SQL SERVER – ColumnStore Frequently Asked Queries
This blog talks about troubleshooting scenarios in FAQ format when dealing with ColumnStore Indexes inside SQL Server. Use a combination of trace flags, query hints, performance counters, extended events discussed in various blogs to gather relevant data and troubleshoot the problem. Sometimes I have seen people use ColumnStore as a…
Read MoreInterview Question of the Week #041 – What is a Merge Join?
Question: What is a Merge Join? Answer: The Merge Join transformation provides an output that is generated by joining two sorted data sets using a FULL, LEFT, or INNER join. The Merge Join transformation requires that both inputs be sorted and that the joined columns have matching meta-data. The user cannot…
Read MoreSQL SERVER – Script Upgrade Mode on Failover – Why?
Troubleshooting Cluster related queries is always a challenge and every once in a while I get mails around these. One of my friend wrote email to me and it caught my attention and I took couple of days to explore and felt worth to share it here: <EMAIL> Hi Pinal.…
Read MoreThe Milestone – Notes from the Field #100
[Note from Pinal]: This is a 100th episode of Notes from the Field series.
SQL SERVER – Looking Forward to Meeting you at SQLPASS 2015
If you are going to at SQLPASS 2015, Seattle, I am looking forward to meet you. I will be there and presenting two technology sessions. Here are the details of my sessions. I will be very happy if you are at SQLPASS and attend my session. If you see me…
Read MoreSQL SERVER – Strange SQL Transaction called UpdateLoginStats
I was preparing a demo for my upcoming presentation which is about couple of weeks ahead. While doing a stress test, I was looking at profiler and found that for every login there is an additional SQL transaction which is having ObjectName as UpdateLoginStats appearing even before Audit Login. Initially…
Read MoreSQL SERVER – To Find Events Mapped to Channels in Extended Events
I have outlined a number of blogs here that point to the basics of working with Extended Events. Some of them also detail you some specific scenarios that you can use inside your environments.
Interview Question of the Week #040 – Difference Between Unique Index vs Unique Constraint
Question: What is the difference between unique index and unique constraint? Answer: Add Unique Constraint ALTER TABLE dbo.<tablename> ADD CONSTRAINT <namingconventionconstraint> UNIQUE NONCLUSTERED ( <columnname> ) ON [PRIMARY] Add Unique Index CREATE UNIQUE NONCLUSTERED INDEX <namingconventionconstraint> ON dbo.<tablename> ( <columnname> ) ON [PRIMARY] There is no difference between Unique Index…
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