SQL involves working with relational databases. For example, Microsoft SQL Server, Oracle, MySQL. They store information in lines: each of them is one unit of memory. This type of database is said to only scale vertically, running on a single server, demanding more and more space over time and growing to enormous sizes. Although in fact a properly built database can have a size of 8 terabytes and work stably. Later, non-relational databases appeare – NoSQL. This is a whole collection of various DBMSs that are unite by the single idea of easy scaling to a cluster of servers and maximum fault tolerance.
A request is a set of instructions
There are different models of NoSQL databases to solve different tasks. For example, columnar, document, key-value and graph databases are very Kuwait Phone Number List common. Some of them really do not support the SQL standard, but there are those that support it almost 100%, for example, columnar databases popular in analytics. — thousands of petabytes. So “NoSQL” doesn’t really mean there’s no SQL. The original interpretation is “not only SQL” or “non relational SQL”. A specialist who knows SQL can go into a non-relational database and work fully — almost all commands (create, drop, change, DML) are supporte there.
The database works under
They may differ slightly in syntax, but minimally. MYTH 5. To write effective queries, it is enough to know the constructions of the language. People often study designs but don’t understand what’s behind them. For effective work, you nee to understand AERO Leads how the hood. Each DBMS has a specific optimizer that works in its own way. In fact, . In relational databases, query performance depends on indexes and statistics (calculate by the DBMS base on previous queries). Base on these statistics, the optimizer evaluates what to expect from each part of the request and how to combine it efficiently.
