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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41 views

MySQL database hangs but less CPU

I create an application for 30 concurrent users using C# and InnoDB of MySQL (mysql-5.1.35). The size of database is more than 100M lines (~20GB). Most of data is come from 7 active table (2M ...
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77 views

Mongodb Huge Number of Open Connections and Write Locks

We are seeing around 800 open connections to our Mongodb. To clarify our issue: We have 5 different clients who write the data into Mongodb. Each of these clients - write four different type of ...
4
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0answers
154 views

Performance inner join vs left join involving parallelism

I have a query which takes about 8 hours to finish. Simplified, the query looks something like this: SELECT [Some attributes, inconsequential] FROM RBM.Financial_Events RFE INNER JOIN ...
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2answers
126 views

Faster query when joining data from multiple tables

I’m looking for a way to make a database query faster. The table parts has over 6 million rows. Each part row is associated with the manufacturers table (a couple hundred rows) by ID. When searching ...
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0answers
87 views

Materialized View - vs. New Calculated table for performance [closed]

I have a problem - I'm trying to de-normalize data tables in a data warehouse in preparation for use in the Business Intelligence/ Presentation layer. By denormalize I mean create a series of joins. ...
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0answers
24 views

Implications of many materialized views in Postgres?

I'm working on a system that includes a scheduling component, which has support for recurring events. After reading many, many posts on storing recurring events, it was suggested that they be ...
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0answers
38 views

How to tune a sql server for a specific process in particular?

I have a specific process that I am want to tune for in a sql server DEV server. The DEV server and the LIVE server are equal, just the DEV has less memory. Both LIVE and DEV read data from the same ...
2
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2answers
52 views

How to optimize performance of backup process? Servers go down during backup

The context - So I am an intern (So I'll appreciate a more noob friendly response) and we have several websites on a server of which we do a backup daily, at midnight. We use MongoDB and there's a ...
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1answer
82 views

What's the biggest bottleneck (time) in writing data to a SQL database?

I'm running an ETL process that is writing about 2 million rows to a SQL Server database. I'm trying to optimize the time it takes for pure inserts (I guess updates is a different story). I'm ...
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0answers
32 views

Increasing system load due to multiple inserts every millisecond

In my project I need to do multiple database inserts every millisecond and thus Postgres takes huge amount of CPU. I need to find a way to reduce CPU load as I need to process about millions of rows. ...
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2answers
108 views

Please recommend changes for my.cnf

I am not having any performance problems per se but want to improve my sites' performance if possible. Would appreciate any advice for how I can improve my.cnf. I have just one server, not ...
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87 views

Performance: Postgres (Read-Committed) vs MySQL (Read-Uncommitted)

I have a workload that involves very frequent writes and reads. It is very performance sensitive, but not accuracy-sensitive. Hence, to maximize performance and minimize locking-delays, my plan was to ...
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11 views

with innodb engine, connection timed out & MySQL server has gone away error occured [duplicate]

I have created chat application which ping server every sec for messages. Currently I have done load test with httperf, with 500 request/sec. "Connection timed out & MySQL server has gone away ...
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5answers
409 views

How to optimize very slow SELECT with LEFT JOINs over big tables

I was googling, self-educating & looking for solution for hours but with no luck. I found a few similar questions here but not this case. My tables: persons (~10M rows) attributes (location, ...
4
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1answer
193 views

MySQL Write performance bottleneck

We are trying to diagnose a MySQL Bottleneck, specifically for data writes. Basically, we have a single process that picks files from a folder and load into a MySQL table X using LOAD DATA CONCURRENT ...
3
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4answers
257 views

Does updating a row with the same value actually update the row?

I have a performance-related question. Let's say I have a user with first name Michael. Take the following query: UPDATE users SET first_name = 'Michael' WHERE users.id = 123 Will the query ...
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0answers
49 views

Inexplicable differences between 2 almost identical databases on the same server

Our situation is as follows: We've got 1 MySQL (5.5.44) database server. The server hosts 2 databases. 1 database is the production database. The other is a copy database that gets copied from ...
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0answers
49 views

Improve performance of count(*) with two exists

I need some help improve performance of this query that runs in Postgresql 9.4 at Amazon RDS: SELECT count(*) AS total FROM people WHERE EXISTS ( SELECT 1 FROM person_values WHERE ...
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2answers
72 views

Improving performance on a join query

I have the following MySQL query that I am attempting to run against a set of tables prepopulated with data: $sql = sprintf(' SELECT video.id, video.name, video.created_at, video.duration, ...
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1answer
55 views

Any potential issues/ DoS risks with frequent connections/ queries to a SQL Server db?

A database team suspects there may be an issue with a third-party ETL application opening, and closing, connections to a SQL server database repeatedly. In terms of exact numbers --- it opens about ...
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0answers
29 views

What is the fastest way to do a REGEXP find and Replace in MySQL database?

I have a table with 700,000 entries and I need to check each entry for 1,000,000 words and then replace the word if found from hello to #~hello~#. Words can occur multiple times in an entry and need ...
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0answers
126 views

iSeries Linked-Server SQL 2012 performance issue

I have a seen a serious performance dive when moving from SQL2008R2 to SQL2012 on my linked server queries. I have set the linked server on the SQL2012 server as a Microsoft OLE DB Provider for ODBC ...
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2answers
69 views

Partitioned Tables and Indexes - what are the downsides?

When talking about Partitioned Tables and Indexes for tables with less than 100 partitions, no nonaligned indexes: with that I mean: Nonaligned index An index partitioned ...
3
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1answer
132 views

SQL Server query on server taking longer than laptop

Our program uses an SQL server database as its back-end (SQL server 2008-r2 - 2014). The program is OK for performance but the Database seems to slow down a bit too much. As part of the nightly ...
2
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1answer
53 views

Is there a Windows Performance Counter which contains the “Log Send Rate” for Availability Groups?

I wish to be able to get the "Log Send Rate kb/s", as per the SSMS AG dashboard (which is also available via log_send_rate column on the DMV sys.dm_hadr_database_replica_states) I'd like to get it as ...
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1answer
38 views

SET ANSI_NULLS - Performance of Stored Procedures

Does setting ANSI_NULLS ON/OFF affect the performance of stored procedures? SET ANSI_NULLS OFF GO SET QUOTED_IDENTIFIER ON GO CREATE PROCEDURE [dbo].[TestProcedure]
3
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1answer
123 views

Faster query with pattern-matching on multiple text fields

I have one Postgres table with more than 20M tuples: first_name | last_name | email ------------------------------------------- bat | man | batman@wayne.com arya | vidal | ...
2
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0answers
58 views

Postgres: CREATE INDEX, but very slowly, to reduce performance hit on rest of database?

I have a large production PostgreSQL (9.1) database running on Ubuntu Linux. It is currently being queried and used. However there is another use I need later, and I will need to create a large ...
3
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0answers
429 views

Slow inserts/updates into partitioned table with lot of partitions

I'm designing the partitioning for our new database, but we are facing performance issues in inserting or updating the partitioned table. For simplicity suppose we have one table T, which have an ...
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0answers
6 views

Reason of poor performance of ANSI joins in Oracle 9i

Please before flagging as duplicate, read the last paragraphs. In an Oracle 9i database this query runs in 0.18 seconds: select count(*) from dba_synonyms s,dba_objects t where ...
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0answers
80 views

MongoDB very poor query performance vs Oracle

I'm a MongoDB noob and trying to import data from an Oracle table. My Oracle table has 1 unique index on a single column, which is an id (a number - primary key). I successfuly imported data to ...
5
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2answers
137 views

Confused about why a particular index is being used

I have a table (with 170M rows) that looks as follows: CREATE TABLE [dbo].[Panel] ( [SubId] [varchar](15) NOT NULL, [LineageId] [int] NULL, [Buck] [varchar](20) NULL, [Lot] ...
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0answers
60 views

Why is a max degree of parallelism 1 recommended and used for Sharepoint in SQL Server?

I am new to Sharepoint, but I used to work with SQL Server a lot. I realized that Sharepoint changes some of the SQL Server settings to non default values. One is the max degree of parallelism, why ...
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0answers
38 views

ORM and performance for SQL Servers

In a past SQLBits, one of the speakers went into some detail about ORM software's effect on SQL Server performance. The example the speaker was referring to was one in which the application was ...
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1answer
66 views

SQL Server - High Performance Record Comparison [closed]

Scenario : I have a collection of records to be inserted/updated into a table. Each record before getting inserted/updated in the table must be checked with the other rows in the table so as to find ...
1
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1answer
72 views

MIN, DATEADD, DATEPART, DATEDIFF functions cause table scan

A performance issue has been brought to my attention. It appears an application executes a query from time to time that takes nearly 3 minutes to execute successfully. The column is of data ...
5
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2answers
102 views

Joining two subqueries with union all and join leads to suboptimal execution plan

I've faced the similar problem on my production environment, but I managed to reproduce this behavior on Northwind DB. Consider the following query: USE NORTHWND; DECLARE @ids TABLE ( Id NCHAR(50) ...
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1answer
61 views

Measuring MongoDB I/O and CPU performance

I am new to MongoDB and I'm experiencing this NoSQL db through a series of very simple queries, with an Oracle exported data set. Aside measuring the execution time with primitives like ...
2
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0answers
46 views

Simple insert with Wait_Info = WRITELOG()

We have a query ( the same as some questions I made here ). a simple insert: INSERT INTO [My_Ttable]([IDChamada],[Evento], [Resposta],[IDTarifador],[ProximoEvento],[NomeDaMaquina],[DataMaquina]) ...
1
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1answer
88 views

CPU Time Slower in SQL Server 2014 than in SQL Server 2008 R2 [closed]

We’re upgrading a virtualized database server from an old SQL Server 2008 R2 Standard (vmware) to a new shiny SQL Server 2014 Standard server (hyper-v). We were doing some performance testing and to ...
2
votes
0answers
58 views

Query that can benefit from index, cluster or hash-cluster

I'm trying to find a equi-join query that shows a decent performance bump when I use an index, cluster or hash-cluster structure on my data. I initially need to run the query on unstructured data ...
2
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0answers
72 views

Every time I run a stored procedure it takes longer to complete until I restart the SQL Server [closed]

I need to optimize a critical stored procedure running on SQL Server 2012. The idea was to measure how long it normally took to run this procedure, make a few changes, measure the improvement and ...
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1answer
54 views

Is it possible to break down query time?

We have a setup of a few cloud servers that connect to a MySQL cluster on dedicated servers over Rackspace's Rack Connect network. We have noticed recently that the time for database queries (via PHP) ...
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0answers
113 views

CPU Time Slower in SQL Server 2014 than in SQL Server 2008

We’re upgrading a virtualized database server from an old SQL Server 2008 R2 Standard (vmware) to a new shiny SQL Server 2014 Standard server (hyper-v). We were doing some performance testing and to ...
0
votes
0answers
36 views

Non-structured Query performs better than on clustered, hash-clustered and indexed?

I am using the following query as a base line on some unstructured data (no indexes, no clusters etc) and the query is performing better on the unstrutured data than when I add indexes to the join ...
8
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3answers
162 views

Poor cardinality estimate disqualifies INSERT from minimal logging?

Why is the second INSERT statement ~5x slower than the first? From the amount of log data generated, I think that the second is not qualifying for minimal logging. However, the documentation in the ...
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0answers
76 views

Slow mysql query full text search tag database

In the database are ~700k images. Each image has its own tag(s). I want to be able to search images by the tags with a full text search query. The query does exactly what I want but it's very slow. ...
2
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1answer
36 views

Excluding rows by lots of ids

I need to exclude some rows that the user has already seen. Currently I am doing this by simply comparing the ids that the user has seen to the row's ids by running this query (there are also other ...
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0answers
123 views

Two servers with the same exact specs taking way different times to run the same query

I have 2 servers with the same exact specs: Test Server and Production Server The same exact database with the same exact data is on both of these servers. I remote into each server using remote ...
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0answers
30 views

Query performance tuning with joins on views with large data

I've this query in oracle. This is basically the query of a BA report which I'm trying to tune. SELECT DIM_PROJECT_OL.PROGRAM_ID, DIM_ANALYTIC_STRUCT_ACCOUNT_OL.STRUCTURE_ID, ...