Category: Java | DevOps | APEX | Scripts

Database, Shell Scripts, SQL | PLSQL, Tools

Scheduler Job for OS Audit Trail Cleanup Routine

Hello all!
As you all know, most of OS files generated by oracle, like traces and logs can be cleared/managed using ADRCI. However, more than once, I saw filesystem get full of Audit Trail files.
In general, I see DBAs and companies implementing shell scripts to house keep those files. Usually some variation of the find with rm I posted some weeks ago. However, we have a very good “official” solition for this, using the DBMS_AUDIT_MGMT.

Basically we can create Scheduler Jobs in our databases to keep track on this. The advantages are seveal. The job clear in both nodes, this keep all Oracle information correctly updated, you may receive OEM notification for failure if monitoring jobs, etc.
You can see more detaiils here in MOS Note 731908.1 New Feature DBMS_AUDIT_MGMT to Manage and Purge Audit Information.

How I did?

1. Initial Cleanup to clear files older than a week.
2. Set last archive to a week ago.
3. Created Purge Job, purging older than a week

As per:

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Database, Security, SQL | PLSQL

12c New Feature: Unused Privileges

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Did you know 12c now has a mechanism to examine which privileges are actually being used by an user, module or for the database as a whole, as opposed to merely the privileges granted?
This is a great security improvement in order give users the privileges that they need precisely without granting too much.

Here’s how is works?

1. First you have to set up a capture process using the new package DBMS_PRIVILEGE_CAPTURE.

# Example:

BEGIN 
DBMS_PRIVILEGE_CAPTURE.CREATE_CAPTURE( 
        name         => 'all_priv_analysis_pol', 
        description  => 'database-wide policy to analyze all privileges', 
        type         => DBMS_PRIVILEGE_CAPTURE.G_DATABASE); 
END;
/

This starts the capture process database wide. Let it run for a bit.

2. Now you can either generate a report:

# Example

BEGIN 
DBMS_PRIVILEGE_CAPTURE.GENERATE_RESULT( 
        name         => 'all_priv_analysis_pol'); 
END;
/

Or examine the new views:

DBA_USED_PRIVS 
DBA_UNUSED_PRIVS 
DBA_USED_OBJPRIVS 
DBA_UNUSED_OBJPRIVS

3. To turn off you proceed with the following:

BEGIN 
DBMS_PRIVILEGE_CAPTURE.DROP_CAPTURE( 
        name         => 'all_priv_analysis_pol'); 
END;
/

So now you ensure that you use the best practice of least privilege for users.

Cheers!

Java | DevOps | APEX | Scripts

RabbitMQ on a Micro-service Architecture

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Microservices ain’t a boom word right now, at least not as it was before… But we still can see a few things about it, and that’s what I’ll talk about today.

When we talk about microservices and how they work and scale, we think how the services will exchange data between them. We have a few options to do it, we can send the data to a reverse proxy that will handle the load balance for us, for example. There is also the option to send directly to a docker service name and let swarm handle it. We can use Kubernets and the service discovery that it provides to us (or use Consul for that).

All these options are fine, but what if we need a huge task to be done, and the service that was dealing with that job crashes? Did we lose our job? Do we need to manage that crash on the communication protocol our selves? How’s the load on the service? Is the service handling the request or they’re slowing? Too many questions right?

The point here is that even a simple and fast service can fail/crash and throw some error to our user or to the consuming service and that’s bad. Here’s where RabbitMQ comes in! it’ll handle the request between our services and ensure every single request has an answer.

Rabbit handle queues and delivery they to the right consumer. Once a job is “delivered” to a consumer, it has two main options:
1) Automatic acknowledge
2) The consumer sends the acknowledge.

The second one is the better way to say that some job was achieved. After the job, the consumer may give an answer back to the producer with some data.

Wanna know the load avg of the services?
Every service has it’s own queue and rabbit can show you how every single queue is doing. With that, you can see if you need more consumers from the same service or can scale down any of them.

You have another approach to solve those questions? Let me know 😉

Linux, Shell Scripts

Change display settings on linux with Disper

From time to time, I change the Linux distro on my laptop or just do a fresh install on it. And once in a while, have random problems with external displays. It can be something really “simple” like don’t detecting the external monitor or something crazy like the image below.

screenshot of the bug

As you can see at the image, the mint detected the display but mirrored it in a crazy way that works but doesn’t at the same time. If you try anything and doesn’t get working, or just wanna skip the whole job of configuring complexes text files, give a try to Disper. Download the latest version. Extract it on any folder, and make install it (on the extracted folder).

make install

After that, you can start using it… There are a few options that will serve you well.

disper -e #extend your display
disper -c #clone your display
displer -s #only your external display

 

Cloud Services, Cloud Services | Exadata | Linux, Database, SQL | PLSQL, Tools

Database in Cloud: Quickest Procedure to Clone a Schema

Hey all!
So, we all know that operating with files/dump files can be tricky when using DBaaS in Public Cloud. In some situations, like Amazon RDS service, we simply don’t have access to SO.

In this scenario, how can we quickly clone a schema in the database? Using IMPDP with Database Link.

Also note that when working on AWS environments, avoiding to use dumpfiles when dealing with expdp/impdp is also encouraged to save IOPS from local disks (it is capped based on machine type).

This is, of course, also valid for On-Premise environments with limited area for dump files.

For this to work, we only need to create a database link pointing to the same database.
Also, of course, it is mandatory to use remap_schema, with optional clause remap_tablespace.

In the following example the link name is loop and proceed with impdp from a jumpbox with an Oracle client and tns configuration to RDS database.

1. Creating Database Link:

SQL> create database link loop connect to my_sysdba identified by "***" using '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=service-name)))';

Database link created.

SQL> select * from dual@loop;

D
-
X

2. Running IMPDP:

[oracle@jumpbox ~]$ impdp schemas=ORIGINAL_SCHEMA network_link=loop remap_schema=ORIGINAL_SCHEMA:NEW_SCHEMA remap_tablespace=ORIGINAL_TBS:NEW_TBS TRANSFORM=oid:n directory=ANY_DIR logfile=duplicate_original.log

Import: Release 11.2.0.4.0 - Production on Wed Fev 7 21:03:54 2018

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

Username: / as sysdba

Connected to: Oracle Database 11g Release 11.2.0.4.0 - 64bit Production
Starting "SYS"."SYS_IMPORT_SCHEMA_02": /******** AS SYSDBA schemas=ORIGINAL_SCHEMA network_link=loop remap_schema=ORIGINAL_SCHEMA:NEW_SCHEMA remap_tablespace=ORIGINAL_TBS:NEW_TBS TRANSFORM=oid:n directory=ANY_DIR logfile=duplicate_original.log
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 1.481 GB
Processing object type SCHEMA_EXPORT/USER
ORA-31684: Object type USER:"NEW_SCHEMA" already exists
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/TYPE/TYPE_SPEC
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
...
. . imported "NEW_SCHEMA"."TABLE1" 0 rows
. . imported "NEW_SCHEMA"."TABLE2" 0 rows
. . imported "NEW_SCHEMA"."TABLE3" 0 rows
Processing object type SCHEMA_EXPORT/FUNCTION/FUNCTION
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/FUNCTION/ALTER_FUNCTION
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Job "SYS"."SYS_IMPORT_SCHEMA_02" completed with 1 error(s) at Wed Fev 7 21:08:52 2018 elapsed 0 00:04:54

Hope it helps,
Cheers!

Java | DevOps | APEX | Scripts

Embeded server for Java Web App and a New author

 

Hi, my name is Maurício and it’s the first time I’m posting here. I’m a Senior Software Engineer and I live in Brazil. I have six years working with web development and love Java and Javascript. I’ll be posting here from time to time development stuff. Hope you enjoy it!

Our subject for today: Once in a while, I do a small Java Web project and every time I think on which application server will host the app, Tomcat, GlassFish, WebLogic, WildFly, Payara and there are plenty more servers. Nowadays almost everybody uses a Docker container to host app’s, and that’s nothing wrong with that, but why load a container if I can just embed the server in a jar file?

If you have a Maven project, there’s almost no work to be done, just add a plugin that targets the package goal and there you go. In the end, you will have a jar file with your app-name-swarm.jar (i know, it’s a WildFly swarm, not a fully WildFly, but it weights just 64Mb). Run it like a normal jar and you will have a running web app.

<plugin>
  <groupId>org.wildfly.swarm</groupId>
  <artifactId>wildfly-swarm-plugin</artifactId>
  <version>2018.2.0</version>
  <executions>
    <execution>
      <goals>
        <goal>package</goal>
      </goals>
    </execution>
  </executions>
</plugin>

After all, if you want, that jar can be loaded in a Docker container and launched at a production server. There are other options like Tomcat embedded, Payara microserver and a few others. Go ahead and give a try to any one of them and share your experience, I’m sure you have something to say about them.

But remember, these options aren’t a full application server, they’re engineered to be small and focused on specific features so read their docs to see what they can and can’t do before using. 😉

 

Errors and Bugs, Java | DevOps | APEX | Scripts

Application Named Variables Returning ORA-01008: not all variables bound

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Hi all,
I saw it a long time ago and last week I was involved in a discussion for this same error. So, this deserve a post for future reference. 🙂

Imagine the situation: You are building an application or a module to perform queries on database. You want to use variables in the query and fill the values using text fields on application. Sounds easy and works fine for SQLServer and others, but Oracle database is returning:

ORA-01008: not all variables bound

What to do?

Fist let’s clear the issue: this is not related to database layer or oracle interpreter/parser. This error happens when a bind variable being used on SQL have no value. The official reasoning is:

Cause: A SQL statement containing substitution variables was executed without all variables bound. All substitution variables must have a substituted value before the SQL statement is executed.

In my case ODP.Net with C# (but apply to other languages). Interesting fact:
“ODP.Net provider from oracle uses bind by position as default. To change the behavior to bind by name, set property BindByName to true.”

This means Oracle may be waiting for “:1”, “:2” as bind variables and this can also not being set correctly by application.
In this case, please try to set BindByName to true in application code for Oracle command. Example below:

using(OracleCommand cmd = con.CreateCommand()) {
    ...
    cmd.BindByName = true;
    ...
}

Now, try again. 🙂

Hope this helps you!
Cheers!

Database, RAC | Data Guard, SQL | PLSQL

Trace on Standby: Tracing MRP Process

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Hey all!
Recently I got the following error when trying to start a trace in a standby. The idea was to start a trace in MRP to check on performance, but when trying to use DBMS_MONITOR.session_trace_enable:

oracle:standby-srvr /tmp: sqlplus / as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Fri Jan 19 14:07:56 2018

Copyright (c) 1982, 2014, Oracle. All rights reserved.

Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Advanced Analytics and Real Application Testing options

SQL> exec DBMS_MONITOR.session_trace_enable(session_id =>1970, serial_num=>55126, waits=>TRUE, binds=>TRUE);
BEGIN DBMS_MONITOR.session_trace_enable(session_id =>1970, serial_num=>55126, waits=>TRUE, binds=>TRUE); END;

*
ERROR at line 1:
ORA-06550: line 1, column 7:
PLS-00201: identifier 'DBMS_MONITOR.SESSION_TRACE_ENABLE' must be declared
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored

OMG!
Don’t panic, you can accomplish the same using oradebug:

-- In my case:
SQL> select process,pid from V$managed_standby where process like '%MRP%';

PROCESS PID
--------- ------------------------
MRP0 45693

SQL> oradebug setospid 19564
Oracle pid: 105, Unix process pid: 19564, image: oracle@standby-srvr (MRP0)
SQL> oradebug unlimit
Statement processed.
SQL> oradebug Event 10046 trace name context forever, level 12
Statement processed.
SQL>

You can apply same for any process/sid you need.

In case you desire to get the spid from a sid:

col machine format a30
col process format 999999
select p.spid,b.sid, p.pid
from v$session b, v$process p
where b.paddr=p.addr
and sid=&sid
/

Ok, and how to stop then?
Easy:

SQL> oradebug setospid 19564
SQL> oradebug Event 10046 trace name context off
SQL> oradebug tracefile_name

Enjoy!

Linux, Shell Scripts

Am I in RHEL or OEL?

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OK, first time accessing a client, and you have this question?

# RHEL:

[grepora-rhel-server]$ rpm -qf /etc/redhat-release 
redhat-release-server-6Server-6.9.0.4.el6.x86_64

# OEL:

[grepora-oel-server]$ rpm -qf /etc/redhat-release
enterprise-release-5-0.0.2

You may also have some other options like:

[grepora-fedora-server]$ rpm -qf /etc/redhat-release 
fedora-release-20-3.noarch

Hope you enjoy it!
Cheers!

Community, SQL | PLSQL, Tools

Guru99: PL/SQL 101 Completely Free!

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Hey all!
Just passing by today to share something I found really inetresting, and the best: it’s all free!
Do you know Guru99?

It’s a preety nice repository with lots of free tutorials and guides for PLSQL, SQL and several other languages, plus some other IT-related knowledge, like Big Data, PMP and etc.

It’s not rare to have people asking me “How to Start learning SQL” or saying “All material (including grepora :D) is too much specific, we don’t have good general documentation”.
Even Oracle having a pretty nice documentation on the products and features, general concepts are usually forgotten. Aaaaand, now I have something to link on those cases! 😀

Having a look on Guru99, First I found this guide PL/SQL First Program: Hello World, including detailed steps on:
– How to access SQL* Plus
– Connecting to Database
– How to write a simple program using PL/SQL
– Declaring and usage of variables in program
– Commenting Codes

Then found an entire category PL/SQL Tutorials. Talking to Alex (Editor), seems over 120 hours were spent on it. And they were well spent, the material is really very easy to read and understand. Chapters on this Course are:
1. Introduction to PL/SQL
2. Blocks in PL/SQL
3. PL SQL First Program: Hello World
4. PL/SQL Data Types
5. Complex Data Types in PL/SQL
6. PL/SQL Decision Making Statements
7. Loops in PL/SQL
8. Subprograms: Procedures and Functions in PL/SQL
9. Exception Handling in PL/SQL
10. SQL in PL/SQL
11. Packages in PL/SQL
12. Triggers in PL/SQL
13. Object Types in PL/SQL
14. Dynamic SQL in PL/SQL
15. Nested Blocks in Pl/Sql
16. PL/SQL Identifiers

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