org.apache.directory.server.xdbm.search

Interface Optimizer

All Known Implementing Classes:

DefaultOptimizer, NoOpOptimizer

public interface Optimizer

An optimizer applies heuristics to determine best execution path to a search filter based on scan counts within database indices. It annotates the nodes of an expression subtree by setting a "count" key in the node. Its goal is to annotate nodes with counts to indicate which nodes to iterate over thereby minimizing the number cycles in a search. The SearchEngine relies on these count markers to determine the appropriate path.

Author:

Apache Directory Project

Method Summary

Modifier and Type	Method and Description
Long	annotate(org.apache.directory.server.core.api.partition.PartitionTxn partitionTxn, org.apache.directory.api.ldap.model.filter.ExprNode node) Annotates the expression node tree for optimized traversal metrics.

Method Detail

annotate

Long annotate(org.apache.directory.server.core.api.partition.PartitionTxn partitionTxn,
              org.apache.directory.api.ldap.model.filter.ExprNode node)
       throws org.apache.directory.api.ldap.model.exception.LdapException

Annotates the expression node tree for optimized traversal metrics.

Parameters:

partitionTxn - The transaction to use

node - the root of the expression node tree

Returns:

The computed value for this node

Throws:

org.apache.directory.api.ldap.model.exception.LdapException - if there are failures while optimizing