Module org.postgresql.pljava

Package org.postgresql.pljava.model

Interface TupleDescriptor

All Superinterfaces:

Collection<Attribute>, Iterable<Attribute>, List<Attribute>, SequencedCollection<Attribute>, TargetList, TargetList.Projection

All Known Subinterfaces:

TupleDescriptor.Ephemeral, TupleDescriptor.Interned

public interface TupleDescriptor
extends TargetList.Projection

Conceptually, a TupleDescriptor is a list of Attribute, with a RegType that identifies its corresponding row type.

The row type might be just RECORD, though, representing a transient, unregistered type.

The Attribute instances may then correspond to nothing that exists in pg_attribute, in which case they will be 'virtual' instances whose CatalogObject.Addressed methods don't work, but which simply hold a reference to the TupleDescriptor they came from instead.

A TupleDescriptor may also contain attribute defaults and/or constraints. These would be less often of interest in Java; if there is a need to make them available, rather than complicating TupleDescriptor, it will probably be more natural to make them available by methods on Attribute.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	TupleDescriptor.Ephemeral	A descriptor that has been constructed on the fly and has not been interned.
static interface	TupleDescriptor.Interned	A descriptor that either describes a known composite type in the catalogs, or has been interned in PostgreSQL's type cache, and has a distinct rowType that can be used to identify it for the duration of the session.

Nested classes/interfaces inherited from interface org.postgresql.pljava.TargetList

TargetList.Cursor, TargetList.Projection

Method Summary

Modifier and Type	Method	Description
default List<Attribute>	attributes()	Deprecated, for removal: This API element is subject to removal in a future version. As a subinterface of Projection, a TupleDescriptor already is a List<Attribute>, and there is no need for this method to simply return its own receiver.
default Attribute	get(String name)	Deprecated, for removal: This API element is subject to removal in a future version. A one-by-one lookup-by-name API forces the implementation to cater to an inefficient usage pattern, when callers will often have a number of named attributes to look up, which can be done more efficiently in one go; see the methods of Projection.
default Attribute	get(Lexicals.Identifier.Simple name)	Deprecated, for removal: This API element is subject to removal in a future version. A one-by-one lookup-by-name API forces the implementation to cater to an inefficient usage pattern, when callers will often have a number of named attributes to look up, which can be done more efficiently in one go; see the methods of Projection.
TupleDescriptor.Interned	intern()	Return this descriptor unchanged if it is already interned in PostgreSQL's type cache, otherwise an equivalent new descriptor with a different rowType uniquely assigned to identify it for the duration of the session.
RegType	rowType()	If this tuple descriptor is not ephemeral, returns the PostgreSQL type that identifies it.

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.List

add, add, addAll, addAll, addFirst, addLast, clear, contains, containsAll, equals, get, getFirst, getLast, hashCode, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, removeFirst, removeLast, replaceAll, retainAll, reversed, set, size, sort, spliterator, toArray, toArray

Methods inherited from interface org.postgresql.pljava.TargetList

applyOver, applyOver, sqlGet

Methods inherited from interface org.postgresql.pljava.TargetList.Projection

project, project, project, project, sqlProject, subList

Method Details

attributes

@Deprecated(forRemoval=true)
default List<Attribute> attributes()

Deprecated, for removal: This API element is subject to removal in a future version.

As a subinterface of Projection, a TupleDescriptor already is a List<Attribute>, and there is no need for this method to simply return its own receiver.

rowType

RegType rowType()

If this tuple descriptor is not ephemeral, returns the PostgreSQL type that identifies it.

If the descriptor is for a known composite type in the PostgreSQL catalog, this method returns that type.

If the descriptor has been created programmatically and interned, this method returns the type RECORD.modifier(n) where n was uniquely assigned by PostgreSQL when the descriptor was interned, and will reliably refer to this tuple descriptor for the duration of the session.

For any ephemeral descriptor passed around in code without being interned, this method returns plain RECORD, which is useless for identifying the tuple structure.

get

@Deprecated(forRemoval=true)
default Attribute get(Lexicals.Identifier.Simple name)
               throws SQLException

Deprecated, for removal: This API element is subject to removal in a future version.

A one-by-one lookup-by-name API forces the implementation to cater to an inefficient usage pattern, when callers will often have a number of named attributes to look up, which can be done more efficiently in one go; see the methods of Projection.

Gets an attribute by name.

This API should be considered scaffolding or preliminary, until an API can be designed that might offer a convenient usage idiom without presupposing something like a name-to-attribute map in every decriptor.

This default implementation simply does project(name).get(0). Code that will do so repeatedly might be improved by doing so once and retaining the result.

Throws:

SQLSyntaxErrorException - 42703 if no attribute name matches

SQLException

get

@Deprecated(forRemoval=true)
default Attribute get(String name)
               throws SQLException

Deprecated, for removal: This API element is subject to removal in a future version.

A one-by-one lookup-by-name API forces the implementation to cater to an inefficient usage pattern, when callers will often have a number of named attributes to look up, which can be done more efficiently in one go; see the methods of Projection.

Equivalent to get(Simple.fromJava(name)).

This API should be considered scaffolding or preliminary, until an API can be designed that might offer a convenient usage idiom without presupposing something like a name-to-attribute map in every descriptor.

Throws:

SQLSyntaxErrorException - 42703 if no attribute name matches

SQLException

intern

TupleDescriptor.Interned intern()

Return this descriptor unchanged if it is already interned in PostgreSQL's type cache, otherwise an equivalent new descriptor with a different rowType uniquely assigned to identify it for the duration of the session.

PostgreSQL calls this operation "BlessTupleDesc", which updates the descriptor in place; in PL/Java code, the descriptor returned by this method should be used in place of the original.