Re: Your opinion please :) explanation of my point of view
- From: "Juan Cachito Reyes Pacheco" <jreyes@xxxxxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 26 Feb 2004 15:37:19 -0400
Don worry I accept my reality I'm a stupid, so nothing can makes me worst
than what I'm am.
doing this kind of papers, specially if you can get the mentoring from tom
kyte or other person with more experience, to check the papers allows you to
learn more.
----- Original Message -----
From: <Kip.Bryant@xxxxxxxxxx>
To: <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, February 26, 2004 1:51 PM
Subject: RE: Your opinion please :) explanation of my point of view
> Hi Juan,
>
> I have to agree with Don's point of view. I think it took a lot of
courage
> to open yourself to criticism like this. I think a lot of us would
probably
> like a cookbook to follow but don't expect to ever find it ("it depends"
> being the "answer" far too often). I'm strictly a "school of hard knocks"
> DBA and what little I know I've learned the hard way. I've found that off
> and on I've had to just "put a stake in the ground" regarding where to
start
> the tuning process for DBA's who report to me just to stir things up. I
> don't expect them to agree with me (it's not about "my way or the
highway")
> but I do expect them to work methodically and put assumptions to the test.
>
> I guess all this makes me an "iggorant PHB"...
>
> Kip
>
> |Let me chime in my 2 cents here. I printed and reviewed your document
and
> |noted a few things that I will discuss with my co-DBA. I liked the
article
> |because in a short document you summarized a number of things that were
> |important in your experience. Some of them seem relevent to what I am
doing
> |so I will spend some time to check them out. As far as you posting it, I
> |personally try to pass on tips and tricks as I learn them and I
appreciate
> |that behavior in others.
>
> |As what we do is often a competitive business I have not often
encountered
> |people personally who freely give away valuable information which they
> |struggled to gain. The top-level professionals who answer questions here
are
> |doing 'pro-bono' work for which I am grateful. It's the same advice that
> |people pay them for. In real life I'm beginning to think it's pretty
> |remarkable when somebody says, "Come on over, I'll show you how it
works."
> |The lists are very valuable to me. I'm not in a position to travel to
> |conferences, seminars, and attend workshops to improve my skills and
don't
> |work for an employer who values (or pays for) this kind of stuff.
>
> |I think you are pretty brave for posting your 'baby.' I have been
holding
> |my breath because I thought it might provoke a lot of disagreement or
> |outright disparagement of your effort. At this point I don't know enough
to
> |say if what you have posted is altogether technically accurate but
> |I always check 'free' advice anyway.
>
> |You are correct, I think, in the way some people approach books. I am
> |struggling to understand some of the features in Oracle and have quite an
> |extensive library of Oracle books. Most of them I haven't read cover to
> |cover. I tend to read them a chapter, or even a paragraph at a time
> |depending on what my issue is. I download a lot of papers, "how-too's",
> |tips and tricks.
>
> |The value of the books on the market to me is to answer the bigger
questions
> |of why and when (or how much) instead of what and how. Its always helpful
to
> |me when somebody says, "On an OLTP system is should be X and on a DS
system
> |it should be Y." It gives me a point at which to start looking. The
oracle
> |books usually provide the exact syntax describing how a feature or
function
> |is implemented but don't answer the question, for me, "Is this an
appropriate
> |thing to do in a small datawarehouse environment..." I know, "It
depends."
>
> |So, thanks for posting!
>
> |Don Freeman
> |Oracle 9i OCP
>
>
>
> |-----Original Message-----
> |From: oracle-l-bounce@xxxxxxxxxxxxx
> |[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Juan Cachito Reyes
> |Pacheco
> |Sent: Thursday, February 26, 2004 9:05 AM
> |To: oracle-l@xxxxxxxxxxxxx
> |Subject: Re: Your opinion please :) explanation of my point of view
>
>
> |Thanks for your opinion.
>
> |Now if you think "kill lazy and bad dbas", I can't do too much about
this.
> |I think every one likes his job, and a paper like this can wake up his
> |interest in reading to a bad dba, and help to introduce a good dba who is
> |starting to read.
>
> |Yes this is true, the idea is to introduce to all this people to tunning.
> |I think if every one would read the Oracle document as they should, 50%
of
> |the book would be useless. If you take randomly a good tunning book and
seek
> |the same in Oracle tunning documentation, 90% is in the Oracle
> |documentation, at least!!
>
> |But even when you read and got an OCP, you need some guide about what
> |you should check first, better and simple explanations, for example about
> |CURSOR_SPACE_FOR_TIME there is not a clear explanation about when to
use
> |them.
> |You need a guide that introduce to tunning. to make you understand what
is
> |important and what is the most important.
>
>
> |----- Original Message -----
> |From: "Igor Neyman" <ineyman@xxxxxxxxxxxxxx>
> |To: <oracle-l@xxxxxxxxxxxxx>
> |Sent: Thursday, February 26, 2004 9:53 AM
> |Subject: RE: Your opinion please :) explanation of my point of view
>
>
> |> If "newbie DBA" doesn't like to read, he/she'd better be in different
> |> business...
> |>
> |> Igor Neyman, OCP DBA
> |> ineyman@xxxxxxxxxxxxxx
> |>
> |>
> |>
> |> -----Original Message-----
> |> From: oracle-l-bounce@xxxxxxxxxxxxx
> |> [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Juan Cachito Reyes
> |> Pacheco
> |> Sent: Thursday, February 26, 2004 7:48 AM
> |> To: oracle-l@xxxxxxxxxxxxx
> |> Subject: Re: Your opinion please :) explanation of my point of view
> |>
> |> Thanks for your opinion, tellme what do you think, about this.
> |>
> |> Point by point
> |> 1) About the set of checklist, I agree, but the goal is to introduce to
> |> tunning, in the market there are several excellent tunning books,
> |> (including
> |> the documentation where is almost all), but people don't read them.
> |> I decided something short, a checklist explaining very very briefly
what
> |> you
> |> can tune, the most important, the first steps, for newbies, now if you
> |> want
> |> more information, you can go to documentation.
> |> For example about statistics, I had two pages of a BRIEF explanation,
> |> but no
> |> body is going to read all that, because instead of 8 pages it will be
60
> |> pages, it will be preferable to read the documentation, but several
> |> questions you should had read some moment, shows people don't like to
> |> read,
> |> people who never took the time to read neither concept manual, so I
> |> decided
> |> to explain the most important, briefly.
> |>
> |> For example, about statistics, the explanation is very short
> |> 1.1 Statistics
> |> The optimizer works based on statistics, if they are old, or inaccurate
> |> you'
> |> ll get a wrong execution plan.
> |>
> |> You must recalculate statistics every time an important change had
> |> happened
> |> in it:
> |>
> |> . Periodically, based on normal changes in a database
> |>
> |> . After importing a big amount of data
> |>
> |> . When distinct values in primary columns change
> |>
> |> . After creating indexes and table
> |>
> |> 1.1.1 Test database
> |> If this is the first time you get statistics, you must remember some
> |> database has fixed execution plans, or any other consideration can
cause
> |> a
> |> statistics recalculation cause serious problems, as general rule do it
> |> first
> |> in ha test database, before doing in the production database.
> |>
> |> 1.1.2 Recalculating statistics
> |> Oracle recommends DON'T USE ANALYZE to gather statistics, the package
> |> USE
> |> DBMS_STATS, this package get more statistics, specially for new
> |> features.
> |>
> |> Don't execute DBMS_STATS on SYS schema.
> |>
> |> This command has dozens of options, like parallel execution, etc. etc.
> |> you
> |> must read them.
> |>
> |> To gather all statistics
> |>
> |> EXEC DBMS_STATS.GATHER_DATABASE_STATS();
> |>
> |> To gather statistics in a schema:
> |>
> |> EXEC DBMS_UTILITY.ANALYZE_SCHEMA('ADM','COMPUTE');
> |>
> |> To gather statistics in a schema, more precisely, the one we use,
> |> because
> |> our database is a small database:
> |>
> |> EXEC DBMS_STATS.GATHER_SCHEMA_STATS( OWNNAME=>'ADM',
> |> ESTIMATE_PERCENT=>100,METHOD_OPT=>'FOR ALL COLUMNS SIZE SKEWONLY');
> |>
> |>
> |> What you understand after this is
> |> -optimizer needs statistics
> |> -changing statistics can cause you problems, first use a test database
> |> -use dbms_stats not analyze
> |> That's all, and I think this is the basic thing you have to understand,
> |> I
> |> know dbas (not ocps) who don't know that simple fact," they have to
> |> recalculate statistics periodically". Because their database are small
> |> and
> |> comparing with sql server it takes a similar amount of time to process,
> |> they
> |> don't see it as a problem or a mistake.
> |>
> |> 2)About the optimizer_index_caching I read a lot, because we have a
> |> problem,
> |> we solved setting this parameter, about this parameter I say:
> |> "This parameter sets the possibility to find blocks accessed through an
> |> index in memory.
> |>
> |> Default value is 0, 0 means that no one block accessed through index
> |> will be
> |> found in memory THIS IS FALSE. A value of 90% is advisable"
> |>
> |> Could you giveme an example how could I explain it better.
> |>
> |> 3) About
> |> "but pays no attention to individual business processes (or indeed
> |> development modules)."
> |> Could you giveme an example what for example I could add ,
> |> But I'm not explaining in this paper things like ORDERED hint, because
> |> for a
> |> newbie, first he have to do the basic things, once he had done all of
> |> them,
> |> if he continue having problems, then the correct way is to read a more
> |> serious document.
> |> Because if you give advanced points, he will try them first, is like
> |> special
> |> hints, I think you heard about them, they are not in documentation
> |> because
> |> it could cause problems to new dbas, because they could try to use them
> |> to
> |> solve problem, when the reality is they can be used only exceptionally.
> |> but
> |> there are book out there once you get the enough experience you could
> |> buy
> |> them.
> |>
> |> Now if you want another point of view, or a better idea about this, you
> |> are
> |> welcome :).
> |>
> |> ----- Original Message -----
> |> From: "Niall Litchfield" <n-litchfield@xxxxxxxxxxxxxxxxxxxxxxx>
> |> To: <oracle-l@xxxxxxxxxxxxx>
> |> Sent: Wednesday, February 25, 2004 7:29 PM
> |> Subject: RE: Your opinion please :)
> |>
> |>
> |> hi
> |>
> |> I have to admit I don't like the paper much. it looks like a set of
> |> checklists with little or no reasoning behind them. for example the
> |> suggestions on optimizer_index_caching have just start at x and work
> |> from
> |> there. where x is apparently an arbitrary number.
> |>
> |> my deeper problem is that the article seems to suggest that it is
> |> possible
> |> to tune systems but pays no attention to individual business processes
> |> (or
> |> indeed development modules). I disagree, the logical unit for tuning is
> |> the
> |> thing that runs badly, the logical time to do it is when writing the
> |> code
> |> for it. setting db wide parameters is sticking plaster on the titanic.
> |> perhaps.
> |>
> |> Niall
> |>
> |> -----Original Message-----
> |> From: AC.GWIA.oracle-l@xxxxxxxxxxxxx
> |> [mailto:AC.GWIA.oracle-l@xxxxxxxxxxxxx]
> |> Sent: Wed 25/02/2004 18:41
> |> To: jreyes@xxxxxxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
> |> Cc:
> |> Subject: Your opinion please :)
> |>
> |>
> |>
> |> Hi I took sometime to do a paper, to help newbies in tunning, this is
> |> not to
> |> become they expert, but at least they know there are statistics in the
> |> database
> |>
> |> If you get some time, and give some opinion about it, like the previous
> |> mistake I did with IN function, you are welcome.
> |> Or something important I'm missing (for newbies dbas of course).
> |> Did you remember the first time you had a tunning problem, before the
> |> ocp,
> |> and you didn't knew where to start to check,and lost long time,
changing
> |> some database parameter to see if that improved something, the idea is
> |> to
> |> save that step.
> |>
> |>
> |> http://www.geocities.com/juancarlosreyesp/101basictunningonOracle9i.pdf
> |>
> |> Juan Carlos Reyes Pacheco
> |> OCP
> |>
> |>
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