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Why does PostgreSQL perform sequential scan on indexed column?
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If the SELECT returns more than approximately 5-10% of all rows in the table, a sequential scan is much faster than an index scan.
This is because an index scan requires several IO operations for each row (look up the row in the index, then retrieve the row from the h...
Difference between Label and TextBlock
...ccording to the Windows Applications Development with Microsoft .NET 4 70-511 Training Kit
5 Answers
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How To: Best way to draw table in console app (C#)
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Patrick McDonaldPatrick McDonald
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a...
Difference between git pull --rebase and git pull --ff-only
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answered Aug 21 '14 at 15:57
Gabriele PetronellaGabriele Petronella
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Can I compile all .cpp files in src/ to .o's in obj/, then link to binary in ./?
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edited Oct 13 '17 at 7:25
answered May 25 '10 at 20:38
bo...
Unique constraint on multiple columns
...ULL,
[scode] [int] NULL,
[dcode] [int] NULL,
[name] [nvarchar](50) NULL,
[address] [nvarchar](50) NULL,
CONSTRAINT [PK_user_1] PRIMARY KEY CLUSTERED
(
[userID] ASC
),
CONSTRAINT [UQ_codes] UNIQUE NONCLUSTERED
(
[fcode], [scode], [dcode]
)
) ON...
What's the point of map in Haskell, when there is fmap?
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95
I would like to make an answer to draw attention to augustss's comment:
That's not actually ...
is of a type that is invalid for use as a key column in an index
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5 Answers
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What does it mean when MySQL is in the state “Sending data”?
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253
This is quite a misleading status. It should be called "reading and filtering data".
This mean...