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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Performance issue in Postgresql9.3

I have very good configuration server dedicated only for PostgresSql. Server is 16 Core 122 GB RAM on Linux machine. select version(); **PostgreSQL 9.3.4 on x86_64-unknown-linux-gnu, compiled by gcc ...
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35 views

Extended Events missing documentation

I have been looking pretty hard for the documentation regarding the RingBufferTarget <RingBufferTarget truncated="0" eventsPerSec="1370714" processingTime="7" totalEventsProcessed="9595" ...
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18 views

View in View slower to execute?

Sometimes it's easier and clearer arranged to create a View from another View. Can this cause some speed losses in relation to selecting everything just in one Big and long View-Command?
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1answer
861 views

Understanding pagefile.sys % Usage performance monitor (perfmon) counter correctly

Lately we run into performance inssues and I started tracking some recommended sql, memory, disk and cpu counters. I informed myself about the recommended values and numbers to look at. One of the ...
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1answer
43 views

Transforming Huge Database table to Another Table

We are migrating lot of data from our old database to new database. Presently, both of them are actively[writing/reading] used based on flows/activity as migration is in progress. Here's the real ...
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43 views

Performance tuning in Sybase

Does Sybase have a tool like AWR in Oracle which can be used to identify high load SQL, tell the important waits that are happening, help in understanding the workload? What are the main tools to be ...
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1answer
42 views

MySQL 5.1: How to rollback partitioned table

I have partitioned a table on the basis of one flag column have value either 0 or 1. Now, I want to roll back these tables. How can I do this?
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1answer
161 views

Running queries directly on DB2 databases

Just have a general query, if it is really fine or safe to run long select queries on RDBMS production Databases specifically DB2? If NO, what are the major risks and issues in executing select ...
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1answer
49 views

Database slowdown at random times using mirroing

Our web application suffers DB query timeouts a few times a day at random times. Can you help to work out the cause, e.g. deadlocks, mirroring (disk or network), etc? We have two identical database ...
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351 views

SQL Server 2012 Local SSD TempDB Slow

I have a production deployment using local SSDs for tempDB. I have 2 SSDs in a RAID1 configuration. I am seeing average reads of 1-2ms but the average writes are showing as 1377ms on all four of my ...
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2answers
102 views

Table design for multi-type data

The information model I am modelling from includes an "any type". For example a customer can have zero or more 'entries' each of which can have a number of values. Each value could be a either date, ...
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2answers
637 views

Ideal values for wait time in SQL server

This is related to my own post here The SQL server starts everyday at 8:30 AM and stops around 9:30 PM.( So wait times will reset everyday) SQL server will be used by around 60 users ...
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1answer
1k views

SQL Server 2008 R2 Express single CPU core usage and need of upgrade to SQL Server 2014 Express

In our office we are using SQL Server 2008R2 Express which is installed in Windows server 2012. The SQL Server database is accessed by more than 60 users in network simultaneously. In recent days we ...
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60 views

How can I control the order of a query regarding to inner join

I have 3 tables. They have table_a 5m records table_b 20m records table_c 20m records I'm performing the query below. SELECT * FROM table_a a INNER JOIN table_b b ON a.a_id = b.a_id AND ...
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70 views

How can I reduce recursion in Couchbase?

Sometimes, you need to access a certain document (A), but you do not know the key for that document (A), as that data is stored in a different document (B). So now, if you want to fetch A, it looks ...
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1answer
51 views

How to optimise very simple query with subquery that only needs to execute once

SELECT products_id, products_model, products_iban_no, products_allocation_number FROM products WHERE products_model IN (SELECT products_model FROM products GROUP BY products_model HAVING ...
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232 views

Do OR conditions in Oracle SQL queries spoil index use / cause full table scan?

I have a query on Oracle 11g of the following type, which results in a series of highly inefficient full table scans: select t.Id, t.ObjectId, t...[other Tasks columns] , od1...[ObjectData1 ...
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1answer
510 views

How to configure my.cnf for Mysql 5.1, which is using too much CPU?

I am new Database engineer. I am having trouble in my server which is using too much CPU on database query(simple count statement). I have googled about it, so i found out it depends on system ...
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1answer
106 views

Redo log size results into performance degrade

We are continuously doing heavy insert and update query, but after 10 hours data base is returning answer late in minutes normally it takes around 1 ms. I observed that "free buffer wait" and "redo ...
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1answer
353 views

Slow delete caused by many foreign keys

My DB has about 90 tables. Most of the tables have an UpdatedBy and AddedBy column that have foreign keys pointing back to the user table. With even moderate amounts of data spread throughout the ...
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23 views

Approaching multiple values in same column

I'm developing an Android-application that scrapes the schedule for my university and presents it nicely since the current system is a nightmare. I'm processing a lot of data and it gets down to ...
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1answer
596 views

How to know which process is causing high memory usage on DB?

I've got one Onesight alert mail stating below: Short Description: Onesight Alert: ZEUS DB Monitor (zeus04) Description: Solaris 5.8: vmstat memory(free) - Free Memory for zeus04 2065112 8:06:02 ...
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1answer
597 views

Slower queries after upgrade from mysql-5.5 to mysql-5.6

There is lots written about how MySql 5.6 is faster than MySql 5.5 (e.g. http://dev.mysql.com/tech-resources/articles/mysql-5.6.html) but we upgraded our Amazon RDS instance (using the new upgrade ...
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19 views

Storing generated documents that can not be updated by changes in relationships

I have a system running with PostgreSQL and Yii Framework, which generates a few medical documents that, once ready, can't be changed. For example: If my full name comes out on this document today, ...
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1answer
63 views

MySQL from table to table data transfer

I've got some problem with my MySQL. I have the database with many many data. Well, there is only one table actually with huge ammount of data, over 1 billion rows. For some reasons I need to create ...
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22 views

What is the best type of database for numerous multi-threaded access? [closed]

I am developing a simulation and have limited experience working with databases (very limited SQLite3 exposure). Here is my task: Server that stores a potentially large database (no size requirement ...
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2answers
58 views

SQL Server Backup and Query Execution

Is SQL Server Backup affects the query execution performance? Is there an effect while running the SQL Server backup in remote query execution? Thanks.
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51 views

Oracle 9i Low performance on Windows Server Enterprise 2003

I'm facing some problems with performance with my Oracle database running on a virtual machine with Microsoft Windows Server Enterprise 2003 with 8GB RAM. It works pretty well after the database is ...
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120 views

MySQL: after query optimization the CPU is still over 100%

my first time here! First of all I want to say that I'm not a DBA and I have a very little experience with MySQL but I like to study and understand what I'm doing. I have a virtual machine (2gb RAM, ...
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64 views

Oracle after insert trigger vs update performance in plsql block

I want to know whether an after insert trigger is better than an insertion statement followed by update statement in plsql block.
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1answer
32 views

Why does AttachDBFile make everything slower?

In my ASP.NET app, I had tested a query against a 200.000 rows table with two connection strings, one connect to a remote SQL Server and once use AttachDBFile to attach to a database file in App_Data. ...
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2answers
168 views

Oracle 11.2 using too few memory

it is about one year that I have changed my server from Oracle 10g to 11.2g (and also changed the hardware and Windows from 2003R2 to 2012). The problem is that with more than doubled cpu power, ...
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1answer
56 views

Is array serialization always bad idea?

I'm making form-generating app in php. I have Widget table with type_id (html input) field, and I would like to add options field, like width/height, step, range, etc. Different widgets do have ...
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39 views

Querying number of tries since last successful log, checking IP as well as user

I asked this question before on stackoverflow, but it might fit better here, since it is mainly about database performance. The actual question With performance in mind, how would you go about ...
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1answer
313 views

SQL Server “TOP 101” much slower than “TOP 100”

SQL Server shows huge decrease in performance when query is written like: select top 101 name from Dogs order by name compared to select top 100. As far as I know, this happens for the reason that ...
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1answer
170 views

inserting large quantity of data into mysql table

I need to insert about 400 000 000 rows of test data into the InnoDB table. Table is quite simple: CREATE TABLE IF NOT EXISTS `tgt` ( `id_1` int(10) unsigned NOT NULL, `id_2` int(10) unsigned NOT ...
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1answer
626 views

SQL Server 2012 performance degradation

We are running SQL Server 2012 SP1 on Windows Server 2012. The issue we have is that after some time the server automatically reboots. Checking the logs did not show any errors. When looking into ...
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68 views

Significant difference between duration for querys in SHOW PROFILE and SHOW PROFILES?

I have use mysql profiler to optimize an opencart query which takes more than 10 seconds to executes. mysql> SHOW PROFILES; ...
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2answers
110 views

Slow INSERT/UPDATE on InnoDB

I have a problem with the performance of my MySQL server, let me explain: I instaled a MySQL server, version 5.5.20 Server version: 5.5.20-log Source distribution SELECT queries runs fast on ...
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75 views

Why is this query stuck if there are no waits?

I am working with a vendor's activity logging system. One of the tables has 70+ million records and is constantly increasing at several hundred records per minute. They have a utility to delete old ...
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1answer
74 views

Oracle: index vs. table stats [closed]

In Oracle, when would I want to gather index stats, instead of just gathering stats on the table? In which use case would index stats make a difference?
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1answer
615 views

Improve MySQL Query Performance - Too many records

I am using MySQL RDMS for a contact management system. Now a days my database grew in size and contains more than 1 million records. Checking duplicate phone numbers became a big issue during ...
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1answer
586 views

MongoDB insert performance rapidly dropping

I'm currently experiencing a rapid decrease of the insert Performance. I have a rather simple data model { "Id": "ObjectId", "SomeProp": "xy", "SomeTags": [ { "key": ...
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76 views

Oracle: separate column histograms for partitions

I have a partitioned table like MY_TABLE(PART_KEY, DATE_KEY, ...) with a local partitioned index on (PART_KEY, DATE_KEY). When I collect stats on the table, I end up with a HEIGHT BALANCED histogram ...
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98 views

SLEEP_TASK and PAGELATCH_XX peaking after upgrade to R2 SP1

I wanted to just add a comment to this question: SLEEP_TASK Wait Type in SQL Server - What does it indicate? But I'm having not only SLEEP_TASK wait but also PAGELATCH_SH and PAGELATCH_EX wait types. ...
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2answers
290 views

DBCC CheckDB causing high values for resource_semaphore wait type

On one of our production server, where SQL Server 2008R2 (Service Pack 2) is installed with 24 GB memory and 24 CPU cores grouped into two NUMA nodes, we are facing high counts for resource_semaphore ...
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1answer
198 views

Oracle using index on partitioned table when full scan would have been better

Trying to make some sense out of this observation in Oracle. Query: SELECT ... FROM MY_TABLE WHERE PART_KEY=x and DT_KEY between 20120101 and 20120731 Uses an index scan on PART_KEY/DT_KEY, even ...
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2answers
101 views

Seeking help to test a use case on sql server memory

This is a question which came out of curiosity to know of how sql server handles memory. Assume I set a very low value for max server memory and I increase my workload like running dbcc checkdb, ...
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1answer
136 views

poor and/or unreliable InnoDB performance

I recognize that there are a ton of posts like this, but after reading up on InnoDB performance problems, nothing I tried has helped. I have a database containing four InnoDB tables. The largest ...
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24 views

How can I determine the performance (rows/second) for a certain query on one of my tables?

I want to find the performance (rows/second) for an UPDATE query on one of my tables so I can adjust my WHERE clause to select an appropriate number of records. The table has around 10 million rows. ...