Improving the performance characteristics of a database application or system.

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SQL Server 2012: query to see queries that are consuming more resources [duplicate]

I'm trying to find/build a query to show me those queries that are consuming more resources in SQL Server so that I can optimize them or at least have a statistical idea of what is really happening. ...
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31 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 ...
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33 views

PostgreSQL Performance - Many Large Databases

I run an internal (development) database server containing 25 databases each ~71GB in size. There are usually between 50 and 100 active connections at any given time. What can I do to help improve ...
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39 views

Can I throttle individual databases instances on one SQL Server 2005 box

I am running a very old server that has a database that is being permanently retired within 14 months. My company will not invest anymore in hardware or software for this system as we are moving to a ...
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1answer
30 views

maximum allocate RAM for MS SQL Server

I have MS SQL Server with different size of RAM. So I would like to control the values which are set for the RAM. Somewhere I read a 'rule' to calculate the maximum of RAM. These SQL Server are only ...
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28 views

How bigger page size effect at performance?

I know in case of Cluster index bigger page size improve peformance for range and multipoint query. Does bigger page size can effect to degrade performance when we have non cluster index .Because ...
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41 views

How to identify whether a log backup or job executing a SP is causing High Page Reads/sec

For one of my servers( SQL server 2008R2) we can continuously witness High Page Reads/sec during business hours say: from 7 AM to 9 PM EST. I kept the counter settings to monitor the same and found ...
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2answers
77 views

How to auto assign ordinal ranking in mysql with as minimal queries for new rows?

+----+---------+---------+-----------------+ | id | view_id | user_id | ordinal_ranking | +----+---------+---------+-----------------+ | 1 | 10 | 1 | 1 | | 2 | 10 | ...
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1answer
34 views

Does SQL Server redistribute data after adding an additional data file?

Imagine a database about 30GB in size using 3 data files on the same disk. Someone told me to have one data file per processor implemented to get full performance on all cpus. So if I now add three ...
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1answer
122 views

Table with clustered Index consuming max memory causing low PLE alerts

For one of my server with below configuration i am continuously receiving alerts for low PLE which ranges between 20- 400 and an average of 90-100 in a day: Server: SQL server 2008R2 Databases : ...
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1answer
17 views

What is exactly a uniform server in a galera cluster setup?

In many manuals about performance tuning and avoid Galera's MySQL cluster limitations they write the below suggestion. It is possible for a slow/overloaded master node to affect performance of ...
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48 views

SQL aggregate function performance in a table with many records that is well-indexed

My question is about 3 tables that stores data of a single entity, and there is a report generation feature that refers these tables and calculate COUNT and AVG information. There are three tables: ...
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300 views

use an Index correctly to optimize queries

I have an SQL database with millions of records and when I'm querying the data like select * from ActCosts where ScenarioID= 456 The tables has 1,323,718 rows and it gives me like 50,000+ rows ...
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29 views

Query plan reads vs statistics io reads

I have a very strange problem. When I run a query with SET STATISTICS IO ON, it shows that I had a total of 183 reads. But when I look at the query plan dmv it shows I did 555,132 reads. I cleared the ...
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19 views

Best ratio for files and file groups for a highly partitioned table

I have a number of tables with exactly 1000 partitions. Each table can be up to 200G with 100M rows and cannot be compressed. Data in partitions distributed quite equally. The SQL Server has 8 ...
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1answer
61 views

Optimizing intersect query in MySQL

I'm facing a performances problem in our MariaDB server. We have a table linking users to pages, a user belongs to 1+ pages. I have a page that have users and I want to get the 10 best pages based ...
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1answer
60 views

Is my SQL Job causing the High Disk usage?

I have a concern regarding High Average disk queue length for one of my server with below configuration: Version: SQL 2005 with SP3, standard edition. windows: version 2003 r2 SP2 No Processors= 4 ...
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2answers
64 views

Using Database Engine Tuning Advisor in production

I have a SQL Server 2008R2 OLTP database which is experiencing performance issues during work hours. I would like to run Database Engine Tuning Advisor on this instance but I don't know how it will ...
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33 views

Why does retrieving fewer rows take longer? [duplicate]

I have a view that (left outer) joins multiple recursive CTEs. There are about 10k rows. The results of running SELECT * FROM MyView ORDER BY MyPrimaryKey, with statistics time and io on: SQL Server ...
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56 views

reporting space consumption to files in filegroup - how to reverse-engineer the algorithm spreading data across files

I would like to know how to calculate the distribution of data consumed per file in a filegroup, back to the index (HEAP, CLUSTERED, NONCLUSTERED) storing it. My intention is to define which I/O goes ...
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1answer
96 views

OS Paging too high in sql server

For one of my servers with below configuration: Total RAM: 32 GB CPU: 8 Max Server Mem: 22.5 GB Min Server:: 4 GB Edition: Enterprise Edition with 2k8R2 installed on SP3 ...
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1answer
47 views

Select two aggregate functions on the same column using different criteria - performance

Dear stack exchange users, first question here. The database in question is a service database where a user hires a service. Now I would like to show the person that was hired an overview of how many ...
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3answers
482 views

Do I need to reindex mysql table after bulk delete?

I have a table in MySQL with a lot of INSERT and SELECT at every second. And there is a bulk delete of some older data once in a day. Do I need to reindex the table after delete? I want to increase ...
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91 views

Do I need to reindex my table in mysql after delete?

I have a table in mysql with a lot of INSERT and SELECT at every second. And there is a bulk delete of some older data once in a day. Do I need to reindex the table after delete? I want to increase ...
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1answer
102 views

Query optimization for multiple joins postgres

ER Diagram Brief description The database to be used is postgres. The database might contain upto 2 million AccountHolder records. Since the AccountHolder table is accessed and updated frequently ...
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26 views

Intermittent MySQL 5.17 issues - extremely slow queries

I am experiencing major issues with intermittent mySQL issues. To give some background the website runs optimally for the majority of the time, however 3-4 times a day queries that should take a split ...
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24 views

PostgreSQL buffer page size limitations - rebuild with larger size?

We just ran into a limit on indexing due to the 'index size cannot be more than 1/3 of page size (2712)' error. This indicates the buffer page size is 8192 (8k). This seems awfully small during the ...
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579 views

Hyperthreading & MySQL InnoDB Thread Concurrency Performance

I have a dedicated DB Server with the following specs" Ubuntu 12.04 LTS Server Intel(R) Xeon(R) CPU X5670 @ 2.93GHz 12 Cores MySQL 5.5.29 64 GB RAM RAID10 We are currently doing Hyperthreading ...
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729 views

SQL SERVER – Find Most Expensive Queries

I am running the following script to find most expensive queries. However I want to narrow it down to only queries ran on Saturday 18th October 2014 Is there any way to do this? SELECT TOP 50 ...
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1answer
70 views

What do these pstart and pstop values mean?

I'm attempting to tune a query and I want to be able to tell if partition pruning is happening. On one part of the query, the I'm getting a Pstart and Pstop value = "KEY": | Id | Operation ...
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78 views

Window function sorting performance

For background, I am on an instance of SQL Server 2012 Enterprise Edition. I have three tables that join on the same set of three keys - all of them are INT. All tables have their keys clustered in ...
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2answers
236 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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39 views

is there any limit of MySQL status variable value?

As we know MySQL status variable is a counter variable since the service start. MySQL service in my DB server restart every week (on sunday). Below is my observation since last few week: Suddenly ...
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76 views

MySQL: What do we mean by 0 value in in_use column of show open tables statement?

If I run show open tables command, system return 73 records. But, in_use column value for every record is 0. What does this mean? Are these tables available in cache but not used by any thread?
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30 views

How to handle too many instances of multiple tables?

If there is a table accessed by multiple DB threads ( for example 100) at a time then how many instances of that table will be opened? If I run show open tables and see that in_use column value of a ...
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90 views

MySQL: What should I do if too many tables opened during peak hours?

In Peak hours: When I run below statement, I found around 100 tables out of 250 have opened. show open tables where in_use>0; There are around 10 tables for which in_use value are >50. Storage ...
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1answer
27 views

Do threads in cache still use memory?

I was studying about how and how much memory allocated to each connection thread and found below MySQL tutorial: http://dev.mysql.com/doc/refman/5.1/en/memory-use.html There is a point mentioned as ...
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17 views

SSIS Performance tunning [duplicate]

I have few questions on SSIS Performance tunning. Suppose My system has 8GB RAM and I have installed SQL Server 2012 along with DataTools. SQL Server uses 7GB memory. Will SSIS uses the 7GB memory or ...
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2answers
138 views

Identifying cause of high I/O

I'm trying to diagnose the bottleneck for high-write I/O activity on a percona master (with replication to a slave). The pattern of behaviour is roughly cyclic and regular: 60 mins of 75-90% ...
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73 views

DB Design: Looking for Performance improvement with a Column used in all SQL Queries

I recently got added to a new ASP .NET Project(A web application) .There were recent performance issues with the application, and I am in a team with their current task to Optimize some slow running ...
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104 views

Very Slow MySql Stored Procedure

I'm working with a web app running on MySQL. It uses stored procedures for all database-related tasks. The original web app and the database were designed by another developer; I'm only maintaining it ...
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47 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 ...
7
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1answer
138 views

Lower performance on newest servers

We have several db servers on production, 4 of them with very similar hardware configuration. Dell PowerEdge R620, only difference is that 2 newest ones (bought and configured 3 months ago) have RAID ...
2
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1answer
118 views

Searching a big table for a few results without scanning the whole table

I need to search a very big PostgreSQL table (500+M rows), I want to limit the returned search results, but using the "limit" keyword cant prevent the search over the whole set of data(is it correct?) ...
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1answer
97 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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14 views

Multiple Trace Files or Replay

I am just wondering how useful the replay functionality of SQL profiler is. The issue I have is that I can capture a workload from production with little overhead, however I would not be able to ...
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61 views

MongoDB read performance

I have an ingestion process which loads data into a specific collection at a very high rate. Some of these documents have to be loaded into another system in batches of 100K . Means as soon as I find ...
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1answer
53 views

MySQL: How turning off the logging affect the performance?

OS: RHEL5 DB: MySQL 5.1.73 community edition DB size: ~1GB I have setup a testing environment and turned off all logging - general logs, binary logs, slow query logs etc. I am using Oracle ...
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67 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 ...
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3answers
502 views

Collecting Wait Stats

We currently use a monitoring tool which shows us our top wait stats either by number of waiting tasks or total wait time. Below are the wait stats by number of tasks waiting and also wait time per ...