Performance tuning done by adjusting database parameters or physical layout of the database.

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12
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2answers
942 views

SELECT TOP 1 harms query performance; is there a dba-accessible way to overcome this?

In a production application (C# talking to SQL Server 2014 Standard) there's a query that looks like this, below. Most of the time it runs in milliseconds. But occasionally (for certain values of @Id),...
0
votes
0answers
20 views

Innodb Change Buffer merge

I have been testing the performance of my innodb mysql. I ran a script which inserts and selects one after the other for 100000 times. So according to the change buffer concept, the inserted ...
0
votes
1answer
46 views

What happens when the buffer pool size is insufficient in mysql

Let us assume I run a query for a table whose size is very huge. My buffer pool size is as low as possible. What happens now? whether I will get an error regarding the insufficient space in buffer ...
1
vote
3answers
260 views

MySQL database uses too much CPU

I have a MySQL database which uses too much CPU. I am actually performing benchmarking to the web servers which queries the database. Right now the database is being the bottleneck, it uses too much ...
3
votes
1answer
76 views

What indexing to be used over string columns(text type) with string length around 3000 characters

I am using open source columnar dbms (postgresql+Cstore). I am trying to speed up the response time of queries. My database has tables with strings mostly. String columns contain huge data (up to ...
1
vote
0answers
23 views

Several Data Importation Illogical Latency in MySQL [closed]

I am used to importing a 4GB of data from an .sql file towards a testing server (hardware). I tweaked the database to speed up inserts, and, so far, the script takes 6 hours, more or less. We were ...
3
votes
1answer
230 views

PostgreSQL doesn't use all the RAM it could

I'm having performance issues with my PostgreSQL 9.4.1 server. I have tuned the server using the usual best practices (pgtune + google). Here's the relevant config: # <snip> the default config ...
1
vote
0answers
59 views

Tuning MySQL MyISAM for large joined updates

I have a database with two tables that I would consider small. I need to update values on the larger of the two tables (1,100,000 rows, 75M MYD, 120M MYI) from the join of the two tables. The smaller ...
3
votes
1answer
445 views

Postgres 4x Slower Than It Was

Our Postgres performance has gone down to 1/4 of what it was, and we can't figure out why. We have two machines with identical hardware (let's call them A and B): Intel(R) Xeon(R) CPU E5-4640 0 @ 2....
2
votes
0answers
29 views

Tuning Issue / Temporary Tables

I've got a MySQL database (MyISAM) that handles a lot of read/writes and uses temporary tables quite frequently. Recently it's started having massive load spikes at peak load, and noticed that there ...
0
votes
1answer
42 views

Feasibility of Automated and Continuous Performance Tuning in the future [closed]

First a quick background: I'm a software developer, not a DBA and have been developing for more than 10 years. Recently I had to optimize a stored procedure and had to run execution plans, create/...
0
votes
1answer
76 views

Creating a flexible table containing prices and periodes

I'm creating a system of availability for rooms and with a calendar according to the days, with every day have it's own price. Room Type | 01 | 02 | 03 | 04 | 05 | ... | 31 | -------------...
0
votes
1answer
38 views

Big Size Database and increasing number of users [closed]

Me and my colleagues are using quite big size normalized database. Basically it's used for warehouse management and daily minimum 100 of the user perform data manipulation operations. 80% of the ...
0
votes
0answers
52 views

Mysql - too many Deletion - Insertion

I'm creating cron jobs for my OLAP system. I have a cron job that deletes the records from the summary table first and then insert the records in it again: Say Deleting 1 month records, and ...
0
votes
0answers
320 views

Plesk 12 Debian 7 MySQL CPU usage is too high

I have a problem with MySQL and MySQL CPU usage at Plesk. I have a news site with Joomla, and about 100-150 online user. CPU: AMD Opteron(tm) Processor 6366 HE 3 core Memory: 4GB HDD: 250 GB Plesk 12 ...
0
votes
0answers
240 views

MySQL replication: most important config parameters on slave for performance on master server?

This query is almost the same as this question. But in this case, a configuration to make the master perform faster or just the same. Case We have a Master-Slave setup on a Mysql 5.0.77 - MariaDB 5....
0
votes
0answers
30 views

MySQL 5.5 only use 1 thread and 30% cpu

i have a big issue, every day i need to update or insert like 3.3 milion rows, i have trying to do what ever i can but it still only run like 605 query/s i use VirtualBox so my setup are testing on 1, ...
0
votes
0answers
119 views

Performance issue after reorganizing table in MYSQL

There is MYSQL(5.6.22-log Community Edition) database environment which has databases size varies between 1-40GB and using INNODB storage engine, it's serves for the several number of OLTP based ...
0
votes
1answer
316 views

Large sequence cache in Oracle

There was a situation of 108,368,168 executions along with 7,373s elapsed time for "update seq$ set increment$=:........" statement while loading massive(i.e. populating million rows) data in the ...
1
vote
1answer
57 views

75% of RAM for Innodb_buffer_pool size

I have read many documentation including percona and MariaDB documentation where they recommend setting innodb_buffer_pool_size to 70-80% of RAM. My question is, is that total RAM or available RAM? ...
1
vote
1answer
57 views

Does InnoDB Log Files take RAM space or Disk Space

When I set InnoDB Log File size to 512M, does it take the space (512M * 2) from RAM or the SSD Disk space? When I explored, I can see that the log files are located inside /var/lib/mysql folder. So ...
0
votes
1answer
43 views

Effects of monolothic databases on performance and security?

Please note: although I'm specifically calling out MySQL here, I would also appreciate/entertain generic answers that apply to all/most relational systems. As a developer I don't see the design ...
1
vote
2answers
923 views

Very high load avg for MySQL database [closed]

I have a backend server which response to my clients app, it has more than 20k~25k hit per second and this make my server load average very high, I believe that my MySQL config is not appropriate. In ...
2
votes
1answer
388 views

Postgres query plans and tuning parameters

I have a query for which the explain plan indicates that the cost for using a seq scan is lower than the cost for using an index that I have set up. However the actual time for the query is 20 times ...
0
votes
1answer
349 views

MySQL uses more than 500% of the CPU

Everything was going fine, but since a couple of hours ago MySQL is using from 400% to 550% of the CPU. I'm getting a lot of these errors: 1003 14:03:17 [ERROR] /usr/sbin/mysqld: Incorrect key file ...
2
votes
1answer
209 views

Reading a SQL Server Execution plan

I am very new to any type of tuning but have been learning more.. One of my specific databases one of the problems identified with slow queries are a number of Implicit conversions. It is my ...
0
votes
1answer
963 views

MySQL: Adding innodb_log_file_size in my.cnf causes not starting MySQL service [duplicate]

I checked and found that InnoDB pluginis active. By default, Innodb_log_file_size=5MB. As per the MySQL Documentation, its ideal values range from 1MB to 1/N-th of the size of the buffer pool, where ...
1
vote
1answer
155 views

How do i increase the total MyISAM indexes?

I have just made a check for my server with mysqltuner. -------- Storage Engine Statistics ------------------------------------------- [--] Status: +Archive -BDB +Federated +InnoDB -ISAM -NDBCluster ...
1
vote
0answers
140 views

Tuning MySQL On Azure Windows Server Setup

I have a MySQL 5.5 running on Azure VM Windows Server 2012. Once per second the log db gets about 2K inserts through LOAD DATA INFILE... once a day I need to run stats and when the stats are crunching ...
1
vote
2answers
412 views

Need Help maintaining multiple databases for a multi-tenant application?

i need some information about multiple databases for a multi-tenant application ? I am working on a project in which we are maintaining separate database for every company? The Companies Database ...
1
vote
1answer
277 views

Tuning Mysql and Monitoring

I would like to know if anybody can point me towards a tool/way for MySQL database tuning. Actually the tuning of my.cnf is like below: My database engine is MyISAM | Mysql 5.1.73 key_buffer = ...
1
vote
0answers
744 views

Optimization Tips For MYSQL Tuner/Primer

So I have a site that has a crap ton of traffic. I see a decent amount of latency when the site has over 1,000 active visitors on it. I have new relic installed and it seems Im only using 10% of the ...
1
vote
1answer
269 views

Postgres: my “data/backup” directory is way too large

In my postgres 9.3 data directory, there exists a subdir called "backup" that is 6.1G compared to my pg_xlog which is only 130M. I understand that pg_xlog is the WAL logs, so what is in the backup? ...
2
votes
1answer
227 views

Maintenance plan using external tool to execute query and stored procedures giving off no results

My situation is as follows: I am using a third party tool (VisualCron) to run stored procedures and sql queries on several database servers. The stored procedures are from http://ola.hallengren.com/ ...
2
votes
1answer
637 views

What are these files in MongoDB?

I was looking into my server and I found this: [root@host ~]# cd /var/lib/mongo/journal/ [root@host journal]# ls -lh total 3.1G -rw-------. 1 mongod mongod 1.0G Apr 7 01:18 j._0 -rw-------. 1 mongod ...
3
votes
2answers
187 views

Tuning Postgres for Single connection use? Or is postgres wrong tool?

Any rules of thumb for work_mem, maintenance_work_mem, shared_buffer, etc. for a database that DOESN'T anticipate concurrent connections and that is doing lots of aggregate functions? I'm a social ...
0
votes
1answer
1k views

SQL Server 2012 Tuning process exited unexpectedly. DTAEngine

I am using Windows Server 2012 x64 and SQL Server 2012. I am running the Database Tuning Advisor with these settings : Advisor plan cache. Database workload master. Check my database all the tables....
0
votes
1answer
73 views

Access and filter in oracle plan

I came to a execution plan where oracle choose to access the index but instead of using the columns as predicate it only filter by them. My question is what are the reasons that can cause that(all ...
3
votes
1answer
424 views

Use of integer instead of interval (of one type)

Our DB design presently has a interval column which will only be storing days (no other interval type) so it is making sense to use INT2 (smallint) instead of interval. Reference to documentation. ...
3
votes
5answers
11k views

How to determine why a MySQL server has become slow and requests sometimes time out?

I'm working on my first project that makes heavy use of a MySQL database and am struggling to understand performance issues I'm having. Most of the time, responses are returned quickly from the ...
0
votes
4answers
2k views

What can cause Reads to slow down on SQL Server 2008R2?

Our primary DB is 15GB in size. The server has 16GB of RAM. We are using the simple recovery model. Lately we've noticed that our custom apps lookups - just basic reads with adhoc SQL statements - ...
4
votes
1answer
12k views

Optimize PostgreSQL for a lot of INSERTS and bytea updates

What we have (software): PostrgeSQL 9.3 with base configuration (no changes in postgresql.conf) Windows 7 64 bit Hardware: Intel Core i7-3770 3.9 Ghz 32 Gb RAM WDC WD10EZRX-00L4HBAta Drive (...
4
votes
1answer
5k views

Why does SQL Server run a subquery for each row of the table it's qualifying?

This query runs in ~21 seconds (execution plan): select a.month , count(*) from SubqueryTest a where a.year = (select max(b.year) from SubqueryTest b) group by a.month When the subquery ...
1
vote
1answer
174 views

Please suggest my.cnf configuration based upon mysqltuner findings

I have been facing a lot of slow browsing on my site nerdeky.com. My server administrator suggested me to use mysqltuner.pl to find and tune my databases. Can anyone select me what should be the good ...
3
votes
2answers
977 views

What are the options of reducing tempdb latency?

Took the job of monitoring and tununing a SQL Servers 2012 Enterprise Ed. SP1 (64 bit) on Windows Server 2008 R2 Standard Ed. All of them are running inside virtual machines. One SQL Server per a ...
2
votes
1answer
636 views

Does creating View cause an overhead to DB?

As my subject suggests, I would like to know does creating views cause an overhead to DB in terms of space, storage, performance?
4
votes
5answers
279 views

Does DBA need (a read) access to virtualization infrastructure? And why?

I am in charge of monitoring, troubleshooting, tuning and optimizing a few dozens production SQL Servers 2008 R2/2012 in my company that are being run inside VMWare virtual machines. I've requested ...
2
votes
1answer
930 views

MySQL with high CPU and memory usage

here we have a VPS with 3.2GHz quadcore processor with 2GB of RAM and 4GB of SWAP which need to work with a high intensive legacy system (read: bad coded). The main problem is that the CPU (~80 - 100%)...
0
votes
3answers
364 views

Large database - too much time spent opening and closing tables

I have a MySQL server (5.5.31) with 450 databases of some 200 tables each. (Yes, 90,000 tables) When we're under high load, there's over 100 concurrent queries, of which 70% are either opening or ...
0
votes
2answers
4k views

Database partitioning - Horizontal and Vertical sharding - Difference between Normalization and Row Splitting?

I am trying to grasp the different concepts of Database Partitioning and this is what I understood of it: Horizontal Partitioning/Sharding: Splitting a table into different tables that will contain a ...