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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5
votes
1answer
289 views

MySQL 5.1 to 5.6: massive performance hit

Okay, this is possibly three questions. I want to move my existing MySQL 5.1 database using MyISAM to 5.6 using InnoDB for what I think are a host of obvious -- and possibly even good -- reasons. ...
0
votes
1answer
176 views

Improve Insert performance for 200 Million rows

How can the following insert statement be improved - which varies from 20mins on certain days to 70-140mins on most other days. SELECT DISTINCT od.SourceID, od.OrderID, od.OrderLineNo, ...
0
votes
2answers
50 views

How to change table/indexes structure for a query with two aggregated colums

Do you have any suggestion on how to improve a table structure or its indexes in order to have a single query run faster? The table has this structure: docid | character varying(17) | ...
1
vote
2answers
68 views

Does RAM taken up Shared Memory connection counts against Max Server Memory?

I have an app that's local to the SQL Server and thus has a Shared Memory connection to it. I was wondering whether the RAM taken by the connection (including data transfers) counts against the max ...
0
votes
1answer
154 views

Postgres 8.3 faster than 9.3?

Our software product currently ships on Windows 7 with Postgres 8.3 as its database. On a busy site, there may be 24 automated systems generating 100 rows (x100 columns) per minute, with 3-10 human ...
1
vote
1answer
75 views

Partition : understanding files and file groups

We are trying to partition a large history table. Being new to partitioning, I was trying to understand the concept of files and file groups. File groups can be set up in following three ways : 1. ...
0
votes
2answers
135 views

oracle active sessions waiting for scheduler

Load on my 11g RAC looks like this: and I don't understand how to get insight into what this "scheduler" wait class is. It seems like "scheduler" that it refers to is the process that runs ...
4
votes
1answer
92 views

PostgreSQL does not use all available IOPS on a single operation

Using PostgreSQL 9.3 on Windows 7x64, CoreI7, SSD. Assume a PostgreSQL table with 8 Int32 columns and following C# code to fill the table. using (var connection = new NpgsqlConnection("User ...
4
votes
1answer
794 views

MongoDB performance vs. PostgreSQL with 5.5 million rows / documents

Can someone help me compare these queries and explain why the PostgreSQL query executes in just under 2000ms and the MongoDB aggregate query takes almost 9000ms and sometimes as high as 130K ms? ...
4
votes
1answer
128 views

Is ASYNC_NETWORK_IO wait type anything to worry about?

In looking at the list of sprocs that take long time to execute, one stands out as causing the most wait. However, most of that wait (81%) is ASYNC_NETWORK_IO and I know why: the sproc transfers ...
3
votes
1answer
303 views

How to improve Procedure Cache Hit Ratio?

From what I can tell Procedure Cache Hit Ratio below 95% is a problem. On my box, the values hover from 85 to 95%. How do I fix this issue? The server seems to have plenty of RAM so that ...
2
votes
2answers
96 views

Autogrowth, shrink and database performance

I have already asked some questions about Autogrowth and shrink. But I have some doubts related to it. 1)I have a database which grows about 300 MB every month. So is it best to set Autogrowth of 300 ...
0
votes
1answer
73 views

Poor SQL performance with raid10

Maybe I'll try my luck here. Server Fault site was quite hostile for non-professional server user. I recently bought HP ProLiant ML310e Gen8 v2 server with 8G's RAM and 4 HP 1TB 6G 7.2k rpm SATA ...
1
vote
2answers
102 views

Improving a search query

I have a query for search function. Basically search function allowed user to define what they "have" and "want". Then this query will filter out all the possible result which created by other user. ...
3
votes
1answer
169 views

Why is SQL Server using a clustered index scan for a self referencing FK cascade delete

I have made an example to allow me to show what my issue is: Setup: CREATE TABLE [dbo].[Test]( [TestId] [bigint] IDENTITY(1,1) NOT NULL, [ParentTestId] [bigint] NULL, CONSTRAINT [PK_Test] ...
0
votes
1answer
63 views

DB disk space requirements comparision between MySQL versions

I have 2 labs where MySQL is installed. DataBases are created and deleted dynamically by certain internal processes. InnoDB is the Engine used. In one lab, MySQL version 5.0.77 is installed. The DB ...
2
votes
1answer
61 views

Non-Clustered Index key columns to cover a variable where clause

To whoever reads this, sorry for the long question and thanks so much for your time. I'm needing some help on understanding what columns should be key/non key in the following situation, and what ...
0
votes
3answers
38 views

Should frequently accessed tables containing large blobs with one-to-one relationships be normalized and columns split into two tables?

I have a frequently accessed table containing 3 columns of blobs, and 4 columns of extra data that is not used in the query, but just sent as result to PHP. There are 6 small columns (big int, small ...
0
votes
0answers
67 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) + ...
3
votes
1answer
84 views

PostgreSQL: When should I use fillfactor < 100 for tables on SSD?

PostgreSQL documentation says that choosing smaller fillfactor lets table reserve space for future updates on the same page and "This gives UPDATE a chance to place the updated copy of a row on ...
2
votes
3answers
127 views

How to make stored procedures more readable without harming performance

I come from OOP background, and I need to write and maintain huge stored procedures. Naturally, the sprocs become quite unreadable very quickly, no matter how much I try formatting, giving readable ...
3
votes
1answer
44 views

How to show the related (suggested) keywords?

We do a program for cataloging images by assigning keywords (tags) to them. An image has the following keywords "John", "Jane", "Portrait". Another image has the following keywords "John", "Jane", ...
1
vote
1answer
161 views

Delete data from huge InnoDB table from MySQL Master and Slaves

We have some huge tables in MySQL database, We have already archived/deleted data older than 2012 in 2013, Now we need to archive/delete data older than 2013 means we need to archive data for year ...
1
vote
1answer
31 views

Do the showplan (any or all) events add more overhead than a tuning trace should have

How long (order of magnitude) do the various showplan events take to record? Also is the time these events require counted as part of the "duration" column of the corresponding SQL query?
2
votes
3answers
124 views

MySQL query extremely slow after server restart

I am managing a very large database for a custom application I wrote to keep track of visitors. The DB server was rebooted for the first time in over a year - not even to install any updates, but ...
0
votes
0answers
39 views

Performance difference search on INT or TEXT in SQLite 3

I'm a little bit confused about SQLite 3 type system. SQLite 2 was typeless with only exception of INTEGER PRIMARY KEY. I don't get if SQLite 3 are same or not.. I have in my table PRIMARY KEY of INT ...
2
votes
1answer
49 views

How can I compare the server impact of transaction replication

We are developing a system that must extract data from an existing SQL Server 2008 R2 cluster. One of our design goals is to limit the performance impact on that cluster as much as is practical. ...
0
votes
0answers
205 views

hstore vs redis performance wise (without durability) [closed]

How do PostgreSQL's Hstore and Redis compare performance-wise? This question was asked here, but I would like to compare with a PostgreSQL configuration without durability guarantee, i.e. with ...
3
votes
2answers
250 views

What can cause slow queries with low resource usage?

I am writing an application which builds a database on a SQL server. The application loads data into some staging tables, then executes a series of stored procedures which merge the staging tables ...
0
votes
4answers
128 views

Can migration from MS Access to SQL Server or … make database faster? [closed]

A company asked me to migrate their database from MS Access to SQL Server or MySQL because they think that on those engines their database will run faster. But I wonder if their problem isn't because ...
0
votes
1answer
61 views

How can it take longer to replay a captured trace than to capture it

I am attempting to use trace captures to determine how much of a performance issue was database related and how much was code related. However, the trace is taking longer to replay that it took to ...
2
votes
1answer
60 views

Clustered Index / Index Oriented Table performance in join, worse than nonclustered?

Can a clustered index (or IOT in Oracle) be detrimental, when to be used on a very "broad" table, but only few columns are used? In this case, the "Product" table is used only like a junction table ...
2
votes
0answers
48 views

Identical query & instance but other execution plans & performance [duplicate]

I have 2 identical queries . One is executed with parameters, the other is executed with hardcoded values. Somehow sql server is creating 2 different execution plans for the 2 queries. The first one ...
0
votes
0answers
76 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 ...
1
vote
1answer
110 views

MySQL with high CPU and memory usage

here we have a VPS with 3.2GHz quadcore processor with 2GB of RAM and 4GB of SWAP which need to work with a high intensive legacy system (read: bad coded). The main problem is that the CPU (~80 - ...
1
vote
1answer
108 views

Using OFFSET in a large table by a simple sub-query

The slow performance for using OFFSET in large table has been widely discussed in various blogs, and the most efficient way is to use an INNER JOIN as SELECT * FROM table INNER JOIN ( SELECT id FROM ...
0
votes
0answers
23 views

MySQL cluster with RAID0

I use several EC2 (M1.LARGE) instances with ephemeral storage. Would RAID0 improve write and read performance? I'am only interested in performance. Has someone experience? Is the speedup=2??
1
vote
1answer
35 views

Moving large database to another drive, how to measure performance before, and setup some type of replication for fast fail back?

Sorry if this is kind of more than question at a time, but here goes. Running SQL Server 2008 on windows server 2008 as well. We have a large database just over 200gb right now (it holds images of ...
0
votes
1answer
30 views

Should the value of a select max be indexed when the where clause is already indexed

I have a customer_orders table in a schema designed to be shared between multiple companies. Each customer_order has an invoice number that should always start at 1 and increment based on company ...
1
vote
1answer
65 views

How to isolate that network is issue of bad query performance [closed]

I would like to know how to isolate SQL Server bad query performance is caused by NETWORK and not the SQL Server. Are there any specific tips and tricks in SSMS, wait types, or specific PerfMon ...
1
vote
0answers
61 views

What to look for in query execution plans? [closed]

Assuming the query execution is slow, I have collected the xml plan. What should I look for in the actual execution plan. What are the top 10 things I need to watch out for? I know this is a broad ...
0
votes
1answer
78 views

Does the recovery model affect query speed?

Would using the Full Recovery model make something like a long running DELETE operation slower than it would be under the Simple Recovery model?
1
vote
1answer
328 views

Lazy Writes Performance Issues

My SQL Server sometimes reports high Lazy Writes e.g. "Lazy Writes per second is 119 Writes/sec" What should I be checking to find out why this is high? What are potential causes? Thanks.
0
votes
0answers
25 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 ...
5
votes
1answer
93 views

Why would SQL cast have to be expensive if used on a join column?

I see that sql join internally functions always on some of the three basic operations : nested loops join, merge join and hash join. From multiple articles on the internet I see SQL casting is said ...
2
votes
2answers
148 views

Improve Performance -Update query with OR in WHERE

How do we improve this Update query Performance as currently it is taking 1 Minute to update 17643 Rows. Query -> Declare @date datetime = '09-Dec-2013' update #tmp_sp_abc set ...
0
votes
0answers
22 views

MySQL: system variables and status variables related with Disk I/O

How disk I/O is related with MySQL performance improvement. I have a MySQL-5.1.58 based Intranet application equipped with Windows 2008 server and 8 GB RAM. Even, When my application face performance ...
-2
votes
1answer
70 views

Maximum dataset size for a well-performing SQL Server 2012? [closed]

We're planning a project using SQL Server 2012 for storing about a billion records over less than 50 fields. Assuming good hardware, is SQL Server up to that task? Roughly how many request/second can ...
0
votes
0answers
58 views

MySQL cluster performance very poor on Amazon

We have currently a project running where we need to store 1 to 20,30 million 500B to 2kB records. We need to use MySQL cluster on 4 EC2 instances (8GB Ram, 2 cores) and ephemeral storage (Records ...
1
vote
1answer
41 views

Patterns/Designs to help with concurrency/performance [closed]

I'm working on a SQL Server 2008 R2 DB and I'm experiencing some performance/concurrency issues with probably the main table in the DB. Problems like slow reads, deadlocks, poor performance in ...