Sql-Server

A short time back, I provided an updated script that can be used to rebuild clustered columnstore indexes when necessary.

One thing that wasn’t covered by that script was the ability to only individual index partitions. Below, I’ve provided an updated version of the script that will rebuild only affected partitions if the clustered columnstore index is partitioned.

-———————————————————————

-- Rebuild clustered columnstore indexes when necessary

--

-- Dr Greg Low v2.2

2015-03-05

I make no secret of the fact that I think that table compression was the best thing added to SQL Server 2008.

It seems like every week that I’m talking to clients about it. They have Enterprise Edition but they weren’t using it because they were familiar with O/S level disk compression and they think that compression will mean smaller and slower, yet this often couldn’t be further from the truth for customers whose databases are currently I/O bound or who don’t have enough memory in their buffer cache for it to work correctly.

2015-03-05

I know that many of my readers appreciate finding out when free eBooks become available.

Microsoft Virtual Academy has been releasing quite a few lately.

In particular, SQL Server and database folk might want to take a look at the following:

• Introducing Microsoft SQL Server 2014
• Introducing Windows Server 2012 R2
• Introducing Microsoft Azure HDInsight
• Microsoft Azure Essentials: Fundamentals of Azure
• Microsoft Azure Essentials: Fundamentals of Azure
• Introducing Windows Azure for IT Professionals
• Rethinking Enterprise Storage: A Hybrid Cloud Model

2015-02-20

This is the first year for Microsoft’s new Ignite conference. Many people are keen to go but figure it would break the bank.

Here’s another option:

The Microsoft Virtual Academy have their Heroes program running again. You get one point in the draw for just signing up. Even better though, take some courses and both learn something worthwhile and increase your chances of winning the competition:

Sign up and enter here now: SIGN UP           (NOTE: Australians Only for this one sadly)

2015-02-16

Recently I published a series of blog posts that provided scripts for rebuilding clustered columnstore indexes.

Niko Neugebauer sent me a suggested update to the latest version of those scripts and it makes sense. The change will help to filter out row groups that are not compressed and Niko noted that as Microsoft have started to include more objects (like Tombstone values)  into sys.column_store_row_groups in Azure SQLDatabase, he believes that will help to prevent future SQL versions having a problem with the scripts.

2015-01-31

I’m always telling people that the thing I love about BI projects is that they tend to appeal to the people who pay the bills. This is a good place to be doing project work.

When I look at large companies like Amazon, I can imagine that the people who do the IT work that relates to order processing, invoicing, shipping, etc. do a great job. But I’ll bet that their life is full of budget cutbacks, headcounts, increased pressure to improve productivity, etc. By comparison, I’ll bet the projects that fund parts of their site that make recommendations for possible purchases, etc. are funded at an entirely different level. And that’s because these projects can more directly impact the profitability of the organization, and do so in a more visible way.

2015-01-28

When I attend events like TechEd, like many people I usually find the networking time more valuable than the session time. There is a pretty tight limit on the number of sessions you can attend, no matter how hard you try. So I often watch the sessions later when I can. At one of the earliest TechEd Australia events that I attended, they gave us CDs of the TechEd USA sessions. That was great because that TechEd had around 250 sessions, and there were over 150 that I would have loved to attend. Clearly that wasn’t possible.

2015-01-09

Earlier, I posted a maintenance script that could be used with clustered columnstore indexes to try to determine when they should be rebuilt. Reorganize is not a very useful operation for these indexes as it basically just forces a close of the existing delta store, ready for compression.

One of the problems with a clustered columnstore index is that it doesn’t work as well if the segments have been created at less than the maximum potential size of 1048576 rows per segment. Over use of reorganize options could cause this, but more likely it will be to do with loading the index with small batches of data, rather than loading large batches in BULK INSERT operations.

2015-01-09

For general index maintenance, our friend Old Hallengren has an awesome solution for most people: https://ola.hallengren.com/sql-server-index-and-statistics-maintenance.html

We’ve started to have customers using clustered columnstore indexes in SQL Server 2014, and they need to be treated differently. I checked Ola’s latest scripts today to see what happens with columnstore indexes. It appears that the code ignores nonclustered columnstore indexes (ie: index type of 6), which makes sense as we need to rebuild them whenever the data changes, and in the meantime, the table is read-only. So that makes lots of sense.

2015-01-09

At a client site today and they asked me about a warning that they got every time they manually failed over their SQL Server availability group.

It said: “The current WSFC cluster quorum vote configuration is not recommended for the availability group.” They were puzzled by this as they had a valid quorum configuration. In their case, they had a two node cluster using MNS (majority node set) and a fileshare witness.

2014-12-22