#Sqlite3 to json how to#
#Sqlite3 to json update#
#Sqlite3 to json code#

Through this article, I wanted to show that denormalization isn't a concept reserved for NoSQL. For example, during deletions, we will not be able to use the cascade deletions provided by RDBMS. But, we have to care more about writing operations. Conclusionĭenormalization is a great solution to gain space and reading performances. We're winning on performances and on database size. The denormalized version is two times lighter than the normalized one which includes bars_normalized and bars_wines. These statistics are provided by sqlite3_analyzer. So, in my example, if I need to often load data related to the bar, I should put bars_ids inside table wines instead of keeping wines_ids. It means that making query on the table that doesn't contain the ids array. In addition, we can see that query n☂ is more performant than query n☁. We don't see the same results with the denormalized form which can better handle the growth of data. When we increase the amount of data, the duration grows linearly. We can observe similar results on query n☂. Joints are heavy operations.įor normalized databases, duration is correlated to the join table size. Obviously, the denormalized version is much faster than the normalized one. In ordet to get the results, I ran each queries five times and I took the median value. (number of bars, number of wines, number of wines per bar). On queries below, numbers in parentheses represents : On each query, I changed some parameters.

They are executed like described in the following schema.Įven if it can be strange according to the reading direction, it's perfectly valid on a technical side. That's the point! It's necessary to understand that relatinnal databases are treating queries. If we just read it, it can be strange to see that I'm using the json_each.value inside the SELECT whereas I will get this information into the FROM which is the next line. Let's talk about the query above, or more precisely about the sub-query. value AS idįROM bars_denormalized, json_each (bars_denormalized. After the join, we'll apply a filter based on our needs.

#Sqlite3 to json how to#

With these two queries, we'll be able to see how to get data ob each table.įor the normalized version, we'll make a joint between the wines, bars_normalized and bars_wines tables.

obtain the names of the wines of Portuguese's wines served in UK's bars.

obtain the names of the bars serving wines that are more recent than 2018.

In order to test the performances, of both data models, we'll perform two queries :

the index of the value that we want to remove.

The json_remove function takes two parameters : wines_ids, '$' ) WHERE id = 'bar-uuid-3' SET wines_ids = ( /* 2 - We return an array without the item that should be removed */ SELECT json_remove (bars_denormalized.

#Sqlite3 to json update#

* 3 - We update wines_ids with our new array */ UPDATE bars_denormalized We'll have a many-to-many relationship where each bar can serve multiple wines and each wine can be served into multiple bars. Instead of using the classical example with posts and tags, this time, we'll use wines and bars. If it's still not clear, the following example should help. We forget about 3rd normal form by putting data from joins tables into 'normals tables'. I'll add that it's a mechanism in which we're allowing ourselves to not use the goods practices taught by our teachers #ThugLife. In computing, denormalization is the process of trying to improve the read performance of a database, at the expense of losing some write performance, by adding redundant copies of data or by grouping data.'

#Sqlite3 to json code#

The code used to generate the database is available here What is denormalization?Īccording to Wikipedia, 'denormalization is a strategy used on a previously-normalized database to increase performance. And the benefits it can have on the read performances In this article, we'll see how we can use this extension on a denormalized database. I was reading SQLite's documentation and I discovered an extension called JSON1, which, you guess, allows us to manipulate JSON inside SQLite.