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

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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 ...
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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? ...
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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 ...
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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 ...
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2answers
167 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 ...
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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 ...
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1answer
75 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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79 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 ...
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80 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 ...
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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 ...
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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? ...
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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 ...
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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/ ...
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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 ...
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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 ...
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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 ...
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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 ...
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1answer
106 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. ...
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5answers
775 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 ...
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4answers
655 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 - ...
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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 ...
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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 ...
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2answers
432 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 ...
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183 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?
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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 ...
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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 - ...
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3answers
193 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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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964 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 ...
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1answer
316 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 ...
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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 ...
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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 ...
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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 ...
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1answer
287 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 ...
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1answer
74 views

Indexes and Optimizations for Logging System

I'm designing tables for a new log system and am having trouble figuring out what indexes I'll need (I'm a developer, not a DBA), and am also open to any suggestions/criticisms/etc. for making the ...
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2answers
3k views

Configuring PostgreSQL for read performance

Our system write a lots of data (kind of Big Data system). The write performance is good enough for our needs but the read performance is really too slow. The primary key (constraint) structure is ...
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2answers
183 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 ...
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2answers
732 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 ...
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2answers
6k views

Is my.cnf for mysql 5.5 is suitable and well tuned for below hardware spec?

My Hardware Spec Technology: Ivy Bridge CPU: Intel Xeon E3 1245v2 Intel Smart Cache: 8MB Cores / Threads: 4 / 8 Frequency: 3.4GHz+ / 3.8GHz Turbo Boost RAM: 32 GB DDR3 Hard disk: 2x 2TB SATA3 Raid 1 ...
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1answer
535 views

What causes InnoDB to write 100% more pages while slowing down answering queries?

I have a somewhat big database server: 4 processors, 32 cores, 288GB RAM, 2 ethernet cards bounded together, 2 independent RAID controller cards with 1GB cache each, 24 2.5" disks, being 8 SAS, ...
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1answer
102 views

How to tell if database tuning is fruitful (PostgreSQL)

As a DBA, I regularly observe my database, tune up some queries (either getting the programmers to re-write it or add index or update statistics if that's what is needed, etc). I also tune up the ...