Please provide SHOW CREATE TABLE for the two tables.
Plan A:
Would the anti-UNION problem be solved by hiding the UNION in a subquery? The
outer query would simply return what the UNION found.
Plan B:
Insert every row twice into expression_expression -- (e1,e2) and also (e2,e1).
Then, you need
How fast does this run?
SELECT A.*
FROM A
JOIN B ON B.A_ID = A.id
WHERE B.name LIKE 'X%';
Turning a subquery into a JOIN usually improves performance. (The main
exception is when the subquery consolidates data via GROUP BY, DISTINCT, LIMIT,
etc.)
> -Original Message-
> query B can not used any key because 'like' never can use any key
Not true. LIKE without a leading wildcard is optimized like a BETWEEN.
> -Original Message-
> From: Reindl Harald [mailto:h.rei...@thelounge.net]
> Sent: Friday, July 06, 2012 8:58 AM
> To: mysql@lists.mysql.com
> Subject
Shawn, can you explain why one of the links on that page is broken?
http://bugs.mysql.com/bug.php?id=14248833
Says
"No such bug #14248833 or bug is referenced in the Oracle bug system."
> -Original Message-
> From: Shawn Green [mailto:shawn.l.gr...@oracle.com]
> Sent: Monday, July
Here's a different way to "smooth" numbers. It uses an exponential moving
average instead of "the last 5".
SELECT Time,
@a := (9 * @a + Value) / 10 AS moving_avg
FROM tbl
JOIN ( SELECT @a := 0 ) AS x;
Notes:
* Make 10 larger or smaller, depending on how smooth you want it.
* 9=10-1
*
If the collation for ksd in ..._ci, then it is "case-insensitive", and you can
get rid of both calls to LOWER().
> -Original Message-
> From: Carsten Pedersen [mailto:cars...@bitbybit.dk]
> Sent: Tuesday, July 10, 2012 11:22 AM
> To: Darek Maciera
> Cc: mysql@lists.mysql.com
> Subject: Re
> 120711 8:12:22 [ERROR] /usr/sbin/mysqld: Incorrect key file for table
> './mydb/wp_posts.MYI'; try to repair it
> 120711 8:12:22 [ERROR] Got error 126 when reading table './mydb/wp_posts'
Well, do REPAIR TABLE wp_posts;
> -Original Message-
> From: J M [mailto:jerom...@gmail.com]
> S
Did you really mean to have start/end_date in both tables? Are the values
identical? If they are, that is another reason to use an INT UNSIGNED
AUTO_INCREMENT.
Done correctly, JOIN can usually run faster than two separate queries.
SELECT d.*
FROM item_detail AS d
JOIN item_spine AS
Things like that are hard to optimize. If you have no overlapping ranges, then
this will be much more efficient:
http://mysql.rjweb.org/doc.php/latlng
> -Original Message-
> From: Doug [mailto:d...@hacks.perl.sh]
> Sent: Thursday, July 12, 2012 7:03 PM
> To: mysql@lists.mysql.com
> Sub
On 16/07/2012 17:39, Rick James wrote:
How many rows? If 1K, it does not matter. If 1 billion, we need to
discuss in more detail. Let's assume 1M...
Around 1M in the item_spine table and 10M in item_detail.
Dates should be stored in DATE datatype, which is 3 bytes. Your GUID
is non-standa
What does "simultaneous connection" mean? 1000 open connections is reasonable;
10 _active_ connections is reasonable; 1000-1 queries/second may be
reasonable.
If these are readonly connections, then you could set up any number of Slaves.
100 Slaves with 1000 connections each would achieve
How many rows? If 1K, it does not matter. If 1 billion, we need to discuss
in more detail. Let's assume 1M...
Dates should be stored in DATE datatype, which is 3 bytes.
Your GUID is non-standard, but should probably be stored in CHAR(6) CHARACTER
SET ascii, unless it is expected to have non-
I have a MySQL table (call it, say, item_spine) which contains three
fields which, together, form a unique key. These three fields are a
guid, a start date and an end date. The guid is alphanumeric (a
fixed-length six characters) and the dates are ISO format dates
(-MM-DD).
I also have an
We are looking at installing an NDB cluster and are looking for someone to
assist us in setting it up.
Thanks,
Carl
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