Datastore Overview Google Professional Data Engineer GCP

They are non-relational
easy to scale (horizontally or vertically) better than relational databases
Are either schema-free or have relaxed schemas
No definition of the schema of the data needed
Distributed in nature
Have auto-scaling and fail-over capabilities
May not comply with ACID requirement
Types
- Key-value – simplest, data item stored as an attribute name (or “key”) together with its value.
- Wide-column – store data together as columns instead of rows and are optimized for queries over large datasets.
- Document databases – pair each key with a complex data structure known as a document. Documents can contain many different key-value pairs, or key-array pairs, or even nested documents.
- Graph databases – store information about networks, such as social connections.
Hierarchies or entity groups: – set of entities connected through ancestry to a common root element.
Join operation is not supported, we need to denormalize table
Aggregation and “group by” are not supported
Inequality filters are limited to at most one property
Do not support substring matches, case-insensitive matches, or so-called full-text search.
The NOT, OR, and != operators are not natively supported