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

Class BlockBalancedTreePostingsWriter

java.lang.Object

org.apache.cassandra.index.sai.disk.v1.bbtree.BlockBalancedTreePostingsWriter

@NotThreadSafe
public class BlockBalancedTreePostingsWriter
extends Object

Writes leaf postings and auxiliary posting lists for bbtree nodes. If a node has a posting list attached, it will contain every row id from all leaves reachable from that node.

Writer is stateful, because it needs to collect data from the balanced tree data structure first to find set of eligible nodes and leaf nodes reachable from them.

The leaf blocks are written in value order (in the order we pass them to the BlockBalancedTreeWriter). This allows us to skip reading the leaves, instead just order leaf blocks by their offset in the index file, and correlate them with buffered posting lists.

Constructor Summary

Constructors

Constructor	Description
BlockBalancedTreePostingsWriter()

Method Summary

Modifier and Type	Method	Description
long	finish(IndexOutputWriter out, List<org.apache.lucene.util.packed.PackedLongValues> leafPostings, IndexIdentifier indexIdentifier)	Writes merged posting lists for eligible internal nodes and leaf postings for each leaf in the tree.
void	onLeaf(int leafNodeID, long leafBlockFP, org.agrona.collections.IntArrayList pathToRoot)	Called when a leaf node is hit as we traverse the packed index.

Methods inherited from class java.lang.Object

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

Constructor Details

BlockBalancedTreePostingsWriter

public BlockBalancedTreePostingsWriter()

Method Details

onLeaf

public void onLeaf(int leafNodeID,
 long leafBlockFP,
 org.agrona.collections.IntArrayList pathToRoot)

Called when a leaf node is hit as we traverse the packed index.

Parameters:

leafNodeID - the current leaf node ID in the packed inded

leafBlockFP - the file pointer to the on-disk leaf block

pathToRoot - the path to the root leaf above this leaf. Contains all the intermediate leaf node IDs.

finish

public long finish(IndexOutputWriter out,
 List<org.apache.lucene.util.packed.PackedLongValues> leafPostings,
 IndexIdentifier indexIdentifier)
            throws IOException

Writes merged posting lists for eligible internal nodes and leaf postings for each leaf in the tree. The merged postings list for an internal node contains all postings from the postings lists of leaf nodes in the subtree rooted at that node.

After writing out the postings, it writes a map of node ID -> postings file pointer for all nodes with an attached postings list. It then returns the file pointer to this map.

Throws:

IOException