C# Class NHibernate.Id.Enhanced.TableGenerator

An enhanced version of table-based id generation.

Unlike the simplistic legacy one (which, btw, was only ever intended for subclassing support) we "segment" the table into multiple values. Thus a single table can actually serve as the persistent storage for multiple independent generators. One approach would be to segment the values by the name of the entity for which we are performing generation, which would mean that we would have a row in the generator table for each entity name. Or any configuration really; the setup is very flexible.

In this respect it is very similar to the legacy MultipleHiLoPerTableGenerator (not available in NHibernate) in terms of the underlying storage structure (namely a single table capable of holding multiple generator values). The differentiator is, as with SequenceStyleGenerator as well, the externalized notion of an optimizer.

NOTE that by default we use a single row for all generators (based on DefaultSegmentValue). The configuration parameter ConfigPreferSegmentPerEntity can be used to change that to instead default to using a row for each entity name.

Configuration parameters:

NAME	DEFAULT	DESCRIPTION
TableParam	DefaultTable	The name of the table to use to store/retrieve values
ValueColumnParam	DefaultValueColumn	The name of column which holds the sequence value for the given segment
SegmentColumnParam	DefaultSegmentColumn	The name of the column which holds the segment key
SegmentValueParam	DefaultSegmentValue	The value indicating which segment is used by this generator; refers to values in the SegmentColumnParam column
SegmentLengthParam	DefaultSegmentLength	The data length of the SegmentColumnParam column; used for schema creation
InitialParam	DefaltInitialValue	The initial value to be stored for the given segment
IncrementParam	DefaultIncrementSize	The increment size for the underlying segment; see the discussion on Optimizer for more details.
OptimizerParam	depends on defined increment size	Allows explicit definition of which optimization strategy to use

Inheritance: NHibernate.Engine.TransactionHelper, IPersistentIdentifierGenerator, IConfigurable

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Public Methods

Method	Description
Configure ( IType type, string>.IDictionary parms, Dialect dialect ) : void
DoWorkInCurrentTransaction ( ISessionImplementor session, System conn, System transaction ) : object
GeneratorKey ( ) : string
SqlCreateStrings ( Dialect dialect ) : string[]
SqlDropString ( Dialect dialect ) : string[]

Protected Methods

Method	Description
BuildInsertQuery ( ) : void
BuildSelectQuery ( Dialect dialect ) : void
BuildUpdateQuery ( ) : void
DetermineDefaultSegmentValue ( string>.IDictionary parms ) : string	Used in the cases where DetermineSegmentValue is unable to determine the value to use.
DetermineGeneratorTableName ( string>.IDictionary parms, Dialect dialect ) : string	Determine the table name to use for the generator values. Called during configuration.
DetermineIncrementSize ( string>.IDictionary parms ) : int
DetermineInitialValue ( string>.IDictionary parms ) : int
DetermineSegmentColumnName ( string>.IDictionary parms, Dialect dialect ) : string	Determine the name of the column used to indicate the segment for each row. This column acts as the primary key. Called during configuration.
DetermineSegmentColumnSize ( string>.IDictionary parms ) : int	Determine the size of the SegmentColumnName segment column. Called during configuration.
DetermineSegmentValue ( string>.IDictionary parms ) : string	Determine the segment value corresponding to this generator instance. Called during configuration.
DetermineValueColumnName ( string>.IDictionary parms, Dialect dialect ) : string	Determine the name of the column in which we will store the generator persistent value. Called during configuration.

Private Methods

Method	Description
Generate ( ISessionImplementor session, object obj ) : object

Method Details

BuildInsertQuery() protected method

protected BuildInsertQuery ( ) : void
return	void

BuildSelectQuery() protected method

protected BuildSelectQuery ( Dialect dialect ) : void
dialect	Dialect
return	void

BuildUpdateQuery() protected method

protected BuildUpdateQuery ( ) : void
return	void

Configure() public method

public Configure ( IType type, string>.IDictionary parms, Dialect dialect ) : void
type	IType
parms	string>.IDictionary
dialect	Dialect
return	void

DetermineDefaultSegmentValue() protected method

Used in the cases where DetermineSegmentValue is unable to determine the value to use.

protected DetermineDefaultSegmentValue ( string>.IDictionary parms ) : string
parms	string>.IDictionary
return	string

DetermineGeneratorTableName() protected method

Determine the table name to use for the generator values. Called during configuration.

protected DetermineGeneratorTableName ( string>.IDictionary parms, Dialect dialect ) : string
parms	string>.IDictionary	The parameters supplied in the generator config (plus some standard useful extras).
dialect	Dialect	The dialect
return	string

DetermineIncrementSize() protected method

protected DetermineIncrementSize ( string>.IDictionary parms ) : int
parms	string>.IDictionary
return	int

DetermineInitialValue() protected method

protected DetermineInitialValue ( string>.IDictionary parms ) : int
parms	string>.IDictionary
return	int

DetermineSegmentColumnName() protected method

Determine the name of the column used to indicate the segment for each row. This column acts as the primary key. Called during configuration.

protected DetermineSegmentColumnName ( string>.IDictionary parms, Dialect dialect ) : string
parms	string>.IDictionary	The parameters supplied in the generator config (plus some standard useful extras).
dialect	Dialect	The
return	string

DetermineSegmentColumnSize() protected method

Determine the size of the SegmentColumnName segment column. Called during configuration.

protected DetermineSegmentColumnSize ( string>.IDictionary parms ) : int
parms	string>.IDictionary
return	int

DetermineSegmentValue() protected method

Determine the segment value corresponding to this generator instance. Called during configuration.

protected DetermineSegmentValue ( string>.IDictionary parms ) : string
parms	string>.IDictionary
return	string

DetermineValueColumnName() protected method

Determine the name of the column in which we will store the generator persistent value. Called during configuration.

protected DetermineValueColumnName ( string>.IDictionary parms, Dialect dialect ) : string
parms	string>.IDictionary
dialect	Dialect
return	string

DoWorkInCurrentTransaction() public method

public DoWorkInCurrentTransaction ( ISessionImplementor session, System conn, System transaction ) : object
session	ISessionImplementor
conn	System
transaction	System
return	object

GeneratorKey() public method

public GeneratorKey ( ) : string
return	string

SqlCreateStrings() public method

public SqlCreateStrings ( Dialect dialect ) : string[]
dialect	Dialect
return	string[]

SqlDropString() public method

public SqlDropString ( Dialect dialect ) : string[]
dialect	Dialect
return	string[]