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

2
votes
0answers
72 views

Find Most active databases that can be offloaded from a busy server

I am in the process of identifying the most active databases on the server and will be moving the databases off the current server to alleviate the load. The reason to do it is that our servers are ...
0
votes
2answers
105 views

Running a simple logging program, how to diagnose spikes mongod's CPU activity?

I'm running mongodb 1.4.7 - I've a node server set up which logs incoming requests in a logs collection: {'u':'user123', 'l':'log data'} In addition, once the request happens, the server will check ...
1
vote
0answers
72 views

Can XML columns in Oracle/MS SQL Server replace document oriented databases to some extent?

Just a strategic question: I am currently working with frequently changing data schemas and it takes a lot to keep track of versions and specific content. I do, however, have a classic OLTP ...
0
votes
0answers
53 views

MySQL showing non-linear behavior for a simple insert

I've come across a symptom in MySQL which got me baffled. First, the time it takes to INSERT a certain amount of records changes non-linearily with the amount of records. Second, the time also depends ...
0
votes
0answers
112 views

My queries are slow under load

I am performing a load test for my application. All my SQL queries which are fired from my application, individually look better and perform fast. The same SQL are becoming bottleneck when they are ...
3
votes
1answer
68 views

Restoring with replace going incredibly quickly [duplicate]

So I have a database (on a SQL Server 2008 R2 SP2 instance) that is 2TB uncompressed, with a .bak file that is 500GB compressed. As I have been toying with the fastest way to restore this database ...
4
votes
2answers
1k views

GROUP BY with MAX versus just MAX

I am a programmer, dealing with a big table which the following scheme: UpdateTime, PK, datetime, notnull Name, PK, char(14), notnull TheData, float There is a clustered index on Name, UpdateTime ...
1
vote
1answer
182 views

Using coalesce on an index column

Does doing a COALESCE on an indexed columns in a WHERE clause e.g. WHERE COALESCE(table1.indexed_column, '9999-01-01') > table2.other_date_column affect indexing in a bad way? I think that it ...
0
votes
0answers
122 views

mysqldump & upload to mysql speed impact due to SSD and innoDb?

I am testing an AWS Medium Instance with CentOS (AWS AMI) and comparing it with Hetzner's EX40-SSD (http://www.hetzner.de/hosting/produkte_rootserver/ex40ssd). Software setup on both is comparable( ...
0
votes
1answer
134 views

Best read performance when every query is known, and the data doesn't change

I'm trying to maximise performance on an underpowered PostGIS server - 1 core, 4 CPUs. The data (OpenStreetMap) will be infrequently (monthly?) loaded, and never changes otherwise. Each of the 30 or ...
1
vote
0answers
129 views

Why does removing a RID by creating a clustered index lose parallelism and slow down execution by 2X

If I remove a RID lookup by replacing 2 non-clustered indices (non unique) with 2 identical clustered indicies (non-unique) where there weren't any before, why does this query slow down by a factor ...
2
votes
2answers
561 views

MySQL - Add index to low cardinality text column?

I'm working on project where an enum column is being converted into a text column (I cannot change this). The cardinality of the column is low (7 unique values). Would I gain a performance increase by ...
0
votes
2answers
664 views

Does using LIMIT improve the performance and is it noticeable?

I want to understand the following. Assume that I have a complicated query with let's say a join of 5 tables a group by summations and order by. Letting aside any optimizations to the query itself ...
0
votes
1answer
513 views

How to “warm up” a cold DB server?

1st setup was a DB slave that was used by customers. That was sufficiently fast. 2nd setup (now) is replication of a DB slave that is just used by me. The current setup is slower on query execution ...
1
vote
2answers
296 views

Slow query responce on different mysql versions, percona, MariaDB

LEFT JOIN is supposed to be faster than a NOT IN query. This is what I've read online. But practically, this seems to be opposite. I have the following query here, INSERT IGNORE INTO callrequests ...
5
votes
2answers
2k views

Efficient query to get greatest value per group from big table

Given the table: Column | Type id | integer latitude | numeric(9,6) longitude | numeric(9,6) ...
0
votes
1answer
280 views

Simple PostgreSQL lookup table is inexplicably slow

I'm trying PostgreSQL 8.4.14 for storing triples, pieces of data of the form (String, String, String). For speed, I'm not repeatedly storing strings but rather using two tables: main table triples ...
0
votes
3answers
398 views

Performance of primary key IDs with gaps (but in sequential order)

I know that having non-sequential IDs is bad for index performance. But assuming all my IDs are created in correct order, but with large gaps: i.e: 154300000 283700000 351300000 464200000 ...will ...
0
votes
0answers
139 views

PostgreSQL 9.2 (PostGIS) performance problem

A month ago i got acquainted with PostgreSQL and only now i've noticed that some of my queries are pretty slow. Well, for example, i have table: CREATE TABLE sometable ( gid serial NOT NULL, geom ...
0
votes
0answers
182 views

Improve Speed of MySQL Database Import

I'm importing around 44 GB (14 million rows) of information into an InnoDB MySQL database, and I'd like to do so in a reasonable timeframe. Since I'm doing this on a personal computer, I only have 8 ...
0
votes
0answers
108 views

Slow query with ORDER BY with index created (more than 4mins on 0.6million records

I ran into a very weird query performance situation. If I run this query without order by, it finish in millsecs, with order by, it ends up with more than 4mins. EXPLAIN SELECT `book_book`.`id`, ...
1
vote
3answers
943 views

Conditional Join - Specific Column Select

I have tables like these: Table Employee ( Emp_Id, Full_Name, ...) Table Order ( Submitter_Id, Recipient_Id, ...) Then say that I have conditional join like this: select isnull(Emp.Full_Name, ...
3
votes
1answer
223 views

What is Required to use Oracle Performance Manager to monitor SQL Server?

I am working with a customer who has several SQL Server and Oracle DBMS server instances. My customer would like to setup up performance data collection, monitoring and alerting for all of their ...
1
vote
0answers
99 views

SQL server taking too much time in opening properties in SSMS

I am using sql server express 2008 r2 SP2 from about 2 years. Now a days when i try to check properties of database using sql server management studio it takes too much time(25 to 30 seconds) to open ...
6
votes
1answer
398 views

Extremely Slow StatMan query issue with #SP2010 farm

The issue I’m experiencing is explained in a blog-post I created for this, (easy to refer to and to manage the responses / solutions in 1 location) which can be found here: ...
4
votes
1answer
171 views

Disk usage spikes: good, bad or indifferent?

I'm working on a project where we're receiving data from multiple sources, that needs to be saved into various tables in our database. Fast. I've played with various methods, and the fastest I've ...
0
votes
0answers
314 views

Is it possible to optimize a range query so an explain statement would state “using index” instead of “using index condition”?

I have a very large table where specific queries made by my application are timing out. The table looks something like this: LargeTable ------------ Id [BIGINT(20)] UtcTimestamp [BIGINT(20)] Pivot ...
0
votes
1answer
121 views

Get unmatched rows for foreign key

Consider two tables: CREATE TABLE Users( id INT PRIMARY KEY, name VARCHAR(128) ) Engine=InnoDB CREATE TABLE Tags( id INT PRIMARY KEY, user REFERENCES Users(id), tag VARCHAR(128) ) ...
1
vote
0answers
85 views

What is the most efficient way to create new MySQL database

I need to setup a development environment for several developers. Each of them needs to test the software with a "fresh" MySQL database. There is a SQL file with many CREATE, ALTER and INSERT queries. ...
0
votes
1answer
195 views

MySQL select by primary key against 100M of records within 30ms

I have no expirience with MySQL and database performance tuning in general. Wondering whether it is possible to perform a large number of selects against 100 millions of records by primary key within ...
5
votes
1answer
581 views

TPS too high in PostgreSQL

I created a table: CREATE TABLE foo ( id integer primary key, bar integer NOT NULL ); and inserted one row: INSERT INTO foo (id, bar) VALUES (1, 1); and ran a pgbench of the following ...
0
votes
1answer
82 views

Performance: order of tables in joined statement

I have the following SQL statement, running on a SQLite database on a Windows mobile device. SELECT table1.uniqueidentifier1, table1.int1, table1.varchar1, table1.decimal1, table1.decimal2 ...
4
votes
3answers
141 views

How do you see which database on a Server uses most resources

I have a database server with a couple of databases on it. How can I see where any resource pressure may come from? I would like to get a table of: Database Name Batch Requests per second CPU ...
5
votes
1answer
614 views

Possibilities to speed up InnoDB INSERTs and UPDATEs

My website retains user sessions in an innodb table. This usually works well, but a few hundred times a day, the INSERT and particularly the UPDATE statements run slower. I'm monitoring when, and it ...
2
votes
2answers
2k views

MySQL not using indexes when joining against another table

I have two tables, the first table contains all articles / blog posts within a CMS. Some of these articles may also appear in a magazine, in which case they have a foreign key relationship with ...
0
votes
1answer
134 views

Entity with >150 attributes: One table or many tables with relationships

I have entity with 170 attributes. It's data from vehicle monitoring. Every entity has datatime label and unique id of gps terminal. Datetime and id of terminal - these are conditions for GROUP BY ...
0
votes
2answers
1k views

Oracle query is slower the second time

I have a general question about something I'm seeing in performance tuning in Oracle. I have a query that I'm testing. It's too big and complex for me to provide a simple example, sorry! (I tried ...
2
votes
1answer
67 views

Should I be concerned about excessive Com_change_db commands?

I installed MONyog recently to check for problems on a MySQL server that I admin. Most of the information was useful and helpful, but there's one warning I am not sure is worth fixing. It reports ...
0
votes
4answers
945 views

Sql server full text search performance with additional conditions

We have a performance problem with SQL Server (2008 R2) Full text search. When we have additional where conditions to full-text search condition, it gets too slow. Here is my simplified query: ...
4
votes
1answer
160 views

filtered index null and > 0 disparity — need explanation

I'm getting behavior in a query plan I cannot explain. The difference is between two filtered indexes I'm testing with. One uses a where id is not null and the other uses where id > 0. In my ...
2
votes
0answers
564 views

Mysql slow writes

i have a strange problem with mysql. My selects goes fast. My insert/create/delete/drop/update go very slow. I have done some tests on 2 machines. My old machine and my new machine. Old is worst ...
0
votes
0answers
214 views

How to increase MySQL performance with joins

I have a MySQL database with InnoDB engine. Particularly one of my queries became very slow. The query is shown below: SELECT t1.`ARTREF1` FROM `lijnen` AS t3 INNER JOIN (`kortingen` AS t2, ...
1
vote
1answer
62 views

Do regular ALTERs weaken the performance?

In a project, we need to frequently ALTER the tables to delete or add columns. I wonder if this weakens the database performance in long term. If it has a considerable negative impact, what is the ...
1
vote
2answers
2k views

Oracle: Truncate large table takes forever

Problem I'm truncating a very large table ( +210 million rows ). It's been hours since it started and I have no idea when it will be done. There're several tables like that, that I want to ...
7
votes
3answers
3k views

How to optimization database for heavy I/O from updates (software and hardware)

The situation I have a postgresql 9.2 database which is quite heavily updated all the time. The system is hence I/O bound, and I'm currently considering making another upgrade, I just need some ...
2
votes
0answers
110 views

MongoDB advantages [closed]

I am actually can not understand the real advatage or killer feature of MongoDB storage. As I understand currently MongoDB implements exclusive per-database write lock that is even worse from the ...
1
vote
2answers
1k views

SQL Server: Additional cpus slow down batch

I'm running SQL Server 2012 in Windows 2008R2 in a virtualized environment. I've observed the following under both VMware Workstation 9 and Hyper-V 2012R1 and I don't know how to address it. I've ...
0
votes
0answers
43 views

Is it better performance wise to check if a field needs update if you know the record does

In the queries we use all the records in one table that has data which needs to be placed in a another system had a Insert, Update and Delete flags (i, u, d being 1 in the record), this way we can ...
0
votes
0answers
60 views

designing mysql for large tables

Currently I've been assigned the task to research ways to speed up an existing project. It's going to be rebuild so we can start from scratch, the current implementation has been build by another ...
1
vote
1answer
94 views

A query executed in a backup of a database is performing better than if executed in the original database

We have two databases with the same data, let's call it Database A which is the original and Database B which is the backup from Database A. A query is performing much better in Database B for example ...