Baguette/dodb.cr
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Add a few explanations (basic stuff).

Browse source
This commit is contained in:
Philippe Pittoli 2025-01-24 06:11:40 +01:00
parent 75f433ff95
commit 91244cb815
1 changed files with 22 additions and 14 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

36
paper/paper.ms
View file

@ -187,9 +187,9 @@ This is a simple object
with a name, a color and a list of associated keywords (fast, elegant, etc.).
.SOURCE Ruby ps=9 vs=10
class Car
property name : String
property color : String
property keywords : Array(String)
property name : String # ex: Corvet
property color : String # ex: red
property keywords : Array(String) # ex: [fast, impressive]
end
.SOURCE
.
@ -200,15 +200,15 @@ Let's create a DODB database for our cars.
# Database creation
database = DODB::Storage::Uncached(Car).new "path/to/db-cars"
# Adding an element to the db
# Add an element to the db
database << Car.new "Corvet", "red", ["elegant", "fast"]
# Reaching all objects in the database
# Access all objects in the database
database.each do |car|
pp! car
end
.SOURCE
When a value is added, it is serialized\*[*] and written in a dedicated file.
Inserted entries are serialized\*[*] and written in a dedicated file.
.FOOTNOTE1
Serialization is currently in JSON.
.[
@ -250,7 +250,7 @@ The car is serialized as expected in the file
.QE
.
.
Next step, to retrieve, to modify or to delete a value, its key will be required.
The key of the entry (its number) is required to retrieve, to modify or to delete it.
.
.QP
.SOURCE Ruby ps=9 vs=10
@ -284,12 +284,13 @@ That is when indexes come into play.
A simple way to quickly retrieve a piece of data is to create
.I indexes
based on its attributes.
When a value is added to the database, or when it is modified, a
.I trigger
can be called to index it.
There are currently three main triggers in
.CLASS DODB
to index values: basic indexes, partitions and tags.
When a value is inserted, modified or deleted from the database, an action can be performed automatically thanks to a user recorded callback.
Callbacks are named
.I triggers
in DODB and are used mainly to index data.
There are currently three main indexing triggers in
.CLASS DODB :
basic indexes, partitions and tags.
.
.SSS Basic indexes (1 to 1 relations)
Basic indexes
@ -310,7 +311,14 @@ end
cars_by_name = cars.new_index "name", { |car| car.name }
cars_by_name = cars.new_index "name", &.name
.SOURCE
Once the index has been created, every added or modified entry in the database will be indexed.
The above code presents the creation of a new index on the database
.I cars .
An index requires a name (a simple string), which simply is "name" in this case since the indexed value is the name of the cars.
An index also requires a callback, a procedure to extract the value used for indexing.
In this case, the procedure takes a car as a parameter and returns its "name" attribute.
This procedure can be arbitrary complex and include any necessary data transformation.
Once the index has been created, every inserted or modified entry in the database will be indexed.
Adding a trigger provides an
.I object
used to manipulate the database based on the related attribute.