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Questions tagged [database-tuning]

deals with optimizing the performance of a database. It can be about file design, and selection of the DBMS, OS and platform.

Database tuning is about maximizing the performance of a database. It can include hardware, software, file system, OS and DBMS selection. See the wikipedia article for more.

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MYSQL Query Tuning for updating data of one table by data of next table

I do have two tables: 1. PersonAddressList [About 5,000 records] Columns: ID int TITLE varchar CITY varchar 2. CityList [About 5,000 recods] Columns: ID int City_Name varchar City_State int //[RK to State] Previous designer…
KoolKabin
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Query is extremely slow due to Lazy Index Spool

On a powerful machine the SQL Server query is running too slowly. In the execution plan I can see that most of the time spent goes to a "Lazy Index Spooling" process. In the query some aggregate functions are being used for calculation of values.…
Alexander
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SQL Server database tuning for a self-join without denormalization

I have a TPC-H database and workload and I'm dealing with the following query (query 21 in TPC-H): SELECT TOP 100 S_NAME, COUNT(*) AS NUMWAIT FROM SUPPLIER S JOIN NATION N ON S.S_NATIONKEY = N.N_NATIONKEY AND N.N_NAME = 'JORDAN' JOIN…
Radim Bača
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Tuning up a SQL query, (query optimization)

I am trying to tune a SQL query which have IN clause in the query. I tried replacing IN with Join and looked at the query plans.Both are looking similar in execution times, but the result is different.Can someone help me regarding this? I am using…
S. N
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SQL Server 2008 Index Fragment

I have a table with more than 5,000,000 records. The SQL Query performance on this table impacted by index fragment a lot. Looks like everyday, the fragment increasing so fast. I need to rebuild index every day for user's complain. How to figure…
KentZhou
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postgresql immutable read workload tuning

I have a table where the non-primary key columns are deterministic given the primary key. I think this could be pretty common, for example a table representing memoization/caching of an expensive function, or where the primary key is a hash of the…
user239558
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Mysql server huge memory consumption

On Ubuntu, executing the "top" command shows that mysqld constantly uses 61.9% of the memory.(when idle). I ran "show processlist" on the mysql server and it is idle. Can anyone explain what might be happening?
Ravi
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How to empty or clean some of the system variables value after mysql database is rebuild?

For testing, I almost rebuild the newly designed MySQL database every day recently, I also have a Php application based on that. For my understanding, some of system variables value has been accumulated in every rebuild, such as: mysql> show global…
user1342336
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Why there are 25 'checking permissions' statuses when showing query profile in mysql

After SET PROFILING=1, I ran a multiple joins query (multiple left joins, and inside every left join is a subquery from several same tables). See below the time spent in every status after running twice of this query: mysql> SHOW PROFILE SOURCE FOR…
user1342336
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Database server eating more than 100% from CPU

My database server eating more than 100% from CPU when i run mysqltuner its given following recommendation ]# sudo ./mysqltuner.pl >> MySQLTuner 1.2.0 - Major Hayden >> Bug reports, feature requests, and downloads at…
Piyush Bhardwaj
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How to partition by mysql table into two layers?

I want to partition a table this code will show you the structure of the table. the table currently have about 5 million records. I need the MySql partition syntax this table like so Main partition is the filed trigger_on Partition type range "by…
Jaylen
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What impact do statistics have on a table

When I add an index to a table there is an obvious benefit in searching, however there is also a cost involved with insert/update/delete statements as the index needs to be updated. If i create a new statistic on a table, does it incur similar costs…
Greg
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DB Tuning Advisor for MSSQL 2008 Express

Is there some way to use Tuning Advisor for SQL Express? Is there some kind of tuning tools for Express? For those, who is not DBA, but still want to improve performance of their website?
udar_molota
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Add index and partitioning for Postgress table

I have this table in PostgreSQL database with 6 millions for rows. CREATE TABLE IF NOT EXISTS public.processed ( id bigint NOT NULL DEFAULT nextval('processed_id_seq'::regclass), created_at timestamp without time zone, word character…
Peter Penzov
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Oracle expdp and impdp command?

I want to know the Oracle expdp and impdp command for sys user and scott/tiger user for entire database or a particular table.I will be grateful if you share me the script of expdp and impdp.I also want the script of recovery of a entire database…
tanayals
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