Category: Uncategorized

How to save 250 000 EUR to your customer?

Recently, for the first time in my life I had a customer from India. A far away, beautiful country I had never opportunity to visit, with 1.3 billion of people. I thought it would be interesting experience, and it was indeed.

SQL Server 2017 announcement and quick hello from vacation

We are always thinking about you, sometimes even on vacation! Here is a quick hello video from the island of Brac:

RCSI and LOB data – how tempdb version store is used?

Row Version Store We know RCSI (Read Committed Snapshot Isolation), as well as SI (Snapshot Isolation) use row versioning to store previous verions of rows in part of tempdb called “row version store”. If you are using default isolation level

Page Life Expectancy and 300 sec limit

People blogged about it, including excellent Jonathan’s post here (highly recommended to read), but I will give a little more insight here. Basically, Microsoft says if PLE is below 300 seconds, we should worry about memory pressure (an old recommendation

CHECKPOINT vs LAZY WRITER

Checkpoint and Lazy Writer are somewhat similar: they both write pages from buffer pool memory to the disk. So, what is the difference?

Sort records without ORDER BY?

How often you see some smartie “optimizes” the query by removing ORDER BY, justifying that query always goes by that index, and index is in desired order for the result? Or they say: “I executed this query thousands of times

Do you measure query IO with SET STATISTICS IO ON ?

Introduction In our tuning work and often in presentations we see people use SET STATISTICS IO ON as a handy way to measure IO, especially logical reads. But, not many people know that it skips measuring IO from certain types

READ COMMITTED sucks!

Are you still using READ COMMITTED transaction isolation level? Default transaction isolation level on all SQL Server versions (2000-2014) has serious inconsistency problems, by design. Not many people are familiar how and why is it happening. I am writing this

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