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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116 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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355 views

Firebird database performance after server upgrade/restart

Got a 350 GB database (more than 40M records plus 0 - 1000 BLOBs for each record in another table). After upgrading Firebird to version 2.1.5 (mainly because of filesystem cache issue) database became ...
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284 views

Performance Hit when upgrading to Oracle 11gr2

I am experiencing the same symptoms as noted in this question which was closed and does not have a satisfactory answer. Original Question We've recently upgraded from Oracle 10gR2 (10.2.0.4 ) to ...
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184 views

postgresql 8.3 possible checkpoint and memory misconfiguration

I am using postgresql 8.3 in a read/write heavy application where data are being written to the database from a background process while they are also being read/written from a web application. At ...
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300 views

How to make Greenplum 4.2.3 only scan the intended partition?

When I uses unnest() in a View, and uses that View in a select statement, Greenplum seems to fail in only searching for the intended partition and search through all the partition of the main table ...
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179 views

Most efficient way to sort data fields into SQL

I'm trying to decide on the most efficient way to sort various data values. Here's how the data arrives: Device X sends a text string "name=value&name2=value&name=value" On arrival that ...
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705 views

Efficiently retrieve big amount of data based on date range

Table EVENTS TimeStamp |O.Name |Location |Source | 2008-11-12 |Pretorian|Európe |England | 2009-12-24 |Lex Rosa |Európe |Italy | 2010-01-01 |Nasdaq |USA |Whasington | ...
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160 views

Why is this table structure so slow to CRUD?

I have a table that I am using for queuing emails. Unfortunately, adding to or reading from this table becomes horrendously slow after adding about 50 records. -- Table "mail_queue" DDL CREATE TABLE ...
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1k views

Oracle 10g - Sudden change in execution time for specific query

After the DBAs fiddled with some parameters in our Oracle 10g Production Environment, most queries became a little faster. But a single query (a quite complex one) became dramaticaly slower - it went ...
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526 views

Finding the bottleneck by analyzing Munin graphs

We’ve been experiencing some issues with our database server during peak hours. In our Nginx error-log we can see that a lot of requests get timed out. The requests are also very slow. We have had ...
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110 views

Long disk queue when no traffic

I got dedicated disk (RAID 10 - 4 SAS disks) for Postgres. I am bit worried as recently, I see under Windows Resource Manager disk queues like 3+ in the mornings (low traffic hours), like every 30-60 ...
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20 views

problem with column oriented dbms features

I am currently looking for a free(or at least low cost) column oriented DBMS with really good compression abilities (at least 10:1 ratio) and fast response time. Having evaluated multiple open source ...
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27 views

Sql Server Stored Procedure calling table-valued function - Performance

I'm using Sql Server 2012 and I have a stored procedure that does about 15 left joins and one of those joins is a CROSS APPLY to a table-valued function. The first 14 left joins are not gonna restrict ...
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34 views

Improving query performance involving similarity and full-text search

I have been trying to improving the performance of this query involving similarity and to_tsquery. I have a table (440,000 rows, PostgreSQL 9.5.2) with the following characteristics: test_db=> \d ...
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58 views

Suggestions for indexes or how to partition a table in SQL Server 2008R2

Table structure and DBMS SQL Server 2008 R2 I have a single table structure (flat) that has summarized sales data (YTD,MAT etc) by unique combinations of "Customer", "Product" and "Territory". ...
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40 views

MySQL: So many prepared statements in general log file

One of my clients complained serious performance issues in a web-application written in Java. I was suspecting that there might be some unoptimized queries which are causing the problem. I've enabled ...
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19 views

Performance Comparison using extended events

I am using SQL Server 2012. In my development database I have an old (MySP_Old) and new(MySP_New) versions of a stored procedure. This procedure has around 10 big queries in it. I need to compare each ...
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18 views

Load DATAINFILE extremely slow

I am using the code below to insert a 2.2MB file into a MySQL database in the cloud using Azure (the free version) with 36 thousand rows and 8 columns of doubles. MySqlCommand sqlCmd = new ...
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42 views

MySQL performance differences between two servers

I've a production server (CentOS 5.11) and a development one (Debian 8). Same MySQL version (but different architecture, i686 vs x86_64), same data, same config settings. If I execute a query with ...
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44 views

oracle : Effect of inserting new rows when row movement is enabled

I have a table which is partitioned by key. I want to move few records (which I require later) to another partition so that I can drop this partition and get some free space. I am enabling row ...
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45 views

Performance drops after online backup

We are using DB2 Express-C 10.5.5 on Ubuntu Server 12.04.5 64-bit. Every night we do a full online backup: backup db MYDB online to /home/db2inst1/backup compress include logs after backup we do log ...
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24 views

select aggregates at each funnel step

I'm trying to find a way to efficiently get aggregates at different stages of a funnel. For example, given documents that contain sections, I want to tell how many sections and documents an author has ...
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55 views

How can I restore a MySQL dump faster on Windows?

I am restoring some InnoDB and MyISAM .sql files that are on the order of GBs (ranging from 1 GB to ~ 10GBs) and they are taking a day or longer to restore. The command I am using currently is: use ...
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18 views

Reliability of MySQL Events Table

Is there any limitation of usage of MySQL Events table. Let us say i will have 10K of entries which will be executed across 3k schemas. They all are not same time but at-least 3K events will be ...
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49 views

MySQL performance issue after migration

I have a MySQL performance issue with a brand new server, and am somewhat of a beginner as a database administrator (I'm mostly a general-purpose Linux sysadmin). I'm looking for pointers where to ...
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19 views

MySQL 5.6.18 got signal 11

My MySQL Server 5.6.18 got signal 11 today very randomly. Has not happened before. This is the stack trace : stack_bottom = 7fdb9bcb1e0f thread_stack 0x40000 ...
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61 views

How to optimize this query on oracle?

I have built this query in oracle to get some data i need from the two tables below. At SELECT REGEXP_REPLACE i get the IN_01 as input parameters from the user and it can be much bigger list than ...
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47 views

Linked Server to Oracle seems to be slow

we have a linked server between a SQL Server 2008 R2 instance and an Oracle 11.1.0.7 instance using OraOLEDB.Oracle Provider. The enabled options for provider are: Dynamic parameter Nested queries ...
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38 views

Database calculations question

I am creating a MySQL database that is going to be used to store a lot of timestamps. There are currently 6 timestamp fields that data can be entered for one row. I am utilizing timestampdiff to ...
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21 views

calling multiple procedures from my application Vs calling procedures inside another procedure

I have a scenario of saving user details into my database(MySQL 5.1); i have three tables for saving user details; user_data,user_contact,user_address, so if i insert one user data i have to check for ...
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19 views

T-SQL script to analyse recent changes in SQL Server configuration?

Last week suddenly one of our VMs running SQL Server slowed down considerably and its performance dropped to the level where some of us cannot work on it any more. Just to give you an idea about the ...
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38 views

MySQL performance affected by calling functions from inside procedures?

this is the very first question I post, so please bear with me ... When working on a project, I tried to get the LAST_INSERT_ID for a table, by invoking it from inside a procedure right after an ...
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18 views

Sudden performance gain when performing mysql queries twice, lacking on live host

I was having performance problems and could improve it down to 14 seconds roughly per execution (if you see any way to improve that further, I would be really thankful). Which, is still very slow. ...
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26 views

Correlating Disk Latency on Application side Vs. EMC SAN

Our OLTP databases have encountered several I/O issues. During those events: Avg disk sec read on the data file was 0.2 second or higher We found windows eventlog entries stating: "SQL Server has ...
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774 views

MySQL 5.7 InnoDB is extremely slow on spatial data compared to MySQL 5.6

I have a table area which contains ~300,000 rows. It is defined as follows: CREATE TABLE `area` ( `area_id` bigint(20) NOT NULL AUTO_INCREMENT, `boundary` geometry NOT NULL, `name` varchar(255) ...
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19 views

Need some advice on db layout

I have some data that gets exported from a different system that I want to suck into mysql for some analysis. Currently, the export consists of 2 files, essentially file1 is the list of transactions ...
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26 views

Does extending datafiles affect performance

We have an Oracle 10.2.0.3.0 on Windows 2003 Server which is scheduled for upgrade within the next six months. One tablespace is about 2TB in size with over 250 data files. Some of these were ...
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23 views

Performance issue for daily calculations - Sybase Adaptive Server

I need an advice from the community, there is no wrong answer I'd like to have as many advice that I can ! I manage a process that does every day a lot of financial calculations and they are ...
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52 views

MySQL query hanging while copying to tmp table

I have a query that ran in 10+ seconds last week, but now is hanging even after 10 minutes. I'm running this in a test environment so the data hasn't changed much and I am baffled at what could be ...
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29 views

Any risks to pure inserts + delete duplicates, instead of insert/ update for SQL Server?

I saw a related question but it was more of the how vs. the why. I'm wondering in SQL Server why one would attempt an "insert/ update" with incoming data ... instead of just running pure inserts ... ...
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43 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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48 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 ...
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34 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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104 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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50 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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33 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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8 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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58 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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38 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 ...
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94 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. ...