If you have a table with columns A & B, and might do a where on A or B,
or an order by A, B, would single column indexes on A and B suffice or
would performance on the order by query be improved by an index on A,B?
Thanks
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I don't have a direct answer for you, just some thoughts:
* traditionally, "localhost" is thought of as an alias for 127.0.0.1
* mysql however, tends to not interpret it like when connecting to the local
server and instead tries to connect to the socket
* to force mysql client to connect over
- Original Message -
> From: "Alex Schaft"
>
> If you have a table with columns A & B, and might do a where on A or
> B, or an order by A, B, would single column indexes on A and B suffice
> or would performance on the order by query be improved by an index on
> A,B?
Depends on usage :-)
Just to clarify having key indexes of (a,b) or (b,a) have no difference ?
On 11 Oct 2011, at 09:36, Johan De Meersman wrote:
> - Original Message -
>> From: "Alex Schaft"
>>
>> If you have a table with columns A & B, and might do a where on A or
>> B, or an order by A, B, would single
The difference is based on the relative frequency of queries where a is
important vs. where b is important. Either way, what will happen is that the
index scan will isolate the first item mentioned, then scan the result set
to isolate the second term.
e.g.
SELECT * FROM someTable WERE a = someVal
> Just to clarify having key indexes of (a,b) or (b,a) have no difference ?
They DO.
See it as lookup table which starts with 'a' in the first case, and 'b' in the
second one. Looking for anything that matches 'b' for an index (a,b) requires
a full scan as you don't know 'a', likewise searchin
On 2011/10/11 02:22 PM, Rik Wasmus wrote:
Just to clarify having key indexes of (a,b) or (b,a) have no difference ?
They DO.
See it as lookup table which starts with 'a' in the first case, and 'b' in the
second one. Looking for anything that matches 'b' for an index (a,b) requires
a full scan
On 2011/10/11 02:30 PM, Alex Schaft wrote:
On 2011/10/11 02:22 PM, Rik Wasmus wrote:
Just to clarify having key indexes of (a,b) or (b,a) have no
difference ?
They DO.
See it as lookup table which starts with 'a' in the first case, and
'b' in the
second one. Looking for anything that matches
> Next question. If you have the two separate indexes and then do two
> queries, one for a and one for b. If you then get a list of unique id's
> of both, would it be faster to create an intersection yourself rather
> than have the server do the legwork?
If you only have 2 unrelated indexes on a &
In this instance would you create four indexes key(a) key(b) key(a,b) key (b,a)
? Or is the decision based on the query response time ?
On 11 Oct 2011, at 13:40, Rik Wasmus wrote:
>> Next question. If you have the two separate indexes and then do two
>> queries, one for a and one for b. If you
> In this instance would you create four indexes key(a) key(b) key(a,b) key
> (b,a) ? Or is the decision based on the query response time ?
Depends on the data and usage, but probably I'd go for a index(a,b) &
index(b,a) if reads heavily outnumber writes. As index(a) is covered by
index(a,b), a
I have the following query:
SELECT COUNT(signature) AS count, MAX(timestamp) AS maxTime,
INET_NTOA(src_ip), map1.cc as src_cc, INET_NTOA(dst_ip), map2.cc as
dst_cc, signature, signature_id, ip_proto FROM event LEFT JOIN
mappings AS map1 ON event.src_ip = map1.ip LEFT JOIN mappings AS map2
ON event
On 10/11/2011 8:11 AM, Paul Halliday wrote:
I have the following query:
SELECT COUNT(signature) AS count, MAX(timestamp) AS maxTime,
INET_NTOA(src_ip), map1.cc as src_cc, INET_NTOA(dst_ip), map2.cc as
dst_cc, signature, signature_id, ip_proto FROM event LEFT JOIN
mappings AS map1 ON event.src_ip
- Original Message -
> From: "Rik Wasmus"
>
> Depends on the data and usage, but probably I'd go for a index(a,b) &
> index(b,a) if reads heavily outnumber writes. As index(a) is covered
> by index(a,b), and index(b) by index(b,a), we don't need to add those,
> which saves time on modifi
Is there any reason why you are using ports and not the native 64-bit DMG from
mysql.com?
http://www.mysql.com/downloads/mysql/#downloads
I run the latest version (5.5.15) on my macbook running lion and the install
goes without a hitch.
Brandon
On 10/10/2011 07:34 PM, Tim Johnson wrote:
I f
Hi Brandon,
MacPorts is practically dead. I tihnk you will have more luck with
http://mxcl.github.com/homebrew/
I have not built mysql with it though on lion.
regards,
Vladislav
On Tue, Oct 11, 2011 at 3:56 PM, Brandon Phelps wrote:
> Is there any reason why you are using ports and not the na
I only use ports for a very few number of apps, such as irssi, newer versions
of perl, etc.
I was recommending the OP use the DMG installer, as it comes with everything
necessary, including startup scripts.
-Brandon
On 10/11/2011 10:05 AM, Vladislav Geller wrote:
Hi Brandon,
MacPorts is pra
Hey, welcome to the lists,
Be mindful that your query is using 2 tables and 'SELECT *'.
On Tue, Oct 11, 2011 at 4:11 PM, Biz-comm wrote:
> I am trying to write a query for a web page that shows a list of users in a
> particular group.
>
> There are 3 tables:
> pm1_users that uses UserID
> pm1
- Original Message -
> From: "Andrew Moore"
>
> Be mindful that your query is using 2 tables and 'SELECT *'.
Which probably means not so much to someone who doesn't even know what a join
is :-)
Have a look at http://www.w3schools.com/sql/sql_join.asp .
--
Bier met grenadyn
Is als
* Tim Johnson [111010 15:37]:
> I familiar with mysql on linux, as of late - ubuntu.
> I am installing mysql on a mac mini, with the Lion - osx 10.7
> operating system.
>
> mysql-server was downloaded and built with macports.
> Following instructions included has not resulted in a successful
> st
Thanks for the pointer. Digging out reference books to learn how to do a join.
:-)
On Oct 11, 2011, at 11:23 AM, Johan De Meersman wrote:
> Which probably means not so much to someone who doesn't even know what a join
> is :-)
>
> Have a look at http://www.w3schools.com/sql/sql_join.asp .
R
Tim,
Just a reminder, as I am not sure if it is documented or not; After you get
MySQL up and running via the DMG package be sure to install the System
Preferences pane (it didn't use to install by default, not sure if it does now)
which should be one of the icons you get when the DMG first o
* Brandon Phelps [111011 07:43]:
> Tim,
> Just a reminder, as I am not sure if it is documented or not;
> After you get MySQL up and running via the DMG package be sure to
> install the System Preferences pane (it didn't use to install by
> default, not sure if it does now) which should be one o
On Tue, Oct 11, 2011 at 10:37 AM, Peter Brawley
wrote:
> On 10/11/2011 8:11 AM, Paul Halliday wrote:
>>
>> I have the following query:
>>
>> SELECT COUNT(signature) AS count, MAX(timestamp) AS maxTime,
>> INET_NTOA(src_ip), map1.cc as src_cc, INET_NTOA(dst_ip), map2.cc as
>> dst_cc, signature, sig
- Original Message -
> From: "Paul Halliday"
>
> Is it OK to keep adding to those joins? In a view there could be say
> 50 countries. The user can keep on adding more to exclude. So would I
> just expand on the ANDs like so:
>
> AND map1.cc !='CA' AND map1.cc !='US' AND map1.cc !='LV'...
Hello,
I have a problem with the following query:
SELECT subject_identifier, COUNT(*) FROM asr_sentence_score WHERE
total_words = correct_words GROUP BY subject_identifier;
OutPut:
++--+
| subject_identifier | COUNT(*) |
++--+
|
Thanks for the information. One final question in what ways should we use
EXPLAIN EXTENDED statement to help improve our query performance.
On Tue, Oct 11, 2011 at 2:51 PM, Johan De Meersman wrote:
> - Original Message -
> > From: "Rik Wasmus"
> >
> > Depends on the data and usage, but
On 10/11/2011 12:26 PM, Paul Halliday wrote:
On Tue, Oct 11, 2011 at 10:37 AM, Peter Brawley
wrote:
On 10/11/2011 8:11 AM, Paul Halliday wrote:
I have the following query:
SELECT COUNT(signature) AS count, MAX(timestamp) AS maxTime,
INET_NTOA(src_ip), map1.cc as src_cc, INET_NTOA(dst_ip), ma
Generally when one has this problem one joins this query with something from
which one can get the whole list, something like this:
SELECT identifier, IFNULL(c, 0) AS Good,
(query with COUNT) AS P RIGHT JOIN table-of-identifiers ON P.identifier =
table-of-identifiers.identifier
The "c" is
I find that, when under Vista the MySQL daemon has been shut down, by giving
the command
start mysqld -b"%CD%"
in the root directory where MySQL 5.5.8 (the version running on this computer)
has been stored from an instance of command prompt with administrator authority
issued by a user that lack
so why do you search a list of known bugs instead update your mysql?
5.5.8 is the FIRST ga version of 5.5
currently we have 5.5.16
no, i do not know if 5.5.16 is solving your problem but hwat i know
is that the updates were bot relöeased just for fun
Am 12.10.2011 06:28, schrieb Hal?sz S?ndor:
>
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