database-performance Questions
9
I want to store large amount (~thousands) of strings and be able to perform matches using wildcards.
For example, here is a sample content:
Folder1
Folder1/Folder2
Folder1/*
Folder1/Folder2/Fold...
Phreno asked 22/2, 2013 at 12:55
2
Solved
Would it generally be faster to read from a table where there are no varchar or other variable length data stored? In MySQL, this is faster because it can calculate exactly where a row will be stor...
Monophonic asked 14/12, 2010 at 10:45
4
I am building a comment system, where a comment can have many replies.
If I were to implement this in mysql, I would build a comments table, and have the columns:
comment_id,
parent_comment_i...
Faris asked 3/2, 2013 at 9:37
1
Solved
I found that OrientDB is too slow (at least much slower than Neo4j) even on relatively small (150K) datasets when searching records by text pattern despite the presence of indices.
For example I h...
Direct asked 28/1, 2013 at 15:47
2
Solved
I have a partitioned table in MySQL that looks like this:
CREATE TABLE `table1` (
`id` bigint(19) NOT NULL AUTO_INCREMENT,
`field1` varchar(255) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,...
Durkheim asked 19/1, 2013 at 12:2
1
Solved
Does the multiplication factor of a column's length somehow influence the database performance?
In other words, what is the difference between the performance of the following two tables:
TBL1:
...
Ripping asked 17/1, 2013 at 8:54
2
I have a problem with the speed of a query in Firebird. The slowness is in the sorting and distinct.
If I try the query in MySQL then he is one second faster.
Firebird -> 1,3s a 1,6s
MySQL -> 0,3...
Markswoman asked 14/11, 2012 at 20:47
1
Solved
I have big table with 22 millions records.
I want to execute next query:
select auto_alerts from alerts_stat where endDate > "2012-12-01"
To improve performance I added BTREE index for endD...
Athome asked 21/12, 2012 at 13:24
1
Solved
I understand that this is very broad so let me give you the setting and be specific about my focus points.
Setting:
I am working with an existing PHP application using MYSQL. Tables almost ...
Darrick asked 19/12, 2012 at 12:8
3
Solved
I have a general question about this. There are many times we want to change data-types of fields or collations when lots of data is inserted before. Consider these situations :
converting varch...
Yser asked 19/12, 2012 at 10:15
2
Solved
My intention is to obtain a paginated resultset of customers. I am using this algorithm, from Tom:
select * from (
select /*+ FIRST_ROWS(20) */ FIRST_NAME, ROW_NUMBER() over (order by FIRST_NAME)...
Paroicous asked 21/11, 2012 at 16:38
3
Solved
I have a table in postgresql that contains an array which is updated constantly.
In my application i need to get the number of rows for which a specific parameter is not present in that array colu...
Ivie asked 25/10, 2012 at 18:48
2
Solved
In MySQL, how to build index to speed up this query?
SELECT c1, c2 FROM t WHERE c3='foobar';
Noonan asked 24/10, 2012 at 14:24
2
Solved
I have query which needs to be dynamic on some of the columns, meaning I get a parameter and according its value I decide which column to fetch in my Where clause. I've implemented this request usi...
Naraka asked 16/9, 2012 at 9:19
1
Solved
I'm using symfony 1.4/propel 1.4 for a project, which was made by other developer earlier. On that project, propel connection is taken by using following code
$con = Propel::getConnection(UsersPee...
Kensell asked 11/9, 2012 at 8:12
8
Solved
I have a data load scenario where I create dynamic sql query to pull data and cache in our service. There is 1 table that contains all product data : ProductHistory (47 columns, 200,000 records + a...
Husbandry asked 20/7, 2011 at 9:55
5
Solved
I have a simple mysql query, but when I have a lot of records (currently 103,0000), the performance is really slow and it says it is using filesort, im not sure if this is why it is slow. Has anyon...
Rodarte asked 27/8, 2012 at 20:14
4
Solved
I have written a daemon processor which will fetch rows from one database and insert them into another for synchronizing. It will fetch rows based on a boolean indication flag sync_done.
My table ...
Regime asked 19/8, 2012 at 7:58
2
Solved
I have a table structure like
comment_id primary key
comment_content
comment_author
comment_author_url
When I fire query like
explain SELECT * FROM comments ORDER BY comment_id
It outputs t...
Asturias asked 12/8, 2012 at 8:51
1
Solved
I've been working on optimizing my project's DB calls and I noticed a "significant" difference in performance between the two identical calls below:
connection = ActiveRecord::Base.connection()
pg...
Tensible asked 18/6, 2012 at 9:8
6
Solved
Is there a keyword or metainformation in SQL Server that'll tell you if TOP took effect?
EX:
Select TOP 5 * From Stuff
RESULT: 5 rows
What is the best way to determine if there would have been ...
Misbehavior asked 13/6, 2012 at 18:30
1
Solved
Consider the following two EXPLAINs:
EXPLAIN SELECT * FROM sales WHERE title != 'The'
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE sales ALL title NULL NULL NULL 41...
Epizoon asked 12/6, 2012 at 0:16
2
Solved
i have a big query (in my query builder) and a lot of left joins. So i get Articles with their comments and tags and so on.
Let's say i have the following dql:
$dql = 'SELECT blogpost, comment, ta...
Raby asked 22/5, 2012 at 12:10
2
Solved
Is this condition sargable?
AND DATEDIFF(month,p.PlayerStatusLastTransitionDate,@now) BETWEEN 1 AND 7)
My rule of thumb is that a function on the left makes condition non sargable.. but in some ...
Rothwell asked 1/6, 2012 at 16:8
1
Solved
I've got a little question: what is the difference in performance between the primary and secondary indexes? what causes this difference?
I'm googling around, and I've seen that secondary indexes ...
Holtz asked 3/5, 2012 at 8:39
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