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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2
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1answer
70 views

Will MySQL be effective when selecting a row from a table with billions of records?

Note: this is a hypothetical scenario Lets say that: I'm running MySQL, InnoDB engine, UTF-8 encoding I have a table with 50+ billions of rows The tables primary key is a BIGINT The table also has ...
1
vote
1answer
58 views

Maintaining mongodb for a huge list of message “documents”?

Intro: I am working on an app right now for live messaging and it's almost complete. The database strategy is in order. So when a new message is created it is sent as an object fitting my mongoDB ...
0
votes
0answers
48 views

Efficient way to fetch/update X records in a loop

What I need is a simple process that handles requests. I have setup a simple table as follows: CREATE TABLE Requests ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, request_param VARCHAR(250) ...
1
vote
1answer
46 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 ?
1
vote
1answer
90 views

Innodb buffer pool and multiple joins

assume we have 1 Billion records and want to store them in One or Three tables by post_type. post_id -> primary key post_type -> ( page, group, user ) user_id -> index date -> ...
0
votes
4answers
95 views

SQL Where Clause Efficiency

Say I have a SQL statement: SELECT * FROM MyTable WHERE KeyColumn1 = 1 OR KeyColumn1 = 2 OR KeyColumn1 =3 OR ... KeyColumn1 = 10 And another: SELECT * FROM MyTable ...
0
votes
0answers
36 views

Sql Server Standard VS Enterprise

I have been bench-marking SQL Server Enterprise and Standard, Enterprise is using Partitioning by month on the table. The table only has 3 fields, Date-time (DateTimeOffeset(3)), Value (integer in the ...
3
votes
2answers
138 views

Enhance performance of update query

I have a query that is running against a table with 50 million rows. The phone number is stored as a CHAR(10) and an ETL process is changing the phone number if it has certain values. We are seeing ...
4
votes
2answers
261 views

Sudden performance decrease in SQL Server

I've got a problem with a SQL Server 2008 R2 instance. Last week the performance suddenly broke down. All inserts are very very slow. It takes 4-5 times longer than before. On the hardware we found no ...
0
votes
1answer
119 views

How should I config the my.ini(or my.cnf) file for mysql?

Thanks for taking your time to look at my question, and I hope that you can help me with this. I have a Windows Server 2012 server, it has: Memory : 3840MB Ram Processor: Intel(R) Xeon(R) CPU ...
0
votes
4answers
99 views

T-SQL: Complete Database in one table

at a relational data model every logical relation is a single table with values and so on. I know someone who is this too much work and he wants to create only one table which contains all. This could ...
1
vote
1answer
101 views

MySQL 5.1: Upgrade innodb plugin

My application is running on MySQL 5.1.58 community edition. As I studied on SO websites that After acquisition by Oracle, new InnoDB plugin has been released and MySQL 5.1 with InnoDB plugin is the ...
1
vote
0answers
35 views

Database tuning and possibly unexpected results

(This is cross-posted from stackoverflow; I initially put it in the wrong place.) So I have a database that's working a bit slower than I would expect and I'd like to describe what I'm doing so ...
0
votes
0answers
32 views

How can the performance of a query that has a condition on two fields of each row be improved?

I have an images table with approximately 5 million rows in it. For the purposes of this question lets say the table looks like this: CREATE TABLE `images` ( `id` int(11) NOT NULL AUTO_INCREMENT, ...
1
vote
1answer
38 views

What's the complexity of renaming a column in MySql?

We want to rename a column in our MySql (version 5.5) database with something like this: ALTER TABLE t1 CHANGE a b INTEGER; Is this an O(N) (N=number of rows in the table) or an O(1) operation? I ...
0
votes
0answers
130 views

index usages on table with recursive relationship

we are working on a project that uses jpa and oracle. In this project we have a table with a recursive relation: Create table alarm ( id varchar2(200), ... alarmcode varchar2(50), parent_id ...
2
votes
2answers
93 views

SQL Server 2008 R2 Missing Index

I am performing index maintenance on a database. I have run SQL script that uses DMVs to provides a list of indexes SQL Server believes should be created. I am not creating indexes just because the ...
0
votes
0answers
96 views

Performance measurement in PostgreSQL

When developing server-side stored procedures performance measurement is an important issue. EXPLAIN ANALYZE is very usefull, but when it comes to simple queries like SELECT name FROM clients WHERE ...
0
votes
1answer
44 views

Access and filter in oracle plan

I came to a execution plan where oracle choose to access the index but instead of using the columns as predicate it only filter by them. My question is what are the reasons that can cause that(all ...
2
votes
1answer
76 views

How to monitor load on database server

Could anybody please suggest me a way to monitor the load on my database server? What perfmon counters should I monitor on daily basis and confirm that load on the server is increasing day by day [or] ...
1
vote
2answers
125 views

Baffled with MySQL LEFT JOIN query that I have to speed it up

I am kind of a puzzled with this query trying to optimize it but no way I am able to (due to my limited knowledge as a DBA). So, I asked the experts. In my setup I have three (primary) tables. ...
1
vote
0answers
55 views

Do supertables produce bottlenecks?

There are several alternatives to using polymorphic associations and one of them is to use the so-called "concrete supertable". From my point of view, this is the neatest solution and is pretty easy ...
0
votes
1answer
161 views

How to interpret undo statistics in Oracle AWR report? [closed]

How can I use undo statistics in oracle AWR report for tuning Oracle? which indicators are important to identify that size of undo segments needs to be increased?
1
vote
1answer
129 views

SQL statement slower on as400 console than from remote odbc [closed]

I am having a strange problem on one of my i systems running 7.1 I am using jdedwards 8.0 as erp but the issue is not related as i just found out. After some research it came down to this. I run the ...
1
vote
3answers
90 views

Is bulk-logged recovery model ever a good choice if point-in-time restore is not needed?

Is the Bulk-Logged recovery model in SQL Server ever preferable to Simple if point-in-time restore is never needed? I have read many articles about transaction log models, but cannot find a clear ...
0
votes
1answer
70 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 ...
7
votes
4answers
970 views

How do I best measure the query performance?

I have 2 stored procedures, where the second stored procedure is an improvement of the first one. I'm trying to measure by exactly how much that is an improvement. 1/ Measuring clock time doesn't ...
0
votes
0answers
64 views

Explain difference between insert as select and select

Can someone explain why there is plan difference? Same query, same time the explain plan taken. I understand what happen (different order of getting the data) and how to fix it(move to forall insert ...
2
votes
1answer
182 views

Disk Latency vs Throughput

I've searched the web for a little while and haven't found an answer I'm confortable with. I am testing a SQL Server on a VM that was presented new disc. If disk latency is reduced, shouldn't ...
3
votes
1answer
180 views

Why does this limit make the postgres planner use a much slower index scan instead of a much faster bitmap heap/index scan?

I have a table of about 700k rows in Postgres 9.3.3, which has the following structure: Columns: content_body - text publish_date - timestamp without time zone published ...
2
votes
1answer
187 views

In Oracle AWR report how to use “Latch statistics” section in analysis

Latch statistics in AWR report contain following sections 1.Latch Activity 2.Latch Sleep Breakdown 3.Latch Miss Sources 4.Parent Latch Statistics 5.Child Latch Statistics How can I use these ...
3
votes
1answer
122 views

Frequent Delete & Insert, impact on performance

In my application, we have very few updates. Most of the data gets deleted and inserted. My question is, how this will impact the performance? We are using SQL Server 2012. Table statistics (will ...
3
votes
2answers
1k views

High CXPACKET and LATCH_EX waits

I am having some performance issues with a data processing system which I am working on. I have gathered wait stats from a one hour peroid which show a large amount of CXPACKET and LATCH_EX wait ...
0
votes
0answers
76 views

Mysql profiler different duration information_schema.profiling

Hi! I have a problem and no idea how to resolve it. I'm trying to use mysql profiler. I'm using the command: set profiling=1; to turn it on. Later, i execute my query which is correlated ...
0
votes
1answer
62 views

Is there a table size above which SELECT performance degrades significantly?

In MySQL, does SELECT performance degrade significantly after a certain table size? I have a table with about 107 million rows and some queries seem stuck in "Sending data" for a long time. Of course, ...
1
vote
5answers
258 views

How to determine why a MySQL server has become slow and requests sometimes time out?

I'm working on my first project that makes heavy use of a MySQL database and am struggling to understand performance issues I'm having. Most of the time, responses are returned quickly from the ...
9
votes
3answers
1k 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 ...
2
votes
1answer
249 views

Debugging why postgres is snowballing with system cpu usage

I am having an issue where my postgres database which run on a dedicated machine is getting hammered with kernal level cpu usage. This essentially takes down the web service that run on this database. ...
0
votes
1answer
100 views

performance difference between < and <=

I remember that there is a performance issue with SQLs that use "<" against "<=" because of statistics and/or histograms and/or the data itself, but I dont remember exactly the issue. I know ...
11
votes
1answer
849 views

GO After every T-SQL statement

What is the reasoning behind using the GO statement after every SQL statement? I understand that GO signals the end of batch and/or allows the reputation of statements but what advantage does it have ...
4
votes
1answer
71 views

How can a connection for one DB block a connection to another DB in SQL Server?

We have an interesting scenario. For weeks, we have been experiencing 'outages' on SQL Server 2008 -- where our websites have slowed to a crawl and mass timeouts for all customers who have DB's ...
-1
votes
1answer
106 views

Approximate MySQL Query Time For A Where Clause On A 10 Million Records Table

I'm looking forward to designing a database (in MySQL) but before I start I need to have some calculations to make sure that my application will remain efficient even if there are 10 Million+ rows ...
1
vote
0answers
171 views

Poor performance in my pgpool cluster

I've configured a postgres cluster with pgpool2 using the following link. The replication seems to be ok, but I ran some benchmarks (pg_bench) and the performance is lower than a single node, for ...
1
vote
1answer
64 views

How can I improve performance of update query in PostgreSQL

I have a table with about 80 million records. I have added a new attribute (heigth_category) which I want to fill based on another attribute (heigth). If the heigth is between 0 and 6, I want to fill ...
0
votes
1answer
118 views

PostgreSQL - Return unique combinations of columns based on where clause

This is quite a long question, please bear with me. So I'd like to first explain I have a database of firewall logs created using the following command: CREATE TABLE firewall_logs_mapped ( ...
0
votes
0answers
40 views

query comes in slow query when log_queries_not_using_indexes is enabled

This query comes in slow query log when log_queries_not_using_indexes is enabled. SELECT a.id, d.id AS city_id, d.city FROM booking a, sub_area_master b, area_master c, city_master d WHERE ...
6
votes
1answer
229 views

Estimating IO Requirements for Bursty Usage

We have an application that queries a SQL database periodically throughout the day. There are periods of zero or only light activity, interspersed with individual requests for relatively large ...
2
votes
1answer
90 views

Avoiding Deadlocks

We currently have a trigger-based system in place that does the following: When records in certain tables are modified, a trigger fires that makes a field NULL in a varying number of records in ...
0
votes
0answers
50 views

TempDB causing high IO writes - dependent on server's max memory setting [duplicate]

I have a mirrored SQL Server 2012 database. The first server has a hugh tempdb write IO load when the maximum memory limit is set above 8192 mb. These 8192 where the original setting for both the ...
0
votes
1answer
53 views

DB2 - how to track IOPS statistics?

DB2 9.7. Is there some easy way in every moment go have statistics about IO operations per second? I am not interested for hit ration on Buffer Pool but really on IOPS? THANK YOU