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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3
votes
2answers
287 views

Query planner thinks doing a sequential scan on a very large table is faster than using an index?

I've got a query that selects the most favorited photo for each of the last 12 editions for a particular domain (this is just a segment of a larger query, but the problem seems to stem from here): ...
0
votes
1answer
506 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
votes
0answers
5 views

Can MySQL Index Merge an Composite index with a single column index?

I am tuning a query and currently have an index as following : Index 1 : (col1, col2) An example query would be : SELECT * FROM t1 WHERE col1 = '1' AND col3 = '2'; I have created an index on ...
3
votes
2answers
367 views

SQL server query is slow *without* including execution plan

I have just set up fresh installation of SQL Server 2012 on a new server and I'm experiencing very strange performance problems. Long story short, for some reason not including execution plan makes my ...
2
votes
1answer
84 views

SELECT query with DISTINCT on a table-structure for graphs is very slow

I have 2 tables where nodes contains about 60m rows and edges about 500m rows (both growing fast). These two tables represent a directed graph. CREATE TABLE edges ( node_from bigint NOT NULL, ...
4
votes
2answers
55 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 ...
0
votes
1answer
194 views

DB disk space requirements comparision between MySQL versions

I have 2 labs where MySQL is installed. DataBases are created and deleted dynamically by certain internal processes. InnoDB is the Engine used. In one lab, MySQL version 5.0.77 is installed. The DB ...
1
vote
2answers
632 views

What is com_set_option?

As the title says, I'm wondering what is this command and why am I seeing a large amount of this query on my database? It's currently 13.30% of my total queries. I've tried googling this but there's ...
0
votes
1answer
89 views

Oracle 11g max login fail attempts workaround

My problem with database starts with situation where I cant really modify anything in database. My project specialist has limited time to help me. Here is the thing: My user in Oracle database has ...
0
votes
1answer
48 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 ...
1
vote
1answer
24 views

Best approach to get last value inserted

I have several devices that report via Edge network their position (and more data) to a UDP server which directly inserts this data in a SQL 2008 r2. I want to know which is the best approach to ...
1
vote
2answers
174 views

Improving a search query [on hold]

I have a query for search function. Basically search function allowed user to define what they "have" and "want". Then this query will filter out all the possible result which created by other user. ...
3
votes
1answer
37 views

PostgreSQL 9.4 analysis, performance of normal column, indexed column and jsonb key

If I have a table containing: CREATE TABLE test( id SERIAL PRIMARY KEY, name VARCHAR(200), age INT, data JSONB ); and data column populated with {"name": xxx, "age": yyy}, sometimes ...
0
votes
2answers
74 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 ...
2
votes
0answers
56 views

Prepared statement overhead

I am using libpqxx to communicate with a PostgreSQL 9.3 server. For multiple table inserts, if they are split into individual prepared statements, they cost approximately 2ms each. If they are all ...
-5
votes
0answers
31 views

How much space does database takes to store twitter data? [on hold]

Context I am going to collect twitter-data(user,s followers, timestamp, content, url and Hashtags) weekly and it continues for an year. I have a total of 160 hash-tags, and I will be creating an ...
1
vote
2answers
65 views

Security or performance risks using SQL CLR [closed]

Are there any particular security or performance risks in using the CLR in SQL Server ?
1
vote
0answers
49 views

What is more important for Oracle DB performance, number of cores or memory size? [on hold]

Oracle has quite drastic licencing policy based on the number of cores. Can we save by providing a server with less cores, but more memory? Or is the number of cores the most crucial factor for the ...
0
votes
2answers
769 views

How to fix slow LIMIT queries with big offsets without heavily rewriting them?

Imagine a very basic example of your average discussion board. For example: CREATE TABLE threads ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, title VARCHAR(100), PRIMARY KEY (id) ) CREATE ...
0
votes
2answers
172 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 ...
0
votes
1answer
108 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.
0
votes
0answers
37 views

Physical Table being used a Temp Table in a warehosue. Any advantage?

As I stated in previous posts I've inherited a warehouse based on SQL Server framework. In my continuous review of existing components and the practices adopted by the predecessors I found something ...
3
votes
2answers
274 views

Why is my CPU usage increase after setting database to read-only on SQL Server 2008 R2 [on hold]

I administrate a reporting database. We run all the de-normalization process on a database DB1 daily, then we copy all the data to an another database DB2 on the same server which is queried by web ...
0
votes
1answer
172 views

MySql - is possible that performance issues are caused by dynamic SQL?

We have this MySQL SP, which uses dynamic SQL. It seems it does NOT perform well under load. It is possible that this SP becomes slow under load because it uses dynamic SQL? Can dynamic SQL cause ...
0
votes
2answers
17 views

Large long-running reporting queries are causing very slow new mysql connections

Usually, mysql's connecton time is in the 0.001 second range. However, when I run a large reporting query (that spans multiple tables with aggregates), I get tons of warnings saying that new mysql ...
1
vote
1answer
120 views

Handling a chat room in a database

I have been searching all day to find a better answer to my question but those I found was useful but do not critically analyse my question. I am building a chat room using php, mysql, jquery and ...
0
votes
0answers
18 views

Database design for price comparison site - too complex?

I'm working on a regular price comparison site with two exceptions. I want to show price history and also allow users to subscribe to a product with a specific size and color. As a result, I've ended ...
0
votes
1answer
39 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 ...
1
vote
1answer
22 views

MySQL Latest Deadlock Explanation

Can someone explain this deadlock to me? It seems as if there are 2 inserts happening within milliseconds of each other with the same Primary Key. I'm not sure how this can cause a deadlock. At most a ...
0
votes
2answers
61 views

Does it make sense to order condition in where query?

We have a clustered index in table Tbl with order of A,B,C. Does it make senses to write a query to have WHERE A = @a, B = @b, C = @c or it'll be as same as WHERE C = @c, B = @b, A = @a Does the ...
0
votes
1answer
31 views

large SQL Performing quite slow (roughly 2 seconds for 290 rows) when having to deal with entries that can be NULL

SELECT version_stamp, pscdesc_id, psc, pscdesctext FROM pscdesc_history WHERE ( psc IN (SELECT psc FROM pso_history AS c ...
7
votes
1answer
1k views

How to determine if there are [idle connections with] uncommitted transactions in PostgreSQL?

According to a comment on this question I asked about idle connections in PostgreSQL 9.2, some uncommitted transactions (possibly related to some of those idle connections) might cause some ...
0
votes
1answer
310 views

Amazon RDS CPU Usage keep increasing without any long running process in Show Processlist

We are using Amazon RDS(db.m2.2xlarge), CPU usage is suddenly increasing gradually even after we reboot the DB Server. This is happening just past 2 days and we didn't give any new build recently. I ...
0
votes
1answer
593 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 ...
0
votes
2answers
105 views

MySQL/MariaDB Limitations

we're running MariaDB on our DB server. We have to install multiple databases on each DB instance (in fact each DB server runs multiple MariaDB instances) because each database must be separated. ...
0
votes
2answers
109 views

Slow INSERT/UPDATE on InnoDB

I have a problem with the performance of my MySQL server, let me explain: I instaled a MySQL server, version 5.5.20 Server version: 5.5.20-log Source distribution SELECT queries runs fast on ...
0
votes
1answer
196 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 ...
13
votes
6answers
25k views

How to efficiently check EXISTS on multiple columns?

This is an issue I come up against periodically and have not yet found a good solution for. Supposing the following table structure CREATE TABLE T ( A INT PRIMARY KEY, B CHAR(1000) NULL, C ...
0
votes
1answer
73 views

How to prepare executon plan for given sql query on a server with 4 processors (Oracle database)

4 processors means the query runs in parallel. Select /*+ parallel(4) */ T1.A FROM T1,T2,T3 WHERE T1.A = T2.A AND T1.B=T3.B AND T1.C=T3.C Tables T1,T2 and T3 have 4,8, and 16 partitions ...
2
votes
1answer
227 views

Is this amount of disk IO expected with MySQL?

I am running MySQL 5.5.34 on an Amazon EC2 micro instance with EBS (elastic block storage). The instance has been running for around 10 days and according to Amazon I've accumulated around 8.5 ...
0
votes
3answers
36 views

SQL Server Compact - Will it perform well with heavier traffic sites? [closed]

I'm using Orchard CMS, and on initial setup, the default setting is to use SQL Server Compact. I'm not too knowledgeable about different database types and performance. So, will SQL Server Compact be ...
-1
votes
0answers
27 views

How index work in case of write operation?

We have two cases:- Insertion :- Cluster Index:-- Insertion :- we have number of user which we doing insertion new records. For .........example 27 users had inserted 27 rows in 1 ...
1
vote
1answer
90 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 ...
0
votes
2answers
24 views

MySQL rapid Data Replication from multiple Databases

I am a Freelance Web Developer but not a Database Administrator at all except basic Database Operations like DML etc. Today I got a client asking me to develop a Web based application but there is a ...
0
votes
0answers
31 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 ...
1
vote
1answer
37 views

Oracle performance loss from 10.1.0.2 to 10.2.0.5

I am testing an application on two database servers with the same data : 10.1.0.2 on Windows (for development) 10.2.0.5 on Solaris (for validation). We have a script which recreates a huge table ...
0
votes
1answer
20 views

my.ini configuration for a huge server

I have developed a web based app in PHP MySQL and Flash Builder. It was running fine until a few days ago when the client began to connect a lot of users. Then the app started to freeze and sent ...
1
vote
1answer
22 views

Limit distinct count of group by

Suppose for simplicity that I have a table t with columns id and value. I can find the ids that have more than one distinct value using a query such as SELECT id, COUNT(DISTINCT(value)) AS count FROM ...
1
vote
0answers
28 views

Did I Properly Diagnose That It's Not A SQL Server Issue?

We have a job that populates about 450,000 rows nightly in an update/insert job via a stored proc nightly. The .Net app pulls in data from a noSQL DB via an API call then pushes it out via a stored ...
0
votes
2answers
50 views

Can an EXISTS clause be improved when the condition is checked for the same value multiple times?

Assume that I'm modelling a Blog engine. Blogs have n Posts. Each User can be granted a role on different Blogs (Admin, Approver or Editor stored as enums/ints). Each Post can have a State (Draft, ...