Page Comparison

...

An ObjectMappedTable is a system dataset that can write Java objects to a Table by mapping object fields to Table columns. It can also be explored in an ad-hoc manner.

Creating an ObjectMappedTable

When creating an ObjectMappedTable in your application, you must specify the Java type that will be stored in your table:

...

(rowkey STRING, catalogid STRING, customer STRING, price INT, product STRING, purchasetime BIGINT, quantity INT)

Limitations

• The record type must be a structured type, that is, a Java class with fields. This is because SQL tables require a structure type at the top level. The fields must be primitives. That is, they must be an int, Integer, float, Float, double, Double, bool, Boolean, String, byte[], or ByteBuffer. UUID is supported and will translate into a binary field.

• The record type must be that of an actual Java class, not an interface. The reason is that interfaces only define methods but not fields; hence, reflection would not be able to derive any fields or types from the interface.

• Fields of a class that are declared static or transient are ignored during schema generation. This means that the record type must have at least one non-transient and non-static field. For example, the java.util.Date class has only static and transient fields. Therefore a record type of Date is not supported and will result in an exception when the dataset is created.

• You cannot insert data into an ObjectMappedTable using SQL.

Formulating Queries

When creating your queries, keep these limitations in mind:

...