Improving the performance characteristics of a database application or system.

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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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137 views

How to optimize query

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 Is ...
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125 views

Optimizing queries for 25+ million rows

I am using MS SQL, and I have to run several queries on the same table on different criteria. At first I ran each query on the original table although they all share some filtering (i.e Date, status). ...
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189 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 ...
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1answer
144 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 ...
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17 views

Optimizing query for large number of rows in mysql

I have the following database table in MySQL : and is running the following query SELECT `scratch_tickets`.`id` AS ticket_id, `scratch_tickets`.`created_at`, `scratch_tickets`.`prize_type`, ...
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24 views

Good encryption performance

I'm converting a sql server database to postgresql 9.4. I'm stuck on something that is really really slow. I use copy to bulk insert 200 files of 5000 lines each into 200 tables (one file per table). ...
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1answer
76 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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25 views

Extremely long startup time for MongoDB server

I have a MongoDB Server with just over 2 million documents in one collection. Individual documents can contain large amounts of data (some are several megabytes each) but none of that data is in ...
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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 ...
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68 views

Large MySQL operations slowing down SELECT queries on unrelated tables

On a fairly busy SQL server, we sometimes need to do large index-building operations (after importing ~6GB tables). The indexes are built using the more efficient "Repair by sorting" method, rather ...
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82 views

What perfmon counters should I use to get the fastest restore possible on an idle system?

I have a development VM running Windows 2012-R2 and Sql Server 2014. I have one disk from a SAN holding the OS and SQL. My backup file is stored locally on the disk. I want to restore database as ...
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929 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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98 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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3answers
930 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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29 views

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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40 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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46 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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1answer
42 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
35 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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42 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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31 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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1answer
44 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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60 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
135 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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23 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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315 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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33 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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67 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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73 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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393 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 ...
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20 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
67 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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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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118 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
2k 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 ...
2
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1answer
5k views

Amazon RDS MySQL 5.5 Innodb Lock wait timeout exceeded

Ever since we've moved to Amazon RDS, we've had some pretty crazy performance issues, and today we started having locking issues. Because of that, I figured it was just a timeout issue, and went to ...
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63 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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454 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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2answers
102 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 ...
0
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1answer
170 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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35 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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36 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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2answers
177 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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1k 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
91 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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2answers
300 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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82 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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113 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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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 ...