org.apache.calcite.rel.type

Enum StructKind

java.lang.Object

java.lang.Enum<StructKind>

org.apache.calcite.rel.type.StructKind

All Implemented Interfaces:

Serializable, Comparable<StructKind>

public enum StructKind
extends Enum<StructKind>

Describes a policy for resolving fields in record types.

The usual value is FULLY_QUALIFIED.

A field whose record type is labeled PEEK_FIELDS can be omitted. In Phoenix, column families are represented by fields like this. PEEK_FIELDS_DEFAULT is similar, but represents the default column family, so it will win in the event of a tie.

SQL usually disallows a record type. For instance,

SELECT address.zip FROM Emp AS e

is disallowed because address "looks like" a table alias. You'd have to write

SELECT e.address.zip FROM Emp AS e

But if a table has one or more columns that are record-typed and are labeled PEEK_FIELDS or PEEK_FIELDS_DEFAULT we suspend that rule and would allow address.zip.

If there are multiple matches, we choose the one that is:

1. Shorter. If you write zipcode, address.zipcode will be preferred over product.supplier.zipcode.
2. Uses as little skipping as possible. A match that is fully-qualified will beat one that uses PEEK_FIELDS_DEFAULT at some point, which will beat one that uses PEEK_FIELDS at some point.

Enum Constant Summary

Enum Constants

Enum Constant and Description
FULLY_QUALIFIED This is a traditional structured type, where each field must be referenced explicitly.
NONE This is not a structured type.
PEEK_FIELDS If a field has this type, you can see its fields without qualifying them with the name of this field.
PEEK_FIELDS_DEFAULT As PEEK_FIELDS, but takes priority if another struct-typed field also has a field of the name being sought.
PEEK_FIELDS_NO_EXPAND As PEEK_FIELDS, but fields are not expanded in "SELECT *".

Method Summary

Modifier and Type	Method and Description
static StructKind	valueOf(String name) Returns the enum constant of this type with the specified name.
static StructKind[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

NONE

public static final StructKind NONE

This is not a structured type.

FULLY_QUALIFIED

public static final StructKind FULLY_QUALIFIED

This is a traditional structured type, where each field must be referenced explicitly.

Also, when referencing a struct column, you need to qualify it with the table alias, per standard SQL. For instance, SELECT c.address.zipcode FROM customer AS c is valid but SELECT address.zipcode FROM customer it not valid.

PEEK_FIELDS_DEFAULT

public static final StructKind PEEK_FIELDS_DEFAULT

As PEEK_FIELDS, but takes priority if another struct-typed field also has a field of the name being sought.

In Phoenix, only one of a table's columns is labeled PEEK_FIELDS_DEFAULT - the default column family - but in principle there could be more than one.

PEEK_FIELDS

public static final StructKind PEEK_FIELDS

If a field has this type, you can see its fields without qualifying them with the name of this field.

For example, if address is labeled PEEK_FIELDS, you could write zipcode as shorthand for address.zipcode.

PEEK_FIELDS_NO_EXPAND

public static final StructKind PEEK_FIELDS_NO_EXPAND

As PEEK_FIELDS, but fields are not expanded in "SELECT *".

Used in Flink, not Phoenix.

Method Detail

values

public static StructKind[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (StructKind c : StructKind.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static StructKind valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null