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Author: Kevin Feasel

Azure SQL Database Size Quotas

Dimitri Furman discusses the MAXSIZE property on an Azure SQL Database:

Customers can use this ability to allow scaling down to a lower service objective, when otherwise scaling down wouldn’t be possible because the database is too large.

While this capability is useful for some customers, the fact that the actual size quota for the database may be different from the maximum size quota for the selected service objective can be unexpected, particularly for customers who are used to working with the traditional SQL Server, where there is no explicit size quota at the database level. Exceeding the unexpectedly low database size quota will prevent new space allocations within the database, which can be a serious problem for many types of applications.

One more thing to think about, I suppose.

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Restoring An Azure SQL Database

Arun Sirpal discusses ways to restore a database within Azure SQL Database:

You won’t have the ability to use the same name of the restoring database and the database that you want to replace; if you try you get the screen shot below: To get around this I think you would need to drop the old one once the new one has restored then do a rename.

This is a big difference compared to the on-prem version, so be sure to practice this before you find yourself in a crisis.

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Migrating To Azure SQL Database

Mike Fal discusses BACPACs, DACPACs, and migrating on-prem databases to Azure SQL Database:

SQL Server Data Tools(SSDT) have always had a process to extract your database. There are two types of extracts you can perform:

  • DACPAC – A binary file that contains the logical database schema and possibly the data. This file retains the platform version of the database (i.e. 2012, 2014, 2016).

  • BACPAC – A binary file that contains the logical database schema and the data as insert statements. This stores the platform version, but is not locked into it.

Mike also walks through SqlPackage.exe.

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Change Data Capture With Apache NiFi

Satish Bomma uses Apache NiFi to perform change data capture on a MySQL database:

The main things to configure is DBCPConnection Pool and Maximum-value Columns

Please choose this to be the date-time stamp column that could be a cumulative change-management column

This is the only limitation with this processor as it is not a true CDC and relies on one column. If the data is reloaded into the column with older data the data will not be replicated into HDFS or any other destination.

This processor does not rely on Transactional logs or redo logs like Attunity or Oracle Goldengate. For a complete solution for CDC please use Attunity or Oracle Goldengate solutions.

That last paragraph in the snippet is key:  it’s not a true replacement for CDC-friendly products.  It is, however, a good example for showing how to use NiFi to connect to a relational database and pump data out of it.

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Firewall Configuration With Powershell

Slava Murygin gives an introduction to firewall configuration using Powershell:

The Script has list of adjustable filters:
$Direction – Direction of firewall rule: Inbound or Outbound;
$Action – Action rule performs: Allow or Block;
$Enabled – Status of a rule: Enabled – True or False;
$RuleGroup – Group rule has been assigned. By default script uses “$Null” variable, which filters all rules without assigned group. However you can specify a group a name if necessary;
$DisplayName – Name of a rule. By default I use an expression “*SQL*” to search for rules which have word “SQL” in their name. To retrieve all rules us “*”. To retrieve any particular rule use rule name.

He looks at viewing rules as well as creating, modifying, and deleting them.

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SARGable Predicates

Gail Shaw discusses what makes a particular predicate SARGable:

Any1 function on a column will prevent an index seek from happening, even if the function would not change the column’s value or the way the operator is applied, as seen in the above case. Zero added to an integer doesn’t change the value of the column, but is still sufficient to prevent an index seek operation from happening.

While I haven’t yet found any production code where the predicate is of the form ‘Column + 0’ = @Value’, I have seen many cases where there are less obvious cases of functions on columns that do nothing other than to prevent index seeks.

UPPER(Column) = UPPER(@Variable) in a case-insensitive database is one of them, RTRIM(COLUMN) = @Variable is another. SQL ignores trailing spaces when comparing strings.

This is a straightforward concept with significant performance implications.

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Create An Azure SQL Database Instance From Powershell

Arun Sirpal walks through the steps of setting up an Azure SQL Database instance and database using Powershell:

What I have done here is hard-code three parameters ( database edition, start IP address and end IP address) which for my situation won’t change but I have given the ability to pass in the environment name, SQL Server name and database name.

So a prompt will be presented to the user – here you should enter the relevant details and click enter.

It’s not that difficult to do, and the scripts themselves are probably faster than fumbling around the UI.

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Diagnosing And Solving A Performance Problem

Monica Rathbun had a major performance problem; this is how she solved it:

Symptoms:

  • Very High Disk Latency as high as 300,000 milliseconds (ms) is not unusual
  • Average: 900 – 15,000ms
  • Memory Pressure
  • Slow User Experience

Problem:

  • Bad hardware
  • Over-provisioned VM Hosts (what happens on one VM effects the other)
  • Old NetApp SAN
  • No infrastructure budget for new hardware

Challenge: Make the system viable with no hardware changes or tweaks

Those disk latencies are scary.  I like the systematic approach Monica takes, and the end result was very positive.

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