Kill DB sessions the easy way with SQLcl

Seems I can not tweet these animated GIFs anymore. So this is another very short blog post to show real case for adding a new command into SQLcl which can be downloaded here.

It's hard annoying tedious to find SID and SESSION then alter to kill that when needed.  What if there was a simple kill command.

Here a sample one that takes in the 2 options:
  kill sid serial#
  Example :   kill 1 2
OR
  kill USERNAME
  Example: kill KLRICE

SQLcl and Query Change Notification

The database has had Query Change Notification for a while but to use it required a custom program. Such as Tim outlines on his blog https://oracle-base.com/articles/10g/dbms_change_notification_10gR2


Since SQLcl has Nashorn, now it can be integrated with a few lines of javascript to get notified when changes happen.  The script is below and posted.  The catch is QCN only works on Varchars and Numbers.

ORDS and PL/SQL

Seems I've never posted about PL/SQL based REST endpoints other than using the OWA toolkit.  Doing the htp.p manually can give the control over every aspect of the results however there is an easier way.

With PL/SQL based source types, the ins and outs can be used directly without any additional programming.  Here's a simple example of an anonymous block doing about as little as possible but should get the point across of what's possible.

The interesting part is on the Parameters tab.  There is where to define the IN , OUT, or IN/OUT.  These are a INs can be from the URI or from the HTTP Header.  This means if you want USER_AGENT to be useful in the the plsql block just define it and assign it to a bind variable.  Here is the :ct and :myval being defined.  The :ct is bound to the HTTP HEADER Content-Type.  The :myval is bound to RESPONSE. More robust support for UDTs is in the works.



Hopefully, this is no surprise as to what the output looks like.

DIY SQCL Commands

As mentioned once or twice or 100 times, sqlcl exposes javascript scripting with nashorn to make things very scriptable.  To learn more on Nashorn itself there's a lot of great write ups such as http://www.oracle.com/technetwork/articles/java/jf14-nashorn-2126515.html  So far, the scripting examples have been along the lines of conditional or looping of existing sqlcl commands.

Here's an example of creating a brand new command only from javascript.  This is a pretty simple one that for ALL command will snapshot the start time and print the elapsed time.  It also adds the new command "kris".

Just to show this is really nothing that new to sqlcl, here's a blog post from 2006 about how to make a Java based CommandListener in SQL Developer. This hasn't changed since then.

This all adds up to if we forget to add some feature, you want to override a command, perform something before or after commands, it's very simple to DIY your sqlcl.

// SQLCL's Command Registry
var CommandRegistry = Java.type("oracle.dbtools.raptor.newscriptrunner.CommandRegistry");

// CommandListener for creating any new command
var CommandListener =  Java.type("oracle.dbtools.raptor.newscriptrunner.CommandListener")

// Broke the .js out from the Java.extend to be easier to read
var cmd = {};

// Called to attempt to handle any command
cmd.handle = function (conn,ctx,cmd) {
   // Check that the command is what we want to handle
   if ( cmd.getSql().indexOf("kris") == 0 ){
       ctx.write("Hi Kris, what up?\n");

       // return TRUE to indicate the command was handled
       return true;
    }
   // return FALSE to indicate the command was not handled
   // and other commandListeners will be asked to handle it
   return false;
}

// fired before ANY command
cmd.begin = function (conn,ctx,cmd) {
   var start = new Date();

   // stash something for later like the start date
   ctx.putProperty("cmd.start",start);
}

// fired after ANY Command
cmd.end = function (conn,ctx,cmd) {
   var end = new Date().getTime();
   var start = ctx.getProperty("cmd.start");
   if ( start ) {
      start = start.getTime();
      // print out elapsed time of all commands
      ctx.write("Elapsed Time:" + (end - start) + "\n");
   }
}

// Actual Extend of the Java CommandListener

var MyCmd2 = Java.extend(CommandListener, {
        handleEvent: cmd.handle ,
        beginEvent:  cmd.begin  ,
        endEvent:    cmd.end
});

// Registering the new Command
CommandRegistry.addForAllStmtsListener(MyCmd2.class);

SQLCL Monitoring itself with Longops

Longops is a great way to monitor things that take some time to do work.  There's an easy example of using longops on oracle-base here.  I borrowed the script from there and put it into a file named my_slow_thing.sql.  Now here's a nice example of what's possible with sqlcl.




The easy way to using this is add it to your login.sql which is what I did. Of course the script could run at anytime instead of in the login.sql

script longops.js klrice klrice

The results