Improving the performance characteristics of a database application or system.

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70 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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1answer
48 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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2answers
1k 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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0answers
136 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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1answer
693 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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0answers
134 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 ...
8
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1answer
186 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
318 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
264 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 = ...
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0answers
80 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 ...
0
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1answer
260 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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1answer
133 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
2k 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 ...
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1answer
1k views

Oracle average active sessions high threshold

I am trying make sense of the DB load from the AWR report for a period handed over to me by DBA. Researching a bit, I see the "Average active sessions" is a metric widely used to measure DB load. It ...
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0answers
717 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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0answers
950 views

What to do with unused RAM on a MySQL database server?

For years I have been running dedicated servers with more or less limited ressources, resulting in unsatisfying performance of the web application (Drupal). Tools like Matthew Montgomery's MySQL ...
0
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1answer
59 views

Need DDL for an Oracle Table that would be 1 row = 1 8K Block

For performance testing in our performance environment we want a means to turn over SGA the way production does. Our performance environment is a fraction of production and production's very nature ...
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2answers
1k views

Optimize MySQL query_cache_min_res_unit

My query cache settings are the following: mysql> SHOW GLOBAL STATUS LIKE 'Q%'; +-------------------------+----------+ | Variable_name | Value | +-------------------------+----------+ ...
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1answer
7k views

Understanding pagefile.sys % Usage performance monitor (perfmon) counter correctly

Lately we run into performance inssues and I started tracking some recommended sql, memory, disk and cpu counters. I informed myself about the recommended values and numbers to look at. One of the ...
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2answers
291 views

Cannot tune database any further; what next?

We have a vendor-supplied application. It is under support and we are talking to their developers (we have their largest database size by an order of magnitude), but in the meantime, we have the ...
2
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1answer
912 views

Sort Warnings, finding out the query behind them

I'm troubleshooting a SQL Server 2012 that has started timing out as of a few weeks ago. The server is filled with thousands of sort warnings, at a rate of about 15 warnings per minute. To get the ...
2
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1answer
218 views

High I/O for part of query

I have a large query that I'm trying to tune. I write lots of queries but haven't done a lot of tuning. I've included a screenshot from SQL Sentry Plan Explorer Free (SSPEF): In the above part of ...
2
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1answer
281 views

poor and/or unreliable InnoDB performance

I recognize that there are a ton of posts like this, but after reading up on InnoDB performance problems, nothing I tried has helped. I have a database containing four InnoDB tables. The largest ...
2
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2answers
133 views

Need help performance tuning a query

Basically, here is the design of the table (the part that is necessary): id | dt -------- 1 | 2014-05-13 2 | 1900-01-01 3 | 1900-01-01 4 | 2014-05-12 5 | 1900-01-01 So what I am trying to do ...
5
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1answer
3k views

Understanding sys.dm_exec_query_stats execution_count vs creation_time

I've just downloaded the SQL Server 2012 'Performance Dashboard Reports' and am having some issues interpreting the data shown by one of the results and linking it back to the DMV ...
2
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1answer
218 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
99 views

DBCC sqlperf(waitstats) contains signal wait time longer than last time waitstats was cleared

I'm trying to troubleshoot some performance problems on our SQL2000 production server. I ran DBCC SQLPERF(waitstats) and noticed the stats hasn't been cleared in a long time. So I cleared them and ...
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1answer
1k views

InnoDB engine is not loading after tuning parameters

After installing MySQL-5.1.73, I placed default my-huge.cnf into /etc/my.cnf and started the mysql service. It was running without any issue. Now, I tunned some parameters in /etc/my.cnf file. Below ...
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2answers
180 views

How to optimize query

I'm using SQLite3 and the following query, It seems like there should be a better performing way to write this query; Is there? Select Name, Sum(Case When Used ...
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0answers
150 views

Big Mysql table optimization

I have a table that I use to cache google translate API answers. Table structure is orig_string and group are indexes Now it has more that 1million rows with 35000 distinct values in group field. ...
0
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1answer
86 views

MySQL: How to find MySQL 5.1 (with built-in InnoDB) or MySQL 5.1 (with InnoDB-plugin)?

My DB server has MySQL 5.1.58-community-log and I am planning to upgrade it to MySQL 5.6 with specific purpose of improving my system performance and removing the bottleneck issue. So, I have gone ...
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0answers
116 views

MySQL query with order by decreased performance

Here is my schema: CREATE TABLE `UserMst` ( `UserID` mediumint(8) unsigned NOT NULL AUTO_INCREMENT, `EMailID` varchar(50) DEFAULT NULL, `UserName` varchar(20) DEFAULT NULL, `FullName` ...
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0answers
263 views

Remote scan in OpenXMl

I'm looking for some advice on OPENXML. Specifically, the performance. I am seeing very slow performance on a very small piece of XML. Something about this is causing a Remote Scan. Any ideas on how ...
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2answers
465 views

Instead of static list, using a table select result for IN key

I use a static list for some queries WHERE clause like WHERE STypeID IN ('12', '13', '14', '265') This list will be changed in the future; new values will be added. When list changed, I don't want ...
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1answer
688 views

Different thread states in query execution

My MySQL 5.1 based Intranet system is facing very bad performance during high load. When observed through MonYog, I found below thread states: We can simply understand the different thread state by ...
4
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1answer
1k views

Database under heavier load — all SQL queries start timing out after a period of hours/days

I make a web application which has experienced heavy growth in the past week and it appears my database is seizing up because of it. You can see that everything seemed to be OK until about 3AM this ...
4
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1answer
11k 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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2answers
398 views

Database is slow once in a while

I am executing a web service for 100 times. The average response time of this service is 1.5 seconds. But when I look at the response time of each execution individually, there are a few executions ...
1
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1answer
217 views

Get maximum number with combination of columns [closed]

I have table with columns like AutoID, Number, Name, City, State, Country. What I wanted is the maximum number entered in the “Number” column with the combination of Name, City, State and Country. ...
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0answers
83 views

performance improvement - left join

How do I rewrite to improve performance of the below query. select S.col1, S.col2, MaxDDate from s_tbl s left join (select col1, MAX(DDate) MaxDDate from F_tbl group by col1 ...
2
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1answer
778 views

SQL Server : How to make “Update Statistics” faster?

We have a table with a 1 column Primary Key on and an UNIQUE Non-Clustered Index with 16 columns. This table has more than 20695780 Rows and on every day new records inserted ...
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0answers
248 views

MySQl: slow query is not using index in joining

Below is the configuration of my DB server: Apache version : Apache/2.2.22 (Win32) mod_ssl/2.2.22 OpenSSL/0.9.8 PHP version : 5.3.13 MySQL version : mysqlnd 5.1.11 Windows Server 2008 Standard ...
2
votes
1answer
726 views

Slow SELECT against clustered index [closed]

I have a table which will hold 10 million rows. I'm seing performance issues when quering it, and wonder if I can somehow improve the schema or query, or if I need to look into sharding. I've used SQL ...
0
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1answer
92 views

Is it any good for performance to have master and slave on the same server

There are similar questions on this site, but they mostly cover server failure and data backup aspects. I'm concerned only as far as query performance. If master and slave share the same resources, ...
0
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1answer
376 views

Which index types do not support online index rebuilds?

In SQL Server 2012 Enterprise Ed., which index types do not support online index rebuilds? and why? and which activity-operations can prevent online index rebuilds?
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0answers
57 views

Help with Mysql with 100K+ Table

Hi im trying to develop a database design in which its gonna have 100K+ tables residing in it. My major concern here is will Mysql be able to hold that much amount of tables with no performance ...
2
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2answers
443 views

What can be done to further enhance performance of Multiple Join and Aggregate Queries?

I have a typical star schema simulated here, and I am mentioning two queries: first query simply joins the fact table with 2 dimension tables and 1 calendar table, and the second query joins and ...
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2answers
1k views

Should I load the data into Temp table or keep calling it from the normal table? [closed]

I am writing a procedure and find myself using the same select statement with the same where clause a lot. Currently the table holds over 55000 rows and grows about 100 or so rows each day. The two ...
4
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5answers
2k views

How can I prove that the following T-SQL is bad for performance?

I have recently inherited a codebase with a large amount of Stored Procedures. The system they are supporting is encountering numerous performance problems which I am looking in to. A number of the ...
2
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1answer
868 views

MySQL Performance Issues

Over the past 3 weeks we have been having bottle-necking issues at our MySQL server. I have been using MonYOG to watch the processlist in an attempt to get a grasp on the issues. We are aware that ...