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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MySQL: What should I do if too many tables opened during peak hours?

In Peak hours: When I run below statement, I found around 100 tables out of 250 have opened. show open tables where in_use>0; There are around 10 tables for which in_use value are >50. Storage ...
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41 views

What is the recommended pgpool mode?

I'm trying to determine which pgpool mode to use (http://www.pgpool.net/docs/latest/pgpool-en.html#config). In order of importance my requirements are: All nodes accessible via shared public ...
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63 views

Optimal config for a small vserver with ispconfig

I have a vserver with debian wheezy, 1GHz CPU single core, 512MB RAM and only 8GB HDD. Owncloud is running, but has its own database-engine How should I configure Mysql so it doesn't slow down the ...
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141 views

Will I still benefit from provisioned IOPS in RDS on a smaller non-PIOPS-Optimized instance type?

Quote from the docs: If you are using Provisioned IOPS storage, we recommend that you use the db.m3.xlarge, db.m3.2xlarge, db.m1.large, db.m1.xlarge, db.m2.2xlarge, db.m2.4xlarge, ...
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94 views

Very slow response even with a high number of available connections

I'm running this server for data mining purposes. It runs several compute-intensive data mining applications in parallel and does simultaneous access to the MySQL server. Here are the ...
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292 views

General error: 1615 Prepared statement needs to be re-prepared

I have been running into this issue every time I try and sync a medium size JSON object to my database so we can perform some reporting on it. From looking into what can cause it I have come across ...
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20 views

Joining 2 big tables turn into a server down problem

Recently I was using a database (MySQL with Workbench) in the company that I work for (I'm a business analyst, not a DBA), and wrongly I created a query joining 2 tables that basically are the same. ...
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105 views

Why would call to scalar function inside a Table Value Function be slower than outside the TVF?

I am writing a Table Value Function, calling the function takes 10x as long as directly running the code. I traced this to a call to a multi-line scalar function inside the TVF. The call to the ...
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22 views

How to figure out how to split a table using the proper scheme

If you have a big table that you want to partition and you have 2 candidates as the partitioning key (in the sense that 50% of the queries use one column and 50% of the queries use the other column ...
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56 views

is this dead simple query too slow?

I have added and removed a few indexes from my user table and, while testing, didn't see the performance gains I had hoped. As a result, I removed the indexes and tried a simple query to see what my ...
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138 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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43 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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41 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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82 views

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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32 views

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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59 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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46 views

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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49 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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128 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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43 views

performance questions in database design

I need to describe a set of studies that are practiced to a patient, every patient have a "Clinical History", that are described in another table called "Clinical History Lines"(hclines) Every visit ...
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22 views

What is the optimal way to get a tabular view from an Entity-Attribute-Model table?

Following up on my previous question, I have created a table for storing measurements of different physical quantities. The schema looks like this: CREATE TABLE sensorreadings ( time TIMESTAMP, ...
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98 views

Database design for large incoming data

I've been tasked to design a database to handle a large volume of incoming traffic from sensor readings, possibly 1,000s an hour when it's at full strength. Each reading will be relatively short - ...
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69 views

A working view now starts timing out

I have 2 identical databases (one larger, one smaller) with identical views. Recently a view on the smaller DB started timing out. Google searches seems to point to deadlocking of some sorts. If I ...
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36 views

Mysql table with only two columns, nothing unique: Will an index increase search performance?

If my table only has two columns (username, groupname) and a million or so rows, will an index improve performance at all? Wouldn't it take just as long to search the index file as it would to search ...
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120 views

MySQL 5.5, Xubuntu 14.04 - INSERT and UPDATE bottleneck

DBAs: I have been developing and maintaining plugins for Moodle for the last ~2 years, and have recently decided to try using my local desktop again, rather than my institutions ESX VMs, as a ...
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21 views

Sysadmin tools for SQLAnywhere

I'm seeing a performance issue in a 3rd party application based on SQLAnywhere 7. The DB engine seems to be dramatically underperforming on the hardware provided. It seems to have a upper limit on the ...
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16 views

Page cache installation in magento admin panel

Hi just added pagecache from varnish in Magento through the magento connect. It went in ok, just wanted to know, the correct configuration. In magento admin panel for the correct set up in the page ...
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140 views

Performance: Interleaving several statement handles in MySQL

Does interleaving several statement handles slow the system down? Example (Perl): $sth1->execute(...); $sth2->execute(...); $sth1->execute(...); $sth2->execute(...); (interleaved) vs ...
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63 views

Excesive use of RAM on MysqlServer

The RAM of a server where I have installed mysql is always 100% and looking at the processes that are running, MySQL is the most consumer on CPU and memory and I can see the cause of great use RAM.   ...
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87 views

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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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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27 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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67 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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159 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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85 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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155 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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26 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. ...
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40 views

more queries vs storing results in database

Environment: Embedded (smartphones) Data Structures: Object Table A: id, field1, field2... Object Table B: id, field1, field2... Object Table C: id, field1, ... , Object A, Object B ... many ...
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68 views

Adding additional condition significantly degrades performance

Have the following query: SELECT * FROM table_A INNER JOIN table_B ON /* conditions */ INNER JOIN table_C ON /* conditions */ INNER JOIN table_D ON /* conditions */ WHERE table_B.state = 'active' ...
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637 views

Are mongodb bulk inserts really increase server perfomance (and faster)?

Bulk inserts always are faster in client side because of saving round-trips, but at the server-side is there any sensible performance improve? It seems the code for bulk inserts, just loops over ...
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116 views

Big Mysql table optimization

I have a table that I use to cache google translate API answers. Table structure is orig_string and group are indexes Now it has more that 1million rows with 35000 distinct values in group field. ...
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78 views

Efficient way to fetch/update X records in a loop

What I need is a simple process that handles requests. I have setup a simple table as follows: CREATE TABLE Requests ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, request_param VARCHAR(250) ...
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213 views

index usages on table with recursive relationship

we are working on a project that uses jpa and oracle. In this project we have a table with a recursive relation: Create table alarm ( id varchar2(200), ... alarmcode varchar2(50), parent_id ...
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287 views

Performance measurement in PostgreSQL

When developing server-side stored procedures performance measurement is an important issue. EXPLAIN ANALYZE is very usefull, but when it comes to simple queries like SELECT name FROM clients WHERE ...
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76 views

query comes in slow query when log_queries_not_using_indexes is enabled

This query comes in slow query log when log_queries_not_using_indexes is enabled. SELECT a.id, d.id AS city_id, d.city FROM booking a, sub_area_master b, area_master c, city_master d WHERE ...
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134 views

H2 database binary file full of @^@^@^@^

I am investigating H2 database performance and was curious to why the database file was several megabytes long when only storing hundreds kilos of text, I therefore opened the database file with vim ...
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237 views

Mysql View Performance on Aggregate Functions

I've a table that contains weekly statistical infos. ex. Society - Week - Year - Data AAA Inc - 1 - 2014 - 10250 AAA Inc - 2 - 2014 - 5235 BBB Inc - 2 - 2014 - 3210 ... Over this table i need to ...
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75 views

Order before Group

I have this query: SELECT HOTEL.hotelname AS NAME, HOTEL.`boardbasis` AS board, HOTEL.`engine`, HOTEL.`itemcode`, Group_concat(Round(((hotel.cheapestprice / 2) + ...
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188 views

MySQL Load Avg High — CPU bound or IO Bound or Memory Issues

We are using MySQL 5.5 and the database is approximately 10TB. The load avg is constantly high during day time. Following are the configurations and a snap shot of a 'top' command. I wanted ...
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74 views

Why does a scrambled junction table destroy the speed of my query?

I have two schema in a MySQL database, one containing raw data in MyISAM tables and the other containing the results of some processing tasks performed on the raw data, also in MyISAM tables. For ...