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

learn more… | top users | synonyms

0
votes
0answers
7 views

Tuning SQL Query which returns REF CURSOR

I am using reference cursor in function to return values. This function is getting called recursively for different input values. My package Definition is as follows. create or replace PACKAGE ...
0
votes
0answers
11 views

Which DBMS for huge amount of time-based archive data? [closed]

I'm currently planning the desired rewrite of some components that have been developed with C# and SQL Server. One of the main tasks is the continuous logging of time-based values in an industrial ...
1
vote
1answer
68 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
2answers
78 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 ...
0
votes
1answer
1k views

How to change page size in an existing sybase database

I have an existing database with 1 kb page size i want to increase that to 16kb and increase cache to take advantage of my memory for best performance. sybase documentations said you can't change page ...
2
votes
2answers
92 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
79 views

Tuning Mysql and Monitoring

I would like to know if anybody can point me towards a tool/way for MySQL database tuning ... Actualy the tunning of my.cnf is like below My database is in MyISAM | Mysql 5.1.73 key_buffer = 500M ...
1
vote
1answer
18 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
20 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
2answers
21 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
166 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 ...
0
votes
1answer
74 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 ...
0
votes
1answer
36 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
76 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 ...
1
vote
1answer
46 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 ...
0
votes
0answers
14 views

Database Engine Tuning Advisor - is number of queries important or not

By number i don't mean number of unique signature queries I mean raw number For example i have this query select name from my table where id=3 It is a single unique signature Having it only 1 ...
4
votes
2answers
730 views

Slow SSRS Report in production

I have an SSRS report which gets its data by firing a series of stored procedures. Now the report is timing out big time when run in production, yet when I pull down the prod database and restore to ...
1
vote
0answers
38 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 ...
5
votes
2answers
3k views

Designing a user authenication (Roles & Rights) module

I am trying to model a User Authentication module for a MS SQL Server database that will be the back end to a Delphi UI Application. Basically, I want to have user accounts where the user belongs to ...
4
votes
3answers
2k views

Dropped tables are not going to Recycle Bin

To start, I am a student and just getting my feet wet with Oracle. Quick history Virtual Box XP running Oracle express with SQL Developer. Created a user and tablespace for myself. (Key here is ...
1
vote
1answer
3k 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 ...
1
vote
0answers
296 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
84 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? ...
0
votes
0answers
51 views

Performance and maintainablity of a large MySQL table with hundreds of columns

For a project of mine I need to have a table with around 400 hundred columns of type nullable indexed VARCHAR(128), this table is going to store at least 50 million rows and has one column of type ...
1
vote
1answer
109 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
69 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 ...
0
votes
1answer
366 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 ...
0
votes
1answer
2k 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 ...
7
votes
2answers
15k views

MySQL creates temporary tables on disk. How do I stop it?

We are running a site (Moodle) that the users currently find slow. I think I have tracked down the problem to MySQL creating temporary tables on disk. I watch the variable created_tmp_disk_tables in ...
0
votes
1answer
50 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 ...
1
vote
5answers
765 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 ...
3
votes
1answer
105 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. ...
0
votes
4answers
653 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 - ...
3
votes
1answer
1k 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 ...
2
votes
2answers
430 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 ...
25
votes
2answers
1k views

Where can I find database tuning exercises for learning?

As a developer, often DBAs take responsibility for resolving performance issues at the database level so we don't get that much experience diagnosing, tuning, refactoring queries etc. I'm looking ...
2
votes
1answer
181 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?
3
votes
5answers
195 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
291 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 - ...
0
votes
3answers
191 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
218 views

What is the default size of text field in Postgres?

In the official documentation (http://www.postgresql.org/docs/9.1/static/datatype-character.html), it states text field is variable unlimited length. I wonder what is the default size of this field ...
0
votes
1answer
2k views

Oracle 11g Enterprise downgrade to Standard One

I'm checking possibilty of downgrade Oracle 11g from Enterpise Edition to Standard One edition. I've cross-checked edition comparison with select name from dba_feature_usage_statistics where ...
2
votes
1answer
315 views

Getting the most out of SQL Server with a million rows a day [closed]

I have a windows service that is inserting 1000 rows at 1 minute intervals to a SQL Server 2008 Standard database table that looks like: id, datetime, key_id, value key_id is a foreign key to ...
0
votes
1answer
963 views

How to measure a perfomance of SQL Server database? [closed]

I have the task to improve the performance of a SQL Server 2012 database (one of 4 in an instance) by 60% confirmed by corresponding statistics. So, I need to measure "performance" of the RDBMS ...
0
votes
0answers
186 views

After RAM upgrade on 32-bit Oracle server, ORA-04031: unable to allocate x bytes of shared memory

We are in the process of upgrading our Oracle database server at work, from SUSE Linux Enterprise Server 10.4 / Oracle 10g / 4GB RAM (Intel 32-bit) to Scientific Linux 6.4 / Oracle 12c / 8GB RAM ...
0
votes
1answer
33 views

Retrieve list of matched words in PostgreSQL

I'm new to PostgreSQL and really more than your more basic queries/inserts. I've created a TSVector column to my table that I'm searching and have set the column to look at the specific column in ...
3
votes
2answers
182 views

Tuning advisor with Extended events?

With SQL traces I was able to analyze them with Database Engine Tuning Advisor to obtain basic recommendations for perf. tuning(missing indexes, statistics,...). Now, with SQL 2012 and Extended ...
0
votes
2answers
2k views

How to optimize MySQL for large BLOB updates

I have a table that holds large BLOBs (up to 10M), and is updated frequently. The problem is that UPDATE statements can take up to 1 second to execute, and due to app design this blocks UI. I need to ...
6
votes
1answer
485 views

Optimizing PostgreSQL for transient data

I have several tables with 100-300 columns of integer types each, that hold highly volatile data. The datasets are keyed by one or two primary keys, and when refresh occurs, the whole dataset is ...
5
votes
1answer
284 views

How can a fill factor of 0 or 100 be the same?

As of my understanding, Fill factor of 80 implies that 20 percentage of each leaf-level page will be empty to enable future growth. I can't correlate how fill factor of 0 and 100 can be the same! Am I ...