Package org.apache.calcite.model

Class JsonView

  • public class JsonView
extends JsonTable
    View schema element.

    Like base class JsonTable, occurs within JsonMapSchema.tables.

    Modifiable views

    A view is modifiable if contains only SELECT, FROM, WHERE (no JOIN, aggregation or sub-queries) and every column:

    • is specified once in the SELECT clause; or
    • occurs in the WHERE clause with a column = literal predicate; or
    • is nullable.

    The second clause allows Calcite to automatically provide the correct value for hidden columns. It is useful in, say, a multi-tenant environment, where the tenantId column is hidden, mandatory (NOT NULL), and has a constant value for a particular view.

    Errors regarding modifiable views:

    • If a view is marked modifiable: true and is not modifiable, Calcite throws an error while reading the schema.
    • If you submit an INSERT, UPDATE or UPSERT command to a non-modifiable view, Calcite throws an error when validating the statement.
    • If a DML statement creates a row that would not appear in the view (for example, a row in female_emps, above, with gender = 'M'), Calcite throws an error when executing the statement.
    See Also:
    Description of schema elements

    • Field Summary

      Fields 
      Modifier and Type Field Description
      java.lang.Boolean modifiable
      Whether this view should allow INSERT requests.
      java.util.List<java.lang.String> path
      Schema name(s) to use when resolving query.
      java.lang.Object sql
      SQL query that is the definition of the view.

    • Constructor Summary

      Constructors 
      Constructor Description
      JsonView()  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void accept​(ModelHandler handler)  
      java.lang.String getSql()
      Returns the SQL query as a string, concatenating a list of lines if necessary.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Field Detail

      • sql

        public java.lang.Object sql
        SQL query that is the definition of the view.

        Must be a string or a list of strings (which are concatenated into a multi-line SQL string, separated by newlines).

      • path

        public java.util.List<java.lang.String> path
        Schema name(s) to use when resolving query.

        If not specified, defaults to current schema.

      • modifiable

        public java.lang.Boolean modifiable
        Whether this view should allow INSERT requests.

        The values have the following meanings:

        • If true, Calcite throws an error when validating the schema if the view is not modifiable.
        • If null, Calcite deduces whether the view is modifiable.
        • If false, Calcite will not allow inserts.

        The default value is null.

    • Constructor Detail

      • JsonView

        public JsonView()

    • Method Detail

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • getSql

        public java.lang.String getSql()
        Returns the SQL query as a string, concatenating a list of lines if necessary.