A composite index on both columns may be used by queries involving
either both columns, or the first column in the index.
http://dev.mysql.com/doc/refman/5.0/en/multiple-column-indexes.html
So, an index on (receiver_id, sender_id) may be used by predicates on
both columns or receiver_id
3:50 AM
To: Ananda Kumar
Cc: James Tu; MySQL List
Subject: Re: index, unique index question
A composite index on both columns may be used by queries involving
either both columns, or the first column in the index.
http://dev.mysql.com/doc/refman/5.0/en/multiple-column-indexes.html
So, an index
questions? Check the forum!
http://www.databasedevelopmentforum.com
-Noah
-Original Message-
From: Kristian Myllymäki [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 14, 2007 3:50 AM
To: Ananda Kumar
Cc: James Tu; MySQL List
Subject: Re: index, unique index question
A composite index on both
-
From: Kristian Myllymäki [mailto:[EMAIL PROTECTED]
Sent: Tuesday, August 14, 2007 3:50 AM
To: Ananda Kumar
Cc: James Tu; MySQL List
Subject: Re: index, unique index question
A composite index on both columns may be used by queries involving
either both columns, or the first column
I have a table that has a Primary key using the 'id' column.
The table also has a 'receiver_id' and a 'sender_id'.
I have queries that will use
(1) WHERE receiver_id =
or
(2) WHERE sender_id=
but never WHERE receiver_id='###' AND sender_id='###'
Also, I want the receiver_id/sender_id pair to be
Hi James,
Since your queries have both receiver_id and sender_id in the where
condition and u want this to be unique, just create one combined unique
index on both these columns.
Do this at db level will give you much better options, performance, rather
than doing at code level, which might
On Sat, Feb 24, 2001 at 09:43:45AM -0700, Karl Stubsjoen wrote:
I'm trying to understand MySQL indexing but am having trouble
understanding the differnences (and when to use each) between
Primary Key, Key, Unique, an Index. Can you help?
Index and Key are the same.
A Primary Key is
Hello,
I'm trying to understand MySQL indexing but am having trouble understanding the
differnences (and when to use each) between Primary Key, Key, Unique, an Index. Can
you help?
Thank you!
On Sat, Feb 24, 2001 at 09:43:45AM -0700, Karl Stubsjoen wrote:
I'm trying to understand MySQL indexing but am having trouble
understanding the differnences (and when to use each) between
Primary Key, Key, Unique, an Index. Can you help?
Index and Key are the same.
A Primary Key is a
on a related but slightly different example, what would happen if you had a
Primary Key consisting of 2 columns a b (so the pkey enforces a unique
combination of a b) and then created an index on one of the columns eg b.
Would the index on b have any effect, or does a primary key on 2
Is there any idea in using both a INDEX() and UNIQUE() index on the same
table field ?
-
Before posting, please check:
http://www.mysql.com/manual.php (the manual)
http://lists.mysql.com/ (the list archive)
38
Subject: INDEX() / UNIQUE()
Is there any idea in using both a INDEX() and UNIQUE() index on the same
table field ?
-
Before posting, please check:
http://www.mysql.com/manual.php (the manual)
http://lists
PROTECTED]
Subject: Re: INDEX() / UNIQUE()
Why would you want to? UNIQUE() is an INDEX() the only difference being
that UNIQUE can not have the same value a number of times whereas INDEX you
can.
- Original Message -
From: "Jacob Friis Larsen" [EMAIL PROTECTED]
To: [EMAIL PROTE
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