hadoop configuration file (hadoop-env.sh). You need to add the following line to the file:export HADOOP_OPTS="$HADOOP_OPTS -Djava.library.path=."This will prevent Hadoop from using the native zlib compression library and force it to use the default Java compression library instead.