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When is MaxDop not MaxDop?
MaxDop is in some sense a bit of a misnomer, in that you would think ‘Max Degree of Parallelism’, set by the system administrator would be the last and final word on the matter; That is your maximum,...
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How to Remember the Next Used Filegroup in a Partition Scheme
Within SQL, the partitioned table feature provides an excellent way to store and roll forward data windows across large datasets without incurring huge loading and archiving penalties to the main...
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Do Filtered Index Have Different Tipping Points?
I’ve been taking a look at filtered indexes and they do initially look particularly useful, but I was wandering what effect the filtered index has on the tipping point. The tipping point was described...
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Finding Next Identity Value, and a Wild Goose Chase.
A question asked on stack overflow was to find the next identity value that would occur on a table, without being required to add a record to work it out. The problem lies in that if the highest row is...
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What is the SQL Server 2008 DateTime2 Internal Structure?
SQL Server has a number of new date time formats, but the one I am most interested in is DateTime2. The internal format of the SQL DateTime is commonly mistaken as 2×4 byte integers, with the latter...
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What is the SQL Server 2008 DateTimeOffset Internal Structure?
After decoding the DateTime2 internal structure I thought I would take a quick look at the DateTimeOffset structure, since it should not present too many difficulties and post it up quickly, but was...
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Guidance on How to Layout a Partitioned Table across Filegroups
SQL Server’s Table Partitioning was one of my favourite features within the 2005 release. It really brought SQL into the mainstream when it came to holding very large data quantities and allowed us to...
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When is Bulk Logged Mode Not What it Says?
Somewhat of a ‘doh’ moment when dealing with a SQL server in bulk logged mode, the transaction log was behaving very weirdly and growing very large for smaller index operations. When performing an...
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Can a Covering NC Index be Tipped?
Non-clustered indexes normally have a ‘tipping point’, which is the point at which the query engine decides to change strategies from seeking the index with a nested loop operator back to a seek on the...
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Inconsistent Date Literal Parameterization Behaviour
I have mentioned query parameterization before and the process by which SQL extracts literal values from a query and re-writes the query in effect to use parameters to get a query plan cache hit, which...
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Prodata SQL Academy Events
If you haven’t seen them advertised, Bob Duffy from Prodata is running a series of SQL Academy half day training session in Dublin, hosted at the Microsoft Auditorium in their offices in Leopardstown –...
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How Can You Spot the Procedure Cache Being Flooded?
This comes from a question I had a couple of days ago – the SQL Server: Buffer Manager : Page Life Expectancy provides a performance counter that indicates the current lifetime of a page within memory....
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Rolling a Partition Forward – Part 1
I have covered how to layout a partitioned table across filegroups previously, but have not gone through the steps of rolling a partitioned window – it sounds a simple process but with all the file...
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Rolling a Partition Forward – Part 2
The first part of this topic provided a mini-guide to loading data into a partitioned table and a few helpful DMV based statements that can help you automate the process. The unloading of the data...
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How Can You Tell if a Database is in Pseudo Full/Bulk Logged Mode?
I was asked on Friday, “how do you tell if a database logging mode is reporting bulk or full, but it is still in simple?” – as mentioned before, a database is not in really full / bulk logged unless a...
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Is Dynamic Partitioning in SQL Server Possible?
I often see people asking whether dynamic table partitioning exists in SQL Server, or they provide a scenario that would effectively be asking the same question. So let’s get the easy answer out now –...
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Dynamic Partitioning : Wishlist
Whilst I consider dynamic partitioning something that really doesn’t serve a valid purpose that I can find yet, I decided to use it as an exercise to program a basic form of it within T-SQL over the...
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Dynamic Partitioning : What objects are using a Partition Schema? (SQL...
As part of the look at dynamic partitioning one of the first problems I have come across is finding what objects are currently placing data within a partition schema, this can be both tables as well as...
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Case Sensitivity in the Query Plan Cache
A surprising facet of the query plan cache is that it matches ad-hoc queries not only on their text, but the case of the query text must exactly match as well. This is documented quite clearly on MSDN...
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Why Are Date Tricks in SQL 2005 a Problem in Waiting?
One of the long time annoyances about the Date functions in SQL is that a number of them do not function as developer would wish, the prime example I’m going to focus on is the DateDiff function. The...
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Decoding a Simple Update Statement Within the Transaction Log
After decoding the delete statement within the transaction log, I thought I would tackle another statement – an update statement, although I am attempting the simple version of the update which is only...
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Locating Table Scans Within the Query Cache
Some time back, Pinal Dave published a blog entry with an example of an XML script that used XQuery to examine the query cache – the script in itself is a very useful example of using XQuery against...
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Query Parameterization and Wildcard Searches
Time flies when you’re busy, and it has been far too long since I last posted. To business however, and I noticed a problem in query parameterization the other day which does not make much sense at...
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SQL Immersion Event – Dublin 2010
I attended the SQL Immersion event last year in Dublin and can honestly say that it was the best training course I have ever attended. The level of detail is phenomenal and the interaction with Paul...
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Immutable Primary Key vs Immutable Clustered Key
It is often said that a primary key should be immutable, and this advice is echoed on a multitude of sites some of which strengthen it to a ‘law’ - but we know with databases that absolutes are rare...
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SQL Server Hash Partitioning
It’s been a while since the last post, primarily due to changing jobs and now spending most of my time on Oracle – although it is always good to see the other side of the coin and see what it has to...
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Subtle change to ::fn_dblog in SQL 2008
Bizarrely given that transaction log decoding is not really viable as a technique beyond interest, it’s quite surprising how many people visit just to understand or learn how to do it. Either a lot of...
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Blank Transactions
Busy time with a new addition to the household – sleep is clearly an optional parameter these days, but on to one of those oddities you might see in the transaction log. On many occasions you will see...
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Interval Partitioning in SQL Server 2008
Another one of those features in Oracle that we do not natively have in SQL Server is interval partitioning, where you can automatically have partitions generated based on an interval automatically...
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SQL Internals Viewer
As Captain Oates once said, ‘I am just going outside and may be some time’ – feels like quite a while since I had to time to see down and write something. I had a bit of time to take a look at the SQL...
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Which User Made That Change?
If you have spent any time tinkering about in the transaction log, you will of already come across a bit of a problem when trying to decide what was done and by whom – the ‘what part’ I have decoded in...
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