What Is a Data Grid?
ActiveSpaces stores data in data grids. In a data grid, data is stored in the form of tables. A data grid is equivalent to a database of a traditional RDBMS.
- Tables
- A table comprises multiple rows that are spread out in the data grid. The tables are similar to the tables in a traditional RDBMS, made of rows and columns. Unlike the traditional RDBMS where all the data in the table reside on one computer, a data grid segregates the table row-wise and stores the rows in different ActiveSpaces processes called nodes.
- Rows
- Like the traditional RDBMS, a row comprises a set of columns and is uniquely identified by the primary index. A row becomes the unit of measurement for the data grid. Rows are distributed across the data grid. When scaling up, the data grid controls where a newly added row must be stored.
- Columns
- A row is made of a collection of columns. Every column uniquely identifies a piece of information. Every column has a type and a value associated with it. For example, the Employee Name column is of data type String and has the value "Joe Smith".
- Primary Index
- Uniquely identifies a row in a table. It is equivalent to a primary key in a traditional RDBMS. You can have more than one column that forms a primary index.
- Secondary Index
- Is similar to a primary index but can refer to multiple rows in a table. A secondary index comprises one or more columns of a table and is used to efficiently retrieve the rows of a table by reducing the number of rows scanned for retrieval by queries. Without a secondary index, this would involve a full table scan to identify which rows match the query. With a secondary index, additional space is used to help speed up the query and quickly identify matching rows without a full-table scan.
- Supported Data Types
- A column can be of the following data types:
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