Package org.apache.cassandra.index.sai.disk.v1.postings

Class MergePostingList

java.lang.Object

org.apache.cassandra.index.sai.disk.v1.postings.MergePostingList

All Implemented Interfaces:

Closeable, AutoCloseable, PostingList

@NotThreadSafe
public class MergePostingList
extends Object
implements PostingList

Merges multiple PostingList which individually contain unique items into a single list. While the individual lists contain unique items, there can be duplicate items between lists so the class also checks for duplicates and only returns unique items in sorted order.

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.cassandra.index.sai.postings.PostingList

PostingList.EmptyPostingList

Field Summary

Fields inherited from interface org.apache.cassandra.index.sai.postings.PostingList

EMPTY, END_OF_STREAM, OFFSET_NOT_FOUND

Method Summary

Modifier and Type	Method	Description
long	advance(long targetRowID)	Advances to the first row ID beyond the current that is greater than or equal to the target, and returns that row ID.
void	close()
long	maximum()
static PostingList	merge(List<PostingList> postings)
static PostingList	merge(PriorityQueue<PeekablePostingList> postings)
static PostingList	merge(PriorityQueue<PeekablePostingList> postings, Closeable onClose)
long	minimum()
long	nextPosting()	Retrieves the next segment row ID, not including row IDs that have been returned by PostingList.advance(long).
long	size()	Returns the upper bound of postings in the list.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

merge

public static PostingList merge(PriorityQueue<PeekablePostingList> postings,
 Closeable onClose)

merge

public static PostingList merge(PriorityQueue<PeekablePostingList> postings)

merge

public static PostingList merge(List<PostingList> postings)

minimum

public long minimum()

Specified by:

minimum in interface PostingList

maximum

public long maximum()

Specified by:

maximum in interface PostingList

nextPosting

public long nextPosting()
                 throws IOException

Description copied from interface: PostingList

Retrieves the next segment row ID, not including row IDs that have been returned by PostingList.advance(long).

Specified by:

nextPosting in interface PostingList

Returns:

next segment row ID

Throws:

IOException

advance

public long advance(long targetRowID)
             throws IOException

Description copied from interface: PostingList

Advances to the first row ID beyond the current that is greater than or equal to the target, and returns that row ID. Exhausts the iterator and returns PostingList.END_OF_STREAM if the target is greater than the highest row ID.

Note: Callers must use the return value of this method before calling PostingList.nextPosting(), as calling that method will return the next posting, not the one to which we have just advanced.

Specified by:

advance in interface PostingList

Parameters:

targetRowID - target row ID to advance to

Returns:

first segment row ID which is >= the target row ID or PostingList.END_OF_STREAM if one does not exist

Throws:

IOException

size

public long size()

Description copied from interface: PostingList

Returns the upper bound of postings in the list. During a merge individual postings may be de-duplicated, so we can't return the exact size only the upper bound of the size.

Specified by:

size in interface PostingList

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface PostingList