Tagged Questions
2
votes
0answers
32 views
How can one improve the performance of a query that selects on a low cardinality column in MySQL?
I have a "State" column that has a low cardinality (three possible value), on which most of my queries perform an equality selection (WHERE col = 'blah') AFAIK you need something like a bitmap index ...
1
vote
2answers
166 views
Query Performance Tuning on a huge table
I have the following table Transactions. The table looks like this:
CREATE TABLE [dbo].[Transactions](
[TransactionID] [bigint] IDENTITY(1,10) NOT NULL,
[PlayerID] [bigint] NOT NULL,
...
1
vote
1answer
61 views
Performance impact of including result column in indexed columns
I have a database (in MySQL, using InnoDB) that I am using for texture identification in a 3D image. In it, there will be a table of texels(texture pixels) with hue included, in the form of:
texelid ...
1
vote
2answers
106 views
How to optimize this query?
Query:
Select *
from `t_event`
where `create_user_id`=7
and (`event_create_date`)=('2012-12-18 00:00:00')
and `event_type_cd`=11
and `domain_id` =602
and `job_id` =1
limit 1
Table structure:
...
1
vote
1answer
131 views
Simplify and optimize a complex query
Our site has a chronological event feed that uses MySQL. We have noticed that some of the queries tend to run for quite a bit longer than others. For example, some queries for our heaviest users take ...
1
vote
1answer
96 views
What would be a optimal index for this query in mysql
I'm trying to optimize this query.
SELECT * FROM sales_reps
WHERE account_id = 1
AND (state = 'enabled')
AND (clients >= 5 OR revenue >= 10000)
ORDER BY name, platform, client_group, ...
1
vote
1answer
90 views
What is the best relationship model for high performance?
I want to model a relationship between Customer and Transaction.
However, because Customer is only described by a unique string and no extra info, I have two possibilities to implement it in the ...
5
votes
2answers
466 views
How can I improve the speed of a query on a 20 million+ row table?
I have a query that is used for getting internet traffic statistics of certain IP addresses.
There are separate IP address fields for hosts and blocks of IPs called assignments. The data is stored ...
2
votes
1answer
99 views
Where to place non clustered index
Execution plan clearly showing that one of my table used in query is useing Clustered Index Scan. From this node, how can i guess that which columns should be part of my non clustered index key and ...
0
votes
3answers
1k views
Will more indexes on a table affect performance? [duplicate]
Possible Duplicate:
How do indices impact query performance?
How to know when/if I have too many indexes?
Say ‘X’ report using some "where" condition in the statement so we are creating ...
1
vote
1answer
447 views
Index Strategies on Text or NVARCHAR(MAX) Fields
I have the following query (simplified for question) I'm trying to speed up for a read only DB ...
SELECT
[sysid]
,[Date]=CONVERT(CHAR, DATEADD(D, [date], '1800-12-28'),101)
,[From]=[from_addr] ...
0
votes
1answer
95 views
Creating Indexes to optimize query
I have this query and I want to increase its performance by adding appropriate Indexes.
DELETE
FROM MYTAB1
WHERE MYID1 IN
( SELECT MYID2 FROM MYTAB2 );
I am not familiar with the ...
3
votes
2answers
246 views
Why is a secondary index chosen over a clustered index for SELECT COUNT(*) …?
In this query:
select count(*) from largetable;
a secondary index is chosen:
mysql> explain select count(*) from largetable;
...
