docs(SDB): add new terms to concept page MTA-3562

serverless/sql-databases/concepts.mdx

@@ -11,9 +11,9 @@ categories:
 ---
 
 <Concept opened>
-  ## Serverless SQL Database
+## Active state
 
-  Scaleway Serverless SQL Databases are fully managed databases that automatically scale both in storage and compute according to your workloads.
+A database is in an active state when it receives queries frequently (at least one every 15 minutes). If it receives no query for 15 minutes, the database switches to an idle state.
 </Concept>
 
 <Concept opened>
@@ -23,7 +23,80 @@ categories:
 </Concept>
 
 <Concept opened>
- ## Credentials
+## Backup
 
- Credentials let you connect to your database via a secret key.
-</Concept>
+A database backup is a copy of the operational state, architecture and stored data of a database. It allows to restore a database if it crashes, is corrupted or is lost.
+</Concept>
+
+<Concept opened>
+## Cold start
+
+Cold start is the time an idle database takes to handle the first request. It usually takes less than five seconds.
+</Concept>
+
+<Concept>
+## Connection pooling
+
+Connection pooling is a cache of database connections maintained so that the connections can be reused when future requests to the database are required. It enhances performance of executing commands on a database. 
+</Concept>
+
+<Concept>
+## Credentials
+
+Credentials let you connect to your database via a secret key.
+</Concept>
+
+<Concept>
+## Engine
+
+A database engine is the software that stores and retrieves your data from a database. Serverless SQL databases use the PostgreSQL engine.
+</Concept>
+
+<Concept>
+## High availability
+
+Databases are replicated on a copy of themselves that is not accessible by the user. This "standby" database guarantees that the service remains available in case of failure.
+</Concept>
+
+<Concept>
+## Idle
+
+A database switches to an idle state if it receives no query for 15 minutes. You are not billed for compute resources while your database is in an idle state.
+</Concept>
+
+<Concept>
+## Logs
+
+Logs register the activity of your database. they provide useful information for debugging or to know more about the behavior and activity of your databases.
+</Concept>
+
+<Concept>
+## PostgreSQL
+
+PostgreSQL is an open source object-relational database system known for its reliability, robustness, and performance. 
+</Concept>
+
+<Concept>
+## Region and AZ
+
+<Macro id="region-and-az" />
+
+</Concept>
+
+<Concept>
+## Relational database
+
+A database type that uses the relational model, which means that it stores and provides access to inter-related data points within the same database. Relational databases provide an intuitive, straightforward way of representing data in tables.
+</Concept>
+
+<Concept>
+## Serverless database
+
+A serverless database is a fully managed database-as-a-service (DBaaS) that allocates and scales compute and storage resources automatically to match the incoming workload.
+</Concept>
+
+<Concept>
+## Status
+
+The status of a database changes according to its activity. It can be either "active" or "idle".
+</Concept>