Просторы интернета

19 Февраль 2015
Earlier
Ср, Окт 16, 2019

Originally drafted July 2018

“How do you find out what the clustering_factor of an index would be without first creating the index ?”

I'm not sure this is really a question worth asking or answering[1], but since someone asked it (and given the draft date I have no idea who, where, when [...]

Source: jonathanlewis.wordpress.com
Пт, Окт 11, 2019

Here's an odd, and unpleasant, detail about querying v$session in the “most obvious” way. (And if you were wondering what made me resurrect a posting on “my ssession id” a couple of days ago, this is the reason). Specifically if you want to select some information for your own [...]

Source: jonathanlewis.wordpress.com
Ср, Окт 09, 2019

Here's a funny little detail that I don't think I've noticed before – needing only a simple demo script:

rem rem Script: cursor_sharing_oddity.sql rem Author: Jonathan Lewis rem [...]
Source: jonathanlewis.wordpress.com
Ср, Окт 09, 2019

Here's a little note that's been hanging around as a draft for more than eight years according to the OTN (as it was) posting that prompted me to start writing it. At the time there were still plenty of people using Oracle 10g. so the question didn't seem entirely [...]

Source: jonathanlewis.wordpress.com
Пн, Окт 07, 2019

There are two questions about temporary space that appear fairly regularly on the various Oracle forums. One is of the form:

From time to time my temporary tablespace grows enormously (and has to be shrunk), how do I find what's making this happen?

The other follows the more basic pattern:

My process sometimes [...]

Source: jonathanlewis.wordpress.com
Пт, Окт 04, 2019

This is just a list of the notes I've written about the opt_estimate() hint.

opt_estimate – using the hint to affect index calculations: index_scan and index_filter opt_estimate 2 – applying the hint to nested loop joins, options: nlj_index_scan and nlj_index_filter opt_estimate 3 – a couple of little-known options for the [...]
Source: jonathanlewis.wordpress.com
Чт, Окт 03, 2019

A recent blog note by Martin Berger about reading trace files in 12.2 poped up in my twitter timeline yesterday and reminded me of a script I wrote a whle ago to create a simple view I could query to read the tracefile generated by the current session while [...]

Source: jonathanlewis.wordpress.com
Ср, Окт 02, 2019

At the recent Trivadis Performance Days in Zurich, Chris Antognini answered a question that had been bugging me for some time. Why would Oracle want to set the default value of _cursor_obsolete_threshold to a value like 8192 in 12.2 ?

In 11.2.0.3 the parameter was introduced with the default value 100; [...]

Source: jonathanlewis.wordpress.com
Сб, Сен 28, 2019

At the Trivadis Performance Days 2019 I did a presentation on using execution plans to understand what a query was doing. One of the examples I showed was a plan from an Exadata system (using 11.2.0.4) that needed to go faster. The plan was from the SQL Monitor report and [...]

Source: jonathanlewis.wordpress.com
Пн, Сен 16, 2019

Here's a quick “how to”.

If you want to update a column in table A with a column value from table B, then there's a simple way to check if the required result can be achieved through an updatable join view.

Step 1: write a query that joins table A to table [...]

Source: jonathanlewis.wordpress.com
Пн, Сен 16, 2019

A peripheral question in a recent comment (made in response to me asking whether a loop had been written with a sleep time of 1/100th or 1/1000th of a second) asked “How do you sleep for 1/1000th of a second in pure PL/SQL?”

The answer starts with “How pure is pure [...]

Source: jonathanlewis.wordpress.com
Сб, Сен 14, 2019

Use ORAMDS for all XSD / WSDL files on the project (oramds:...) in all composite.xml and wrappers in location tag. Doing that you will guarantee that you can deploy anywhere even when you don't have remote access to a environment.

Also, in this way it is not necessary to change [...]
Source: oracleanil.blogspot.ru
Сб, Сен 14, 2019
Background Transaction context between different BPEL services are controlled by mainly two properties/attributes. Those are Delivery and Transaction attributes.
Details Case 1 : If BPEL Process is Async or one-way process then, Delivery policy attribute can have three values. Those are 1)- async.persit 2)- async.cache 3)- sync
meaning: - async.persit: Delivery [...]
Source: oracleanil.blogspot.ru
Пт, Сен 13, 2019

Bobby Durrett recently published a note about estimating the volume of non-logged blocks written by an instance with the aim of getting some idea of the extra redo that would be generated if a database were switched to “force logging”.

Since my most recent blog notes have included various extracts [...]

Source: jonathanlewis.wordpress.com
Пт, Сен 13, 2019

At the UKOUG TechFest 2019 event in Brighton this year I'll be chairing the CBO Panel session on Monday 2nd December at noon. The panellists will be Maria Colgan, Nigel Bayliss, Christian Antognini and Richard Foote.

It will be possible to propose questions on the day – written or spoken, but [...]

Source: jonathanlewis.wordpress.com
Пт, Сен 13, 2019
Первоначально проблема представлялась просто как запрос с нестабильным временем выполнения на Read-Only Standby , при более внимательном рассмотрении выяснилось, что запрос не просто небыстро выполняется, а периодически-трагически гибнет: с сообщениями в alert.log: LMHB trace file: *) обращает на себя внимание, что ожидание LGWR library cache lock не превышает max=5.500000 sec [...]
Source: iusoltsev.wordpress.com
Вт, Сен 10, 2019

Somewhere I think I've published a note about an anomaly that's been bugging me since at least Oracle 10g – but if it is somewhere on the Internet it's hiding itself very well and I can't find it, though I have managed to find a few scripts on my laptop [...]

Source: jonathanlewis.wordpress.com
Пн, Сен 09, 2019

Upgrades cause surprises – here's a pair of results from a model that I constructed more than 15 years ago, and ran today on 12.2, then modified and ran again, then ran on 11.2.0.4, then on 12.1.0.2. It's very simple, I just create a table, gather stats, then update every [...]

Source: jonathanlewis.wordpress.com
Ср, Сен 04, 2019
Аналогично описанному для версий 11-12.1 — JPPD в присутствии удалённой таблицы и View Merging — и справедливому до 19.3 включительно (тесткейс там есть — можно проверить) наблюдению, CBO версии 12.2 также может полностью блокировать применение Join Predicate Push Down с резолюцией JPPD bypassed: Remote table referenced — в этот раз [...]
Source: iusoltsev.wordpress.com
Вт, Авг 27, 2019

This is another of the blog notes that have been sitting around for several years – in this case since May 2014, based on a script I wrote a year earlier. It makes an important point about “inconsistency” of timing in the way that Oracle records statistics of work done. [...]

Source: jonathanlewis.wordpress.com
Пн, Авг 26, 2019

A recent thread on the Oracle Developer Community starts with the statement that a query is taking a very long time (with the question “how do I make it go faster?” implied rather than asked). It's 12.1.0.2 (not that that's particularly relevant to this blog note), and we have [...]

Source: jonathanlewis.wordpress.com
Пт, Авг 23, 2019

I've got a number of examples of clever little tricks the optimizer can do to transform your SQL before starting in on the arithmetic of optimisation. I was prompted to publish this one by a recent thread on ODC. It's worth taking note of these tricks when you spot one [...]

Source: jonathanlewis.wordpress.com
Ср, Авг 21, 2019

This note is a short follow-up to a note I wrote some time ago about validating foreign key constraints where I examined the type of SQL Oracle generates internally to do the validation between parent and child tables. In that article I suggested (before testing) that you could [...]

Source: jonathanlewis.wordpress.com
Ср, Авг 21, 2019
In this article we will see how to stop a running SOA composite process. It is normal to stop from Enterprise Manager (http: // {hostname}: {port number} / em), but I thought this was not "user friendly".

How can I use the API to identify the SOA composite instance ID? [...]
Source: oracleanil.blogspot.ru
Ср, Авг 21, 2019
This content has already been introduced in many entries, but I will keep it personally as many people still ask me.
Log in to Enterprise Manager Fusion Middleware Control.
http: // {host name or IP}: {port number} / em Open the SOA folder, right click on the soa_infra (soa_server1) folder and [...]
Source: oracleanil.blogspot.ru
Ср, Авг 21, 2019
Two new Oracle Service Bus samples have been registered on the Oracle Technology Network site. The first sample project is osb-205-SimpleREST. This demonstrates how to fully implement a REST service in OSB. “Complete” means that the following HTTP methods are implemented using OSB.
GET POST PUT DELETE HEAD OPTIONS Another REST sample is now over. This is [...]
Source: oracleanil.blogspot.ru
Ср, Авг 21, 2019
Error

When starting the SOA server, the following exception may occur.




log is opened. All server side log events will be written to this file.> cation for user weblogic denied weblogic.security.SecurityInitializationException: Authentication for user weblogic denied at weblogic.security.service.CommonSecurityServiceManagerDelegateImpl.doBootAuthorization(CommonSecurityServiceM at weblogic.security.service.CommonSecurityServiceManagerDelegateImpl.initialize(CommonSecurityServiceManagerDel [...]
Source: oracleanil.blogspot.ru
Ср, Авг 21, 2019

I faced the problem that it took a long time to execute select in DB Adapter. There were three tables that contained a large amount of data and contained many columns, and these tables were being handled by the DB Adapter.

The database side configured a primary key / foreign key [...]
Source: oracleanil.blogspot.ru
Вт, Авг 20, 2019

It's strange how one thing leads to another when you're trying to check some silly little detail. This morning I wanted to find a note I'd written about the merge command and “stable sets”, and got to a draft about updatable join views that I'd started in 2016 in [...]

Source: jonathanlewis.wordpress.com
Ср, Авг 14, 2019

What happens when you execute dbms_stats.gather_system_stats() with the ‘Exadata' option ?

Here's what my system stats look like (12.2.0.1 test results) after doing so. (The code to generate the two different versions is at the end of the note).

System Stats ============ Status: COMPLETED Timed: 13-Aug-2019 15:00:00 - 13-Aug-2019 15:00:00 -------------------------------------------------- CPUSPEED [...]
Source: jonathanlewis.wordpress.com
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