[LUCY-118] Lucy::Index::DataReader - Abstract base class for reading index data.

• Type: New Feature
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Component/s: Index
• Assignee: Marvin Humphrey
• Reporter: Marvin Humphrey
• Created: 22/Jun/10 23:47
• Updated: 25/Jun/10 01:42
• Resolved: 25/Jun/10 01:42

Description

DataReader is an integral part of our modular index system, serving as a base
class for all component classes which read from the index - including both
single-segment readers and composite multi-segment readers. Index components,
which may be added or omitted using Architecture, typically consist of a
DataReader/DataWriter pair, e.g. PostingListReader/PostingListWriter.

DataReader's members include a Schema and a Folder, a Snapshot which defines
the files the DataReader may access safely, and an array of Segment objects.
Single-segment readers are assigned to one Segment within the array, but also
get access to all the other Segments; this is important, because metadata from
older or newer Segments may be used to make decisions and control behavior.