StackOverflow2013

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plurals

PO
primarykey
Id
8454409
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0
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0
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0
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CreationDate
2011-12-10T04:29:38.767
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0
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2011-12-10T04:29:38.767
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0
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1045444
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3211108
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2
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0
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text
Body
The cost of an index in disk space is generally trivial. The cost of additional writes to update the index when the table changes is often moderate. The cost in additional locking can be severe. It depends on the read vs write ratio on the table, and on how often the index is actually used to speed up a query. Indexes use up disc space to store, and take time to create and maintain. Unused ones don't give any benefit. If there are lots of candidate indexes for a query, the query may be slowed down by having the server choose the "wrong" one for the query. Use those factors to decide whether you need an index. It is usually possible to create indexes which will NEVER be used - for example, and index on a (not null) field with only two possible values, is almost certainly going to be useless. You need to explain your own application's queries to make sure that the frequently-performed ones are using sensible indexes if possible, and create no more indexes than required to do that. You can get more by following this links: For mysql: <a href="http://www.mysqlfaqs.net/mysql-faqs/Indexes/What-are-advantages-and-disadvantages-of-indexes-in-MySQL" rel="nofollow">http://www.mysqlfaqs.net/mysql-faqs/Indexes/What-are-advantages-and-disadvantages-of-indexes-in-MySQL</a> For DB2: <a href="http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.ibm.db2.udb.doc/admin/c0005052.htm" rel="nofollow">http://publib.boulder.ibm.com/infocenter/db2luw/v8/index.jsp?topic=/com.ibm.db2.udb.doc/admin/c0005052.htm</a>
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PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POIndexing every column in a table
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 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USSomnath Muluk
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Querying!

Guidance

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.