Tagged Questions
0
votes
0answers
46 views
MySQL query optimization when no row is returned
I am using explain to figure out what is happening in my query which is:
explain select t from c where u1_id = 1 group by t;
I see "Using where" in the Extra column of the resultset. But this only ...
0
votes
1answer
44 views
Optimizing ORDER BY for simple MySQL query
I'm trying to optimize this really simple query, and it gives me grief for a day now :(
Seems pretty straightforward, I need to select with a JOIN from 2 tables, and get top X results sorted in a ...
0
votes
1answer
46 views
MySQL database schema design help needed
I am developing a PHP application expecting millions of records both parent and children. My goal is to design an optimized database design to achieve high speed and performance.
This application ...
0
votes
2answers
151 views
optimize big sql query
My query has to return a statistics for example for march containing productname and price and its sidedishes (1:n relation) with the right price of each sidedish and the right tax for each sidedish ...
1
vote
2answers
76 views
Database and query optimizacion
I have a database containing three tables: tbl_database (main table is the primary), tbl_cmdatabase and tbl_blacklist. The three tables share the same structure but differ in the number of records ...
0
votes
1answer
46 views
Faster joining on 'most recent' related rows
I have a bug tracking application. The bug table stores very little,
because every state change to a bug happens by adding a comment. For
example, the current state of a bug is determined by the state ...
2
votes
0answers
134 views
MySQL: Improve performance for one row insert into table with unique constraint
I have a table with ~ 40 mil records, with a unique index on the url collumn, of type varchar(255).
Now the insert speed is about 30/s, is this expected? how could I improve it?
I can't use bulk ...
2
votes
1answer
223 views
Mysql - show results from 3 tables excluding NULL or EMPTY values for certain fields
I have 3 simple tables with polls, users and votes. I'd like to show all polls ordered by clean count of votes (sometimes either poll_id or user_id don't get inserted).
Furthermore I'd like to show ...
1
vote
2answers
133 views
How do I force a JOIN to use a specific index in MySQL?
I have a query that JOINs 2 tables; lineitem and part,
select
sum(l_extendedprice* (1 - l_discount)) as revenue
from
lineitem force index for join (l_pk),
part
where
(
...
0
votes
2answers
191 views
Slow query with straight_join for small result
I have a performance-problem with a query in my application and I don’t understand the behavior of mysql.
The query consists of different joins, especially the join to the mentioncache-table. If the ...
2
votes
1answer
186 views
Oracle 10g using collection with sql
I have a stored procedure that takes collection of objects. (TABLE OF MyCustomType). Inside the procedure I'm trying to join this parameter with real tables.
For example, something like
create or ...
2
votes
3answers
442 views
MySQL optimization - year column grouping - using temporary table, filesort
I have a transactions table which is having 600,000 records, I need to list the count for the dashboard on financial year basis. The table used is MyISAM. I tried adding index for the transaction date ...
1
vote
1answer
421 views
Slow complex query with group/order
I have a problem with a very important query in my application.
It is very slow when adding group and order to it.
So the full query is:
SELECT
m.id,
m.title,
m.title_text,
...
1
vote
2answers
304 views
Slow mysql fulltext query
I have a little problem with the performance of a mysql-query which uses a fulltext index.
The following query
SELECT Mention.id
FROM mentions AS Mention
WHERE (MATCH (`Mention`.`title_text`, ...
1
vote
1answer
72 views
Optimising query on view that merges similar tables with a clear discriminator
Using PostgreSQL 8.4, I have a number of tables that have a very similar structure, but that belong to different categories:
CREATE TABLE table_a (
id SERIAL PRIMARY KEY,
event_time TIMESTAMP ...
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 ...
2
votes
1answer
94 views
How to know what to investigate and how for a VERY slow stored procedure
I have inherited a large and slow stored procedure and it's giving me a nightmare:
I'm not a DBA, although I have some knowledge, but I don't know where to start to identify this bottleneck.
I have ...
1
vote
1answer
113 views
query optimization delete nested query [closed]
Can the following query be optimized ?
DELETE FROM COLOR_TAGS
WHERE COLOR_PROJECTID = $id
AND NoteID IN(
SELECT ID FROM note_note
WHERE BibID=$bid AND isdel=0);
9
votes
4answers
770 views
Is it possible to increase query performance on a narrow table with millions of rows?
I have a query that is currently taking an average of 2500ms to complete. My table is very narrow, but there are 44 million rows. What options do I have to improve performance, or is this as good as ...
3
votes
3answers
193 views
optimizing a compare query
Suppose I have two tables, A and B, and I know that size(A) = size(B). I want to confirm that the data in both tables is the same in three given columns, suppose they are X, Y, and Z (there are no ...
2
votes
1answer
632 views
How to speed up mysql query?
I have query :
SELECT
`school`.`ARCO_name`,
`student-`.`ClassSize_7`,
`student-`.`ClassSize_8`,
`degree_o`.`degree_code`,
`accredit`.`full_faculty_3`,
...
1
vote
0answers
500 views
SQL query optimization in Prestashop e-Commerce solution
I'm working on a layered navigation module within Prestashop e-Commerce solution.
I'm trying to optimize a SQL query which creates a temp table during execution. I think this is creating a ...
2
votes
1answer
176 views
datetime index skipped for same query different params
I am running two queries with same query but different parameter and one of them is extemely slow while the other is fast. Both the results are alomost the same. (500 and 575)
Any idea why it skips ...
1
vote
2answers
143 views
Does this cause overhead ? Select name from User where user_name LIKE '%alex%'
I'm wondering if this statement can cause real overhead if many concurrent users
send the same request to mySQL InnoDB storage engine. Let's say I have a table that
has the user_name, and someone want ...
3
votes
1answer
207 views
Measuring the relative performance of queries given the assertion that “cost” isn't reliable
The cost field is a comparative cost that is used internally to determine the best cost for particular plans. The costs of different statements are not really directly comparable.
Source
Does ...
3
votes
1answer
132 views
How to search for an ID and its descendants in this query?
I have the following tables:
Project Unit
------------- ---------------
ID | IDUnit ID | IdParent
I have to select all projects that have the IDUnit ...
8
votes
1answer
659 views
Monumental difference in execution time between queries when using RECOMPILE query hint
I have two almost identical queries running on the same SQL Server 2005 instance:
The first one is the original SELECT query as generated by LINQ (I know, I know... I'm not the application ...
5
votes
4answers
967 views
MySQL subquery slows down drastically, but they work fine independently
Query 1:
select distinct email from mybigtable where account_id=345
takes 0.1s
Query 2:
Select count(*) as total from mybigtable where account_id=123 and email IN (<include all from above ...
