MDX: How to Pass a SSRS Parameter Label into a MDX Parameter

Ok Computer, Sing… us a song …

You have to pass a text string from your Reporting Services parameter (Label) into a MDX dataset as a parameter. An example MDX dataset is outlined here …


SELECT Measures.[some stuff]

ON 0,

FROM [Your Model]

WHERE

(

StrToSet("[Dimension].[Attribute].&[" + @YourString + "]")

)

Always On Availability Groups: Do I need a File Share Witness or No ?

This blog sets about doing a shallow dive – to simply understand how a File Share Witness is used and required in an Always On Availability Group cluster.

An Always On Availability Group cluster requires no shared storage – Windows 2012 supports up to 16 nodes, SQL Server 2012 supports up to 5 nodes in an Availability Group, and SQL Server 2014 supports up to 9 nodes.  A cluster can sustain itself  as it loses nodes and Quorum is described as the state of the cluster.

The basic rule for determining how many nodes your cluster can sustain losing is a “majority” …. I love a good analogy… here is one … Your cluster is like a bar stool … quorum is its ability to remain standing… or rather, how many legs it can lose before it falls over.

So… File Share Witness, Yes or No ? … Mathematically speaking the short answer is …

…Even number of legs = Yes

…Odd number of legs = No

A bar stool with an odd number of legs isn’t an issue, an odd number of legs means a majority can always be determined, but for an even number of legs, losing half of the legs creates an issue – a majority can’t be determined, unless you have a witness (a backup leg).

Lets take a really simple example – a bar stool with 2 legs – this is your 2 node cluster.  Each leg is considered a vote, until it is removed, in which case its vote doesn’t count.

The state of the bar stool (quorum) is determined by how many legs are still standing (votes).  It would be pretty pointless setting up 2 node Always On cluster if you had no redundancy.  The mathematical  formula which explains how many legs a bar stool can afford to lose is… (legs/2)-1 … that’s (2/2)-1 … which equals zero legs.  Without a backup leg (file share witness), the bar stool could not sustain losing any legs… so it has no redundancy.

2legsfailure

File Share Witness -> With a backup leg however (file share witness), the bar stool can lose half its legs (1), form a majority and meet the number of Votes required to keep the bar stool standing.

2legsfailurewitness

Let take a 4 leg bar stool example…because lets face it, they usually do … how many legs can a bar stool afford to lose to keep standing ? …The formula is (legs/2)-1 … that’s (4/2)-1 … which is equal to 1 leg.  If a 4 leg bar stool loses 1 leg … this still forms a majority and the stool maintains its quorum…

4legtable2legsfailure

But if it loses two legs, (half of its legs), we are in trouble… a count of standing legs won’t reach a majority and the quorum can’t be sustained… unless…

4legtable2legsfailure

File Share Witness -> For a bar stool with an even number of legs, a bar stool CAN lose up to half its legs, as long as a backup leg (file share witness) is used.   You can see when half of the nodes are missing, a majority can still be determined and satisfied, when a file share witness is used.

4legtable2legsfailurewitness

In advanced Always On architecture, a node can be configured so that it as no vote.   It still participates in the cluster and the availability group, but for the purposes of counting a majority, the vote doesn’t count.  So a 4 node cluster, with 1 node set to no vote, gives a 3 node vote.  A majority can be determined with an odd number of votes so a file share witness is not needed.   Locating your file share witness in a third datacentre can also provide another level of resilience.

😀

DAX: NAAN is good…NAN is not…use DIVIDE

Just a minute while I reinvent myself …

Measure [ExampleWithoutDivide] divides one measure by another in your Tabular cube…and when you run a query in Management studio you get -1.#IND values …

Screen Shot 2014-06-18 at 1.31.29 pm

And in your Reporting Services dataset you get NaN values …

Screen Shot 2014-06-18 at 1.32.51 pm

Use DIVIDE in your MDX calculation as illustrated in the [ExampleWithDivide] measure above…

ExampleWithDivide:=DIVIDE([Measure1],[Measure2])

Oe Use an alternative result option to return a constant numeric value instead …

Screen Shot 2014-06-18 at 1.50.04 pm

ExampleWithDivide:=DIVIDE([Measure1],[Measure2],1)

See you in places
You’ll be upstairs…
And I’ll be there too…

TSQL: <3 Search all your SQL Server Databases for a Specific Table …

We’re all just searching for something …

Bigger than we’re all able to find …

Chasing all the things that keep us young …

We won’t stop running til we reach the sun …

We’re just chasing what we can’t ever get … ever have …

EXEC sp_MSforeachdb 'USE ?
IF EXISTS(SELECT 1 FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = ''YourTableName'')
BEGIN
SELECT ''?'' AS DATABASE_NAME, TABLE_SCHEMA, TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_NAME = ''YourTableName''
END'
Simple substitute your own table name into the code above and find the table you are looking for in any database on your SQL Server instance… Enjoy ❤

SSRS: Creating Report Labels for Multi Select Parameter Selections

You want to display the selected multi select parameter values within a label in your report.   Add a textbox to your report, then use the following expression in your textbox to display your multi select parameter selections :

Your label will display “All Selected” – when all parameter values have been selected…

“Multiple Selected” – When more than one value has been selected but not all…

and the actual parameter label will be displayed of only one selection is made.

="For Parameter:   " &
IIF(COUNTROWS("YourDataset")=Parameters!YourParameter.Count,
"All Selected",
IIF(Parameters!YourParameter.Count>1,"Multiple Selected",Parameters!YourParameter.Label(0)))