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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24 views

MySQL: Adding innodb_log_file_size in my.cnf causes not starting MySQL service [duplicate]

I checked and found that InnoDB pluginis active. By default, Innodb_log_file_size=5MB. As per the MySQL Documentation, its ideal values range from 1MB to 1/N-th of the size of the buffer pool, where ...
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1answer
76 views

SSIS Performance tuning

Suppose my system has 8GB RAM and I have installed SQL Server 2012 on it along with the DataTools. Sql server engine uses 6GB memory. Will the SSIS uses remaning memory apart from 6GB or it uses 6GB? ...
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13 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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35 views

Query slower than the sum of its parts

I have a query with the following pseudo outline 1. CREATE TABLE #Temp 2. INSERT INTO #Temp 3. INSERT INTO A --90% of time spent here 4. INSERT INTO B --10% of time spent here 5. INSERT ...
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21 views

sql server linked server does not consider indexes [closed]

We have a query with a join between two tables. The first is in the database and the second is in another listener, connected by a linked server. I am executing this query in SQL Management Studio ...
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39 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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2answers
207 views

What is faster, one big query or many small queries?

I have been working for different companies, and I have noticed that some of them prefer to have views that will join a table with all its "relatives". But then on the application some times, we only ...
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68 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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1answer
13 views

“Approximately equal” between Sync and Async operations for PageCleaners

The documentation of num_iocleaners says: The parameter can be reduced if both of the following conditions are true: pool_data_writes is approximately equal to pool_async_data_writes ...
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1answer
84 views

Why isn't this index helping my InnoDB MySQL query?

I'm having trouble understanding why an index I have on one of my tables is doing nothing to help the performance of a JOIN, even when forcing the index. Here is the query: EXPLAIN SELECT * FROM ...
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0answers
19 views

Oracle - physical writes to an index

We have a large UPDATE (affects about 200K records) on a huge table (80M records). Due to a coding mistake, the UPDATE updates the same set of rows (200K) all over again with the exact same value. ...
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39 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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1answer
115 views

Execution plan index suggestion - difference between similar queries

I am trying to analyze queries on this table: CREATE TABLE [dbo].[Values]( [tid] [smallint] NOT NULL, [t] [datetime2](3) NOT NULL, [v] [real] NOT NULL, CONSTRAINT [PK_Values_Unique] ...
2
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0answers
28 views

longitude lattitude performance

I have to store frequently (at least every min) the position (longitude, latitude) of animals in a DB, and perform for each update a search in order to determinate if ananother animal is near to it. ...
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1answer
87 views

What is the fastest way to clone/copy oracle databases on the same machine?

I want to clone oracle 11g databases on the same machine and I need to change user etc. from e.g. PROD to DEV. For that I use expdp/impdp, but this tends to be slow with increasing database size. I ...
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0answers
18 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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0answers
20 views

What is the fastest way to clone/copy oracle databases on the same machine?

I want to clone oracle databases on the same machine and I need to change user etc. from e.g. PROD to DEV. For that I use expdp/impdp, but this tends to be slow with increasing database size. I need ...
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0answers
52 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 ...
2
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1answer
86 views

What is running on my server every night?

My data disk queue is high every night at about 1:00 AM UTC. I did sql profiler trace and found that there are many queries running at the same time similar to these: Can someone tell me what is ...
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1answer
33 views

Print, transaction and cursor performance in Transact-sql

I'm having some performance issues when I run a script. I was reading about the problem with print and its performance, but I cannot figure out how to reduce the impact. The algorithm is O(n^2). The ...
2
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2answers
45 views

Does the system process slow down my Database access?

I have a Fairly large DB containing mostly html documents. I wrote a python script that fetches always 1000 html documents at once from my database cur.execute("SELECT id,url,html_file FROM html ORDER ...
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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 ...
3
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1answer
253 views

Optimizing large database query (25+ million rows, using max() and GROUP BY)

I'm using Postgres 9.3.5 and I have a large table in the database, currently it has over 25 million rows and it tends to get even larger rapidly. I'm trying to select specific rows (all unit_ids with ...
2
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1answer
47 views

Which database technologies to consider for a data search application?

I'm designing an application that only does read queries to some database tables (it's a kind of search application); the queried data is updated at night by the system (so speed is less critical, ...
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1answer
38 views

MySQL/MariaDB Limitations

we're running MariaDB on our DB server. We have to install multiple databases on each DB instance (in fact each DB server runs multiple MariaDB instances) because each database must be separated. ...
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22 views

Mysql performance tunning [closed]

I have 2 VM : one x.x.x.22 "16G RAM" and "Intel(R) Xeon(R) CPU E5620 @ 2.40GHz 8Core " and one x.x.x.21 "8G RAM" and "Intel(R) Xeon(R) CPU E5620 @ 2.40GHz 8core" Now , app is installed ...
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52 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 ...
3
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1answer
282 views

Is there any performance difference in using a unique index on primary key?

I know there are lost of similar questions to this one, but none that really answers this: Is there ANY difference in performance in using an unique index in a primary key, using a MyISAM table on a ...
7
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1answer
124 views

Lower performance on newest servers

We have several db servers on production, 4 of them with very similar hardware configuration. Dell PowerEdge R620, only difference is that 2 newest ones (bought and configured 3 months ago) have RAID ...
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1answer
86 views

How to increase sql server performance? denormalization (making cascade delete off) vs making duplicate data

I have a database with following related table ( sql server enterptise edtion 2014) each state have many citites which each city has may municpalArea and so on State => Cities = > ...
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1answer
85 views

Calculating a running balance to store with transactions

I need to put a read-only copy of balance and transaction data from a legacy system, which will only be used to view/print statements. Balance | id | member_id | product_id | balance | | 1 | ...
2
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1answer
78 views

MySQL CPU & Memory Spikes

Every couple of days, my server's CPU and memory usage spikes up to 100%, making our vBulletin forum almost unusable for 5-10 minutes. CPU is typically at 1-2, Memory at 3GB. During the spikes, CPU ...
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1answer
72 views

Is normalization advisable on transactional data?

I have read a lot of articles about normalized vs denormalized schemas, but I find very little mention of the cost of row insertion. I am considering the impact of converting a 100% denormalized ...
0
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1answer
22 views

Stored Procedure Performance Issue in Sharepoint Report

We have a report stored procedure that runs in about 1 minute in production; however, when executed from the Sharepoint it populates, it rus for over 20 minutes, with exactly the same parameters. ...
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0answers
14 views

RAID configuration for mysql [closed]

I attached 4 10G disks to mysql Server and I used RAID 0 but still same mysql performance the same, Do I have to change configuration in my.cnf to let mysql know about RAID 0
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2answers
159 views

RAID configuration for mysql

I attached 4 10G disks to mysql Server and I used RAID 0 but still same mysql performance the same, Do I have to change configuration in my.cnf to let mysql know about RAID 0. this is my mount ...
0
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1answer
60 views

What's faster: two UPDATEs with WHERE (in / not in) or one UPDATE with CASE?

What's best performance wise, two separate UPDATEs: UPDATE table1 SET enabled = 0 WHERE code NOT IN ( SELECT id FROM table2 ); UPDATE table1 SET enabled = 1 WHERE ...
8
votes
2answers
275 views

Why are simple SELECTs on InnoDB 100x slower than on MyISAM?

I have quite an annoying problem. I want to use INNODB as my main database engine and give up on MyISAM as I need the former for using galera-cluster for redundancy. I copied (description follows) ...
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2answers
92 views

How do I maintain high INSERT-performance on PostgreSQL

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: ...
3
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1answer
130 views

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 UNIQUE PRIMARY KEY, [LastOperationTime] DATETIME NULL DEFAULT GETUTCDATE(), [OwnerId] ...
1
vote
2answers
90 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 ...
2
votes
1answer
46 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 ...
0
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1answer
44 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 ...
0
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0answers
45 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 ...
0
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1answer
76 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 ...
6
votes
1answer
182 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 ...
2
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0answers
34 views

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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0answers
34 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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0answers
24 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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15 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