In this demo, we’ll create a basic table for CUSTOMER data: id, name and a JSON column called “metadata”. Oracle recommends applying the IS JSON check constraint on columns that hold JSON data to ensure that the values are valid JSON instances. JSON data can be stored in an Oracle table using the basic SQL data types: VARCHAR2, CLOB, and BLOB (unlike XML data, which is stored using the abstract SQL data type XMLType). JSON table columns: supported datatypes, IS JSON constraint JSON data may be indexed for performance.A single table can have multiple columns that store JSON data.A table that stores JSON data can also contain columns of various other datatypes (NUMBER, VARCHAR2, etc).JSON data can be projected relationally.SQLs can join JSON data with relational data.With native support for JSON in 12c, Oracle lets you combine the benefits of RDBMS with JSON. For example, contact details linked to a customer - storing this information in JSON might be simpler than storing it in multiple child tables with foreign keys.Īnother use case is agile development - JSON-style storage is conducive to frequent/incremental schema changes. In such cases, relational storage is the way to go.īut let’s say we have metadata associated with the main entity - this metadata will seldom be queried on and is strongly coupled with the main entity. The question is reasonable when one wants to often do RDBMS-y things on the JSON data - for example, filtering inside the JSON, validation or restructuring the data differently for different SQLs. Why not store relationally, get all the benefits of structure and security that comes with relational storage, and serialize/deserialize into JSON only when needed? Those of us with an RDMS way of thinking might not immediately see why JSON format needs to be persisted in the database at all.
More on JSON here: Why would you store JSON in a relational database? The value of each attribute is a string type the value appears to the right of the attribute name, after the colon. The JSON example above represents a Database object with three attributes: dbname, version, rating. Attribute values are enclosed in double quotes if they are of string type numbers and boolean true/false/null are unquoted. The : (colon) symbol acts as delimiter within the name-value pairs.Īttribute names are enclosed in " (double quotes). The JSON object is enclosed in curly braces the data within consists of name-value pairs separated by commas. JSON (short for JavaScript Object Notation) is a text-based format for storing data as a collection of name-value pairs. Here’s a look at how JSON can be persisted in Oracle, and uses cases where doing so would be apt.
With release 12c, Oracle has introduced JSON support too – handy new features for storage and retrieval of JSON data. JSON is a simple data interchange format, an alternative to XML that’s gaining wider favor by the day especially for big data storage and REST web services.
0 kommentar(er)
