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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How Do I Maintain High Insert Performance On Postgres

I'm working on a project which is parsing data from measurement files into a Posgres 9.3.5 database. At the core is a table (partitioned by month) which contains a row for each measurement point: ...
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Why does my query end up with two seeks instead of one and how do I fix that?

I have these two tables: CREATE TABLE [TaskItems] ( [ItemId] UNIQUEIDENTIFIER NOT NULL, [LastOperationTime] DATETIME NULL DEFAULT GETUTCDATE(), [OwnerId] ...
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15 views

Changing compatibility level of database causes performance improvement of stored procedure

We have a Web Application in a Windows Server 2012 Datacenter (IIS 8), running under .NET Framework 4.0, which connects to another Windows Server 2012 Datacenter with SQL Server 2012. My Database has ...
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1answer
20 views

Innodb DB Consuming IO even when no operations are being done

I am currently doing some stress testing where I am pushing inserts to the database as fast as I can. The simulation inserts 10000 records per second. After inserting around 200 million records I ...
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25 views

Optimal way of loading, registering, indexing and querying a huge XMLDB

I've got 35 million highly structured XML documents, with a total size of 500 GB. An XSD is available for this data, and the end goal is to transform the data into an RDB. All fields can be considered ...
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18 views

MySQL DATE vs DATETIME read/write performace

Did anyone perform accurate read/write performance comparisons of MySQL's DATE vs DATETIME column types? Please do not bother writing "It should be faster" or "I think it's faster". I am looking for ...
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39 views

Multi-Column Full Text Search Going Very Slow

I have a full text index on a table articles for the columns content, title and keywords When doing the search on each of the columns, like so select count(1) from articles where ...
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113 views

Huge differences of performance of MySQL in two servers

We have a MySQL server installed in two different machines, a testing server and a production server, both windows, which is used by a web application. The problem is that there are HUGE performance ...
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Sample a Mysql table to increase performance

we are storing all our clients traffic data in a MySQL 5.1.73 database (MyISAM) and then we use it to generate user and internal statistics/graphs, always searchinng for a client id and a date/hour. ...
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27 views

What is “good” single-block read latency?

Is there a reference anywhere that I can go and see what kind of single-block read latency I can expect from Oracle given a certain hardware configuration? I can run a query to show the current ...
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14 views

Optimal layout strategies for Time-Series using Columnar storage

In the context of time-series and specifically columnar storage systems. Question: What are the processes or heuristics that are used to determine how best the columns of contiguous values be grouped ...
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MySQL: What are the pros and cons of running with engine=Memory vs on a memory-mapped filesystem?

What is the difference (in terms of read and write perf, alter tables, backup and recoverability and consistency) of running a MySQL database on a memory-mapped filesystem vs with ENGINE=MEMORY
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Which benchmark assess string pattern matching in a database?

I have a postgresql DB in which I do a lot of string matching ala : UPDATE table1 SET colum1 = TRUE WHERE colum2 LIKE '%teststring%'; colum2 is a whole html file As I said I do A LOT of this and ...
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34 views

creating a 24 hours data table - Suggestions/improvements

I am planing to have a table to store the data based on every hour , in short I have a file with 24 hour data and I need to use this to populate a hourly bar/line graph. Below is a sample 24hr data ...
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45 views

Finding reason behind high write IOPS on MySQL (RDS) server

I am having performance issues with an AWS RDS instance (running MySQL 5.6). This is the backend db to an XMPP server called Tigase. According to Tigase Inc. this type of db instance should be able ...
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34 views

mysql database performance issue [closed]

I have a 2x Xeon Quad Core E5410 2.33 GHz with 24 GB of RAM. running 5.5.31 with the following my.cnf file. It supports lots of reads and writes and transactions(all INNODB). Are there any obvious ...
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38 views

If a query contains two identical subqueries, will they both run?

Say I have a SELECT query that contains two identical subqueries, like the below: SELECT (SELECT SUM(Price) FROM Product p WHERE p.GroupID = g.GroupID) AS 'TotalCost', (SELECT SUM(Price) ...
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21 views

Optimizing bulk update performance in Postgresql with dependencies

Basically my question is the same as this one, but WITH dependencies, so drop/renaming the table is not a trivial option (I assume). We are refactoring a large, poorly designed table which has many ...
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23 views

How do triggers work on partitioned tables?

I have partitioned a table on the basis of a column. This column can either have 0 or 1. So, only two partitions (p0, p1) have been created internally. On this table there are 3 triggers which execute ...
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Performance implications of mixing VARCHAR and CHAR fields in MySQL Table

I read the following answers in this forum: What is the performance impact of using CHAR vs VARCHAR on a fixed-size field? MySQL: Does the order of the fields in a table make a difference in ...
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194 views

Can I update every datetime in bulk?

The current database assumes all times are local to the user. Now we're changing this so the database stores everything in UTC and our application converts the UTC time in the database to the correct ...
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1answer
72 views

If an INNER JOIN in a query returns no rows, do additional INNER JOINS add a significant performance overhead?

If I make a query as follows: SELECT * FROM TableA A INNER JOIN TableB B ON A.AID = B.AID INNER JOIN TableC C ON B.BID = C.BID Does the INNER JOIN with TableC add significantly to the performance ...
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52 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): ...
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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 ...
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30 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 ...
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45 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 ...
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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 ...
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72 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 ...
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1answer
87 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 ...
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27 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 ...
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77 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). ...
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37 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 ...
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55 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 ...
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26 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 ...
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1answer
15 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 ...
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138 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 ...
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36 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 ...
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1answer
32 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 ...
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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 ...
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120 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 ...
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Why would SELECT * be magnitudes faster than SELECT foo?

Consider a table of values and hashes, like so: +------------+----------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | ...
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41 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 ...
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38 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 ...
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182 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 ...
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2answers
44 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 ...
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2answers
55 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 ...
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398 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) ...
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41 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 ...
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63 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 ...
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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 ...