com.bigdata.rdf.lexicon
Interface ITermIndexCodes

All Known Implementing Classes:

LexiconKeyBuilder

public interface ITermIndexCodes

This interface defines the signed byte values indicating the type of a term in the term index. The purpose of this is to partition the term:id index into disjoint key ranges where the order of the terms in each of those partitions is well defined. I.e., URIs are in one key range and the total order over the URIs is well defined. The literals are broken down into a key range corresponding to the plain literals, the language type literals, and the data type literals (which is further broken down by the data type in order to produce well-defined total orders).

Note: when these signed bytes get encoded as unsigned bytes in a key their values change. For example, 2 becomes 130.

Version:

$Id: ITermIndexCodes.java 2265 2009-10-26 12:51:06Z thompsonbry $

Author:

Bryan Thompson

See Also:

ITermIdCodes, defines bit masks that are applied to the low bits of the assigned term identifiers and which indicate directly (without consulting the term index) whether a term is a URI, Literal, BNode, or Statement.

Field Summary

static byte	TERM_CODE_BND indicates a blank node.
static byte	TERM_CODE_DTL indicates a literal with a data type URI.
static byte	TERM_CODE_DTL2 Deprecated. This is a place holder for a namespace for an alternative coding of datatype literal keys.
static byte	TERM_CODE_LCL indicates a literal with a language code.
static byte	TERM_CODE_LIT indicates a plain literal.
static byte	TERM_CODE_STMT Indicates a statement identifier (used for statements about statements where the statement identifier is used in any of the subject, predicate, or object positions).
static byte	TERM_CODE_URI indicates a URI.

Field Detail

TERM_CODE_URI

static final byte TERM_CODE_URI

indicates a URI.

See Also:

Constant Field Values

TERM_CODE_LIT

static final byte TERM_CODE_LIT

indicates a plain literal.

See Also:

Constant Field Values

TERM_CODE_LCL

static final byte TERM_CODE_LCL

indicates a literal with a language code.

See Also:

Constant Field Values

TERM_CODE_DTL

static final byte TERM_CODE_DTL

indicates a literal with a data type URI.

See Also:

Constant Field Values

TERM_CODE_BND

static final byte TERM_CODE_BND

indicates a blank node.

See Also:

Constant Field Values

TERM_CODE_STMT

static final byte TERM_CODE_STMT

Indicates a statement identifier (used for statements about statements where the statement identifier is used in any of the subject, predicate, or object positions).

Note: Statement identifiers are assigned the highest code so that they will be processed last when doing an ordered write of terms on the terms index. This allows us to ensure that the component term identifiers in the statement have been resolved before the statement itself is written into the terms index.

See Also:

Constant Field Values

TERM_CODE_DTL2

static final byte TERM_CODE_DTL2

Deprecated. This is a place holder for a namespace for an alternative coding of datatype literal keys.

See Also:

Constant Field Values