Lambda Expressions

Mark Reinhold, Oracle’s Chief Architect, gives a useful talk on Lambda Expressions at The JavaOne 2013 Technical Keynote.


Click here for the full article.


Keywords: java 1.8 lambda expressions

Overview of the .NET Framework

The .NET Framework is a technology that supports building and running the next generation of applications and XML Web services. This article also gives an explanation of Common Language Runtime (CLR) and .NET Framework class library.

 

Click here to read the full article.

Gather Statistics for the Cost Based Optimizer

The following article describes gathering statistics for the CBO (Cost Based Optimizer).

Goal

Provide pointers to the various articles outlining the recommended methods for gathering statistics for the Cost Based Optimizer for use by Database Administrators

See also

How To: Gather Statistics for the Cost Based Optimizer (Doc ID 1226841.1)

Keywords: oracle cbo stats statistics cost based optimizer

Explain Plans and DBMS_XPLAN

This post gives an overview of using DBMS_XPLAN and selecting a SQL_ID to use.


Run the following SQL query to obtain some information regarding the SQL_ID of interest..

=~=~=~=~=~=~=~=~=~=~=~= PuTTY log 2014.12.17 18:32:47 =~=~=~=~=~=~=~=~=~=~=~=
run
  1  SELECT DISTINCT sql_id,
  2     address,
  3     hash_value,
  4     child_number,
  5     plan_hash_value
  6  FROM   v$sql_plan
  7  WHERE  sql_id = '2x409g450hfyc'
  8* ORDER  BY child_number

SQL_ID      ADDRESS       HASH_VALUE CHILD_NUMBER      PLAN_HASH_VALUE
------------- ---------------- ---------- ------------ ---------------
2x409g450hfyc 00000002DCF6C808  168311756          0      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          1      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          2      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          3      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          4       240831378
2x409g450hfyc 00000002DCF6C808  168311756          5      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          6      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          7      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          8      1748903202
2x409g450hfyc 00000002DCF6C808  168311756          9      1748903202
2x409g450hfyc 00000002DCF6C808  168311756         10      1748903202

11 rows selected.

Or even:

SELECT sql_id,
       sql_text,
       hash_value,
       plan_hash_value,
       child_number
FROM   v$sql
WHERE  Regexp_like (sql_text, 'fred', 'i');

Now use the supplied Oracle package DBMS_XPLAN to obtain the explain plan.


SELECT * FROM table (
DBMS_XPLAN.DISPLAY_CURSOR('2x409g450hfyc',7,'ALL'));


where 2x409g450hfyc is the SQL_ID of interest and
7 is the child number.

By using different child numbers, you can select which plan hash value you wish to display. Child number 2, for example, displays the plan with a hash value of 1748903202 whilst child 4 gives you 240831378.


Keywords: oracle xplan explain plan sql_id

Tuning Inter-Instance Performance in RAC

Tuning Inter-Instance Performance in RAC and OPS (Doc ID 181489.1)


This note was written to help DBAs and Support Analysts understand Inter-Instance Performance and Tuning in RAC.

Real Application Clusters (RAC) uses the interconnect to transfer blocks and messages between instances. If inter-instance performance is bad, almost all database operations can be delayed. This note describes methods of identifying and resolving inter-instance performance issues.

See Oracle Support Doc ID 181489.1 for details.

RAC interconnect traffic

Summary


I was looking for RAC cluster interconnect throughput and so accessed to Oracle Database Reference 11g Release 2 (11.2) documentation and surprisingly, at least for me, I was not able to find a V$ view simply displaying it.


This is a nice article on the subject of RAC interconnect traffic.

Click here to read the article.

ADD_COLORED_SQL Procedure

From the Oracle supplied documentation:

This procedure adds a colored SQL ID. If an SQL ID is colored, it will be captured in every snapshot, independent of its level of activities (so that it does not have to be a TOP SQL). Capture occurs if the SQL is found in the cursor cache at snapshot time.

This can be very useful in the interests of fault finding or diagnosing problems.


SQL> execute dbms_workload_repository.add_colored_sql('6rj1tt5s6n497');

To confirm the SQL_ID has been colored, run the following SQL statement:
SQL> select * from sys.WRM$_COLORED_SQL

This will give you:

fred SQL> select * from sys.WRM$_COLORED_SQL
  2  /
      DBID SQL_ID        OWNER CREATE_TIME
---------- ------------- ----- --------------------
 413071501 6rj1tt5s6n497     1 11-Dec-2014 19:02:51
1 row selected.


and the following SQL will remove the color:
SQL> execute dbms_workload_repository.remove_colored_sql('6rj1tt5s6n497');

See also

AWR Colored SQL 11g

Oracle Support document
How to Determine the Execution Plan for a SQL Statement for a Range of AWR snapshots? (Doc ID 795204.1)

Oracle Support document
Information Center: SQL Query Performance Overview (Doc ID 1516494.2)



Keywords: oracle sql_id

11g Interactive Quick Reference

Oracle Database 11g: Interactive Quick Reference

Your Essential Guide to Oracle Database 11g Release 2

Oracle Database 11g Release 2 Enterprise Edition provides comprehensive features to easily manage the most demanding transaction processing, business intelligence, and content management applications.

Now you have easy access to information that you need to administer your Oracle Database with our downloadable Interactive Quick Reference. We have taken our traditional printed poster for Database Administrators, and created an electronic format packed with even more information.

Use this helpful reference as a cheat sheet for writing custom data dictionary scripts, locating views pertinent to a specific database component, and more.


Click here for the article.



Keywords: oracle 11g cheat sheet reference

Basics of SSIS and Creating Packages

SQL Server Integration Services (SSIS) – Part 1: Basics of SSIS and Creating Packages

In this article, we will see what a SQL Server Integration Services (SSIS) is; basics on what SSIS is used for, how to create an SSIS Package and how to debug the same.

Cick here for the article.