Order of Predicate Execution #2

In the previous post I talked about the order of predicate execution based on the predicate position and inline view. As promised, in this post I’ll add statistics and see what happens. Creating extended statistics In this demo I’m using functions, so Oracle doesn’t really know what the output of the function is. That’s why … Continue reading Order of Predicate Execution #2

Impdp Resumable Mystery

Resumable operations are operations that can be suspended instead of failing, allowing us to fix the problem and resume the operation. When importing data using impdp, if (for example) a tablespace gets full, instead of failing the entire import (and force us to restart it from the beginning), we can identify that and add some … Continue reading Impdp Resumable Mystery

Order of Predicate Execution #1

In my previous post, I wrote about the parsing operation and what happens first. In the footnote I said that the order doesn’t affect performance, the cost based optimizer doesn’t care about the order of stuff in the query, right? Well, not quite. Preparing the environment In order to check that, I’ll create a table … Continue reading Order of Predicate Execution #1

Parse Order and Analysis

Over the years I’ve heard and learned quite a lot about how Oracle does stuff. Some of it was logical, some just details to remember (I have a really lousy memory, but somehow, I actually remember some of the details). Not too long ago I wrote a query and got a parse error, and that … Continue reading Parse Order and Analysis

Playing with RAC Voting Disks

Lately I ran into a case of losing of a voting disk, so this lead me to create a GI environment on my laptop (using virtual box) and play with voting disks failures. In this post I’ll explain what I did and what happened. Background I’m not going to explain too much about the voting … Continue reading Playing with RAC Voting Disks

Did You Know #23 – Name Uniqueness

Every day you can learn something new, even after 20 years in the field. For some reason, I was always under the impression that within a single schema, objects must have a unique name. Apparently, this is not the case. I just saw a case where a table and an index have the same name … Continue reading Did You Know #23 – Name Uniqueness

Analyzing the Listener.log

A little bit more than a month ago I spoke at OSWOUG event (and wrote this post about it). In the event, Jared Still talked about free tools for Oracle database. He basically said that there is a lot of stuff out there on the internet, and if you can’t find what you need, then … Continue reading Analyzing the Listener.log

ODC Appreciation Day – Plan Statistics

If you don’t know that by now, OTN (Oracle Technology Netowrk) has changed its name to ODC (Oracle Developer Community), so OTN Appreciation Day becomes ODC Appreciation Day. This initiative started by Tim Hall from ORACLE_BASE last year. In this day, every blogger writes something to thank Oracle for. You can read about the concept … Continue reading ODC Appreciation Day – Plan Statistics

Did You Know #22 – Reproduce SQL Issue

During OOW17 a customer ran into a wrong result issue in, which is very bad. I diagnosed this and found out that it happens because of bloom filter, so we just disabled that and it was solved. But I still opened an SR so Oracle can find and fix this bug. Wrong results bug … Continue reading Did You Know #22 – Reproduce SQL Issue

The English Language

I wrote this post quite a while ago and it stayed as draft since. A few days ago, during Oracle Open World 2017, I had a long chat with Jim Czuprynski and somehow we got to talking about the English language. As you well know by now, I’m not a native English speaker, but Jim … Continue reading The English Language