database-performance Questions

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I like to run simulated test-clients that act as if e.g. 1000 clients execute tasks at the same time on a mongodb and see how the server stands. Together with profiling tools I like to be able to i...
Maddalena asked 5/9, 2016 at 14:28

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I have a MySQL 5.6.27-0ubuntu0.14.04.1 that run on a Google Compute instance with 4 CPU. I noticed that if I have a connection that Sleep for a long time, then the CPU of the server will increase ...
Gyasi asked 27/11, 2015 at 15:45

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If I'm not mistaken, to perform a count of items, in DynamoDB we have to use the query action and provide Select: 'COUNT' as parameter. Let's consider that I'd like to count the number of items tha...

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For performance issues I would like to execute an optimization algorithm on an in memory database in django (I'm likely to execute a lot of queries). I know it's possible to use a sqlite in memory ...
Skelton asked 13/5, 2016 at 18:12

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Before you mark this question as duplicate, PLEASE HEAR ME OUT!! I have already read the questions asked here on how to improve performance e.g. just to mention a few Improve INSERT-per-second perf...
Deodorant asked 12/3, 2012 at 13:44

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I am having a strange issue with a slow query under certain conditions: I have made a few tests and was able to isolate the issue to one single table called products_description (all the tables are...
Enlistment asked 19/4, 2016 at 19:48

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i want to store some data in my neo4j database. i use spring-data-neo4j for that. my code is like the follow: for (int i = 0; i < newRisks.size(); i++) { myRepository.save(newRisks.get(i)); ...
Cataplasm asked 5/3, 2012 at 14:22

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I come from the front-end world in web development where we try really hard to limit the number of HTTP requests issued (by consolidating css, js files, images, etc.). With db connections (MySQL),...
Merryman asked 2/4, 2016 at 2:25

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Suppose I run a very expensive query at 12:00pm. If at 12:01, I open SQL Server Activity Monitor and look at the recent expensive queries, I assume I'll see it there. What about 12:10? 12:30? 5pm? ...
Lauber asked 23/3, 2016 at 9:49

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I have developed a user bulk upload module. There are 2 situations, when I do a bulk upload of 20 000 records when database has zero records. Its taking about 5 hours. But when the database already...
Encage asked 25/2, 2016 at 12:41

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I am new to Cassandra, in this example i am using a cluster with 1 DC and 5 nodes and a NetworkTopologyStrategy with replication factor as 3. Keyspace: activityfeed Read Count: 0 Read Latency: ...
Calpe asked 15/1, 2015 at 12:53

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I have a MongoDB-based database with something about 100K to 500K text documents inside and the collection keeps growing. The system should support the queries by different fields of the documents,...

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I have a database representing metadata of a security camera NVR. There's a 26-byte recording row for every 1-minute segment of video. (If you're curious, a design doc is in progress here.) My desi...
Director asked 18/1, 2016 at 2:38

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I've been doing some research around the performance of read-only versus read-write database transactions. The MySQL server is remote across a slow VPN link so it's easy for me to see differences b...

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At my job, I often have two tables in my django models and have to connect them to return this data as an csv for example. That data is not connected by a foreign key, but they have an identifier t...

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I have a table called profile, and I want to order them by which ones are the most filled out. Each of the columns is either a JSONB column or a TEXT column. I don't need this to a great degree of ...
Emilyemina asked 7/12, 2015 at 21:0

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I have a case where I need to cleanup table from orphans regularly, so I'm looking for a high performance solution. I tried using 'IN' clause, but its not really fast. Columns have all the required...
Simile asked 24/11, 2015 at 17:10

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I have a table that contains several thousand rows, having a Varchar column that contains numbers. Despite discussing why this column is not a numeric type then, selecting rows from that table show...
Enwind asked 23/4, 2012 at 2:53

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My website has a very heavy read traffic. A lot heavier than write traffic. To improve the performance of my website I have thought of going with master/slave database configuration. The octupus ...

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We need to be able to compute table hashes for an external environment and compare it to pre-computed hash from an internal environment. The use of this is to ensure that data in the external...
Eppes asked 20/11, 2015 at 10:39

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I'm doing a parse batch save requestas follows: Parse.Object.saveAll(nameGenderArrayToSave) nameGenderArrayToSave is an array with thousands of objects to save. I'm also interested in guarante t...
Berkly asked 17/11, 2015 at 16:40

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I have the following setup with ActiveRecord and MySQL: User has many groups through memberships Group has many users through memberships There is also an index by group_id and user_id described ...

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I'm curious. I have flow like that: We have big collection/table with a lot of data. And have some select oriented query which is long and takes 3 seconds. However we looking to highly concurrent ...
Covin asked 13/10, 2015 at 15:39

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Assuming one table CAR with two columns CAR_ID (int) and VERSION (int). I want to retrieve the maximum version of each car. So there are two solutions (at least) : select car_id, max(version) as...
Whereto asked 17/2, 2012 at 12:31

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I know there's a lot of these questions, but I can't find one that relates to my question. Looking at this question, Is Changing IF EXIST(SELECT 1 FROM ) to IF EXIST(SELECT TOP 1 FROM ) has any si...
Adoration asked 11/9, 2015 at 2:50

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