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.

learn more… | top users | synonyms

0
votes
0answers
46 views

Adding additional condition significantly degrades performance

Have the following query: SELECT * FROM table_A INNER JOIN table_B ON /* conditions */ INNER JOIN table_C ON /* conditions */ INNER JOIN table_D ON /* conditions */ WHERE table_B.state = 'active' ...
2
votes
1answer
65 views

SQL Server - Data and Log Separation

We have a SQL Server 2008 R2 which has, among others, a 12K RPM HDD and a 7.2K RPM HDD. The original intention was to store the data files on the 12K drive and the log files on the 7.2K drive, as is ...
0
votes
0answers
14 views

using the wordpress approach for storing taxonomies

multiple tables vs single table a user table will not need every social link in the database column, since every one will not enter all their social links and are used only on user profile ...
4
votes
0answers
42 views

Major Discrepancy Between SQLIO IOPS/Throughput Stats and DBCC CHECKDB Operations

I'm conducting time trials on a new SSD array running both SQLIO tests and a real-world workload of DB restores and DBCC CHECKDB calls. I'm seeing a major discrepancy between the IOPS and throughput ...
2
votes
1answer
22 views

Need help tuning my.cnf file

I need help tuning mysql. Currently it is using a lot of CPU. I dont find any query that last longer than 3 seconds in SHOW PROCESSLIST and there are only around 20-25 running most of the time. Still ...
1
vote
2answers
44 views

Does having many databases affect MySQL performance?

I have huge unused databases in MySQL. Do they affect my MySQL engine performance even if they are unused? Do they consume memory on their own? Thanks
0
votes
0answers
14 views

Are mongodb bulk inserts really increase server perfomance (and faster)?

Bulk inserts always are faster in client side because of saving round-trips, but at the server-side is there any sensible performance improve? It seems the code for bulk inserts, just loops over ...
0
votes
0answers
10 views

Best design of mongo replica set for DB read/write speed

I'm building a Node app that uses MongoDB. Whilst it would probably be fine to have node and mongo sitting on the same VPS, I want to ensure that the MongoDB is backed up and maintain high ...
-2
votes
2answers
46 views

Index is not used with same Query on two Servers

I have two notebooks with same specs (same model, only ram is 24GB/32GB, same ssd) and exact same database and same sql server version. SQLIO is 3300 and 3600. Now I run a query on one notebook and ...
1
vote
1answer
51 views

Optimistic Paging and separate query for COUNT?

I am using SQL SERVER 2012 FETCH/OFFSET after searching a lot that this will give me the best performance. But for paging to work, I need a Total count. There are 2 ways to achieve this. 1) Paging ...
1
vote
1answer
50 views

Optimizing a slow MySQL query

I'm trying to optimize a ~100GB database. All data values are in one single innodb table, is this bad? Here's what a common query looks like: SELECT `CensorCode`, `LocalDateTime`, `UTCOffset`, ...
1
vote
0answers
23 views

Any way to speed up my queries in MariaDB with tables less than a 4 GB in size?

I'm doing some text mining work and a bit frustrated that queries are taking 6 to 10 minutes to run. My workstation has a 3.5ghz Xeon, 32GB of RAM, and 2 SSD as RAID 0. Is it possible to do ...
0
votes
1answer
25 views

How can I rewrite the following removing the date_format function?

I have a table with a column when that is of type datetime. I am doing the following filter which can not use and index: AND DATE_FORMAT(t1.when, '%Y-%m-%d') <= LAST_DAY(now() - interval 1 month ) ...
0
votes
1answer
24 views

Impact of replication compression & encryption on performance, traffic?

What is the impact of MySQL compressed-slave-protocol on replication traffic? According to High performance MySQL it can lower the traffic to a third of the same replication without the compression. ...
1
vote
1answer
39 views

Increased performance from single statement, multiple row inserts?

I'm currently obsessing over bulk inserts via prepared statements with libpqxx. I am far from a database expert and even further when it comes to Postgres, but just thinking superficially, it doesn't ...
0
votes
0answers
15 views

Performance : MySQL replication or only one big server?

I'm searching about the best choice. We have to host a website with 10.000 - 20.000 visitors per day actually, growing. At the beginning, which would be the best : Having 2 MySQL servers (12 GB ...
1
vote
1answer
61 views

What mongodb database layout would fit better

I'm currently writing an application using the MEAN stack, pretty much only for fun and because MEAN is "cool" at the moment. Therefore I'm thinking about the database layout. The data needed to be ...
0
votes
2answers
39 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 ...
1
vote
1answer
59 views

How to improve the performance of this select query?

I have two tables: TABLE1 and TABLE2. And I am running this select query to fetch the data. It takes long time to run: SELECT TABLE1.* , TABLE2.COL1 , TABLE2.COL4 FROM TABLE1, TABLE2 WHERE ...
1
vote
2answers
71 views

Oracle becomes too slow after system crash

I am using Oracle 11.2 as a database for my application. For this purpose I should import my data (around 100m records) to this database. For this purpose I used SQL Developer. Unfortunately at the ...
0
votes
0answers
24 views

Big Mysql table optimization

I have a table that I use to cache google translate API answers. Table structure is orig_string and group are indexes Now it has more that 1million rows with 35000 distinct values in group field. ...
1
vote
0answers
22 views

“dynamic set” in a MySQL table

I have a table where one column will have a few values many times (maybe 20 different values). Now I would like to use something like the set to improve performance and memory consumption. The problem ...
0
votes
1answer
44 views

Slow MySql server - even on a super fast server

I have just upgraded my 12 year old server to a really fast new one. It is a dedicated server, Dell R620 1 x Intel E5-2620 (2.0GHz, 6C) CPU 32GB RAM - 4 x 250GB SSD RAID 1, in short vastly faster in ...
6
votes
2answers
113 views

Improve performance of COUNT/GROUP-BY in large PostgresSQL table?

I am running PostgresSQL 9.2 and have a 12 column relation with about 6,700,000 rows. It contains nodes in a 3D space, each one referencing a user (who created it). To query which user has created how ...
3
votes
2answers
439 views

A little clarification on how 'LIMIT' works

Not being a full blooded member of the DBA clan, but more of a dev clan, I find myself trying to figure out some slow running queries. The subject of my question however is not 'Why my queries are ...
1
vote
2answers
44 views

Oracle result cache behaviour

Oracle by default caching the query results and function results(Buffer cache). I have noticed this with AutoTrace utility, where the physical reads are huge on first execution, but from next ...
1
vote
1answer
70 views

Inserting to table: Insert rows with Left Outer Join or Insert rows then Update?

I have a table of Orders and another table of Deliveries. The Orders table will contain a reference to the Deliveries table if there is a corresponding row. Not every row in Orders will have a row in ...
0
votes
1answer
32 views

HOW does ROWNUM work with this “optimization”

I'm trying to optimize a query in which I have some requirements where I need to be able to arbitrarily select a row ROWX from a query. Why is it that SELECT XML_DATA FROM (Select ROWNUM AS ...
2
votes
1answer
35 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
32 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
31 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
30 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
46 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
87 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
23 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 ...
0
votes
0answers
68 views

Why has the backup time significantly increased?

I'm using Sql Server 2012. The problem is that the backup takes about twenty minutes now, whereas only a few days ago it took a matter of seconds. The database has increased by about a sixth since ...
3
votes
2answers
113 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
190 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
57 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
93 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
48 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
30 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
29 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
33 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
94 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
47 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
64 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
38 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
63 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] ...
0
votes
1answer
59 views

Which database (Graph, Riak, etc.) would most aptly solve the following problem?

I am working on a project and was wondering if a Graph database would best solve the following problem: (This is a simplified question) Say that you have a list of friends and you want to see when ...