Materialized View with DBLink: ORA-00600: internal error code, arguments: [kkzuasid]

Hello guys!
Not being able to refresh you Materialized View because of this error?

bamdb> exec dbms_mview.refresh('PROD_ORABAM.MVIEW_TEST','C');
BEGIN dbms_mview.refresh('PROD_ORABAM.MVIEW_TEST','C'); END;

*
ERROR at line 1:
ORA-00600: internal error code, arguments: [kkzuasid], [2], [0], [1], [], [], [], [], [], [], [], []
ORA-06512: at "SYS.DBMS_SNAPSHOT", line 2809
ORA-06512: at "SYS.DBMS_SNAPSHOT", line 3025
ORA-06512: at "SYS.DBMS_SNAPSHOT", line 2994
ORA-06512: at line 1

The bad new is there is no workaround (I usually prefer workaround for this, is quicker and less complicated).
But the good new is there is a patch for this: Patch 17705023 : ORA-600 [KKZUASID] ON MV REFRESH

More“Materialized View with DBLink: ORA-00600: internal error code, arguments: [kkzuasid]”

Upgrade your JDBC and JDK before Upgrade your Database to 12c Version!

Ok, now it’s everyone upgrading to 12c, right? Thanks God, this version was released in 2013!

But there is some things to be aware when planning an upgrade, specially regarding old applications and legacy. But pay attention! Not all of the requirements are necessary inside database. It’s the case os JDBC version requirement.

The database 12c documentation explicit mentions that JDBC versions 11.1.x and below are not supported anymore. It doesn’t mean that they don’t work, it’s only unsupported and you’ll have no assistance from MOS if you need. It’s better to avoid, right?

Anyway, if you check the JDBC support matrix, if you are in version 11.2 or below you are not supported since August/2015. So the Database 12c is helping you, that don’t have patching policy, to keep on right way. Thanks to Database 12c!

If this is your situation, I highly recommend you to upgrade the directly to JDBC version 7, the last available by now. See JDBC matrix version as:

captura-de-tela-2016-10-22-as-16-59-57

But test! Test in you dev/test/QA environments before upgrading in Production environment!

Why? Because JDBC also have his compatibility matrix. JDBC 7, for example, demands your JDK to be at least in version 7 (released in 2011!). So, it’s needed to be at least in JDK version 6, as you can see below.

captura-de-tela-2016-10-22-as-16-37-18(Click in the image to access the link)

OK doke?

Some interesting links for you:
Verifying a JDBC Client Installation
What are the various supported Oracle database version vs JDBC compliant versions vs JDK version supported?
Checking the Oracle JDBC Driver Version on a Weblogic Server (by Cristóbal Soto)

Matheus.

Whats is the main characteristics/skills of a DBA? [part Osborne]

Another video post!
Almost 2 years ago I spent some time thinking about “Whats is the main characteristics/skills to be a DBA?”..
I wrote 2 posts about:
Whats is the main characteristics/skills of a DBA? [part 1]
Whats is the main characteristics/skills of a DBA? [part 2]

I found a great video with Kerry Osborne talking about what he searches in a guy (or girl) to be a great professional with Oracle… Very interesting:

I’d like to paraphrase Kerry to make my own ‘best moments summary’:
“A little bit of lazyness, a good cue and a lot of calm underpresure and keeping optmimistic.”

Have a nice week!

Solving Simple Locks Through @lock2s and @killlocker

Hi guys!
This post is to show the most simple and most common kind of locks for objects and the simpliest way to solve it (killing the locker). 🙂
It’s so common that I scripted it. Take a look:

greporadb> @lock2s
 Inst        SID SERIAL# UserName  STATUS   LOGON_TIME          LMODE  REQUEST LC_ET TY       ID1        ID2       CTIME LOCKWAIT         EVENT                                                                                           
----- ---------- ------- --------- -------- ------------------- ------ ------- ----- -- ---------- ---------- ---------- ---------------- -----------------------------------                                                             
    1        354   18145 MATHEUS   ACTIVE   17/06/2016 14:25:19 X      NONE    4032  TX     393238     424490        715 00000000DB0DF900 enq: TX - row lock contention                                                                   
    1        169   25571 GREPORA   ACTIVE   17/06/2016 14:22:48 NONE   X        714  TX     393238     424490        714 00000000DB0D5ED8 enq: TX - row lock contention                                                                   
    1        252   63517 MATHEUS   INACTIVE 17/06/2016 14:17:49 X      NONE     714  TX     655363    1550347       4195                  SQL*Net message from client                                                                     
    1        846   65011 GREPORA   ACTIVE   17/06/2016 14:20:18 NONE   X       4075  TX     655363    1550347        715 00000000DB0ECB88 enq: TX - row lock contention                                                                   
    1        354   18145 GREPORA   ACTIVE   17/06/2016 14:25:19 NONE   S       4032  TX     655363    1550347        715 00000000DB0DF900 enq: TX - row lock contention                                                                   
5 rows selected.

You can identify the Locker by LMODE column. And all his Waiters by REQUEST column marked by not ‘NONE’, below each Locker…

So, let’s kill the lockers:

greporadb> @killlocker
'ALTERSYSTEMKILLSESSION'''||SID||','||SERIAL#||'''IMMEDIATE;'                                                                                                                                                                                                                                                                                                                                          
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------                                                                                                                                                                                                                       
alter system kill session '252,63517' immediate;                                                                                                                                                                                                                                                                                                                                                       
alter system kill session '354,18145' immediate;                                                                                                                                                                                                                                                                                                                                                       
2 rows selected.
greporadb> alter system kill session '252,63517' immediate;      
System altered.
greporadb> alter system kill session '354,18145' immediate;      
System altered.
greporadb> @lock2s
no rows selected

Solved!
My magic scripts? Here it goes:

get lock2s.sql:

set lines 10000
set trimspool on
col serial# for 999999
col lc_et for 999999
col l1name for a50
col lmode for a6
col username for a25
select /*+ rule */
distinct b.inst_id,a.sid,b.serial#,b.username,b.status,
--b.audsid,
--b.module,
--b.machine,b.osuser,
b.logon_time,
decode(lmode,1,'null',2,'RS',3,'RX',4,'S',5,'SRX',6,'X',0,'NONE',lmode) lmode,
decode(request,1,'null',2,'RS',3,'RX',4,'S',5,'SRX',6,'X',0,'NONE',request) request,
b.last_call_et LC_ET,a.type TY,a.id1,a.id2,
d.name||'.'||c.name l1name,a.ctime,b.lockwait,b.event
--distinct b.inst_id,a.sid,b.username,a.type,d.name||'.'||c.name l1name,a.id1,a.id2,
--decode(lmode,1,'null',2,'RS',3,'RX',4,'S',5,'SRX',6,'X',0,'NONE',lmode) lmode,
--decode(request,1,'null',2,'RS',3,'RX',4,'S',5,'SRX',6,'X',0,'NONE',request) request,a.ctime,b.lockwait,b.last_call_et
from gv$lock a, gv$session b,sys.obj$ c,sys.user$ d,(select a.id1 from gv$lock a where a.request  0) lock1
where a.id1    = c.OBJ# (+)
and a.sid      = b.sid
and c.owner#   = d.user# (+)
and a.inst_id=b.inst_id
and b.username is not null
and a.id1 = lock1.id1
order by id1,id2, lmode desc
/

get killlocker.sql:

select 'alter system kill session '''||sid||','||serial#||''' immediate;' 
from v$session where sid in (select BLOCKING_SESSION from v$session where BLOCKING_SESSION is not null);

Now you can put in your Linkedin you are a JR DBA… 😛
haha

Matheus.

GrepOra Anniversary!

Hello guys,
This November GrepOra is completing 1 year!

It’s being a great adventure for all of us. In this first year we already shared 150 posts and had over 18k accesses!

Every month we keep having more access then the month before, and this is because of you. So thank you for reading, accessing and keeping us on track and motivated. 🙂

In October we had more than 3.500 accesses. We expect to keep sharing interesting subjects and grow even more for the next month and next year.

captura-de-tela-2016-11-05-as-11-17-34

As way to celebrate that first year, we decided that, for the next Saturday on, I and all authors will make a post telling what GrepOra means to ourselves and what we learned in this past year.

And for you, thanks for your partnership and have a nice week! 😀

Backup Not Backuped Archivelogs and Delete Input

Hi all!
Sometimes you are caught in a situation where your database is not backuping archivelogs and need to generate a quick backup commands for those are not backuped yet and deleting it, right?
I saw this situation in this archived discussion at OTN. Unfortunately I couldn’t give my answer… But it’s how I do:

select
'backup archivelog from sequence '||sequence#||' until sequence '||sequence#||' thread '||thread#||' filesperset=1 delete input;',first_time
from v$archived_log where backup_count=0 and name is not null
order by first_time desc;

It generates an output like:

greporadb> select
  2  'backup archivelog from sequence '||sequence#||' until sequence '||sequence#||' thread '||thread#||' filesperset=1 delete input;',first_time
  3  from v$archived_log where backup_count=0 and name is not null
  4  order by first_time desc;
'BACKUPARCHIVELOGFROMSEQUEN                                                                                                                                             
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
backup archivelog from sequence 152153 until sequence 152153 thread 1 filesperset=1 delete input;                                                                       
backup archivelog from sequence 152152 until sequence 152152 thread 1 filesperset=1 delete input;                                                                       
backup archivelog from sequence 152151 until sequence 152151 thread 1 filesperset=1 delete input;                                                                       
3 rows selected.

And be happy!

But an observation! It not works this way for databases with dataguard. For these cases you’ll need to add “and name’&dgname’” at select where clause… 😉

See ya!
Matheus.

MySQL Network Connections on ‘TIME_WAIT’

Hi all!
Recently I caught a bunch of connections in ‘TIME_WAIT’ on a MySQL Server through ‘netstat – antp 3306’…
After some time, we identified this was caused by the environment not using DNS, only fixed IPS (uuugh!)…

As you know, for security measures MySQL maintains a host cache for connections established. From MySQL docs:

“For each new client connection, the server uses the client IP address to check whether the client host name is in the host cache. If not, the server attempts to resolve the host name. First, it resolves the IP address to a host name and resolves that host name back to an IP address. Then it compares the result to the original IP address to ensure that they are the same. The server stores information about the result of this operation in the host cache. If the cache is full, the least recently used entry is discarded.”
9.12.6.2 DNS Lookup Optimization and the Host Cache

For this reason, there is a DNS ‘reverse’ lookup for each login was hanging this connections.

The solution?
Right way: Add an A type registry in DNS for the hosts. Use DNS!
Quick way: Add on /etc/hosts from database server the mapping for the connected hosts, avoiding the DNS Lookup.
Quicker way: Setting the skip-name-resolve variable at /etc/my.cnf. This variable avoids this behavior in database layer for new connections and solve the problem.

This is a good (portuguese) post about it: http://wagnerbianchi.com/blog/?p=831

See ya!
Matheus.

RAC on AIX: Network Best Practices

Hi all!
A few time ago I passed by some performance issues on AIX working with instances with different configuration (proc/mem). The root cause was basically the inefficient configuration of networking for interconnect (UDP).
As you know, the UDP is a non-response (for that reason with less metadata and faster) protocol. By the default, every server have a pool to send udp (and tcp) messages and another to recieve.
In my situation, once there was an ‘inferior’ instance, the pools were automatically set smaller in this one, and it was causing a high interconnection block sending statistics from other instances. In deed, it was lots of resends caused by overflows in this smaller instance…

There is one one to evaluete how much loss are you having for UDP in your AIX server:

netstat -s | grep 'socket buffer overflows'

If you are having considerable number of overflows, it’s recommended to reavaluate the sized of your udp_recvspace. And, of course, maintain the calculation of pools.

Oracle recommends, at least:

tcp_recvspace = 65536
tcp_sendspace = 65536
udp_sendspace = ((DB_BLOCK_SIZE * DB_FILE_MULTIBLOCK_READ_COUNT) + 4 KB) but no lower than 65536
udp_recvspace = 655360 (Minimum recommended value is 10x udp_sendspace, parameter value must be less than sb_max)
rfc1323 = 1
sb_max = 4194304
ipqmaxlen = 512

This and others details about configuring RAC on AIX ban be found in note: RAC and Oracle Clusterware Best Practices and Starter Kit (AIX) (Doc ID 811293.1)

I’d recommend you take a look too.

Have a nice day!
Matheus.

Compilation Impact: Object Dependencies

Hi all!
It’s not necessarily the DBA function, but how often someone of business came and ask you wich is the impact on recompiling one or other procedure?
It probably happen because the DBA usually make some magic and have a better understanding about objects relationship. It happens specially in cases there is no code governance…

So, you don’t have to handle all responsability and can switch some of that with developer, through DBA_DEPENDENCIES view.

The undertstanding is easy: The depended objects and the refered objects. If ou change the refered, all depended will be impacted by.

GREPORADB> @dependencies
Enter value for owner: GREPORA
Enter value for obj_name: TABLE_EXAMPLE
OWNER              Name                                TYPE       DEPE REFERENCED REFERENCED_OWNER   REFERENCED_NAME                         
------------------ ----------------------------------- ---------- ---- ---------- ------------------ -----------------------------------     
GREPORA            TOTALANSWEREDQUESTIONS              FUNCTION   HARD TABLE      GREPORA            TABLE_EXAMPLE                        
GREPORA            USERRESPONSESTATUS                  FUNCTION   HARD TABLE      GREPORA            TABLE_EXAMPLE                        
GREPORA            VW_INPROGRESSFEEDBACKOPTS           VIEW       HARD TABLE      GREPORA            TABLE_EXAMPLE                        
GREPORA            EVENTSTARTDT                        FUNCTION   HARD TABLE      GREPORA            TABLE_EXAMPLE                        
GREPORA            HAVEUSERANSWEREDANYTHING            FUNCTION   HARD TABLE      GREPORA            TABLE_EXAMPLE

Nice, hãn?

## @dependencies
col owner for a18
col name for a35
col type for a10
col referenced_owner for a18
col referenced_name for a35
col referenced_type for a10
select owner,name,type,dependency_type,referenced_type,referenced_owner,referenced_name from dba_dependencies
where referenced_owner like upper('%&owner%') and referenced_name like upper('%&OBJ_NAME%');

See ya!
Matheus.