Databases
StackOverflow2013
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    <p>According to MSDN:</p> <p><a href="http://msdn.microsoft.com/en-us/library/ms191242.aspx" rel="noreferrer">http://msdn.microsoft.com/en-us/library/ms191242.aspx</a></p> <blockquote> <p>When either the READ COMMITTED SNAPSHOT or ALLOW SNAPSHOT ISOLATION database options are ON, logical copies (versions) are maintained for all data modifications performed in the database. Every time a row is modified by a specific transaction, the instance of the Database Engine stores a version of the previously committed image of the row in tempdb. Each version is marked with the transaction sequence number of the transaction that made the change. The versions of modified rows are chained using a link list. The newest row value is always stored in the current database and chained to the versioned rows stored in tempdb.</p> <p>For short-running transactions, a version of a modified row may get cached in the buffer pool without getting written into the disk files of the tempdb database. If the need for the versioned row is short-lived, it will simply get dropped from the buffer pool and may not necessarily incur I/O overhead.</p> </blockquote> <p>There appears to be a slight performance penalty for the extra overhead, but it may be negligible. We should test to make sure.</p> <p>Try setting this option and REMOVE all NOLOCKs from code queries unless it’s really necessary. NOLOCKs or using global methods in the database context handler to combat database transaction isolation levels are Band-Aids to the problem. NOLOCKS will mask fundamental issues with our data layer and possibly lead to selecting unreliable data, where automatic select / update row versioning appears to be the solution.</p> <pre><code>ALTER Database [StackOverflow.Beta] SET READ_COMMITTED_SNAPSHOT ON </code></pre>
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    1. USGeoff Dalgas
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    1. CO"NOLOCKS will mask fundamental issues with our data layer" ... What sort of problems does NOLOCK mask? If I think I need NOLOCK, what problems should I look for?
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      1. USMatt Hamilton
    2. COWhat about this answer makes it "the answer"? I still don't understand why the millisecond read would deadlock-kill the write immediately? I am guessing the answer by "user13484" too bad there's no reference to it if that is the case.
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

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