What to use to locally store data persistently in flutter? - json

I am quite new to the programming environment so any help in which direction to head would be greatly appreciated. What should i use? NoSQL or Sql? What should be my deciding factors?
Should i go with a noSQL db like sembast since my server side application uses mongodb for storage and since i have to mainly deal with JSON data , or should I go with SQL db like sqflite? What should be my considerations when deciding between the two? Are there some other options that i should be aware of too?

SQL databases are called relational databases. They are based on tables, which consists of a number of rows of data. They use SQL (Structured Query Language) for defining and manipulating the data. Thanks to this, SQL database are a good fit for complex querying. The transaction mechanism makes SQL databases a good choice for heavy duty transactional type applications.
NoSQL databases are called as non-relational or distributed database. They are based on key-value pairs document and don't have a standard schema definitions. Queries are focused on collection of documents so they cannot be very complicated. Although NoSQL provides transaction mechanism it's not stable enough for a complex transactional applications. NoSQL databases fit best for the hierarchical data storage (similar to JSON data) so they are highly preferred for large data set of data (big data).

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Storage: database vs in-memory objects vs in-memory database

I'm doing a project where I have to store data for a NodeJS express server. It's not a LOT of data, but i have to save it somewhere.
I always hear that a database is good for that kinda stuff, but I thought about just saving all the data in objects in NodeJS and back them up as JSON to disk every minute (or 5 minutes). Would that be a good idea?
What im thinking here is that the response time from objects like that are way faster than from a database, and saving them is easy. But then I heared that there are in-memory databases aswell, so my question is:
Are in-memory databases faster than javascript objects? Are JSON-based data backups a good idea in this aspect? Or should I simply go with a normal database because the performance doesn't really matter in this case?
Thanks!
If this is nothing but a school assignment or toy project with very simple models and access patterns, then sure rolling your own data persistence might make sense.
However, I'd advocate for using a database if:
you have a lot of objects or different types of objects
you need to query or filter objects by various criteria
you need more reliable data persistence
you need multiple services to access the same data
you need access controls
you need any other database feature
Since you ask about speed, for trivial stuff, in-memory objects will likely be faster to access. But, for more complicated stuff (lots of data, object relations, pagination, etc.), a database could start being faster.
You mention in-memory databases but those would only be used if you want the database features without the persistence and would be closer to your in-memory objects but without the file writing. So it just depends on if you care about keeping the data or not.
Also if you haven't ever worked with any kind of database, now's a perfect time to learn :).
What I'm thinking here is that the response time from objects like that is way faster than from a database, and saving them is easy.
That's not true. Databases are the persistence storage, there will always be I/O latency. I would recommend using Mysql for sql database and MongoDB or Cassandra for nosql.
An in-memory database is definitely faster but again you need persistence storage for those data. redis is a very popular in-memory database.
MongoDB store data in BSON (a superset of JSON) like formate, so it will be a good choice in your case.

Using MySQL or MariaDB to store locations

I am designing a transportation system in which I need to store location of the vehicles at least once or twice a minute. I want to find out which database is better to choose (MySql or MariaDB) for this case in terms of performance and scalability. How much it worth if I switch to NoSQL databases such as MangoDB or whatever!?
If you want to use features provided by NoSQL you may choose MariaDB.It has Cassandra engine and you may use dynamic column to store data as like NoSQL inside MYSQL engine.
In terms of scaling
NoSQL’s simpler data models can make the process easier, and many have been built with scaling functionality from the start. That is a generalization, so seek expert advice if you encounter this situation
In terms of performance
NoSQL’s simpler denormalized store allows you to retrieve all information about a specific item in a single request. There’s no need for related JOINs or complex SQL queries.
Where you need NoSQL ?
unrelated, indeterminate or evolving data requirements
speed and scalability is imperative
Where you need MYSQL?
logical related discrete data requirements which can be identified up-front
data integrity is essential
EDIT :
You may check this link.He explained RDBMS vs NoSQL very well !!

Mongo db vs (My Sql OR Sql Server) for a classified application

We have a classified website. I read few things but still not got a solid reason to choose between these.
My requirement is to just create user, listing and manage these. These are paid listings so monetary transactions would be there.
As per my research (https://www.mongodb.com/compare/mongodb-mysql) I found that mongo db has edge over other options except for complex transactions. What are complex transaction in this context? Any specific examples?
What factors should I consider before choosing one. I have experience with My SQL and Entity framework so its more appealing to me now but are these really bad for scaling when compared with mongo?
Feel free to suggest any other good performance option apart from these choices.
There is a vast difference between mongoDB and MySQL or SQL Server.
MongoDB is a NoSQL database meaning it is schemaless and doesnot follow CODD Rules of RDBMS whereas MySQL/SQL Server is relational Database.
Each are meant for different use cases. As per mongoDB doc
Why use MongoDB instead of MySQL?
Organizations of all sizes are adopting MongoDB because it enables them to build applications faster, handle highly diverse data types, and manage applications more efficiently at scale.
Development is simplified as MongoDB documents map naturally to modern, object-oriented programming languages. Using MongoDB removes the complex object-relational mapping (ORM) layer that translates objects in code to relational tables.
MongoDB’s flexible data model also means that your database schema can evolve with business requirements. For example, the ALTER TABLE command required to add a single, new field to Craiglist’s MySQL database would take months to execute. The Craigslist team migrated to MongoDB because it can accommodate changes to the data model without such costly schema migrations.
MongoDB can also be scaled within and across multiple distributed data centers, providing new levels of availability and scalability previously unachievable with relational databases like MySQL. As your deployments grow in terms of data volume and throughput, MongoDB scales easily with no downtime, and without changing your application. In contrast, to achieve scale with MySQL often requires significant, custom engineering work.
What are common use cases for MongoDB?
MongoDB is a general purpose database that is used for a variety of use cases. The most common use cases for MongoDB include Single View, Internet of Things, Mobile, Real-Time Analytics, Personalization, Catalog, and Content Management.
When would MySQL be a better fit?
While most modern applications require a flexible, scalable system like MongoDB, there are use cases for which a relational database like MySQL would be better suited. Applications that require complex, multi-row transactions (e.g., a double-entry bookkeeping system) would be good examples. MongoDB is not a drop-in replacement for legacy applications built around the relational data model and SQL.
A concrete example would be the booking engine behind a travel reservation system, which also typically involves complex transactions. While the core booking engine might run on MySQL, those parts of the app that engage with users – serving up content, integrating with social networks, managing sessions – would be better placed in MongoDB
As there is no concept of join in MongoDB so if you want to store data, either you have to create a hack to store data in two table(although it is expensive cal to join in MongoDB) or you have to store data as a single document,, making your document too complex.In these cases MySQL has upperhand.

MongoDB or MySQL

I am working on a website which would be having all the restaurant related details for a particular country. I was considering which DB would be best suitable for this kind of scenario,very similar to this.
I was considering to use MongoDB just because it would provide me with flexible schema and Simple queries for data retrieval. I am rethinking over my decision as neither my data is going to be too large as of my now so there wont be nay blockage for me w.r.t data size in MySQL.
What would be best way to choose between the 2.
It depends truly on whether you want data integrity and ACID features of a Relational Database. If a Relational Database is built correctly using the Relational Model and E.F Codd's rules, you will never have a problem with having duplicate data, inconsistencies, and other maladies.(This is assuming you use a RDBMS that is worth its salt, like oracle or SAP ASE)
However, you also have the option of MongoDB, which as you pointed out, is very flexible. However, through my experience, you will have to do a lot more manual work ensuring data accuracy and integrity.
However, certain things are easier in it, and it is by no means not successful. I use Mongo as a data back end for simulation servers I run, and it performs beautifully. Where mongo truly exceeds is with its atomic documents, and that's where Mongo pulled ahead of other NoSQL systems like CouchDB.
What it truly comes down to is what kind of data you are storing. If you are storing relational data, use a RDBMS. If it is more document based, use Mongo or a similar data storage engine. I do not like the idea of choosing a data storage engine by what is popular or what is new. Use what fits your data.
I hope this answers you question satisfactorily, if not please comment below.

Converting Mysql to No sql databases

I have a production database server running on MYSQL 5.1, now we need to build a app for reporting which will fetch the data from the production database server, since reporting queries through entire database may slow down, hence planning to switch to nosql. The whole system is running aws stack planning to use DynamoDb. Kindly suggest me the ways to sync data from the production nosql server to nosql database server.
Just remember the simple fact that any NoSQL database is essentially a document database; it's really difficult to automatically convert a typical relational database in MySQL to a good document design.
In NoSQL you have a single collection of documents, and each document will probably contain data that would be in related rows in multiple tables. The advantage of a NoSQL redesign is that most data access is simpler and faster without requiring you to write complex join statements.
If you automatically convert each MySQL table to a corresponding NoSQL collection, you really won't be taking advantage of a NoSQL DB. This is because you'll end up loading many more documents, and thus make many more calls to the database than needed and thus loosing simplicity and speediness of NoSQL DB.
Perhaps a better approach is to look at how your applications use the MySQL database and go from there. You might then consider writing a simple utility script knowing fully well your MySQL database design.
As the data from a NoSQL database like MongoDB, RIAK or CouchDB has a very different structure than a relational database like MySQL the only way to migrate/synchronise the data would be to actually write a job which would write the data from MySQL to the NoSQL database using SELECT queries as stated on the MongoDB website:
Migrate the data from the database to MongoDB, probably simply by writing a bunch of SELECT * FROM statements against the database and then loading the data into your MongoDB model using the language of your choice.
Depending of the quantity of your data this could take awhile to process.
If you have any other questions don't hesitateo to ask.