DBA Blogs

During Extract Upgrade “extract not ready to be upgraded because recovery SCN” returned

VitalSoftTech - Mon, 2019-06-24 23:59

During the upgrade of a Classical extract process to Integrated extract I get the "extract not ready to be upgraded because recovery SCN". How do I work around this?

The post During Extract Upgrade “extract not ready to be upgraded because recovery SCN” returned appeared first on VitalSoftTech.

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Contextual Targeting vs Behavioral Targeting

VitalSoftTech - Tue, 2019-06-18 12:19

Let’s suppose these are the olden times and you have to advertise for a new circus in town. Do you paste the posters on the walls of places of entertainment like a movie theater, a bar, horse racing tracks, or a casino? Or do you spend a little time about town and look around for […]

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Categories: DBA Blogs

Looking for errors in the Clusterware and RAC logs? Dash through using the TFA Collector

VitalSoftTech - Mon, 2019-06-17 09:49

The Oracle Trace File analyzer utility has been originally developed by Oracle to help collect and bundle up all the pertinent diagnostic data in the log files, tracefiles, os statistics, etc.. This is a very common task when Oracle Support engineers request this information to help troubleshoot issues and bugs.

The post Looking for errors in the Clusterware and RAC logs? Dash through using the TFA Collector appeared first on VitalSoftTech.

Categories: DBA Blogs

Batch Query Reduced from 12 hours to 45 Minutes

Bobby Durrett's DBA Blog - Thu, 2019-06-13 16:38

I was asked to look at a batch SQL query that ran for 12 hours on June 4th. I messed around with some other ideas and then went back to my best method for tuning long running batch queries. I ripped it apart. My code ran in 45 minutes.

This only works if you have the code and can change it. I work with a lot of PL/SQL code in Unix shell scripts running SQL*Plus. If someone comes to me with a SQL statement in this kind of code, I do not tear my hair out trying to tune it in some clever way. Also, this assumes that I cannot use a SQL Profile. SQL Profiles are my first choice for production performance problems. But for long running SQL that I have full control over and cannot use a SQL Profile I tear it apart.

Ripping or tearing a SQL statement apart means that I become the optimizer. In this case the problem query joined 5 tables. It summarized 3 months of data from a large fact table and the other 4 tables were joined together with the fact table. I replaced the one query with 5 queries each of which saved their results in a table. This first query summarized the fact table and the remaining four joined one more table to the current results. Something like this:

  • Summarize 3 months of fact table data – table 1
  • Join table 2 on surrogate key
  • Join table 3 on surrogate key
  • Join table 4 on natural keys
  • Join table 5 on natural keys

So, I created 5 tables each of which held the results of the previous joins. I dropped the tables as I was done with them to save space.

I have a feeling that I could use some clever hint to force the join order and access methods to match my 5 queries. But my time is short and this works, so I did not bother trying. When you have a query that runs for 12 hours it’s not very motivating to try various hints to get it to run faster. How long do you wait for each try before you give up? Working on one table at a time is nice. I have had this approach work for me time and time again. It is almost a mechanical process without a lot of painful thinking.

Anyway, I pass this on to the internet. People may think that breaking up a 5 table join into 5 queries is ugly, but it works.

Bobby

Categories: DBA Blogs

Another On Call Week, Another SQL Profile (or two)

Bobby Durrett's DBA Blog - Thu, 2019-06-13 16:14

I was on call again last week and Sunday night I used a SQL Profile to fix a performance problem. We rolled out some updates Saturday night and the modified query ran fine in some cases, but others ran for hours. When I got on there were 60 sessions running the bad plan and the load on the system was very high. It took me a while to identify the good plan, but then I found it, put in a SQL Profile, killed the 60 bad sessions, and the problem jobs ran in 2 minutes each. A similar situation came up Monday morning after I went off on call and a coworker took over and he ended up applying another SQL Profile on a similar query.

I spent the past couple of hours doing my typical SQL tuning exercise to see if I could figure out why Sunday’s query sometimes chose the bad plan.

The typical scenario includes these elements:

  1. Partitioned table with some near empty partitions and a lot of full partitions
  2. Bind variables used to determine partition choice

In our case we have certain tables that partition data by a code number. Certain numbers were used in the past or for other reasons are not active now. My guess is that the bad plans that we see come from bind variable values that point to the empty partitions. The bad plan works fine with empty partitions but then the optimizer uses it on full partitions and the query spins for hours.

I started to research this further to see if I could come up with a better fix than putting in SQL Profiles but did not get very far. I thought I would just pass this post along as is.

Bobby

P.S. I originally wrote this June 4th, but decided to just publish as is today.

Categories: DBA Blogs

Slides and My Impressions from May 17th AZORA Meetup

Bobby Durrett's DBA Blog - Tue, 2019-06-11 18:44

We have the slides from the two talks at our May 17th AZORA Meetup.

Here are Stephen Andert’s slides: Networking is NOT just cables and fiber!

Here are Doug Hood’s slides in three parts:

  1. Using SQL and PLSQL for Mid-Tier Database Caching
  2. Oracle TimesTen Scaleout – World’s Fastest OLTP DB
  3. Oracle In-Memory Data Processing

I wanted to share my impressions of the two talks and the meeting as well as share the slides. Of course, these are my opinions shaped by my own experiences and not universally true of everyone!

This meetup had two very different types of talks. I thought of Stephen’s talk as a career development or soft skills sort of talk. I have been to a number of talks like that at national Oracle user group conferences such as Collaborate. They help balance out the purely technical Oracle database content. Once Stephen got into his talk, I really started to appreciate the quality of the content. To me he was talking about keeping in touch with people in an intentional but sincere way. I like the idea of planning on contacting people a certain number of times per year for example.

Years ago, in my first job I worked for Campus Crusade for Christ (now Cru) and I raised money to support myself and my family. I networked with people that I met through churches and friends and family members. It was different than networking as part of a DBA career because I was directly asking for money instead of making career-oriented connections. But the core idea that I remember from Stephen’s talk applied then. Stephen’s idea was to genuinely seek to help the folks in your network without focusing on what they could do for you. In my CCC days the support raising training told us that we were not “fundraising” but instead “friend raising”. I had some great experiences meeting people and getting to know them and I think it was best when my focus was on how to inspire and encourage the people I met rather than to anxiously think about whether they could give money to support what I did.

The other less serious connection I saw between Stephen’s presentation and my Cru days is that Stephen has a hand-written database setup to keep track of his people. Back in the day I had a Paradox database from Borland running on MS-DOS to do a lot of the same things. So, hearing Stephen talk about his contact database was a blast from the past for me.

I am not really doing much in the way of networking myself these days. I write this blog. I speak at conferences every couple of years or so. I help with the local Oracle user group AZORA. But I am not intentionally making and maintaining relationships with other technical people in the way Stephen described so his talk gave me something to think about.

Doug Hood’s talk was at the other end of the spectrum with some cool technology. Doug spoke on several things and with a lot of detail so I cannot do a good job of summarizing what he said. Check the slides for more details. But I do want to write down my impressions. Listening to Doug’s talk reminded me of some of the computer science study that I have been doing on my own recently. I have sort of gone back to school as an independent learner. When Doug talked about the memory hierarchy and caching it tied right back to the assembly language and algorithms study I have been doing.

Doug presented some cool hardware that puts persistent memory close enough to the CPU that it changes the way we think about memory hierarchy. What if you replace your RAM with persistent RAM that did not get cleared when you power off your computer? Evidently in some architectures (maybe all the modern ones these days I don’t know) the RAM is closely connected to the CPU and does not have to be accessed over the bus in the way I/O is. So, persistent RAM would be much faster than some solid-state disk being read over the bus no matter how fast the SSD is. Anyway, see Doug’s slides. I am sure that I am butchering the details, but I am giving my impression and my memory so keep that in mind.

In general database work and database performance has a lot to do with caching. I have heard a little bit about how algorithms can be designed to work well with CPU caches. I recently read a chapter about the B-Tree data structure that is used in databases and it was a big contrast to the other data structures I had studied because it took disk reads and memory accesses into consideration. Anyway, at a high level I took away from Doug’s talk notions about memory and caching and different ways people can tweak the memory hierarchy to get better database performance.

I had to leave a little early to head for the mountains for the weekend but as always, I valued the time I spent at AZORA, my local Oracle user group. I appreciate Stephen and Doug stepping up and giving their presentations. I hope that my links and the way I characterized their talks is accurate enough. I am sure that I made mistakes, but I got something out of my time and appreciate their efforts.

AZORA is taking a break for the hot Arizona summer but coming back strong with our next meeting on September 27th. The details are being finalized so keep an eye on our Meetup page.

Bobby

Categories: DBA Blogs

anytype from java for anydataset

Tom Kyte - Thu, 2019-06-06 10:06
Hello TOM :) I try to make anytype in java stored procedure and use it to create anydataset in PL/SQL. But I get error ORA-22625. Why this error occures and how can I fix it? I do it according to guides, for example https://docs.oracle.com/databas...
Categories: DBA Blogs

Best performance of Top N by X

Tom Kyte - Thu, 2019-06-06 10:06
I have the following 2 tables: <code>CREATE TABLE accounts( id NUMBER unique not null, account_name VARCHAR2(30) ); CREATE TABLE log_data( account_id NUMBER not null, log_type NUMBER, log_time TIMESTAMP, msg CLOB );...
Categories: DBA Blogs

PLS_INTEGER versus NUMBER versus "dynamic types"

Tom Kyte - Thu, 2019-06-06 10:06
It has been suggested to me that I use PL/SQL declarations like PROCEDURE foo ( p_id IN PLS_INTEGER )... instead of PROCEDURE foo (p_id IN NUMBER ) ... or PROCEDURE foo (p_id IN mytable.my_id%TYPE ) I've always preferred the last option, si...
Categories: DBA Blogs

Using MERGE to update data 2 times

Tom Kyte - Thu, 2019-06-06 10:06
I am having a Full dump of 1m records arriving every day.I need to obtain this set into STG. There is soft delete records thus when I compared between Full dump(source) and STG(target), the records in STG always larger than source. I have researc...
Categories: DBA Blogs

Function comparing dates in a range

Tom Kyte - Thu, 2019-06-06 10:06
I have a function that will extract records from a databaase with specific dates and times. One of the parameters passed is a date. This functions runs twice a day On of the parameters passed is AM or PM). My functions works for morning (times are ...
Categories: DBA Blogs

Pivot with dynamic dates column

Tom Kyte - Thu, 2019-06-06 10:06
Hi Tom, I want to show the absence of my people in an APEX form / editable grid. The absence is shown for every day and the day column should be generated automatically. Current SQL code: <code>with rws as ( select person.name, absence....
Categories: DBA Blogs

Synchronizing database sequences during manual data replication

Tom Kyte - Thu, 2019-06-06 10:06
Hi Tom, Experts, I am in a need to replicate manually all objects from one schema to another (manually, because my schemas, both source and target, reside in the cloud and I have no access to any OS level utility, nor sql*net access to the databas...
Categories: DBA Blogs

Filter Incremental Data in Oracle DB

Tom Kyte - Thu, 2019-06-06 10:06
Hi TOM, I have requirement to filter differential/Incremental data in Oracle Database. Primary key that I use is composite key (combination of 2 columns). They are in such a shape that I am unable to prepare 'where' condition that can help me to id...
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Connection Storm with Inactive sessions on ORACLE RAC

Tom Kyte - Thu, 2019-06-06 10:06
Hi All, We recently migrated from Solaris to AIX and moved to Oracle RAC : Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production PL/SQL Release 11.2.0.4.0 - Production CORE 11.2.0.4.0 Production TNS for...
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Using Oracle best way

Tom Kyte - Thu, 2019-06-06 10:06
Hi, We have set of Mainframe programs which connects to Oracle database and queries set of tables. Our application and DB servers are in 2 different locations (which we cannot change at the moment), which i believe is causing considerable delays w...
Categories: DBA Blogs

Troubleshooting By Tracing GoldenGate Sessions

VitalSoftTech - Mon, 2019-06-03 09:56
Find out how troubleshoot by tracing GoldenGate DB sessions or the GoldenGate process from GGSCI and the process parameter file.
Categories: DBA Blogs

Partner Webcast – Oracle CASB - Enabling Security Monitoring for Oracle Cloud Infrastructure

As customers adopt cloud-based infrastructure as part of their digital journey, protecting this infrastructure becomes a critical security imperative to ensure that applications that are built on top...

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Partner Webcast – Oracle APEX on Cloud: architecture, functionality and features

Oracle Application Express (APEX) is a low-code development platform that enables you to build scalable, secure enterprise apps, with world-class features, that can be deployed anywhere. With...

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