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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1answer
129 views

Application is hanging when database upgraded from SQL Server 2000 to SQL Server 2008 R2

Presently we are working with SQL Server 2000, the database is perfectly working with our software for retail sales counter application developed with VB 6.0. But after upgraded to SQL Server 2008 R2, ...
0
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2answers
107 views

Please recommend changes for my.cnf

I am not having any performance problems per se but want to improve my sites' performance if possible. Would appreciate any advice for how I can improve my.cnf. I have just one server, not ...
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2answers
2k views

VARCHAR primary key - MySQL

Currently, I have a categories table with 2 columns - category VARCHAR(50) NOT NULL PRIMARY KEY and parent VARCHAR(50). The parent column is a foreign key (FK) to the category column. This seems like ...
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2answers
130 views

novice-design: Are FOREIGN KEYs always necessary? Joins on columns which are not PK

I've been wondering if following approach is bad or really very bad:). Question#1: can we use indicator_id to combine data from indicator_values and indicator_details tables (without using FOREIGN ...
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0answers
38 views

MySQL 5.6 Performance Tuning Issue

I have read and try lots of things about MySQL optimization and tuning. I tried most of them one by one according to our needs but nearly I got nothing. I am doing my test using some simulation ...
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2answers
2k views

Improve MySQL Query Performance - Too many records

I am using MySQL RDMS for a contact management system. Now a days my database grew in size and contains more than 1 million records. Checking duplicate phone numbers became a big issue during ...
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1answer
230 views

How to track IOPS statistics?

Is there a way to access statistics about IO operations per second in DB2 9.7? I am not interested in the buffer pool hit ratio, just IOPS.
10
votes
2answers
341 views

Minimizing Indexed Reads with Complex Criteria

I'm optimizing a Firebird 2.5 database of work tickets. They're stored in a table declared as such: CREATE TABLE TICKETS ( TICKET_ID id PRIMARY KEY, JOB_ID id, ACTION_ID id, STATUS str256 ...
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4answers
27k views

When a previously-fast SQL query starts running slow, where do I look to find the source of the issue?

Background I have a query running against SQL Server 2008 R2 that joins and/or left-joins about 12 different "tables". The database is fairly large with many tables over 50 million rows and about 300 ...
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0answers
21 views

How can I restore a MySQL dump faster on Windows?

I am restoring some InnoDB and MyISAM .sql files that are on the order of GBs (ranging from 1 GB to ~ 10GBs) and they are taking a day or longer to restore. The command I am using currently is: use ...
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0answers
13 views

Reliability of MySQL Events Table

Is there any limitation of usage of MySQL Events table. Let us say i will have 10K of entries which will be executed across 3k schemas. They all are not same time but at-least 3K events will be ...
3
votes
1answer
7k views

Why does MySQL (InnoDB) table get faster after OPTIMIZE TABLE, but then don't work?

I have a Django web application that stores data in a MySQL InnoDB database. There is a particular page that is accessed a lot on the django admin, and the query is taking a long time (~20 seconds). ...
3
votes
4answers
198 views

Does updating a row with the same value actually update the row?

I have a performance-related question. Let's say I have a user with first name Michael. Take the following query: UPDATE users SET first_name = 'Michael' WHERE users.id = 123 Will the query ...
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2answers
46 views

Un-optimize a MySQL database?

I want to run ANALYZE TABLE and OPTIMIZE TABLE on a large production MySQL database (v 5.0) to increase performance. But as this would lock tables causing downtime for an unknown amount of time, I ...
4
votes
1answer
219 views

PostgreSQL performance worse when adding CPUs

I ran into a strange behaviour when benchmarking PostgreSQL. The setup is like this: Virtual box VM, with 3 GB of RAM. The host has 16GB of RAM and 4 CPUs. Ubuntu 14.04, standard PostgreSQL 9.3 ...
4
votes
1answer
38 views

Measure Performance for INSERT, UPDATE and DELETE commands on DB2

I have a DB2 database with a table for daily transactions, which is cleared to a history table at the end of the day, every day. I insert rows to this table via java-JDBC INSERT commands and they ...
1
vote
3answers
513 views

Oracle Compatible Parameter to set

Is there any difference in setting the Compatible Parameter to 11.2.0.0 vs 11.2.0.4 ? Are there any advantages / dis-advantages ?
6
votes
1answer
2k views

Why is my Azure SQL Server so slow?

We currently have a VM that is very underpowered and are proposing to move to an Azure VM with better specs. The problem is, the Azure VM is much slower than the original VM even though it is of a ...
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votes
3answers
5k views

Frequently slow queries while in the 'Update' state

I have two tables that I update very frequently, one with a direct UPDATE .. and another INSERT .. ON DUPLICATE KEY UPDATE ... Normally these queries are instant but at times will take 0.1s to 1+ ...
1
vote
1answer
119 views

Automatic migration failed on Azure Database

I am using Entity Framework 6.1.1. The database has three million records; migration has to change the precision of a column of type decimal. The migration timeout window is set to the maximum value, ...
4
votes
4answers
146 views

Should I normalize my string arrays, or just keep it a simple string?

I am working on a project involving cards from the Magic: The Gathering game. To be of any use, I must load the basic information about each card into my database, but some of the fields may contain ...
10
votes
3answers
8k views

Should I add an arbitrary length limit to VARCHAR columns?

According to PostgreSQL's docs, there's no performance difference between VARCHAR, VARCHAR(n) and TEXT. Should I add an arbitrary length limit to a name or address column? Edit: Not a dupe of Would ...
3
votes
4answers
366 views

Is there any scenario where the existence of one or more Indexes in a table can prejudice it?

The title sums it up. I've learned and always heard that indexes in tables improve CRUD operations. A developer that I met last weekend told me that he does not like Indexes because they are bad - ...
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votes
3answers
200 views

Application querying empty tables

My company uses an application which has pretty major performance issues. There are a number of problems with the database itself which I am in the process of working through, but many of the problems ...
1
vote
1answer
41 views

Best way of order processing

I would like to write a procedure for order processing Single Order can have multiple items, how can I process the order ? Consider below JSON is an example: { "Order": { ...
8
votes
2answers
35k views

SELECTing multiple columns through a subquery

I am trying to SELECT 2 columns from the subquery in the following query, but unable to do so. Tried creating alias table, but still couldn't get them. SELECT DISTINCT petid, userid, (SELECT ...
4
votes
1answer
315 views

MS SQL high tempdb disk I/O during merge replication of BLOBs

Having a merge publication for replicating BLOBs (sql type - image), got very high tempdb disk I/O for my size of data. Publication is download-only and has no filters. High disk I/O is caused by ...
0
votes
1answer
36 views

sqlite database table with 1000's of columns

I am using sqlite3 in an application to conduct an alalysis of distances between sets of points. Distances between these points have been precomputed using dijkstra's algorithim and left me with a ...
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2answers
531 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 ...
1
vote
1answer
144 views

Print, transaction and cursor performance in Transact-sql

I'm having some performance issues when I run a script. I was reading about the problem with print and its performance, but I cannot figure out how to reduce the impact. The algorithm is O(n^2). The ...
1
vote
1answer
48 views

Vertica performance on select from view with union

We have a huge number of rows(tens of millions), and for each table we have an associated view that is a select with UNION ALL between that table and several others. Now, we are doing a select from ...
3
votes
1answer
614 views

Select * from statement execute very slowly, innodb io read speed is low

I have a very simple query " select * from ap_statistic " running in my servers. the servers have the same hardware and software configuration (CPU 8 core, mem :32G, OS: redhat 5.5, mysql version: ...
1
vote
3answers
229 views

mysql need help optimizing query

I have a table containing servers logs, and another table containing rules to match certain and drop them. The logs tables contains around 1 million rows, and there are about 20-30 rules. The ...
6
votes
1answer
120 views

What is more appropriate sp_updatestats or UPDATE STATISTICS?

In a system there is a nightly data load process where all the foreign keys are dropped, all tables are truncated, repopulated from an external source, and the foreign keys are put back in place. At ...
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0answers
40 views

MySQL performance issue after migration

I have a MySQL performance issue with a brand new server, and am somewhat of a beginner as a database administrator (I'm mostly a general-purpose Linux sysadmin). I'm looking for pointers where to ...
7
votes
1answer
18k views

High Buffer I/O SQL Server 2008 R2 causes?

Am trying to troubleshoot performance on an SQL server that we have for our document management server and today performance has hit an all time low. Looking at the MDW I setup recently I can see a ...
0
votes
2answers
209 views

Fastest way to do bulk import in MYSQL

I have got a question about the fastest way to copy a large number of records (around 10 million) from 1 table to another in MySQL. The target table has 1 primary key, 4 indexes and 3 foreign key ...
0
votes
1answer
16 views

Perfmon Counters that relate to SQLIO

I am trying to benchmark a new virtual SQL server. this will be the first time I have virtualized a production SQL server. I don't think this is a supper busy server. 100-200 users, of varying ...
5
votes
3answers
350 views

Warning about implicit convert

I have table with 2 name columns: CREATE TABLE Test ( TestID int identity primary key clustered , Name_Eng nvarchar(50) , Name_Nat nvarchar(50) ) Now I need a query to get this Name column ...
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0answers
41 views

insert performance of Mysql InnoDB vs Mongodb

I often heared that Mongodb has a better performance than mysql while mysql has more consistence than Mongodb. Then I did a experiment using the following python code based on MySQL-python and ...
2
votes
1answer
710 views

MySQL: Optimize query with a range and distinct count

I have a query on a large table with millions of rows that looks like this: SELECT COUNT( DISTINCT clicks.tx_id ) AS unique_clicks_count , clicks.offer_id FROM clicks WHERE ...
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0answers
16 views

PostgreSQL: Improve system performance, KNN modification with GiST Index

In my PostgreSQL 9.5beta2, Postgis 2.2.0 compiled by Visual C++ build 1800, 64-bit I am running a Nearest-Neighbor-Query with the additional complication of unique assignment. I am running this on ...
4
votes
1answer
186 views

Creating MSSQL Performance Baseline Monitoring

In order to get an overview and compareable data my current task is to create a performance baseline to get some figures about the different productive sql instances. My thoughts are: I want to ...
7
votes
4answers
920 views

DDL contention on TempDB

I have a SQL Server 2005 Standard x64 that is experiencing issues with TempDB DDL contention for the past few months. The server will experiencing contention on wait resource 2:1:103 (the wait type ...
1
vote
1answer
28 views

Update all rows when sort/ordering value is changed for single row?

I am in the process of creating a GIS application with multiple layers and many pieces of content shapes on each layer. Currently each layer/shape is drawn in the order that it was returned from the ...
0
votes
1answer
41 views

AWS EBS I/O Bottleneck

I'm hoping someone can help me understand some EBS Bottlenecks that we are experiencing with a new Windows SQL Server instance we're configuring. We're running some tests by conducting a full backup ...
0
votes
0answers
15 views

MySQL 5.6.18 got signal 11

My MySQL Server 5.6.18 got signal 11 today very randomly. Has not happened before. This is the stack trace : stack_bottom = 7fdb9bcb1e0f thread_stack 0x40000 ...
19
votes
2answers
885 views

IF EXISTS taking longer than embedded select statement

When I run the following code it takes 22.5 minutes and does 106million reads. However, if I run just the inner select statement by itself it only takes 15 seconds and does 264k reads. As a side note, ...
0
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1answer
441 views

Select Query takes more than a minute to retrieve data

I have a table that has 99 columns, all of them are not needed but they were there when we started. There is a Primary Key (Objectuid) which is a GUI and has the Clustered Index on the PK. The Table ...
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0answers
37 views

SQL Server 2012 AG replication issues

We just went away from SQL Serer clusters in SQL Server 2008 to SQL Server 2012 with AG – have five servers with replicas in a secondary datacenter and syncing over a dedicated eline/LAN layer 2 ...