Columnar databases

- [Instructor] We now move to columnar databases.…They are also called wide column databases.…RDBMS stores data row by row internally.…Columnar databases store data column by column.…A single row can contain a large number of columns.…Only columns with actual values are stored internally.…For the outside world, columnar databases…looks similar to RDBMS.…

They have tables and column families…but they do not have a schema.…These databases are key driven.…Each row has a unique key that identify the specific row.…A key is a combination of one or more columns.…They support multiple data types…including complex data types.…Empty column data is not stored.…This is an optimized storage…where a table can have a large number of columns…but only a few columns that have data.…

Here are some of the most popular columnar databases.…Let us do an assessment for Cassandra now.…Cassandra supports a query language CQL…that looks and works like SQL.…This provides excellent querying capabilities…with ease of use.…Cassandra is great with updating existing data.…