Oracle

pete.sharman's picture

Enterprise Manager Silent Installation

Introduction

This is another post in my series on silent installations using response files. In previous posts, I covered silent installations for the Grid Infrastructure, RDBMS, post installation configuration steps, and creating the listener and database using response files. In this post, I’ll cover installing Enterprise Manager using a response file.

pete.sharman's picture

Creating the Listener and Database in Silent Mode

Introduction

In previous posts, I talked about a customer where I needed to do a silent installation of the Grid Infrastructure and Database, as well as the post installation configuration steps. For that particular customer, I didn’t create an empty database but used RMAN to duplicate the existing database. But what about if you want to create a new listener and database in silent mode as well? That’s what this post covers.

fritshoogland's picture

A look into oracle redo: index and overview

I gotten some requests to provide an overview of the redo series of blogposts I am currently running. Here it is:

kevinclosson's picture

SLOB Can Now Be Downloaded From GitHub.

This is a quick blog entry to announce that the SLOB distribution will no longer be downloadable from Syncplicity. Based on user feedback I have switched to making the kit available on GitHub. I’ve updated the LICENSE.txt file to reflect this distribution locale as authorized and the latest SLOB version is 2.4.2.1.

Please visit kevinclosson.net/slob for more information.

fritshoogland's picture

A look into oracle redo, part 10: commit_wait and commit_logging

The redo series would not be complete without writing about changing the behaviour of commit. There are two ways to change commit behaviour:

1. Changing waiting for the logwriter to get notified that the generated redo is persisted. The default is ‘wait’. This can be set to ‘nowait’.
2. Changing the way the logwriter handles generated redo. The default is ‘immediate’. This can be set to ‘batch’.

There are actually three ways these changes can be made:
1. As argument of the commit statement: ‘commit’ can be written as ‘commit write wait immediate’ (statement level).
2. As a system level setting. By omitting an explicit commit mode when executing the commit command, the setting as set with the parameters commit_wait (default: wait) and commit_logging (default: immediate).
3. As a session level setting. By omitting an explicit commit mode, but by setting either commit_wait or commit_logging it overrides the settings at the system level.

Franck Pachot's picture

Covering indexes in Oracle, and branch size

A covering index is an index that contains all the columns required by your query, so that you don’t have to do a TABLE ACCESS BY INDEX ROWID, which is the major cost of an index range scan. You don’t need any special feature to do that in Oracle. Just add the required columns at the end of the index. In the execution plan you will see the columns used as index keys for the range scan displayed in ‘access’ predicates, and the further filtering done on the remaining columns with ‘filter’ predicates. The ‘projection’ shows the columns that are returned in the rowset result.
However you may have seen that SQL Server has a special ‘INCLUDING’ keyword to separate those non-key columns added only for filtering or projection but not for access. What does it bring that Oracle doesn’t have?

Jonathan Lewis's picture

exp catch

No-one should be using exp/imp to export and import data any more, they should be using the datapump equivalents expdp/impdp – but if you’re on an older (pre-12c) version of Oracle and still using exp/imp to do things like moving tables with their production statistics over to test systems then be careful that you don’t fall into an obsolescence trap when you finally upgrade to 12c (or Oracle 18).

exp/imp will mess up some of your histograms if you’re still using them to move tables/statistics in 12c.

fritshoogland's picture

A look into oracle redo, part 9a: commit – concurrency considerations

During the investigations of my previous blogpost about what happens during a commit and when the data becomes available, I used breaks in gdb (GNU debugger) at various places of the execution of an insert and a commit to see what is visible for other sessions during the various stages of execution of the commit.

However, I did find something else, which is very logical, but is easily overlooked: at certain moments access to the table is blocked/serialised in order to let a session make changes to blocks belonging to the table, or peripheral blocks like undo, for the sake of consistency. These are changes made at the physical layer of an Oracle segment, the logical model of Oracle says that writers don’t block readers.

Jonathan Lewis's picture

SQL Monitor

I’ve mentioned the SQL Monitor report from time to time as a very useful way of reviewing execution plans – the feature is automatically enabled by parallel execution and by queries that are expected to take more than a few seconds to complete, and the inherent overheads of monitoring are less than the impact of enabling the rowsource execution statistics that allow you to use the ‘allstats’ format of dbms_xplan.display_cursor() to get detailed execution information for a query. The drawback to the SQL Monitor feature is that it doesn’t report predicate information.

dbakevlar's picture

Lady Coders Conference, Denver 2017

This weekend I’m not going to have to say, “No, this is not my husband’s code” for a change.

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