Press "Enter" to skip to content

Category: Administration

Creating A Big Data Cluster

Published 2019-02-06 by Kevin Feasel

Chris Adkin continues a series on big data clusters in SQL Server 2019:

This post post will focus on creating a big data cluster so that you can get up and running as fast as possible, as such the storage type used will be ephemeral, this perfectly acceptable for “Kicking the tyres”. For production grade installations integration with a production grade storage platform is required via a storage plugin. Before we create our cluster, with the assumption we are doing this with an on premises infrastructure, the following pre-requisites need to be met:

Read the whole thing, but wait until part 4 before putting anything valuable in it.

Comments closed

Apps To Manage SQL Server On Azure VMs

Published 2019-02-04 by Kevin Feasel

Kevin Chant has a list of tools you can use to manage SQL Server on Azure VMs:

From experience I know it’s important to know what applications you can use locally with Azure to manage SQL Server solutions. So you have the right tools for the job.

For instance, I was talking with some people at a client’s site the other day about deciding what application to use to future proof themselves.

In this post I will cover applications for use with Windows, MacOS and Linux distributions. 

I don’t think I’m spoiling too much in saying that about 80% of these are the same tools you would use for on-prem work.

Comments closed

The Costs Of Rebuilding Indexes Online

Published 2019-01-31 by Kevin Feasel

Tibor Karaszi explains that TANSTAAFL (There A’int No Such Thing As A Free Lunch) applies to online index rebuilds:

The time it takes to rebuild the index can be substantially longer for ONLINE. Many of us has other things to do with the database during night-time and/or weekends. Yes, these are the typical window in time where we try to find things such as index rebuilds. Say that you do it night-time and it currently take 4 hours. Wouldn’t it be nice if you could cut that time down to 1.5 hours? That would leave more time for imports, massaging of data, CHECKDB and other things you want to do. Sure, you can do it ONLINE, but it will slow down access during the rebuild. Also the more data you modify during the rebuild, the more space you need in tempdb.

Betteridge’s Law of Headlines applies too, so that’s two important principles in one post.

As far as the post goes, Tibor makes a fair point: there is a trade-off between availability and efficiency with index rebuilds. But having worked with clustered columnstore indexes in 2014, you’ll pry the online operations in subsequent versions out of my cold, dead hands.

Comments closed

Azure Kubernetes LoadBalancer External IP Woes

Published 2019-01-31 by Kevin Feasel

Andrew Pruski writes up some issues he had with creating a LoadBalancer service in Azure Kubernetes:

I logged a case with MS Support and when they came back to me, they advised that the service principal that is spun up in the background had expired. This service principal is required to allow the cluster to interact with the Azure APIs in order to create other Azure resources.

When a service is created within AKS with a type of LoadBalancer, a Load Balancer is created in the background which provides the external IP I was waiting on to allow me to connect to the cluster.

Because this principal had expired, the cluster was unable to create the Load Balancer and the external IP of the service remained in the pending state.

There were a lot of steps here; click through to see just how many.

Comments closed

QueryMemoryLimit In SSAS 2019

Published 2019-01-30 by Kevin Feasel

Shabnam Watson covers a new setting in Analysis Services 2019:

The purpose of this setting is limit the amount of memory any single query can take. This setting is extremely useful when you want to limit the amount of memory consumption per query for queries across the board. Before this setting, it was possible to have an extremely poorly written query eat up all of a server’s memory and bring all other queries down to a halt. You can see an example of a such a query and SSAS memory settings in my previous post here.

Read on for details about what it does and what happens when a query reaches the memory limit.

Comments closed

Could Not Clear Differential Bitmap

Published 2019-01-30 by Kevin Feasel

Jack Vamvas takes us through a reason why you might get error 3041:

An error message has started appearing in the SQL Server Error Logs during a nightly full backup.

Could not clear ‘DIFFERENTIAL’ bitmap in database ‘Database1’ because of error 9002. As a result, the differential or bulk-logged bitmap overstates the amount of change that will occur with the next differential or log backup. This discrepancy might slow down later differential or log backup operations and cause the backup sets to be larger than necessary. Typically, the cause of this error is insufficient resources. Investigate the failure and resolve the cause. If the error occurred on a data backup, consider taking a data backup to create a new base for future differential backups.

Click through for the root cause and solution.

Comments closed

Authentication With Azure Managed Instances

Published 2019-01-29 by Kevin Feasel

Hamish Watson explains that Windows authentication is not available with Azure Managed Instances:

Azure SQL Managed Instances do not utilise windows authentication – so your two methods of authenticating applications and users are:
– SQL Authentication:This authentication method uses a username and password.
– Azure Active Directory Authentication:This authentication method uses identities managed by Azure Active Directory and is supported for managed and integrated domains. Use Active Directory authentication (integrated security) whenever possible.

Hamish also elaborates on some of the trickier bits about Azure Active Directory for someone used to on-prem AD solutions.

Comments closed

Optimizing For Ad Hoc Workloads

Published 2019-01-23 by Kevin Feasel

Bert Wagner looks at the optimize for ad hoc workloads option in SQL Server:

Instead of filling the execution plan cache with plans that will never get reused, the optimize for ad hoc workloads option will cache a plan stub instead of the full plan. The plan stub is significantly smaller in size and is only replaced with the full execution plan when SQL Server recognizes that the same query has executed multiple times.

This reduces the amount of size one-time queries take up in t he cache, allowing more reusable plans to remain in the cache for longer periods of time.

I’ve run into several cases where this has helped SQL Server and don’t think I’ve found a scenario where it actively hurts.

Comments closed

Adding ML Services On Windows Server Core

Published 2019-01-23 by Kevin Feasel

Kevin Chant shows us how to add SQL Server ML Services to an already-existing SQL Server installation on Windows Server Core:

It’s important to try and use an install set that is the same level of Service pack as your current install. Otherwise, you could end up installing multiple patches to get the SQL Launchpad service to work. Which is something discussed in a previous post here.

I know some companies have a central installer for SQL Server and then have all the updates in another location. Hence, if you are in such an environment be prepared to run multiple updates from that location after the install.

This is definitely one of the features which is easier to install from the beginning than to install after the fact.

Comments closed