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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20
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2answers
15k views

Optimizing bulk update performance in PostgreSQL

Using PG 9.1 on Ubuntu 12.04. It currently takes up to 24h for us to run a large set of UPDATE statements on a database, which are of the form: UPDATE table SET field1 = constant1, field2 = ...
1
vote
2answers
497 views

How to design database table to store process status?

I have an application (ProcessMonitor) that monitor some constantly running process at fixed interval (like 30 seconds, but can be changed by user) and store the process status to a database table, ...
0
votes
1answer
133 views

Efficient way to perform approximated search?

I have to perform a join between table_a and table_b, using three fields as key being one of them the date of the event, say, both tables have id1, id2 and evnt_time for eache record. As it happens ...
1
vote
2answers
438 views

Is there slowdown inserting into an InnoDB table that has no index set?

I have an old application with lots of InnoDB tables, that have no indexes at all, not even a primary ID or such. Those tables only contain a few thousand rows. Would it be faster to INSERT data ...
5
votes
2answers
8k views

Cannot Utilize Maximum CPU and Memory Usage for MySQL

Good day. I know this may be a duplicate of other questions however I have applied all the suggestions in many of the threads, but I remain with the same problem. I have a single stored procedure ...
8
votes
1answer
213 views

Start/Stop MySQL

I'm seeking help to understand what happens when the following command line is executed: root@prodn$ service mysqld stop Yes, it shuts down the MySQL server so access to it is no longer available ...
2
votes
1answer
611 views

How to enhance the SQL query performance for thousands and millions of huge data

Now Our team are involved in a forum data analysis project. Its target data is so huge(I think). We should find the potential informations from it. Such as the popular products,the customers ...
4
votes
1answer
1k views

Simple MySQL query randomly takes forever

I'm having an issue on my server with a simple PHP send emails script that runs every minute via a cronjob. The script contains a MySQL query that runs very fast most of the time, but randomly will ...
1
vote
2answers
543 views

How should I store multiple relationships (many posts to many categories)?

I have posts stored in a posts table and I want each post to have multiple categories, what is the most efficient way to store the categories and their relationships ? I thought of it this way first: ...
2
votes
1answer
330 views

Switching to NoSQL for native JSON use?

I am rather comfortable writing concrete schemas with explicit primary keys, foreign keys, indexes, views and stored procedures. For queuing I use a NoSQL solution called: Redis. Recently I heard a ...
6
votes
2answers
3k views

Why use separate databases for high traffic/volume tables?

While looking at the database structure of an application I am using I recognized that it uses 3 different databases on the same SQL Server instance for different things. The first one contains the ...
4
votes
1answer
1k views

.mdf vs .ldf Performance considerations

I just learned from an answer to this question that the .mdf and .ldf files that SQL Server uses are an important pair for the database. I previously thought the .ldf was just a non-critical log for ...
20
votes
2answers
42k views

How to optimize a query that's running slow on Nested Loops (Inner Join)

TL;DR Since this question keeps getting views, I'll summarize it here so newcomers don't have to suffer the history: JOIN table t ON t.member = @value1 OR t.member = @value2 -- this is slow as hell ...
6
votes
2answers
3k views

Linked Server Risks

I'm implementing a new feature which requires data from databases on multiple servers. I just need to union data from all these servers and sort it. The two options that come to mind are: Use linked ...
7
votes
1answer
3k views

PostgreSQL concurrent increment of counter

I need to maintain a statistical table for a project, composed by a list of items and their usage (Think about something like a website in which you would like to count pageviews). Each time an item ...
1
vote
1answer
2k views

Can putting mysql DB into memory or having the innodb_buffer_pool_size match the size of DB increase performance?

We have a mysql database that has roughly 80 gigabytes (GB) of data using inno_db engine. We are looking to increase performance on the database (we looked at the slow log and gone through and ...
0
votes
3answers
1k views

Reclaiming space from a large partitioned database

We have a database where one of the business group decided to remove several millions of rows as part of their upgrade process. (we removed for them..).. This database is partitioned based on a date ...
1
vote
1answer
774 views

Temporarly disable cache in oracle 11g

I want to disable the caching for my session in oracle 11g to see how long a query takes. Is this possible or is there a better way for meassuring the time a query takes to run?
1
vote
0answers
692 views

sql server 2008 execution plan different on two production servers [closed]

We have two servers running SQL server 2008 R2, with identical databases, where we implemented a datawarehousing solution. The cube processing operation was taking a VERY long time in one of the ...
0
votes
0answers
88 views

Linked server performace issue?

I have created a linked server in SQL Server 2008 R2 Enterprise Edition for MySQL i.e. MySQL database is accessible under SQL Server environment. I have a created a trigger in SQL Server such that ...
2
votes
3answers
961 views

SQL server disk write queue dramatically grows sometimes

I have SQL Server 2008 and a single database with full recovery model. Usually, the queue length is less than 1. But sometimes it grows up to several thousands (3000!!) for a few seconds. At this time ...
3
votes
2answers
574 views

How to implement posts with “seen by” like facebook?

Inside a Facebook group there is a feature when every time see the group newsfeed it mark all posts as seen by me. And if I see a specific post inside a group thought a url ...
2
votes
1answer
4k views

SQL Server bulk insert performance

I’m running sql server 2012 and the installed ram on that machine is 128 GB. The performance of the bulk insert is very low. The bulk insert of 10 million records takes about 2 hours. We have checked ...
11
votes
1answer
4k 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 ...
6
votes
1answer
6k views

Could too many idle connections affect PostgreSQL 9.2 performance?

Some queries on my database server seem to take a long time to respond, and I believe the CPU usage is high. When running ps aux, I see ~250 "idle" connections (which I believe to be too many). I ...
0
votes
2answers
167 views

Why does using a variable make a difference in performance?

I have a table that constantly doing insert, and I am trying to run a delete script to remove old record. The delete script looks like this: DECLARE @StarDate DATETIME = '2013-01-13'; DECLARE ...
2
votes
1answer
14k views

What is the best way to insert a XML input to an oracle table in stored procedure?

I want to write a stored procedure which has a XML input (clob type) and inserts the data to a table. my XML structure is something like this: <rowset> <row> ...
0
votes
1answer
787 views

Mysql: order by field or select union?

As a newbie, I expected Mysql to return the rows of this query ordered by their ids order in the id clause select * from test where id in (3,1,2) Unfortunatelly for me, that's not true. The results ...
1
vote
2answers
855 views

Exploring and optimizing SQL performance of your system (PostgreSQL and Hibernate)?

Imagine you have inherited some project with extensive usage of SQL queries. Let us assume that Hibernate is used as ORM and PostgreSQL as database, but thats not the point. A question is: could ...
1
vote
1answer
610 views

Mysql DB server hits 400% CPU

I have been facing problem with my database server quite a month, Below are the observations that I see when it hits the top. - load average 40 to 50 - CPU % - 400% - idle % - 45% - wait % - ...
1
vote
4answers
630 views

SQL Server 2008 DB Performance on single disk

I have a database in SQL Server 2008 with around 20 GB in size. And it is increasing rapidly. Somehow I can not add multiple independent harddisks to increase IO performance. If a add large table ...
0
votes
1answer
47 views

Modify legacy table schemas that have no primary key

I've been tasked with updating our database (SQL Server 2008) so that every table in it has a proper primary key defined. Due to various reasons over the years we have somehow built up some legacy ...
3
votes
2answers
926 views

Bandwidth comparison between log shipping and transactional replication

Which technique uses more network bandwidth: Log shipping Transactional Replication Can some one share any benchmarks for the same ? What would be the Memory and I/O impact on the Primary server ...
2
votes
1answer
2k views

Innodb Slow queries since convert from MyISAM

a few days ago we converted some write intensive tables from MyISAM to InnoDB hoping to have a better performance due the better locking system of InnoDB, but instead of gain performance, we start to ...
4
votes
1answer
6k views

Why is a hash match operator in this very basic query

I'm beginning to learn some about looking at execution plans and making queries more efficient Consider these two basic queries select distinct pat_id, drug_class, drug_name from rx select pat_id, ...
-8
votes
2answers
1k views

How can I check for SQL Server performance problems using T-SQL? [closed]

I know how to use the Profiler, Performance Monitor, and Activity Monitor. I want to find a way to troubleshoot performance using T-SQL. How can I check for Microsoft SQL Server performance problems ...
1
vote
1answer
298 views

For a InnoDB only DB, which of these elements can be removed?

So, I'm trying to set up a Drupal 7 my.conf file that's combining best practices from various performance blogs. I'm realizing though that some of them are older than others, and many aren't assuming ...
3
votes
2answers
425 views

Should I use a compound or surrogate PK in a many-to-many table?

I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` VARCHAR(255) NULL DEFAULT NULL, PRIMARY KEY (`isbn`) ) COMMENT 'Books used at this ...
1
vote
1answer
82 views

Mysql performance for a nullable unique id column in a large table that references a record in another table

We have a large table of contacts (8 million records) that we promote to with mailings. When these people register we store them in a different members table. But we want to go back and update the ...
3
votes
2answers
7k views

Oracle insert through dblink performance issue

I'm trying to do an insert as select to a table via dblink. The query looks like this: Insert into MARS_SUPERVISORS_PUB@EDHPUB select {...} from edhper a, edhper b where ...
4
votes
1answer
205 views

Oracle BLOB store performance

LOBs in Oracle are stored in-row when they are less than 4K in size and out-of-row otherwise. I'm wondering how do SECUREFILE storage options COMPRESS and ENABLE STORAGE IN ROW work? I have a lot of ...
6
votes
1answer
379 views

Landed as BI, but databases are a big WTF, what to do?

Maybe a duplicate, but I believe my case is a bit different. From one of the answers I got to this post on SQL Server Central that also comes handy too but is not quite the same scenario: 9 Things to ...
3
votes
6answers
11k views

SQL Server split mdf into multiple files

I have a database called example.mdf with a total size of 1GB which suffers from performance issues. I checked the allocated hardware and it is higher than required, I double checked the design and ...
3
votes
1answer
105 views

Does avg_query for PgBouncer include update and inserts?

Trying to tune our application and would like to know if the stats data that pgBouncer shows as avg_query, according to the PgBouncer docs on usage: avg_query Average query duration in ...
5
votes
1answer
428 views

RESOURCE_SEMAPHORE_QUERY_COMPILER waits in Microsoft SQL Server 2008 Enterprise

Could fragmented indexes on Microsoft SQL Server 2008 Enterprise cause RESOURCE_SEMAPHORE_QUERY_COMPILER waits? The last two weeks one of our applications has had downtime due to ...
6
votes
2answers
525 views

Sql server snapshot isolation overhead when read_committed_snapshot is enabled

When SQL Server's read committed snapshot is on (and thus some amount of row versioning is necessary), is there any additional overhead caused merely by enabling snapshot isolation? Snapshot ...
7
votes
1answer
5k views

Why does that query cause lock wait timeouts?

From time to time, I find a lot of these errors in my PHP error log: MYSQL.1213: Deadlock found when trying to get lock; try restarting transactionSQL The problem persists for about 2 or 3 minutes. ...
3
votes
1answer
1k views

SQL Server Performance Counters Relating to Disk Access and Log Files That Appear Concerning

I want to validate the optimal performance of our SQL Server and in doing so, I have gone through all the performance counters listed at the following link and create a trace log to analyze the data. ...
2
votes
3answers
6k views

When to periodically RESTART SQL SERVER 2008 R2? [closed]

So I've read that it's really a bad practice to restart SQL Server on a production environment.. Does restarting SQL Server speed it up? Automatically restart SQL Server 2008 Why are periodic ...
6
votes
3answers
10k views

Investigating high SQL waits, especically LCK_M_U

Recently I have been struggling with SQL server performance and although we have fixed a huge multitude of basic errors in the config it is still performing badly. To clarify it is not overall ...