Oracle-Database on The Lars Breddemann Blog

Answers Pinboard

Mon, 19 Dec 2022 04:33:45 +0000

Apart from writing blog posts I have written answers to many questions on several Q&A sites like StackOverflow and SAP Community. Some of those answers received good feedback and/or the answer surprised me once I worked it out.

New year, same issues and some tips.

Tue, 08 Jan 2019 04:34:44 +0000

Most folks working with SQL DBs for a while will likely come to see how beginners in this area struggle with “declaritive code” and “tell the DB what you want not how to do it”

How to know "all these things"

Tue, 23 Oct 2018 22:29:06 +0000

There is one predominant reason why databases and database technology get a spot in the conversation of “the business”: performance.
Understanding system performance and coming up with ideas for improving it typically requires a form of end-to-end understanding with different levels of detailed insight on how a query from a client application is processed by SAP HANA.

How most BW performance support messages are solved

Fri, 21 Oct 2011 14:00:15 +0000

As the fourth quarter of the year started everybody seems to check the goals that had been set for this year and what has already been reached. Looking back on the messages I worked on I found a very clear pattern, when the message was about BW on Oracle and performance.

SAP Support case “FOR ALL ENTRIES disaster”

Fri, 12 Aug 2011 14:00:18 +0000

Last week a colleague from the WHM (data warehouse management) support team called me to get some assistance with a customer message he was processing.

The customer complained about short dumps with the infamous “TSV_TNEW_BLOCKS_NO_ROLL_MEMORY” error, which is basically the way an ABAP work process reports that it ran out of memory.

Partition count contest!

Tue, 19 Jul 2011 14:00:03 +0000

Let’s have a contest! #

One of my last blog posts started off a discussion (e.g. Bala posted his thought in a blog) about the importance of the partitioning feature for an SAP BW installation.

Short note on Line Item and High Cardinality dimensions

Fri, 15 Apr 2011 14:00:37 +0000

One of the quotes I like most I learned from Tom Kyte from Oracle. It’s one from Artemus Ward:

" It ain’t so much the things we don’t know that get us into trouble.
It’s the things you know that just ain’t so."

Question to SAP Support “Why is partition pruning not working in my BW on Oracle?”

Thu, 14 Apr 2011 14:00:01 +0000

Welcome to the problem

As usual understanding, the meaning and the scope of the question is key for the answer to this question, recently filed by a customer.

So, what is the customer complaining about? What does he mean by “partition pruning”?

“Things change for the better” or “How I enhanced the Oracle DBMS software”

Sun, 06 Mar 2011 14:00:49 +0000

Unexpected Behavior #

Last week during an Oracle workshop with my primary support colleagues in the GSC Ireland I came across something new (at least to me). This alone is not worthy of writing even a short note, as it happens all the time, but this time I really thought “Wow - so there was an impact…!”.

BW on Oracle: a performance hunch I see more and more often…

Wed, 19 Jan 2011 14:00:02 +0000

Ok, once again reproducing a problem takes a lot of (waiting-)time for the query to finish.

In the meantime I can also just write a super-short-blog post about a pretty common BW-on-Oracle performance hunch: Inappropriate database optimizer statistics. (yes, ‘inappropriate’ not ‘outdated’!)

A first (BW) issue…

Wed, 05 Jan 2011 14:00:47 +0000

In the second week working in BW support, I noticed that there was a problem reported by customers again and again. The customers complained about “database statistics update fails in process chains” or “brconnect run returns errors”. When checking the relevant log file entries for the actions there was always something like

New shores in sight…

Wed, 05 Jan 2011 14:00:13 +0000

As some of you might have noticed, I haven’t been too active in the DB/OS forums lately. This is because I moved on to a new support team and a new subject for me back in September. Yes, I took the giant leap and moved two offices to the right and am now running with the SAP BW support superheroes ;-)

Quick help for ORA-60 deadlock in BW systems

Tue, 28 Dec 2010 14:00:37 +0000

Today I re-learned a nice option to overcome ORA-60 problems with parallel data loading scenarios.

As most of you will know (from reading note “84348 - Oracle-Deadlocks, ORA-00060” or Michael Braunstein’s Blogs Chasing Oracle deadlocks part I - row level locks/ Chasing Oracle deadlocks part II - block level locks or some other resource) the problem here is caused by Oracle space management on block-level.

Wait a minute – why don’t we have that?

Mon, 25 Oct 2010 14:00:20 +0000

Of course, you look at the other players in your industry, right? You want to know what they are doing and how they do it, right? Maybe you could learn a thing or two as well.

Note 23345 revised – so what?

Thu, 02 Sep 2010 14:00:02 +0000

Last week I edited note 23345 and after some additional administrative tasks, it had been released yesterday with version 61. Why do I tell you this and why do I write a blog about this?

Oracle 11g training, Day #3 and #4 -FLASHBACK!

Sat, 03 Jul 2010 14:00:47 +0000

Hi folks!

Sorry for missing out the last days. The training had been tough, going out afterwards even tougher ;-) and as soon as the training was over, real-life support work set in again. Therefore all I can provide this time is a “flashback course topics” and here we go (in really no order):

Oracle 11g training, Day #2 – Savepoint!

Mon, 28 Jun 2010 14:00:32 +0000

Ok, second day Oracle 11g training - what have we done today?

Basically, two topics were addressed:

SECUREFILES and TABLE COMPRESSION

SECUREFILES #

Securefiles is (no not the new black) but the new LOB implementation for Oracle 11g.
The old LOB implementation had some drawbacks (although these usually didn’t affect SAP installations, given all recommendations had been implemented correctly) so Oracle re-wrote the whole LOB stuff from scratch.

Oracle 11g training, Day #1 – Savepoint!

Sun, 27 Jun 2010 14:00:53 +0000

Ok, management wisely decided to afford the Oracle 11g training for me and my primary support colleagues (thanks, thanks, thanks!), so this week we find ourselves sitting in a meeting room with Juergen Kirschner (yes, THE J. Kirschner) both as the victims and witnesses of his very own special way to make sure every attendee understands how Oracle works.

SAP Support Case “Why is Oracle writing out so many archivelogs in my BI recently?”

Tue, 15 Jun 2010 14:00:46 +0000

Sometimes support messages have to go a rather long way to finally get a solution.

The following problem came up in a support message recently and since neither the analysis steps nor the solution were obvious, I decided to make a blog out of it.

ORA-01007 in ABAP stack and what to do about it.

Sun, 25 Apr 2010 14:00:32 +0000

Recently a colleague asked me about how to analyze the following short dump:

 Database error text........: "ORA-01007: variable not in select list"
 Database error code........: 1007
 Triggering SQL statement...: "FETCH NEXT "
 Internal call code.........: "[DBDS/NEW DSQL]"

The error was raised within a standard SAP report with the following statement:

How to run a SAP landscape (or so)

Thu, 15 Apr 2010 14:00:51 +0000

It’s been quite a while since my last blog post and we’ve been pretty busy in the primary support department. A major change for us had been the introduction of “Enterprise Support” (ES) and the offer to customers to not only get support with technical issues but also to get free consulting to a certain degree.

A fix is not a solution!

Mon, 07 Sep 2009 14:00:15 +0000

Browsing through closed support messages while looking for a possible approach to a certain Oracle CBO problem I came across a quite problematic issue.

Some support colleagues sometimes seem to focus too much on removing the symptoms of a software defect rather than analysing it correctly and forwarding it to the development team so that they create a fix for it.
Of course, there is a reason behind this kind of message handling: the way the performance of support consultants is evaluated motivates them to focus on message closings.

‘Mind the gap…’ (#4 – reading query execution plans)

Sun, 10 May 2009 14:00:28 +0000

In my mini-series " Mind the gap" I will try to shed some light on where the little or big differences between MaxDB and Oracle databases are and what to keep in mind when working with them.

Now step back and start thinking!

Sat, 07 Mar 2009 14:00:41 +0000

The default reaction #

When working in support you get to see a lot of bugs, mistakes and errors.

That’s of course how things are going and there’s not much to whine about.

Understanding database performance for developers

Wed, 07 Jan 2009 14:00:42 +0000

Let’s face it - the really really bad performance issues are usually not due to some weird database bugs. Instead, a wrong system setup or the bad usage of the database prevents a high performance.

‘Mind the gap…’ (#3 – Backup/Restore – Part 2)

Sat, 20 Sep 2008 14:00:21 +0000

Before starting with this blog, I’ve to apologize for being so late with this issue of “Mind the Gap”. Since the last part of this series (‘Mind the gap…’ (#3 - Backup/Restore - Part 1)

Oracle – Popular Misconceptions: Tables without Segments

Tue, 19 Aug 2008 14:00:40 +0000

Perhaps some of you know the SAP note #825653 Oracle: Common errors in which Martin Frauendorfer collected many “myths” and all-time misconceptions about Oracle databases.

Here’s another one: " For all tables in an Oracle database, there is a segment in DBA_SEGMENTS."

Questions to SAP Support: “How to generate a SQL Script via SQL on MaxDB?”

Sun, 10 Aug 2008 14:00:15 +0000

A customer was facing a problem when generating SQL scripts by using SQL. As this is a common habit in the Oracle world he tried to apply it to his MaxDB.

Oracle Patchset 10.2.0.4 is released – finally.

Tue, 15 Jul 2008 14:00:30 +0000

So after a loooong wait time, it’s finally available to be downloaded by the SAP customers. What a relieve!

Over is the time where tens of patches needed to be installed to run the database on a supported patch level and to avoid trapping into a myriad of nasty optimizer bugs that could render the system unusable.

Oracle Patchset 10.2.0.4 – neat DBMS_STATS enhancement

Thu, 10 Jul 2008 14:00:40 +0000

With release 11g Oracle made many feature enhancements to the database and some of them are now down-ported into the soon-to-be-released patchset 10.2.0.4.

One new feature that I just found by ‘accident’ is the easy comparison of CBO statistics for tables for different points in time.

‘Mind the gap…’ (#3 – Backup/Restore – Part 1)

Mon, 23 Jun 2008 14:00:33 +0000

In my mini-series " Mind the gap" I will try to shed some light on where the little or big differences between MaxDB and Oracle databases are and what to keep in mind when working with them.

Questions to SAP Support: Is ODBC access to the database a good idea?

Sun, 18 May 2008 14:00:26 +0000

Today I got a support message to work on that I believe is of rather broad interest.

Therefore, I decided to “forward” it to the SDN so that all community members can benefit from it.

Some hints to make handling of oracle datablock corruptions more efficient

Sun, 13 Apr 2008 14:00:24 +0000

When faced with error messages like ORA-1578 Oracle database users just got the task to handle a database block corruption. I’ve already written about this topic before and today I’d like to share some tips and tricks to get this task done quicker.

Not my fault – whose then?

Sun, 02 Mar 2008 14:00:04 +0000

I have written some lines about database corruption and the ways to handle them in the past.

The bottom line of everything I wrote (including support notes, SDN blogs, and replies in customer messages) has always been:

How to take care of index corruptions in primary key indexes.

Wed, 20 Feb 2008 14:00:36 +0000

Primary key constraints in Oracle are enforced by using an index. The index does not need to be a unique index, but it has to be possible for the database to look into it and find out if a given key is already present or not.

Point-in-time-recovery considered harmful

Tue, 12 Feb 2008 14:00:12 +0000

When I first got in contact to the possibility to bring back a database to the state it had, when a backup was taken I was not too much impressed.

‘Mind the gap…’ (#2 – Data storage)

Tue, 22 Jan 2008 14:00:08 +0000

More and more customers decide to use MaxDB and with that, the number of customers asking for a comprehensive list of differences or a comparison increases as well.

In my mini-series " Mind the gap" I will try to shed some light on where the little or big differences between MaxDB and Oracle databases are and what to keep in mind when working with them.

Parameters. parameters, parameters … the mantra of db performance troubleshooting

Tue, 15 Jan 2008 14:00:54 +0000

Database performance problems are one of the more complex tasks that brighten the day of a database software supporter.

Each and every single day since I’m doing support for Oracle and MaxDB there had been messages, in which customers complained about bad database performance.

Fragmentation in Oracle LMTS tablespace!

Sun, 09 Dec 2007 14:00:44 +0000

Recently two customers reported independent from each other that their LMTS/ASSM tablespace shows much “fragmentation”. What they meant was, that the repeatedly got errors like:

ORA-1688: unable to extend table SAPWBP./BIC/B0000256000
partition /BIC/B00002560000000000092 by 128 in
tablespace PSAPBWP

‘Mind the gap …’

Wed, 05 Dec 2007 14:00:54 +0000

More and more customers decide to use MaxDB and with that, the number of customers asking for a comprehensive list of differences or a comparison increases as well.

In my mini-series " Mind the gap" I will try to shed some light on where the little or big differences between MaxDB and Oracle databases are and what to keep in mind when working with them.

A dumb mistake … again and again …

Sat, 20 Oct 2007 14:00:57 +0000

Not to long ago I was analyzing a performance issue on a customers system.
In the course of this I needed to see some aggregated data, so I opened a transaction where I can put in custom sql and ran it without removing the number of lines to be returned limitation.

Blogging standard…

Mon, 03 Sep 2007 14:00:47 +0000

As it seems it has become popular to give his readers a glimpse on the bookshelf like it has been practised by many before me (see here , here or here) I will also reveal what is “behind” me. Literally the books are place on top of a locker behind me…

Anybody know OCOPY?

Tue, 21 Aug 2007 14:00:27 +0000

For more than ten years now SAP has provided a unified way to administer the Oracle database via the BR*Tools (Backup/Recovery).

Wether you like the tools or not (if you read We all hate the BR*TOOLS, don’t we? about it, perhabs you’ll at least get used to them) they are used in every SAP installations that runs on Oracle.

Verification Speed…

Tue, 07 Aug 2007 14:00:24 +0000

I recently had to handle a case where a big and important system was rendered unusable by database corruptions. Due to some bad luck and faulty procedures, there was no good backup available. Even worse: the corruption had been detected via transaction abort in the SAP.

Get me my data back! QUICK!

Sat, 04 Aug 2007 14:00:58 +0000

Ok, so your data is gone. You/the report you ran executed a DELETE statement and performed a COMMIT. What to do now?

It is the productive system. So there is no place to discuss that it may have been a great idea to test the report first here. What’s needed is a solution.

Things that happen in support messages that I don’t like… Part II

Mon, 25 Jun 2007 14:00:53 +0000

++ 07.03.2011 ++ UPDATE ++ UPDATE ++ UPDATE ++

The mentioned error message had been improved with Oracle 10.2.0.5 (“Things change for the better” or “How I enhanced the Oracle DBMS software”). Thus, the content of this blog post is only valid for older versions of the Oracle database software.

We all hate the BR*TOOLS, don't we?

Sun, 17 Jun 2007 14:00:24 +0000

You won’t believe how often we in support get asked about if SAPDBA is available for use with Oracle 10g. Even more customers tell us, how they dislike the BRTOOLS and want the SAPDBA back.

Suck that data out! Connect from Oracle to MaxDB

Wed, 04 Apr 2007 14:00:39 +0000

In one of my former jobs, I had been in charge of a rather small project tracking tool for the engineering department. As buying equipment and ordering services were two of the duties of these engineers these tasks had also been modelled into the tool. Of course, the orders had to be transported into the central financial application. Therefore a meeting with the consultants for that ERP system (no, not ours… they had got the wrong one there… ;-)) was set up.

I can repair your corrupt database!

Tue, 20 Mar 2007 14:00:36 +0000

Years in database support, endless experience and access to a whole bunch of internal notes and guidelines have enabled me (as well as all DB Supporters in SAP) to repair corrupt databases. This obscure technique is of course only available to the initiated and should be used with care. But when applied it works just like a wand: puff – the database is OK again.

A classic in disguise…

Tue, 27 Feb 2007 14:00:59 +0000

In my last blog entry “Starting off with a classic…” I presented a classic issue that may appear when the database software is upgraded.

The problem was that sometimes result sets are delivered to the user in a sorted manner even if no ORDER BY was specified. If the user/developer relies on this order it may be a cause for application errors, as the database don’t guarantee the order if ORDER BY is omitted.

Starting off with a classic…

Tue, 13 Feb 2007 14:00:09 +0000

Every now and then a new version of the database software comes along. Upgrades of Oracle or MaxDB often include major improvements concerning stability and performance. These improvements can and should be read as: things run different now.