The tag has no wiki summary.

learn more… | top users | synonyms

3
votes
1answer
72 views

When is mariadb creating tmp tables?

I have found, that copying to tmp table is taking most of the time of a slow query, that I wanted to optimize. I watched the output of 'profiling' in a terminal. This happens on a pics table with 6000 ...
1
vote
1answer
33 views

Slow postgresql query with pagination and filtering

For the DB in question, I have followed the advice of Pagination Done the PostgreSQL Way That is, results are being paginated on a composite index with a definite sort order. Now, my problem is ...
0
votes
1answer
23 views

Join Operation using index defined?

I need to optimize some queries with several joins. I plan to create some indexes for these queries. I am currently using MariaDB with TokuDB storage engine. Should I expect the indexes for the join ...
0
votes
0answers
27 views

Ascending and descending semi-joins

I was reading about semi-joins for a research paper implementation. i have to select the best way to reduce tables in a distributed environment for a particular query. for that it has 2 different ...
0
votes
0answers
39 views

merge in cursor is slow ,any alternative for that in oracle 11g

we have a requirement like below. we need to update one table A from another table B based on joining criteria. both tables are having porper joining columns. Table A has 2 columns missing_order_cw ...
1
vote
2answers
89 views

Index optimization for table that is truncated every day

I have a bunch of tables in SQL Server 2012. These tables are fed by other tables. Every day there are routines that truncate (fully delete) them and run queries whose result are inserted into them. ...
1
vote
1answer
38 views

Should I drop this column or is there a query that can achieve a results table without duplicate columns?

I use a column named active in several of my database tables to adjust whether a particular entry/row/user/etc should be included in future query result tables instead of deleting the information. ...
0
votes
1answer
37 views

MySQL: What is SQL profiler, does it different for MySQL?

Whenever SQL profiling comes in mind, focus goes to two below sections: GUI tools like - MONyog, Neor Profile SQL set profiling =1; Execute Query; show profiles; show profile; I am really confuse ...
0
votes
0answers
17 views

Get tp.address_from and tp.address_to from travel_point table

I'm building a view for get tp.address_from and tp.address_to but I can't get this works. This is the query I'm working on: SELECT `tp`.`address_from` AS `address_from`, `tp`.`address_to` AS ...
0
votes
0answers
54 views

same query different servers,different execution plan and time

I have this query and it runs less than 2 minutes on Test but on Prod it takes 10 minutes. Both are the same version,CPU,RAM,OS the same. I have four tempdb files on Prod but one one Test. I ...
0
votes
1answer
74 views

Help optimizing very slow mySQL query

I have a query which takes about 6 secs to execute. SELECT * FROM (SELECT ord.ID, op.name AS prodName, op.code, ord.date, ord.email, op.total, stat.ID AS statusID, stat.value AS status, ...
-1
votes
1answer
35 views

60M+ InnoDB table simple query performance HELP

I know it is a repeated question but really need help here. What can I do to improve the performance of this query? Considering that I have no freedom to change system variables/configs :( Thanks in ...
0
votes
0answers
142 views

MariaDB 5.5 vs MySQL 5.7 query optimizers

I have a query that optimizes differently in MariaDB 5.5.37 and MySQL 5.0 and MySQL 5.7. When poorly optimized it takes about 400 seconds to run, but on MySQL 5.7 which optimizes it differently, it ...
5
votes
3answers
121 views

Find the user with closest taste of mine

I trying to write in SQL the following requirement: Each user can rate as much films as they like. (1= I don't like, 5=I love it) And the system should provide to the current user a list of films ...
1
vote
0answers
40 views

Need help in optimizing a Slow Query

I am using userpoints module to provide points for different actions that they do on my site. mysql> desc userpoints; +-------------+---------+------+-----+---------+----------------+ | Field ...
2
votes
2answers
128 views

Optimize a query on two big tables

I have a very important query in my system that is taking too long to execute due to huge amount of data on tables. I'm a junior DBA and i need the best optimization I can get for this. Tables have ...
0
votes
1answer
62 views

How to prepare executon plan for given sql query on a server with 4 processors (Oracle database)

4 processors means the query runs in parallel. Select /*+ parallel(4) */ T1.A FROM T1,T2,T3 WHERE T1.A = T2.A AND T1.B=T3.B AND T1.C=T3.C Tables T1,T2 and T3 have 4,8, and 16 partitions ...
0
votes
1answer
211 views

Why query optimizer doesn't use negative filter index

I have a table that has following structure, as you can see, there are one clustered index and two non-clustered indexes, one non-clustered index is IX_ParentId_Include, and another one is ...
2
votes
1answer
217 views

Most efficent DELETE Method

I must choose between three possible DELETE methods in SQL Server. The table: RawData stays at around 500GB. Here is the table: CREATE TABLE dbo.rawData ( rowId INT IDENTITY PRIMARY KEY, ...
4
votes
1answer
121 views

Logical optimization of joins and selections

I am studying query optimization. I have read that it might be preferred to apply relational selections before a logical join operation. Is there a scenario where joining first and then applying ...
1
vote
0answers
346 views

Truncating Table Partitions Containing Data and Global Indexes

I have to truncate a partition (392,000 records) of a table with 20.000.000 records. At the moment, I'm making a truncate table and rebuilding indexes. But the table has 37 indexes and it takes 20 ...
0
votes
1answer
191 views

sql-server optimize query with lots of null checks

I have a query such as: select something from somewhere join stuff on condition join more_stuff on condition where somewhere.sometime is null and somewhere.someone is null and stuff.whatever is null ...
2
votes
0answers
31 views

Set default fields

Is there a way to inform the database that some fields are default (have always the same value) so that I don't need include them in all my queries? Suppose: Select ... where f1=a, f2=b, f3=c, f4=d ...
1
vote
0answers
75 views

MySQL query with order by decreased performance

Here is my schema: CREATE TABLE `UserMst` ( `UserID` mediumint(8) unsigned NOT NULL AUTO_INCREMENT, `EMailID` varchar(50) DEFAULT NULL, `UserName` varchar(20) DEFAULT NULL, `FullName` ...
0
votes
1answer
58 views

SQL query optmization [closed]

This is one thing I have been trying to read from few days. I am not getting any satisfactory explanation anywhere. Tried surfing some blogs and videos in youtube. Appreciate if anyone one can throw ...