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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Postgresql function taking long time on newly restored database

I have developed one function in my PostgreSQL database. It was taking 12-15 seconds to execute. Now I have restored a new PostgreSQL 9.0 dump using following command: pg_restore -hx.x.x.x -p5432 -d ...
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74 views

Oracle specifying join order hint

Oracle 2 node RAC 11G R2 I have a query (this is a simplified version, but still exhibits the same issue as the larger query) that looks like this: SELECT t1.trip_id, t1.origin, ...
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1answer
95 views

Benefit to keeping a record in the database, rather than deleting it, for performance issues?

So I have a client that I am building a Rails app for....I am using PostgreSQL. He made this comment about preferring to hide records, rather than delete them, and given that this is the first time I ...
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2answers
909 views

When to make changes to the cost threshold for parallelism

While examining a performance issue , I have seen an influx on CXPACKETS suggesting I might need to look at the cost threshold for parallelism and perhaps the MAXDOP. Before making any drastic ...
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2answers
123 views

Splitting up tables with similar structures since they contain unrelated data? (huge numbers)

Is my reasoning correct in splitting up tables with similar structures since they contain unrelated data? I'll explain the situation with an example : Suppose there is a server which hosts an online ...
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1answer
154 views

Data center from scratch which way to go

My budget for a data center (hardware,OS licences, SQL Licences WithOut CALS ) is around $50K~$60K. I have needs for around 200 users and my apps works only works in Microsoft environment (Window ...
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1answer
56 views

Does limit impact affected rows or not?

I have this table: CREATE TABLE IF NOT EXISTS `usergroups` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `user_id` int(11) unsigned NOT NULL, `group_id` smallint(5) unsigned NOT ...
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1answer
86 views

How to -create- performance issues? - oracle [closed]

I want to dedicate some time to learn more about performance and tuning issues. I assign for that a clean DB. I want to know how can I load into it some data and performance-problem queries/DML/DDL? ...
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1answer
254 views

Getting the most out of SQL Server with a million rows a day [closed]

I have a windows service that is inserting 1000 rows at 1 minute intervals to a SQL Server 2008 Standard database table that looks like: id, datetime, key_id, value key_id is a foreign key to ...
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1answer
206 views

Slow query and Insert with trigger

I have vehicle tracking system application based on PHP, SQL Server 2008 R2 Enterprise Edition with XEON HP Z800 Server. My database is growing day by day in millions and it makes it very slow to ...
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2answers
112 views

Why doesn't running a full sample *always* improve query performance

Conventional wisdom would suggest that running a full sample of statistics would provide SQL with the optimum information to make the best decisions when forming a query plan for execution and ...
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2answers
823 views

Does a TRIGGER improve the performance?

I understand that TRIGGERs are useful, as they take care of subsequent queries, but do they have an advantage from performance point of view too? Replacing two or three queries as INSERT INTO table1 ...
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1answer
193 views

MySQL / Fusion IO Configuration Question

I need a little configuration optimization. I think what I have is pretty good but feel like there's still room for improvement. Current Config [mysqld] user=mysql datadir=/var/lib/mysql ...
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1answer
496 views

Why do large tables slow down queries in databases?

Kind of a generic question; but I have noticed that large tables in certain CMS's can slow them down to a crawl. The solutions for this I've seen are to just truncate those tables. Why do large ...
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2answers
159 views

Optimize simple query using ORDER BY date and text

I have a query to a table in Postgres with an order based on a date field and a number field, this table has 1000000 records The data types of the table are: fcv_id = serial fcv_fecha_comprobante = ...
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2answers
105 views

Large number of VLF and shrinking the log

If there are lot number of VLF then it will effect the performance of the queries. I saw that solution is to shrink the log file. But shrinking the file is also bad. So how to take control of whole ...
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2answers
271 views

Trace flag and which need to be turned off and Why

In SQL server there are so many trace flags. Why some of them need to be turned off. Some where i saw that trace flag 8017 need to be turned off. So i want to know which trace flag need to be tuned ...
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2answers
330 views

How can you tell when a query plan reuse is causing performance problems

When investigating a performance issue, a workmate suggested running DBCC FREEPROCCACHE to clear the plan cache. He came to this conclusion after noticing performance improved after a reboot. This ...
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1answer
214 views

Oracle intermittent performance problem

I have some complex queries that are usually fast (< 1 sec), but occasionally slow (> 10 sec, even minutes). How do I track this down or identify what condition is causing it? One theory was ...
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1answer
174 views

What database and setup can handle several million inserts per minute? [closed]

We have come to a point where for a few of our customers' systems, at peak times, events are generated at that crazy rate. That is, millions of new events per minute (between 1M and 2M). The ...
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1answer
211 views

performance issue caused by IO?

Just curious to get an issue sanity checked . . . I'm trying to ascertain whether a performance issue experienced by users is the result of the app, server it sits on or SQL Server. Looking at ...
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2answers
2k views

Splitting a large table to improve performance

This is a follow-up to an earlier question. I have a SQL Server 2008 R2 Standard server, that holds a single database, which itself has almost nothing except a large table. The table is 100+ million ...
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1answer
237 views

View with fallback (performance/optimization question)

I have a table with tariffs for stuff; the tariffs table is not important in this scenario, the "tariff values" are. In this Demonstration SQL Fiddle the tariff_plan is the FK to the tariffplans table ...
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39 views

Creating a dedicated HD parition at beginning of disk for data files, benefits and draw backs?

I am thinking of creating a dedicated partition on the harddisk for the mysql database data files in /var/lib/mysql , while considering those 2 points: a dedicated partition will avoid any file ...
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2answers
69 views

Understanding multiple indexes with MySQL (and performance)

I have a "phones" table with around 120 000 records, it contains phone_id, phone_number, phone_user_name, phone_last_contacted, etc. The phone_id is index and looks like: 1,2,3,4 ... 120 000. But I ...
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1answer
71 views

Why isn't the rows of an EXPLAIN accurate?

I have the following table: mysql> select count(*) from employees; +----------+ | count(*) | +----------+ | 10000 | +----------+ 1 row in set (0.03 sec) I do an EXPLAIN: ...
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1answer
71 views

Defining a process for troubleshooting performance issues [closed]

The issue of poor database performance is one which presents itself from time to time and there are many techniques which can be employed to examine the root cause of slowness. Does anyone have a ...
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1answer
124 views

Auto Update Statistics Duration and Interruptions

Our production SQL Server 2008 R2 sometimes begins to perform slowly: all queries begin to work too slow (and sometimes all queries just hang and wait something then continue). This usually lasts ...
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1answer
357 views

LEFT vs CHARINDEX for matching the start of a string in T-SQL

I want to match the beginning of a string in a WHERE clause. While I recognise that so often database-performance is dependant on the underlying data structure, is there a best-practice for doing ...
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1answer
403 views

How important are transaction log VLFs for performance?

How important are VLFs when considering database performance? What would describe an optimal situation for VLFs?
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1answer
52 views

strange “using where” in simple query

I have a table with this structure: mysql> describe user_groups; +----------+----------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | ...
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2answers
169 views

How to index for a query with independent range conditions?

What is the best way to index a table that I query using independent range conditions? E.g. WHERE X < ? and Y > ?
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1answer
319 views

How to partition an Oracle table with 65 million rows?

The table that needs partitioning contains a list of Components and their Values. So one table is tblComponents. Another is tblFields. Then this table, tblValues, contains the values of the ...
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1answer
70 views

Meaning of SQLIO output “counts per second”

I realise that my question isn't strictly 'database' but I know that a lot of DBA's will use the SQLIO tool to check I/O performance on their systems so I'm hoping that somebody here will be able to ...
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3answers
280 views

Indexing for query containing xml column

I have below queries which performs little slow.So i am planning to create index.I created primay xml index and now performance improved little bit(by looking at execution plan) .Queries are shown ...
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2answers
535 views

SQL Query too slow on SUM function

I've a table with around 32 million rows having clustered unique index on CountryID,RetailerID,ProductID,DateID,EventID,TypeID and query is SELECT f.RetailerID , TypeID ...
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2answers
2k views

Index for date column for range query in Oracle?

We have a lot: select count(*) from TBL where XDATE between ? and ? and FLD = ?; We expect to boost performance by tuning index on XDATE column (which have DATE type). What type of indexes more ...
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2answers
2k views

general memory requirements for sql server 2008 r2

I'm not experienced with DBA work, but I'm trying to make a case for requesting additional resources for our sql server and was hoping I could get some smart folks to provide a rough rough estimate of ...
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1answer
52 views

How do I determine when scaling is necessary or helpful?

I have a MySQL Server that I use for the back-end storage of an online game. The game writes to the database to persist character information such as world location, health status, ability stats, etc ...
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1answer
66 views

What indexes to add on MySQL table

I've been trying to optimize my table, but am yet unable to get the desired results. CREATE TABLE IF NOT EXISTS `puzzles` ( `puzzleID` int(7) NOT NULL, `puzzleMask` varchar(30) CHARACTER SET utf8 ...
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1answer
216 views

Using like over charindex to search for pattern

We where using charindex to search for a string as shown below SELECT * FROM tablename WHERE ( Charindex('47a%$.abc',CAST(columnname AS VARCHAR(MAX)))>0 ) I am planning to replace charindex with ...
2
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1answer
2k views

Why is my Amazon RDS instance so slow?

I currently run a Windows Server with SQL Server Express. I'd like follow best practice and separate the application from the database, so I've created an RDS instance and exported my database. ...
3
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1answer
97 views

Forwarded Records, effective way to fix them

I'm dealing with an issue in SQL Server databases of an application. This application is used for Healthcare and I only maintain the databases, I do not create the application. Clients are facing the ...
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0answers
174 views

How to configure pgpool for reasonable speed

I have a problem with pgpool II configured in master-slave mode with replication on slony. I have configured postgres databases on each server to run as fast as they can and this was verified by me ...
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1answer
719 views

Query taking too long to execute

My query takes a lot of time, 22 seconds and above. After 22 seconds, we get more than 900 000 records. We have created indexes on the table which are used in the query: select * from ContactMaster ...
3
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1answer
246 views

Speeding up a NOT IN subquery

Good evening, I'm currently up to try to improve the performance of some of my queries. As far as I know, statements like "IN" or "NOT IN" are even faster with a large amount of values if a subquery ...
3
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1answer
287 views

Group By primary key or DISTINCT increase query time over 1000x with limit

Also see http://stackoverflow.com/questions/17741167/hibernate-jpa-improve-performance-of-distinct-query but I realized this is mainly a PostgreSQL issue. My application uses a 3rd party extension to ...
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0answers
30 views

Solving Page_Latch wait on Date based Partition Table

I need something like the proposed solution in below link, but it was based on INT column not on DateTime. ...
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1answer
1k views

Which is faster among MySQL Community Server, Percona and MariaDB [closed]

I have a small setup of MySQL Community Server version 5.6 running on KVM based VPS. 4 CPU cores are available and total memory is limited to 1GB. I use MyISAM tables mainly for Wordpress and few ...
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3answers
80 views

Performance difference between searching table with 350 columns and searching table with 25 columns

I am currently doing some hibernate performance test. My requirement is to search for data in a particular column of a table containing 8 million rows and 350 columns. Currently, I don't have the ...