What is the screen command ?
When you have long running jobs, you need to keep them active when you disconnect from server.
The screen command allows you to detach your terminal from you session.
By doing this there is no link between your session and your terminal and you can disconnect from server while your terminal and your jobs keep running.
Even better, once you reconnect to the server you can reattach the terminal to your new session and find your terminal exactly like you left it.
who never needed to export data to excel from sqlplus ? everybody had one day needed to do that.
Sqlplus support the HTML markup which provides an excellent result once opened in excel.
With the HTML markup, sqlplus create a table with all columns from your query including the name of your columns as table header.
Here is a small exemple:
SET MARKUP HTML ON ENTMAP ON PREFORMAT OFF ;
select to_char(end_time,'hh24:mi:ss') as sample_time,
where end_time between sysdate - interval '1' hour and sysdate
and group_id = 2
and metric_name = 'Host CPU Utilization (%)'
order by metric_name, end_time;
Unindexed foreign keys can lead to bad database performance due to lock contention and full table scans performed on the child table.
Here is a diagram which illustrate the situation: