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January 2020

SQLPlus goodies with linesize

Anyone that has used SQL Plus since its inception will be familiar with this frustration:

image

Improved Offline Publishing

The best technology is invisible and reliable. You almost forget it’s there, because things just work. Bad technology never disappears into the background — it’s always visible, and worse, it gets in your way. We rarely stop to think “My, what good Wifi!” But we sure notice when the Wifi is iffy.

Good technology in an app requires solid offline support. A WordPress app should give you a seamless, reliable posting experience, and you shouldn’t have to worry whether you’re online or offline while using WordPress Mobile. And if we’ve done our jobs right, you won’t have to! 

We all need fewer worries in life, so if you haven’t already head to https://apps.wordpress.com/get/ to download the apps.

Offline Publishing

Hacking Session: Troubleshooting Complex Oracle Performance Problems (January 2020)

As promised, I will run one more hacking session in the end of January. I aim to make this one more practical than some of the past internals geek-dives :-)
The topic: Troubleshooting Complex Oracle Performance Problems with Tanel Poder Date & Time: Thursday 30 January 2020 (today!) 12pm-1:30pm ET Registration: https://attendee.gotowebinar.com/register/7847585427420817931 Description: In this session I will first present some slides about a complex performance issue where the initial symptoms point somewhere else than the root cause.

Hacking Session: Troubleshooting Complex Oracle Performance Problems (January 2020)

As promised, I will run one more hacking session in the end of January. I aim to make this one more practical than some of the past internals geek-dives :-)
The topic: Troubleshooting Complex Oracle Performance Problems with Tanel Poder Date & Time: Thursday 30 January 2020 (today!) 12pm-1:30pm ET Registration: https://attendee.gotowebinar.com/register/7847585427420817931 Description: In this session I will first present some slides about a complex performance issue where the initial symptoms point somewhere else than the root cause.

Hacking Session: Troubleshooting Complex Oracle Performance Problems (January 2020)

As promised, I will run one more hacking session in the end of January. I aim to make this one more practical than some of the past internals geek-dives :-)
The topic: Troubleshooting Complex Oracle Performance Problems with Tanel Poder Date & Time: Thursday 30 January 2020 (today!) 12pm-1:30pm ET Registration: https://attendee.gotowebinar.com/register/7847585427420817931 Description: In this session I will first present some slides about a complex performance issue where the initial symptoms point somewhere else than the root cause.

Hacking Session: Troubleshooting Complex Oracle Performance Problems (January 2020)

As promised, I will run one more hacking session in the end of January. I aim to make this one more practical than some of the past internals geek-dives :-)
The topic: Troubleshooting Complex Oracle Performance Problems with Tanel Poder Date & Time: Thursday 30 January 2020 (today!) 12pm-1:30pm ET Registration: https://attendee.gotowebinar.com/register/7847585427420817931 Description: In this session I will first present some slides about a complex performance issue where the initial symptoms point somewhere else than the root cause.

Index Advisor ? PostgreSQL, Oracle and SQL Server : yes , MySQL : no

How does one check if there are missing indexes in a database?

Is there a programatic way to do it?

Explain Plan
Most blogs on the subject will say look at the explain plan for your query.
Basic concept is to look for full table scans in the explain plan and the look and see if there is a predicate filter (i.e. SQL text of form “where table.field=value”) with a full table scan or a full table scan in a join ( i.e. tableA.field = tableB.field). There are other considerations, things to check, and other places for indexes, but this is a good start.

Explain Plans for whole database
What if you don’t have a particular query and instead want to check the whole running database?
Is there a programatic way to do it? If the answer to finding missing indexes for one query is looking at the explain plan then by extension the answer for the whole database is looking at the explain plans for the whole database.

SSQ Unnesting

I hesitate to call something a bug simply because Oracle doesn’t do what I thought it would do; but when a trace file says:

“I’m not going to do X because P is not true

followed a little later by

“I’m going to do Y because P is true

then I think it’s safe to say there’s a bug there somewhere – even if it’s only a bug in the code that writes the trace file.

The example is this note is a feature that appeared in 12c (possibly only 12.2) – the ability to unnest scalar subqueries in the select list and transform them into outer joins. Here’s an example to demonstrate the mechanism:

Why no GUI installations anymore?

I had the following comment on a RAC article yesterday.

“this way of training is not good. please train as previous method.”

I believe the person in question didn’t like that I no longer do those massive articles showing how to install RAC using the GUI. Instead I do automatic silent builds using Vagrant and shell scripts. My recent RAC articles just describe the Vagrant builds. I’ve written about this before, but I think it’s worth repeating.

roachcrib… Cockroach Database SQL crib-sheet

Recently, I was creating a developer workshop for CockroachDB and wanted a way to share various commands so people could quickly cut-and-paste various SQL commands while doing the workshop. I had various files where I kept my notes but decided to create a simple github repository to be able to share with the greater CockroachDB Community.

Here are some example SQL tidbits you will find in the repository:

  • How to Partition Tables