Oracle: Create Disabled Triggers

Hey,
I believe you may know about this already, but in case its something new to you: Yes, this is possible since 11g!

Prior to 11g, it was only possible to create triggers in the enabled state, and after creating to disable them. Since 11g they can be explicitly enabled or disabled at creation time using clause ENABLE or DISABLE. As per example:

CREATE OR REPLACE TRIGGER disabled_trigger
BEFORE INSERT ON table_example
FOR EACH ROW
DISABLE
BEGIN NULL; END;
/

If didn’t know it yet. Np! You know it now! 😀

Cheers!

Oracle Invisible indexes

Hi All!
I was reviewing some features in Oracle and, basically, every single time I review them I find something new. Seems Oracle Databases’ features are near to infinite and we frequently find some that can really add value to our solutions.

So here is an 11g feature that is actually when known and I really like to use  when considering to remove indexes on clients or even “testing” a creation in production. How does that work?

Invisible indexes

Oracle 11g allows indexes to be marked as invisible. Invisible indexes are maintained like any other index, but they are ignored by the optimizer unless the OPTIMIZER_USE_INVISIBLE_INDEXES parameter is set to TRUE at the instance or session level. Indexes can be created as invisible by using the INVISIBLE keyword, and their visibility can be toggled using the ALTER INDEX command. Examples of those commands are listed below:

CREATE INDEX index_name ON table_name(column_name) INVISIBLE;
ALTER INDEX index_name INVISIBLE;
ALTER INDEX index_name VISIBLE;

Cheers!

Oracle SQL Join Factorization Transformation (JFT)

Hi All!
Following the line of last week post, let’s talk today about the JFT…

Oracle SQL Join Factorization Transformation (JFT)

The UNION operator is great for merging the results of multiple queries that return similar rowsets, essentially executing each query separately and merging the results together into a single result set. Oracle 11g release 2 come with improvements for SQL optimizer on how Oracle handles UNION ALL performance with the new join factorization transformation (JFT). The Join Factorization Transformation applies only to UNION ALL queries.

The following example show how the optimizer improves the performance of UNION ALL by dynamically re-writing a UNION ALL query into a more efficient form using an in-line view:

Original Query:

select t1.c1, t2.c2     
    from t1, t2, t3     
    where t1.c1 = t2.c1 and t1.c1 > 1 and t2.c2 = 2 and t2.c2 = t3.c2    
union all     
    select t1.c1, t2.c2     
    from t1, t2, t4     
    where t1.c1 = t2.c1 and t1.c1 > 1 and t2.c3 = t4.c3;

Re-Written Query:

select t1.c1, VW_JF_1.item_2
     from t1, (select t2.c1 item_1, t2.c2 item_2
                    from t2, t3
                    where t2.c2 = t3.c2 and t2.c2 = 2
               union all
                    select t2.c1 item_1, t2.c2 item_2
                    from t2, t4
                    where t2.c3 = t4.c3) VW_JF_1
     where t1.c1 = VW_JF_1.item_1 and t1.c1 > 1;

Nice, right?
Cheers!

Oracle: “Invisible” Locks!

Have you ever heard:
“My session was killed. I’m trying again. There is no locks. But My SQL doesn’t run!”

By default, when a session is disconnected from Oracle, the SQLs uncommitted are undone (rollback). So, in case of a long routing there is a probably a rollback in place.

How Oracle rollback take that long? Well, it’s Oracle mechanism. The RDBMS basically assume you know what your are doing and start writing the new blocks so the commit will be very quick. Which, however, is bad in case of rollbacks.

How to check if this is your case?

select ktuxeusn, to_char(sysdate,'DD-MON-YYYY HH24:MI:SS') "Time", ktuxesiz, ktuxesta
from x$ktuxe
where ktuxecfl = 'DEAD'
4 /

KTUXEUSN Time KTUXESIZ KTUXESTA
---------- -------------------- ---------- ----------------
31 07-APR-2018 16:48:53 17705 ACTIVE
48 07-APR-2018 16:48:53 108856 ACTIVE

Hm.. What can I do? Not much really, we need to wait the rollback to complete.
One thing that can be done to increase the rollback is changing the fast_start_parallel_rollback parameter, as per:

SQL> show parameters roll

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
fast_start_parallel_rollback string LOW
rollback_segments string
transactions_per_rollback_segment integer 5
SQL> alter system set fast_start_parallel_rollback=HIGH;

System altered.

Hope it helps!
Cheers!

11g SQL transformations (CBQT, CNT, JE, JPPD)

Hi All!
Let’s save some time to review those?
They usually very important when analysing query performance, specially on 10046 traces. I separated those were included on 11g, to have it as subset. Here it goes:

New 11g SQL transformations (CBQT, CNT, JE, JPPD)

The Oracle cost-based optimizer CBO is constantly being improved in its ability to re-write and transform sub-optimal SQL queries. In general way, CBO work by replacing operations by equivalent optimal when possible, changing clauses or re-grouping to take advantage on in indexes, eliminating subqueries by replacing with joins and not null tests and similar. In 11g new SQL transformations were implemented looking to continue improving this process. They are:

  • Cost-Based Query Transformation (CBQT): This is one of the core mechanisms in CBO, that tries different transformed and untransformed variants of the query and runs them through the costing algorithm. Improvements were done in 11g, specially related to clauses NOT IN into NOT EXISTS.
  • Count Transformation (CNT): If all rows have a value on this column (not null), Oracle CBO can simply count the number of rows. There is no need to actually retrieve the column value. This transformation changes count(col) to count(*).
  • Join Elimination (JE): Join elimination is a query transformation of the Oracle optimizer to remove joins that are not required in a query. Released on 10g, Join Elimination got several improvements and new mechanisms in 11g and even more in 12c.
  • Join Predicate PushDown (JPPD): Allows a view to be joined with index-based nested-loop join method, which may provide a more optimal alternative. The following types of views supports predicate pushdown: UNION ALL/UNION view, Outer-joined view, Anti-joined view, Semi-joined view, DISTINCT view and GROUP-BY view.

Nice?

Hope you enjoy it!

DG Broker ORA-16766: Redo Apply is stopped after a Database Restart

So, the other day I was engaged to check a dataguard, while checking its status with the dg broker I found this error

Error: ORA-16766: Redo Apply is stopped

Checking for it on dg broker:

DGMGRL> show configuration verbose

Configuration - DGCONFIG

Protection Mode: MaxPerformance
Databases:
PRIMARY - Primary database
STANDBY - Physical standby database
Error: ORA-16766: Redo Apply is stopped

Properties:
FastStartFailoverThreshold = '30'
OperationTimeout = '30'
FastStartFailoverLagLimit = '30'
CommunicationTimeout = '180'
ObserverReconnect = '0'
FastStartFailoverAutoReinstate = 'TRUE'
FastStartFailoverPmyShutdown = 'TRUE'
BystandersFollowRoleChange = 'ALL'
ObserverOverride = 'FALSE'
ExternalDestination1 = ''
ExternalDestination2 = ''
PrimaryLostWriteAction = 'CONTINUE'

Fast-Start Failover: DISABLED

Configuration Status:
ERROR

GMGRL> show database verbose STANDBY

Database - STANDBY

Enterprise Manager Name: STANDBY
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 3 seconds ago)
Apply Lag: 1 hour(s) 50 minutes 6 seconds (computed 0 seconds ago)
Apply Rate: 828.00 KByte/s
Real Time Query: OFF
Instance(s):
STANDBY

Database Error(s):
ORA-16766: Redo Apply is stopped

Properties:
DGConnectIdentifier = 'STANDBY'
ObserverConnectIdentifier = ''
LogXptMode = 'ASYNC'
DelayMins = '0'
Binding = 'optional'
MaxFailure = '0'
MaxConnections = '1'
ReopenSecs = '300'
NetTimeout = '30'
RedoCompression = 'DISABLE'
LogShipping = 'ON'
PreferredApplyInstance = ''
ApplyInstanceTimeout = '0'
ApplyParallel = 'AUTO'
StandbyFileManagement = 'AUTO'
ArchiveLagTarget = '900'
LogArchiveMaxProcesses = '4'
LogArchiveMinSucceedDest = '1'
DbFileNameConvert = ''
LogFileNameConvert = ''
FastStartFailoverTarget = ''
InconsistentProperties = '(monitor)'
InconsistentLogXptProps = '(monitor)'
SendQEntries = '(monitor)'
LogXptStatus = '(monitor)'
RecvQEntries = '(monitor)'
ApplyLagThreshold = '0'
TransportLagThreshold = '0'
TransportDisconnectedThreshold = '30'
SidName = 'STANDBY'
StaticConnectIdentifier = '(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=SB_SERVER)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=STANDBY_DGMGRL)(INSTANCE_NAME=STANDBY)(SERVER=DEDICATED)))'
StandbyArchiveLocation = 'USE_DB_RECOVERY_FILE_DEST'
AlternateLocation = ''
LogArchiveTrace = '0'
LogArchiveFormat = 'STANDBY_%r_%t_%s.arc'
TopWaitEvents = '(monitor)'

Database Status:
ERROR

The standby state was APPLY-ON but when checked the standby if the MRP process was running I found none!

sqlplus / as sysdba

SQL*Plus: Release 11.2.0.4.0 Production on Fri Jan 4 17:05:12 2019

Copyright (c) 1982, 2013, Oracle. All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Automatic Storage Management, OLAP, Data Mining
and Real Application Testing options

17:05:12 SYS@STANDBY AS SYSDBA> SELECT PROCESS, STATUS FROM v$managed_standby;

PROCESS STATUS
--------- ------------
ARCH CLOSING
ARCH CLOSING
ARCH CLOSING
ARCH CLOSING
RFS IDLE
RFS IDLE
RFS IDLE
RFS WRITING

8 rows selected.

Elapsed: 00:00:00.01

Checking further I found that the database was bounced while the MRP was running and that was the only explanation that I could see to see a difference between the dg broker also I could not find any error in the dg broker log $ORACLE_HOME/rdbms/log/drc*.log

After setting the state to apply-off and them to apply-on the issue was resolved.

DGMGRL> edit database STANDBY set state='apply-off';
Succeeded.
DGMGRL> edit database STANDBY set state='apply-on';
Succeeded.
DGMGRL> show database verbose STANDBY;

Database - STANDBY

Enterprise Manager Name: STANDBY
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Apply Rate: 0 Byte/s
Real Time Query: OFF
Instance(s):
STANDBY

Properties:
DGConnectIdentifier = 'STANDBY'
ObserverConnectIdentifier = ''
LogXptMode = 'ASYNC'
DelayMins = '0'
Binding = 'optional'
MaxFailure = '0'
MaxConnections = '1'
ReopenSecs = '300'
NetTimeout = '30'
RedoCompression = 'DISABLE'
LogShipping = 'ON'
PreferredApplyInstance = ''
ApplyInstanceTimeout = '0'
ApplyParallel = 'AUTO'
StandbyFileManagement = 'AUTO'
ArchiveLagTarget = '900'
LogArchiveMaxProcesses = '4'
LogArchiveMinSucceedDest = '1'
DbFileNameConvert = ''
LogFileNameConvert = ''
FastStartFailoverTarget = ''
InconsistentProperties = '(monitor)'
InconsistentLogXptProps = '(monitor)'
SendQEntries = '(monitor)'
LogXptStatus = '(monitor)'
RecvQEntries = '(monitor)'
ApplyLagThreshold = '0'
TransportLagThreshold = '0'
TransportDisconnectedThreshold = '30'
SidName = 'STANDBY'
StaticConnectIdentifier = '(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=SB_SERVER)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=STANDBY_DGMGRL)(INSTANCE_NAME=STANDBY)(SERVER=DEDICATED)))'
StandbyArchiveLocation = 'USE_DB_RECOVERY_FILE_DEST'
AlternateLocation = ''
LogArchiveTrace = '0'
LogArchiveFormat = 'STANDBY_%r_%t_%s.arc'
TopWaitEvents = '(monitor)'

Database Status:
SUCCESS

DGMGRL> show configuration

Configuration - DGCONFIG

Protection Mode: MaxPerformance
Databases:
PRIMARY - Primary database
STANDBY - Physical standby database

Fast-Start Failover: DISABLED

Configuration Status:
SUCCESS

DGMGRL> exit

sqlplus / as sysdba
17:17:54 SYS@STANDBY AS SYSDBA> SELECT PROCESS, STATUS FROM v$managed_standby;

PROCESS STATUS
--------- ------------
ARCH CLOSING
ARCH CLOSING
ARCH CLOSING
ARCH CLOSING
RFS IDLE
RFS IDLE
RFS IDLE
RFS IDLE
MRP0 APPLYING_LOG

9 rows selected.

Elapsed: 00:00:00.00

Hope it helps, unti the next one.

Elisson Almeida

 

Oracle 11g / 12c identified by values – set an Oracle password to its current value without knowing the password

This post will be a quick one. I needed to set a Oracle password as it was about to expire but the client did not want to change the password itself.

The simplest way to get the encrypted password was:

select name, password from sys.user$ where name=‘USER’;

But after Oracle 11g/12c seems a better option for security ends to use DBMS_METADATA.get_ddl or select the spare4 column on sys.user$

select name, spare4 from sys.user$ where name=‘USER’;

or

set long 9999999
set longc 9999999
select dbms_metadata.get_ddl('USER','DBSNMP') from dual;

And how to set this password back to the user?

alter user [USER] identified by values '[encrypted password]';

 

Hope it helps!

MySQL: Sed for Scripts using “Show” from Command Line

Hi all,
So, a pretty basics one today… But useful to have handy. How to script an output from  mysql -B -e?

Easy, by using SED. Ok, by replacements are always tricky considering the line braking and etc. So, here goes an example with show tables:

Original Output.

[root@greporasrv ~]# mysql sbtest -B -e 'show tables'
Tables_in_sbtest
sbtest1
sbtest10
sbtest2
sbtest3
sbtest4
sbtest5
sbtest6
sbtest7
sbtest8
sbtest9
Cool, now with all in one line:
[root@greporasrv ~]# mysql sbtest -B -e 'show tables'|sed ':a;N;$!ba;s/\n/ /g'
Tables_in_sbtest sbtest1 sbtest10 sbtest2 sbtest3 sbtest4 sbtest5 sbtest6 sbtest7 sbtest8 sbtest9

Great, so let’s put some useful code on it:

[root@greporasrv ~]# mysql sbtest -B -e 'show tables'|sed ':a;N;$!ba;s/\n/ engine=innodb; \n alter table /g'
Tables_in_sbtest engine=innodb;
alter table sbtest1 engine=innodb;
alter table sbtest10 engine=innodb;
alter table sbtest2 engine=innodb;
alter table sbtest3 engine=innodb;
alter table sbtest4 engine=innodb;
alter table sbtest5 engine=innodb;
alter table sbtest6 engine=innodb;
alter table sbtest7 engine=innodb;
alter table sbtest8 engine=innodb;
alter table sbtest9 engine=innodb;

Hope you can use for your needs.

Cheers!

Statspack top queries script by elspased time

Hi all,

I was engaged on a report request that I needed to gather to get the TOP SQL by elapsed time and using Statspack. I got those and than I was asked to it on the following week and on the following, and you may see when this is going. So I created a script which would give is a report and I would not have to do it manually ever again 🙂

Usage: long_run_sql.sh [-h ] [ -r 

Where:
If no parameters are used 120 minutes and 7 days will be used as default for History, 5 minutes for current running
-r = Set the time in minutes for the current running SQLs
-o = Specifies the minutes to be used for the long running SQLs History
-d = set the time period wanted for the execution history, default is 7 days
-h = Shows this help message

Might still have some bugs but it well enough to share here 🙂

You have some parameters that you need to change at the top, to suite your environment and of course have Statspack working and change the sqlplus connection line

Some tweaks are required as no 2 environments are never 100% alike. But still forth the work.

#!/bin/bash
#---------------------------------------------------------------------------
# Creates a report, using statspack, of the long running sqls from database
#
# History:
# Feb-21-2018 - Elisson Almeida - Created.
#---------------------------------------------------------------------------
#usage
### Environment setup
### Global variables
DIR=/home/oracle/scripts
LOG=/home/oracle/logs
DATE=$(date +%Y%m%d_%H%M%S)
NAME=long_running_sql_report
OUTPUT_FILE=${LOG}/${NAME}_${DATE}.log
ERROR_FILE=${LOG}/${NAME}.err
TMP_FILE=$DIR/$.tmp
CONFIG_EMAIL_TO=
PATH=
ORACLE_SID=
ORACLE_BASE=
ORACLE_HOME=
#tns-admin if needed otherwise comment out
#TNS_ADMIN
RUNNING=5
HISTORY=120
Help()
{
echo "Usage: long_run_sql.sh [-h ] [ -r 

Hope it helps!

Elisson Almeida

Managing listener.log and log.xml with Linux Logrotate

Hi all,
To manage Oracle trace files the way to go is ADRCI. You can see this post from Matheus if you have not read it yet.

In the last part of the script we have a small bash code to configure the ADRCI on all databases running on a server

You could add:

adrci exec="set home $1;purge -age 10080 -type ALERT";

In this case the age parameter is in minutes but still you would be required to run it periodically which could be another script in crontab to be managed.

SO the solution that I found to be best as it takes leverage from an existing solution is called logrotate.

Logrotate is a Unix/Linix based program that helps as its name says, rotate any file that you need. You just need to create a configuration file and place it on /etc/logrotate.d on most Linuxes distributions.

But when you have a server with several databases and listerners and more, it starts to get a bit tedious and time consuming to create this manually.

In this post on the Pythian Blog, will find how to create but it does not handle the listener.log but not the log.xml so I added this piece here

for L in `\ps -ef | grep tnslsnr | grep -v grep | sed s'/-.*$//g' | awk '{print $NF}'`
do
OUT=${DEST}/"logrotate_xml_"${L}
LSRN_LOG=`lsnrctl status ${L} | grep "Listener Log File" | awk '{print $NF}'`
echo ${LSRN_LOG%.*}"*" " {" > ${OUT}
cat << ! >> ${OUT}
daily
rotate 1
compress
notifempty
}
!
echo ${OUT} has been generated
done

Using logroate really helps on the managing on Oracle related files which are not done by ADRCI.

Hope it helps,

Elisson