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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Migration from SQL Server 2012 Ent to SQL Server 2014 STD

We recently migrated from a traditional hosting environment with a back end of SQL Server 2012 ENT to an Azure VM running SQL Server 2014 STD. We did all the cool stuff with BPEs on SSD, etc. The ...
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209 views

Tuning a Postgres INSERT only database

I am designing a database which will have many inserts and selects, but no updates. Are there any considerations to take (in order to have high query performance) while knowing no tuple updates will ...
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85 views

MongoLab: Does hardware effect performance of a find() query [closed]

I asked a pervious question on StackOverflow about if document size affected the performance of fetching that document (the document is 3MB in size) ...
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76 views

Load & traffic balance best practices

I am about to design an enterprise solution for a large scale application in which a windows service, MVC, and many other projects will use a database, so I am thinking about load balancing and best ...
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274 views

Optimizing key lookup in subquery with UNION ALL

I am trying to optimize following query (little bit more complex actually, but this is important part): SELECT Id, StatusDate, [...Lot Of Columns...] FROM ( ( SELECT Id, StatusDate, [...Lot ...
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267 views

Capture and Replay workload

We have a new server which we are migrating too and want to see the potential benefits of the hardware. So the idea is that we capture a workload and replay this against our new box. My question is ...
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45 views

SQL Server Disk IO Performace appears different between otherwise identical servers [closed]

I have two identical servers each running Microsoft SQL Server and performing a batch processing job. Server #2 keeps timing out while processing while server #1 appears to be running smoothly. I ...
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3answers
58 views

Is database performance optimization independent of the size of a database or a table?

If by rewriting an operation or a piece of code the performance has increased by 30% in a program reading and writing to a table with 100,000 records, does that optimization remains same if the table ...
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396 views

Pagination performance, with subquery, inner join and where

I am trying to optimize following query (this is most simplified version I could came up with): SELECT tr.Id, StatusDate FROM ( SELECT tr.Id, tr.StatusDate FROM mon.ArchivedTaskResults_201504 ...
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1answer
139 views

Postgresql performance issues when issuing many small inserts and updates one at a time

I have a production web server with postgresql database. My server gets data from another server every hour on the hour. The other server wakes up and sends many requests to my server, each result in ...
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2answers
698 views

How to calculate mysql server reads per second,writes per second?

Can anyone let me know how to calculate mysql server writes,reads,deletes,updates per second.
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53 views

how big of a role does hardware play? [closed]

I'm the developer, not the DBA. I don't know much about setting up databases but i'm concern of the setup at my current work. The server is installed on desktop PC hardware(i7, 16GB RAM, 1 TB SATA ...
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1answer
52 views

Is there something I can do to make this UPDATE run faster?

I have a relation EnumeratedSensorReading that includes a siteid and a quantityid column. I want to replace these two columns with a single sensorid column. I have added this column, and it is ...
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2answers
1k views

Merge faster than Insert

Are there any advantages/disadvantages of making use of a merge over a insert function? Can an insert statement make use of the `OUTPUT' Note: the ON clause for the merge is set to 1=0 (always ...
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1answer
432 views

Tune Performance by putting large tables into the KEEP Pool

We currently have a database with 20GB SGA space. SQL has been optimized but has to statisfy its use cases as well and some queries are very, very slow, specifically when large result sets are ...
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0answers
18 views

ASE 12.5 - Local variable in stored proc - performance issues

I've been told many times that using a local variable inside a stored procedure (ASE 12.5) will degrade performance because it prevents indexes from being utilized. I've searched allover for more ...
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2answers
100 views

Is copy/rename a good way to improve temp table performance?

An application I am working with contains this sequence of queries at the end of constructing a large temp table; I believe it is an attempt to improve performance by pruning dead tuples - create ...
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1answer
260 views

Soft delete to improve performance: all wrong?

A few years back I read soft delete would improve performance of deletion, because instead of actually removing the item and impact the clustered (and all other) indices, it would just change a value. ...
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1answer
224 views

In MySQL why is the first batch executed through client-side prepared statement slower?

I have around a million lines to be inserted into a MySQL (InnoDB) database, so to speed things up I turned to batch/multi-line insert. To be specific, I connect to the database (I'm using Java, so ...
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1answer
334 views

MySQL/InnoDB - Clustering Index with UUID

In MS SQL Server it is possible to cluster an index on a non-primary, non-unique key. For example, if I wanted to create a clustered index on the insert date to prevent page splits and fragmentation ...
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2answers
129 views

Awful execution plans after migrating from MySQL 5.5.11 to MariaDB 5.5.41

We just migrated our web site database from a server running MySQL 5.5.11 to one running MariaDB 5.5.41. Everything is working mostly fine, except there's at least one query from our storefront that's ...
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2answers
590 views

MySQL - best practices/ how to speed up "update, else insert' queries? Insert + delete faster?

I'm running an ETL process and streaming data into a MySQL table. Now it is being written over a web connection (fairly fast one) -- so that can be a bottleneck. Anyway, it's a basic insert/ update ...
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1answer
84 views

Database design - load multiple excels daily

My first post ever :) Apologies if I am not so clear with my question - here I go... I have a design problem from database schema perspective. My use case is following: On a daily basis, system ...
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2answers
2k views

Many columns vs few tables - performance wise

Yes, I am aware that data normalization should be my priority (as it is). I've got a table with 65 columns storing vehicle data with columns: used_vehicle, color, doors, mileage, price and so forth, ...
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161 views

How to improve performance when joining against coalesce

In an effort to remove a caching layer from our application, I'm building a number of views to encapsulate the different ways a user can have access to a piece of content - one per "rule" of access. ...
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57 views

Performance impact in orders of magnitude with Dynamic SQL [closed]

This started as a problem debugging a SSRS performance problem where I found reports were timing out when they previously weren't. Finally I traced down the SQL the report server was submitting, and ...
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2answers
98 views

Dynamic SELECT and place result in variable columns

Edit: I use Microsoft SQL Server Management Studio, I believe it's SQL 2008R2. Sorry, new to this. I've got a complex question, at least, I think so since I can't find the answer after excessive ...
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2k views

SSRS Blocking Processes

We have a busy SSRS Reporting server (SQL Server 2008 R2) on which we see frequent blocking between the below processes: [dbo].[CheckSessionLock] [dbo].[WriteLockSession] We are aware that some ...
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1answer
1k views

mysql dump import incredibly slow on my developer's machine

I have an SQL dump, it's pretty big (411 MB) and it took 10 minutes to import on server A, the same import on my workstation B has an estimate (pipeviewer) of 8 hours to import (it imported 31 MB in ...
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1answer
51 views

What MySQL activity eats CPU? [closed]

I have noticed weird CPU consumption peaks for MySQL process. When I monitor running queries, it's empty or some reasonable queries being executed. How do I better address the problem? Is there a ...
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1answer
400 views

MS SQL high tempdb disk I/O during merge replication of BLOBs

Having a merge publication for replicating BLOBs (sql type - image), got very high tempdb disk I/O for my size of data. Publication is download-only and has no filters. High disk I/O is caused by ...
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1answer
109 views

How do I optimise XPath Querying over a large dataset?

I have a table that has 220 M rows. Also the table has a xml column that has XML data. I have configured single file for data and another ndf for index. Table's primary key is guid column. When am ...
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79 views

MS SQL Server IO read increase appear randomly [closed]

The number of read (IOPS) in my MS SQL Server database increased randomly even during the night (low activities) from 0.3 MB/SEC (normal) to 25-30 MB/SEC. After like 30 minutes, it's capped to 6 ...
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1answer
92 views

Can this UPDATE be faster with indexes?

update line_items set product_id = dups.latest_product_id from line_items as li join products p on li.product_id = p.id join vendors v on p.vendor_id = v.id join vendorgroups vg on ...
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1answer
153 views

Combine multiple queries into 1 query

I have a message table in Postgres 9.4 that contains a words field of array type, with random words of a message. Currently I have millions of messages: \d messages Table ...
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0answers
351 views

Are there any known benchmarks/statistics on UnQLite?

I came across UnQLite the other day in Stack Overflow and it has me intrigued for some software I'm working on. However, very few tests have been published on how well it performs. There are plenty of ...
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1answer
94 views

Counting per status group makes query very slow

I have an Intranet system developed that takes in orders and every order item has their own status, i.e. "Printed", "Labelled", "Filed", etc. This query will need to count how many items there are in ...
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1answer
57 views

Oracle: How to AUTOTRACE in my program

You can display the results of EXPLAIN PLAN with explain plan for select * from foo; select * from table(dbms_xplan.display); How can I similarly display the results for an AUTOTRACE in my program? ...
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1answer
87 views

Cursor Performance in New Server

I bought a new server with spec : HP ProLiant ML310e Gen8 v2 8 GB Single Memory, Intel Xeon E3-1220v3 3,1 GHz, 500 GB SATA 7.5K RPM, Windows Server 2012 R2 x64, SQL Server Standard 2014 x64, RAID 0 ...
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1answer
34 views

What is a scaleable database design for querying items and only returning those a particular user has not already seen?

I'm looking at database architectures that will allow the storage of a list of items a user has already seen so that I could subsequently query the items table and only show the user items they had ...
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1answer
496 views

Storing multiple IDs in column or in new table

I'm fairly new to the databases and I'm now creating little project where I have a database and I want to store deck of cards into the table where each card has its own ID (for example 52 cards in a ...
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1answer
244 views

How to improve mysql replication performance reading the relay logs in slave?

I have a mysql 5.5 row-based replication being done. The slave is slowly getting delayed relative to the master. On show slave status I see the distance between Master_Log_File and ...
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1answer
48 views

Converting a GraphDB schema to a relational database schema

I currently am using a graph database and am considering moving off of it to a relational database like Postgresql. My concern is that I have lots of relationships between entities (since this is ...
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2answers
407 views

Speeding Inserts of longtext or longblob columns

i'm currently migrating a DB2 database to MySQL, using SQL WORKBENCH Tool It basically does a select from DB2 and Insert to DB2. It works fine, but on the tables with longblob or longtext columns ...
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161 views

Tunning MySQL Variables

we have a dedicated mysql server with 10 CPU and 32G of memory After doing some readings came up with those configs : # This was formally known as [safe_mysqld]. Both versions are currently parsed. ...
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2answers
214 views

Query for a table with paging and filtering vs. CTE (common table expression)

Intro In PostgreSQL 9.3: I am building a query that fetches data for a table that supports sorting, filtering and paging. Think Customers for example, you want to show name, surname, some detailed ...
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2answers
62 views

unusual relation, binary aspect

I have question very unusual for databases. I’m not a good English speaker, but good English reader :) so for explanation I’ll give you examples. Part1 In MySQL, I have two tables with relations ...
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2answers
922 views

Why is “select join insert” so much faster than “loop insert”?

MySQL docs state that the time required for inserts has these approximate proportions: Connecting: (3) Sending query to server: (2) Parsing query: (2) Inserting row: (1 × size of row) ...
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97 views

Performance Implications of Explicit Collation Conversions across Linked Servers

I locally host host databases from two vendors on two different SQL instances, but on the same network. These servers frequently communicate with each other (through joins and whatnot), so we have ...
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1answer
305 views

Can SQL Server 2008 R2 extended events execute stored procedure or query?

I'm trying to use extended events to track queries that never complete using Event Pairing as a target. (see this question I asked a few days ago). The event pairing target should let me find ...