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

1
vote
2answers
671 views

MySQL performance problem using indexed datetime column

I tried to solve the following problem for about one hour now and still didn't get any further with it. Okay, I have a table (MyISAM): ...
1
vote
0answers
142 views

sql query takes too long to execute [closed]

I am having trouble with this query. It takes 10 hours to execute. WITH CONSUM AS ( SELECT C.ID_MEASURER,C.ID_MEASURING_POINT,C.CONSUM_TYPE FROM GCGT_RE_CONSUM_H_E C WHERE C.DAY ...
0
votes
0answers
38 views

Bulk update performance

I have a several process that aggregate some statistics on items (how much was shown, clicked ... around 30 factors). Once in a 5 minutes i flush the aggregate data to postgres (9.1). I have 250K ...
0
votes
1answer
50 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 ...
2
votes
2answers
98 views

Should I drop a foreign key if I use a soft delete?

"ON UPDATE" scenario never happens in my application. As soft delete is used, "ON DELETE" cascade and restrict scenario never happen as well now. Then, should I just drop foreign key because I have ...
3
votes
2answers
116 views

Do MySQL optimizations hold for MariaDB also?

I am a developer who will be starting a new project soon in which database performance will be crucial. The current candidate for the backend is MariaDB. I have worked with MySQL and MariaDB before in ...
2
votes
1answer
196 views

Database design for a table with both bulk insert and single row insert

I have to design a table where records will be inserted in two ways. Bulk insert from a batch process from a delimited text file between 2 - 3 million rows in a short burst. Later the same records ...
0
votes
1answer
39 views

MySQL: What is SQL profiler, does it different for MySQL?

Whenever SQL profiling comes in mind, focus goes to two below sections: GUI tools like - MONyog, Neor Profile SQL set profiling =1; Execute Query; show profiles; show profile; I am really confuse ...
1
vote
1answer
176 views

MySQL: Which join is better between left outer join and inner join

Which join is better peforming if all of them provides the same result? For example, I have a two tables employees(emp_id,name, address, designation, age, sex) and work_log(emp_id,date,hours_wored). ...
0
votes
1answer
113 views

MySQL: How index speed up query execution

I have read multiple articles about MySQL indexes. Some of the important pages are below: http://dev.mysql.com/doc/refman/5.6/en/mysql-indexes.html ...
0
votes
1answer
223 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 ...
1
vote
1answer
29 views

MySQL server performance plummets

Part of our software solution is responsible for processing files that get uploaded to us by our clients. We want to process them as quickly as we can. Our system is architected so that there's a ...
3
votes
1answer
22 views

Is 'internallength' always useful in custom type definition in Postgres?

In our database we use a custom type to store 3D locations: CREATE TYPE float3d AS ( x real, y real, z real); In many examples I see INTERNALLENGTH used as a parameter with the definition of ...
5
votes
3answers
335 views

InnoDB import performance

I'm struggling with bulk importing a quite big InnoDB-Table consisting of roughly 10 Million rows (or 7GB) (which for me is the biggest table I've worked with so far). I did some research how to ...
0
votes
1answer
45 views

MySQL: How turning off the logging affect the performance?

OS: RHEL5 DB: MySQL 5.1.73 community edition DB size: ~1GB I have setup a testing environment and turned off all logging - general logs, binary logs, slow query logs etc. I am using Oracle ...
2
votes
1answer
65 views

What is FT BATCH CMPLETE in the cmd column for sysprocesses?

I was trying to figure out what was causing high cpu usage in our sql server and found two processes that were consuming high CPU. When I queried sysprocesses to see what the spid was doing, it had ...
0
votes
1answer
15 views

How to minimize the writes needed to update a counter field multiple times

I need to minimize the number of queries that are executed just for updating a counter field. One of my example counter fields is raised by 1 everytime a page is visited, I was wondering what could ...
1
vote
2answers
725 views

Redis takes up all the Memory and Crashes

A redis server v2.8.4 is running on a Ubuntu 14.04 VPS with 8 GB RAM and 16 GB swap space (on SSDs). However htop shows that redis alone is taking up 22.4 G of memory! redis-server eventually crashed ...
17
votes
2answers
3k views

Why would SELECT * be magnitudes faster than SELECT foo?

Consider a table of values and hashes, like so: +------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | ...
0
votes
1answer
56 views

Migration query taking time

I'm doing a migration from Oracle to SQL Server and, for one of the tables where we have 3 million records, it is taking a lot of time to complete. When I check the activity monitor, I can see the a ...
0
votes
0answers
76 views

How can I decrease FULLTEXT initialization time?

I'm trying to decrease execution time of the a query. Using SHOW PROFILE, FULLTEXT initialization takes about 0.3, which is too high. Other values are at normal level. How can I decrease FULLTEXT ...
1
vote
2answers
219 views

SQL 2008 Server - performance loss possibly connected with a very large table

Migrated from http://serverfault.com/questions/615129/sql-2008-server-performance-loss-possibly-connected-with-a-very-large-table We have SQL Server 2008 with 3 active databases running on it. DB1 ...
1
vote
2answers
69 views

Optimize rows to columns conversion

I have a big Oracle table (around 40 million rows) that looks like this: ID Name Question Answer Reason 3 Name1 1 Yes blah blah 3 Name1 2 No NA 3 Name1 3 ...
2
votes
2answers
75 views

How do dirty reads at both the transaction and table level provide increased performance?

I ran the following code past our architect as I thought there may have been a tautology between the isolation level and table hint: SET NOCOUNT ON SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ...
6
votes
2answers
524 views

Explanation requested for slow DELETE with SQL Server

I would like to get some extra insights/reasoning for SQL Server delete behavior. We have a fairly large database of over 1800 GB. In there are some very shallow tables (only a few integer columns) ...
1
vote
1answer
130 views

Perl - MySQL/MariaDB - slow with no identifiable bottleneck

I am running a Perl script (using DBI) which reads from raw files from a hard disk, and updates MySQL database (which is on a separate SSD). My performance is rather slow (1000 files processed in ...
1
vote
1answer
179 views

Tuning Mongo (TokuMX) for fastest bulk reads

What options do I have for tuning MongoDB / TokuMX for reading the results of queries with large result sets? I'm currently on a single server (no sharding) with the data on an SSD drive. My queries ...
1
vote
0answers
69 views

firebird update very slow

I am writing a stored procedure for Firebird 2.5 in which I sometimes need to update a single row in a data table more than once in the same transaction. However, I have noticed that the performance ...
0
votes
0answers
39 views

performance questions in database design

I need to describe a set of studies that are practiced to a patient, every patient have a "Clinical History", that are described in another table called "Clinical History Lines"(hclines) Every visit ...
0
votes
0answers
20 views

What is the optimal way to get a tabular view from an Entity-Attribute-Model table?

Following up on my previous question, I have created a table for storing measurements of different physical quantities. The schema looks like this: CREATE TABLE sensorreadings ( time TIMESTAMP, ...
0
votes
0answers
65 views

Database design for large incoming data

I've been tasked to design a database to handle a large volume of incoming traffic from sensor readings, possibly 1,000s an hour when it's at full strength. Each reading will be relatively short - ...
-1
votes
1answer
55 views

Disable MongoDB journaling?

Are there any benefits in disabling mongodb journaling besides performance gain? I know journaling provides write durability and crash resiliency. But I can tune syncdelay parameter to make data files ...
1
vote
2answers
286 views

Rapidly increasing TempDB write latency

We have two servers that were set very similarly, but not identically. These two servers have hugely different performance running the same application. On server A the application runs successfully ...
1
vote
1answer
111 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
63 views

A working view now starts timing out

I have 2 identical databases (one larger, one smaller) with identical views. Recently a view on the smaller DB started timing out. Google searches seems to point to deadlocking of some sorts. If I ...
0
votes
1answer
46 views

mongodb - “replication oplog window” possibly reduced due to profiling - when profiling disabled no change?

PROBLEM I have a 3 member replica set (no sharding) running mongodb version 2.4.8. Using MMS (Mongo Monitoring) I can see that on 7th July 2014 at 12:00 my "replication oplog window" dropped from ...
3
votes
2answers
109 views

SQL Server Baseline and Performance Optimization

I've been struggling a little bit around Performance Troubleshooting including baseline and troubleshooting of SQL Performance. Could anyone help with this or point me to where I can possibly get a ...
1
vote
1answer
129 views

Why is this second query more expensive than the first?

While reading Graph Databases book, I came across this excerpt: I can't figure out why the second query is more expensive than the first. Indeed, both filter on the Bob person. May anyone ...
0
votes
2answers
52 views

Does leaving a connection open for a matter of seconds cause deadlocks?

I have been testing a system application and have noticed that it is slow when it connects to the database overseas. This is to be expected to some extent, but there is a big difference with the ...
1
vote
2answers
343 views

Optimizing large MySQL SELECT WHERE IN clauses

How can the following SELECT WHERE IN case be optimized? I have a table with over 100 million rows with only 3 columns. The primary key (col1) is a 127 varchar. I am performing a SELECT col1 WHERE ...
0
votes
0answers
33 views

Mysql table with only two columns, nothing unique: Will an index increase search performance?

If my table only has two columns (username, groupname) and a million or so rows, will an index improve performance at all? Wouldn't it take just as long to search the index file as it would to search ...
0
votes
1answer
186 views

How performance schema in mysql 5.6 improve performance?

Since MySQL 5.5 performance_schema database has been added likewise information_schema. As we know that tables in information_schema contains statistical information like tables, plugins, partitions, ...
0
votes
0answers
85 views

MySQL 5.5, Xubuntu 14.04 - INSERT and UPDATE bottleneck

DBAs: I have been developing and maintaining plugins for Moodle for the last ~2 years, and have recently decided to try using my local desktop again, rather than my institutions ESX VMs, as a ...
0
votes
0answers
19 views

Sysadmin tools for SQLAnywhere

I'm seeing a performance issue in a 3rd party application based on SQLAnywhere 7. The DB engine seems to be dramatically underperforming on the hardware provided. It seems to have a upper limit on the ...
0
votes
2answers
445 views

MySQL ON DUPLICATE KEY UPDATE performance issue

We have a table with over 200k rows. Every row belongs to a category, there are almost 50k rows per category. What is the best way to update all rows of that category? We are using a script like ...
2
votes
2answers
88 views

Why is this simple join taking so long?

I'm trying to run some reporting queries on a MySQL database, and I'm running into serious performance issues for some reason. One table, page_views, is extremely large (~70 million records), so some ...
0
votes
2answers
92 views

Are #tables and #procedures 'not best practice' or 'bad practice'?

I am working on a project and part of it is an interface tool that executes SQL code stored in a xml file to import/export files. In the file, temp procedures and temp tables are used quite heavily ...
1
vote
1answer
61 views

Detailed optimal column order with large text and bytea

I read this excellent answer on optimal column ordering and noticed the summation: Generally speaking, if you put the 8-byte-types first then the 4-byte-types and the 2-byte-types last you can't ...
0
votes
0answers
15 views

Page cache installation in magento admin panel

Hi just added pagecache from varnish in Magento through the magento connect. It went in ok, just wanted to know, the correct configuration. In magento admin panel for the correct set up in the page ...
0
votes
0answers
94 views

Performance: Interleaving several statement handles in MySQL

Does interleaving several statement handles slow the system down? Example (Perl): $sth1->execute(...); $sth2->execute(...); $sth1->execute(...); $sth2->execute(...); (interleaved) vs ...