- All Implemented Interfaces:
public abstract class PostingsFormat extends Object implements NamedSPILoader.NamedSPIEncodes/decodes terms, postings, and proximity data.
Note, when extending this class, the name (
getName()) may written into the index in certain configurations. In order for the segment to be read, the name must resolve to your implementation via
forName(String). This method uses Java's
Service Provider Interface(SPI) to resolve format names.
If you implement your own format, make sure that it has a no-arg constructor so SPI can load it.
- See Also:
- WARNING: This API is experimental and might change in incompatible ways in the next release.
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description
availablePostingsFormats()returns a list of all available format names
fieldsConsumer(SegmentWriteState state)Writes a new segment
fieldsProducer(SegmentReadState state)Reads a segment.
forName(String name)looks up a format by name
getName()Returns this posting format's name
reloadPostingsFormats(ClassLoader classloader)Reloads the postings format list from the given
public static final PostingsFormat EMPTYZero-length
protected PostingsFormat(String name)Creates a new postings format.
The provided name will be written into the index segment in some configurations (such as when using
PerFieldPostingsFormat): in such configurations, for the segment to be read this class should be registered with Java's SPI mechanism (registered in META-INF/ of your jar file, etc).
name- must be all ascii alphanumeric, and less than 128 characters in length.
public final String getName()Returns this posting format's name
public abstract FieldsConsumer fieldsConsumer(SegmentWriteState state) throws IOExceptionWrites a new segment
public abstract FieldsProducer fieldsProducer(SegmentReadState state) throws IOExceptionReads a segment. NOTE: by the time this call returns, it must hold open any files it will need to use; else, those files may be deleted. Additionally, required files may be deleted during the execution of this call before there is a chance to open them. Under these circumstances an IOException should be thrown by the implementation. IOExceptions are expected and will automatically cause a retry of the segment opening logic with the newly revised segments.
availablePostingsFormatsreturns a list of all available format names
public static void reloadPostingsFormats(ClassLoader classloader)Reloads the postings format list from the given
ClassLoader. Changes to the postings formats are visible after the method ends, all iterators (
availablePostingsFormats(),...) stay consistent.
NOTE: Only new postings formats are added, existing ones are never removed or replaced.
This method is expensive and should only be called for discovery of new postings formats on the given classpath/classloader!