Comments for About Sql Server http://aboutsqlserver.com Database design and development with Microsoft Sql Server Mon, 20 May 2013 15:08:57 +0000 hourly 1 http://wordpress.org/?v=3.5.1 Comment on Sunday T-SQL Tip: Merge into CTE as the Target by Writing T-SQL Merge Statements the Right Way | Made2Mentor http://aboutsqlserver.com/2011/10/09/sunday-t-sql-tip-merge-into-cte-as-the-target/#comment-1130 Writing T-SQL Merge Statements the Right Way | Made2Mentor Mon, 20 May 2013 15:08:57 +0000 http://aboutsqlserver.com/2011/10/09/sunday-t-sql-tip-merge-into-cte-as-the-target/#comment-1130 [...] could be many SQL Server objects such as Tables, Temp Tables, Views, Table Variables, or even Common Table Expressions. The Source could also be a complete Select statement as well. In this case, for the sake of [...]

]]> Comment on Locking in Microsoft SQL Server (Part 17) – Implementing Critical Section / Mutexes in T-SQL by Dmitri Korotkevitch http://aboutsqlserver.com/2013/05/08/locking-in-microsoft-sql-server-part-17-implementing-critical-section-mutexes-in-t-sql/#comment-633 Dmitri Korotkevitch Mon, 13 May 2013 19:18:09 +0000 http://aboutsqlserver.com/?p=1057#comment-633 Hi Jason, Golam and Vladimir!

First of all, thank you very much for the feedback!

Jason, you are absolutely right. AppLock would not conflict with the data related locks. But in this case it’s exactly what we want. We need to serialize access within specific process (stored procedure) that reads the data rather than block access to the table itself. This approach would allow other sessions to insert the data to the table while application servers do the processing. It would also allow application servers to delete the processed data from the table without being blocked by the read SP.

Sincerely,
Dmitri

]]> Comment on Locking in Microsoft SQL Server (Part 17) – Implementing Critical Section / Mutexes in T-SQL by Jason http://aboutsqlserver.com/2013/05/08/locking-in-microsoft-sql-server-part-17-implementing-critical-section-mutexes-in-t-sql/#comment-630 Jason Mon, 13 May 2013 18:22:57 +0000 http://aboutsqlserver.com/?p=1057#comment-630 Keep in mind that the last method (using applocks) only works if the subsequent attempts at the object also try to acquire an applock on the object or make a call to APPLOCK_TEST. Unlike exclusive locks, applocks will not block an UPDATE, DELETE or INSERT that doesn’t attempt to acquire any applock.

]]> Comment on Locking in Microsoft SQL Server (Part 17) – Implementing Critical Section / Mutexes in T-SQL by Golam Kabir http://aboutsqlserver.com/2013/05/08/locking-in-microsoft-sql-server-part-17-implementing-critical-section-mutexes-in-t-sql/#comment-552 Golam Kabir Sun, 12 May 2013 02:21:29 +0000 http://aboutsqlserver.com/?p=1057#comment-552 Excellent post – dba must read

]]> Comment on Locking in Microsoft SQL Server (Part 17) – Implementing Critical Section / Mutexes in T-SQL by Vladimir Zatuliveter http://aboutsqlserver.com/2013/05/08/locking-in-microsoft-sql-server-part-17-implementing-critical-section-mutexes-in-t-sql/#comment-489 Vladimir Zatuliveter Fri, 10 May 2013 17:22:54 +0000 http://aboutsqlserver.com/?p=1057#comment-489 Nice post Dmitri!
Thank you!

]]> Comment on Blog is moving to another hosting site by Dmitri Korotkevitch http://aboutsqlserver.com/2013/05/05/blog-is-moving-to-another-hosting-site/#comment-343 Dmitri Korotkevitch Mon, 06 May 2013 20:16:28 +0000 http://aboutsqlserver.com/?p=1004#comment-343 Thank you, Richard! Appreciate it!

]]> Comment on Blog is moving to another hosting site by Richard L. Dawson http://aboutsqlserver.com/2013/05/05/blog-is-moving-to-another-hosting-site/#comment-342 Richard L. Dawson Mon, 06 May 2013 20:10:56 +0000 http://aboutsqlserver.com/?p=1004#comment-342 It seems to be working. If I find anything I’ll let you know.

Have a great day.
Richard

]]> Comment on Blog is moving to another hosting site by Dmitri Korotkevitch http://aboutsqlserver.com/2013/05/05/blog-is-moving-to-another-hosting-site/#comment-333 Dmitri Korotkevitch Mon, 06 May 2013 16:39:05 +0000 http://aboutsqlserver.com/?p=1004#comment-333 Thank you, Richard! Moving from 1and1 to Dreamhost. Was “pleasantly” surprised by 1and1 recently after they rolled back their blogs database to 1.5 months old version without even notifying the customers. Well, hopefully the new hosting would work better.

In either case it should be only DNS cache issues at this point. Hope everything else is working assuming you can access the site.

Sincerely,
Dmitri

]]> Comment on Blog is moving to another hosting site by Richard L. Dawson http://aboutsqlserver.com/2013/05/05/blog-is-moving-to-another-hosting-site/#comment-332 Richard L. Dawson Mon, 06 May 2013 15:24:05 +0000 http://aboutsqlserver.com/?p=1004#comment-332 Do you know where it’s moving to, yet?

Good luck in any case.
Richard

]]> Comment on Locking in Microsoft SQL Server (Part 1 – Lock types) by Dmitri Korotkevitch http://aboutsqlserver.com/2011/04/14/locking-in-microsoft-sql-server-part-1-lock-types/#comment-269 Dmitri Korotkevitch Thu, 31 Jan 2013 12:36:13 +0000 http://aboutsqlserver.com/2011/04/14/locking-in-microsoft-sql-server-part-1-lock-types/#comment-269 Hi Panco,

(S) locks are compatible with (S) locks – basically it means that multiple sessions can read (SELECT) the same row simultaneously.

(U) locks are issued during update scans. When SQL Server looks for the data to update, it acquires (U) lock while reading/checking if row needs to be updated. Then, if row does not need to be updated, SQL Server releases (U) lock. Otherwise it converts (U) lock to exclusive (X) lock. (S) lock is compatible with (U) lock – so session that reads (SELECT) the data could read the row with (U) lock acquired. It would not be able to read the row in case if (U) lock has been converted to (X) lock (e.g. data has been modified).

Hope this helps.

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