An evaluation of whether a system works well enough to be fit for purpose. Normally performance refers to the speed with which a system completes an operation or set of operations over time.

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57 views

SQL Server Baseline and Performance Optimization

I've been struggling a little bit around Performance Troubleshooting including baseline and troubleshooting of SQL Performance. Could anyone help with this or point me to where I can possibly get a ...
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1answer
104 views

Why is this second query more expensive than the first?

While reading Graph Databases book, I came across this excerpt: I can't figure out why the second query is more expensive than the first. Indeed, both filter on the Bob person. May anyone ...
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2answers
43 views

Does leaving a connection open for a matter of seconds cause deadlocks?

I have been testing a system application and have noticed that it is slow when it connects to the database overseas. This is to be expected to some extent, but there is a big difference with the ...
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2answers
120 views

Optimizing large MySQL SELECT WHERE IN clauses

How can the following SELECT WHERE IN case be optimized? I have a table with over 100 million rows with only 3 columns. The primary key (col1) is a 127 varchar. I am performing a SELECT col1 WHERE ...
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0answers
31 views

Mysql table with only two columns, nothing unique: Will an index increase search performance?

If my table only has two columns (username, groupname) and a million or so rows, will an index improve performance at all? Wouldn't it take just as long to search the index file as it would to search ...
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1answer
51 views

How performance schema in mysql 5.6 improve performance?

Since MySQL 5.5 performance_schema database has been added likewise information_schema. As we know that tables in information_schema contains statistical information like tables, plugins, partitions, ...
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40 views

MySQL 5.5, Xubuntu 14.04 - INSERT and UPDATE bottleneck

DBAs: I have been developing and maintaining plugins for Moodle for the last ~2 years, and have recently decided to try using my local desktop again, rather than my institutions ESX VMs, as a ...
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0answers
15 views

Sysadmin tools for SQLAnywhere

I'm seeing a performance issue in a 3rd party application based on SQLAnywhere 7. The DB engine seems to be dramatically underperforming on the hardware provided. It seems to have a upper limit on the ...
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2answers
52 views

MySQL ON DUPLICATE KEY UPDATE performance issue

We have a table with over 200k rows. Every row belongs to a category, there are almost 50k rows per category. What is the best way to update all rows of that category? We are using a script like ...
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2answers
76 views

Why is this simple join taking so long?

I'm trying to run some reporting queries on a MySQL database, and I'm running into serious performance issues for some reason. One table, page_views, is extremely large (~70 million records), so some ...
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2answers
60 views

Are #tables and #procedures 'not best practice' or 'bad practice'?

I am working on a project and part of it is an interface tool that executes SQL code stored in a xml file to import/export files. In the file, temp procedures and temp tables are used quite heavily ...
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1answer
41 views

Detailed optimal column order with large text and bytea

I read this excellent answer on optimal column ordering and noticed the summation: Generally speaking, if you put the 8-byte-types first then the 4-byte-types and the 2-byte-types last you can't ...
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0answers
10 views

Page cache installation in magento admin panel

Hi just added pagecache from varnish in Magento through the magento connect. It went in ok, just wanted to know, the correct configuration. In magento admin panel for the correct set up in the page ...
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0answers
51 views

Performance: Interleaving several statement handles in MySQL

Does interleaving several statement handles slow the system down? Example (Perl): $sth1->execute(...); $sth2->execute(...); $sth1->execute(...); $sth2->execute(...); (interleaved) vs ...
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1answer
37 views

Two MySQL requests at the same time - Performance issue [closed]

I have a MySQL server with many innodb tables. I have a background script that does A LOT a delete/insert with one request : it deletes many millions of rows from table 2, then insert many millions of ...
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0answers
72 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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1answer
56 views

Does having a big table that I do not query cause the whole DB to be slower?

I have a log table that I use for logging files sent to clients. I'm not querying that table, just use it for logging (INSERT) and when I need to check when something was sent to clients, usually once ...
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1answer
29 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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1answer
37 views

MyISAM InnoDB performance

MyISAM vs InnoDB I keep reading how InnoDB is faster than MyISAM. I wanted to find out myself. When I was using a forloop in PHP to fill my MySQL test database with 100,000 numbers using PDO driver. ...
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0answers
21 views

Excesive use of RAM on MysqlServer

The RAM of a server where I have installed mysql is always 100% and looking at the processes that are running, MySQL is the most consumer on CPU and memory and I can see the cause of great use RAM.   ...
0
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1answer
41 views

MySQL 5.1: change datadir variable value in my.cnf

Below is my system configuration: OS: RHEL5 MySQL: 5.1.73 Default datadir=/var/lib/mysql/ But, the above directory has space crunch. So, I decided to change the path. I found /u000 directory has ...
0
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1answer
74 views

How to deal with async calls to a stored procedure that updates data

I have asynchronous calls from Entity Framework to a stored procedure. The stored procedure selects data to a temp table and later on, it updates the real table. This works fine for sync calls. The ...
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2answers
32 views

Do I need foreign keys in ORMs?

Object Relational Mapping (take ActiveRecord and Rails, for example) allows a programmer to define relations between models, and callbacks on delete. So my question is: do I still need to define ...
2
votes
1answer
79 views

Character varying index overhead & length limit

I have a unique constraint on a character varying column that will mostly have lengths of approximately 600 but could get to 10 million. I have read about B-Trees, but I can't determine how much disk ...
0
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1answer
50 views

Mysql improve Self join performance large table?

I have a task to help identify conflicting IP ranges , I want to highlight when one companies IP range falls within another's ... below is the sample table, I have converted the IP ranges from .dot ...
6
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5answers
533 views

Performance tuning a Great Circle distance calculation

I have a query that I am using to find locations that are within 1km of a known point. To do this, I am using the Spherical Law of Cosines formula with my latitude and longitudes. Currently, the ...
2
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1answer
58 views

File database vs application server database for concurrent performance & bulk data

I asked a question about Ripple's database implementation, and received this response: The ripple server uses SQLite for structured data and a configurable "back end" for unstructured "bulk" ...
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1answer
30 views

How can I measure the number of IOPs for a certain query

I need to estimate the max IOPs for a certain MySQL DB (one that does not exist yet). The OS is Linux and the DB is MySQL 5.1.x (though I don't think the DB brand is important for the asked topic) ...
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0answers
38 views

Guidelines on best indexing strategy for varying searches on 20+ columns

I’m running a search engine for cars. It’s backed by a postgresql 9.3 installation. Now I’m unsure about the best approach/strategy on doing index optimization for the fronted search. The problem: ...
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0answers
67 views

Performance issue in Postgresql9.3

I have very good configuration server dedicated only for PostgresSql. Server is 16 Core 122 GB RAM on Linux machine. select version(); **PostgreSQL 9.3.4 on x86_64-unknown-linux-gnu, compiled by gcc ...
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0answers
26 views

Extended Events missing documentation

I have been looking pretty hard for the documentation regarding the RingBufferTarget <RingBufferTarget truncated="0" eventsPerSec="1370714" processingTime="7" totalEventsProcessed="9595" ...
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0answers
16 views

View in View slower to execute?

Sometimes it's easier and clearer arranged to create a View from another View. Can this cause some speed losses in relation to selecting everything just in one Big and long View-Command?
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1answer
71 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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1answer
31 views

Transforming Huge Database table to Another Table

We are migrating lot of data from our old database to new database. Presently, both of them are actively[writing/reading] used based on flows/activity as migration is in progress. Here's the real ...
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0answers
19 views

Performance tuning in Sybase

Does Sybase have a tool like AWR in Oracle which can be used to identify high load SQL, tell the important waits that are happening, help in understanding the workload? What are the main tools to be ...
0
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1answer
29 views

MySQL 5.1: How to rollback partitioned table

I have partitioned a table on the basis of one flag column have value either 0 or 1. Now, I want to roll back these tables. How can I do this?
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1answer
60 views

Running queries directly on DB2 databases

Just have a general query, if it is really fine or safe to run long select queries on RDBMS production Databases specifically DB2? If NO, what are the major risks and issues in executing select ...
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0answers
21 views

Database slowdown at random times using mirroing

Our web application suffers DB query timeouts a few times a day at random times. Can you help to work out the cause, e.g. deadlocks, mirroring (disk or network), etc? We have two identical database ...
2
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0answers
127 views

SQL Server 2012 Local SSD TempDB Slow

I have a production deployment using local SSDs for tempDB. I have 2 SSDs in a RAID1 configuration. I am seeing average reads of 1-2ms but the average writes are showing as 1377ms on all four of my ...
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2answers
82 views

Table design for multi-type data

The information model I am modelling from includes an "any type". For example a customer can have zero or more 'entries' each of which can have a number of values. Each value could be a either date, ...
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2answers
296 views

Ideal values for wait time in SQL server

This is related to my own post here The SQL server starts everyday at 8:30 AM and stops around 9:30 PM.( So wait times will reset everyday) SQL server will be used by around 60 users ...
1
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1answer
287 views

SQL Server 2008 R2 Express single CPU core usage and need of upgrade to SQL Server 2014 Express

In our office we are using SQL Server 2008R2 Express which is installed in Windows server 2012. The SQL Server database is accessed by more than 60 users in network simultaneously. In recent days we ...
0
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1answer
51 views

How can I control the order of a query regarding to inner join

I have 3 tables. They have table_a 5m records table_b 20m records table_c 20m records I'm performing the query below. SELECT * FROM table_a a INNER JOIN table_b b ON a.a_id = b.a_id AND ...
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0answers
38 views

How can I reduce recursion in Couchbase?

Sometimes, you need to access a certain document (A), but you do not know the key for that document (A), as that data is stored in a different document (B). So now, if you want to fetch A, it looks ...
0
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1answer
39 views

How to optimise very simple query with subquery that only needs to execute once

SELECT products_id, products_model, products_iban_no, products_allocation_number FROM products WHERE products_model IN (SELECT products_model FROM products GROUP BY products_model HAVING ...
2
votes
0answers
85 views

Do OR conditions in Oracle SQL queries spoil index use / cause full table scan?

I have a query on Oracle 11g of the following type, which results in a series of highly inefficient full table scans: select t.Id, t.ObjectId, t...[other Tasks columns] , od1...[ObjectData1 ...
0
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1answer
145 views

How to configure my.cnf for Mysql 5.1, which is using too much CPU?

I am new Database engineer. I am having trouble in my server which is using too much CPU on database query(simple count statement). I have googled about it, so i found out it depends on system ...
0
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1answer
49 views

Redo log size results into performance degrade

We are continuously doing heavy insert and update query, but after 10 hours data base is returning answer late in minutes normally it takes around 1 ms. I observed that "free buffer wait" and "redo ...
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1answer
126 views

Slow delete caused by many foreign keys

My DB has about 90 tables. Most of the tables have an UpdatedBy and AddedBy column that have foreign keys pointing back to the user table. With even moderate amounts of data spread throughout the ...
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0answers
22 views

Approaching multiple values in same column

I'm developing an Android-application that scrapes the schedule for my university and presents it nicely since the current system is a nightmare. I'm processing a lot of data and it gets down to ...