CHANGELOG

2019-02-26
==========
Pre-Release 2.1.0
- (TZ for Improbable) Some cleanup and javadoc updates
- (TZ for Improbable) Improvements for running multiple PH-Trees concurrently:
    - removed AtomicInt entry counter
    - Changed Object/array pools to be unsynchronized and local (to the tree) instead of global and synchronmized.


2018-12-04
==========
Release 2.0.2
- (TZ) Fixed NullPointerException in getStats() 


2018-05-30
==========
Release 2.0.1
This release contains some minor fixes and documentation updates.


2018-05-29
==========
Release 2.0.0 
There are three new versions of the PH-tree:

- v13 has a new much better kNN query then previous versions, but has otherwise only small improvements over 
  the previous v11. v13 is the best version for less than 8 dimensions.
- v16 and v16HD are reimplementations of the PH-Tree. The basic concept is still the same, except that the internal
  structure of nodes is now a B+Tree instead of the previous AHC/LHC nodes. Advantages:
  * Much simpler code.
  * Insertion/removal performance scales much better with dimensionality.
  * The v16HD version supports theoretically up to 2^31 dimensions.
  * Downside: memory requirements have increased, they are now on par with R*Trees or kD-trees.
  * Internal B+Tree structure (with configurable page sizes) makes it more suitable for disk based storage.
  * **API Contract Change**: The PH-Tree now stores keys (long[]/double[]) internally. Modifying them
  after storing them in the tree will make the tree invalid.
- The `PhTree` factory class will automatically choose one of v13, v16 and v16HD, depending on the number of dimensions. 



2017-09-17
==========
- (TZ) Fixed bug PhTreeF kNN: distance was not returned. 


2017-01-08
==========
- (TZ) Fixed bug in CritBit (used by old PH-Tree), see 
       https://github.com/tzaeschke/zoodb-indexes/issues/7

2016-10-26
==========
- (TZ) Update: PhTreeRevisited.pdf v1.2

2016-09-17
==========
- (TZ) Updated API classes to improve extensibility
- (TZ) Fixed bug in kNN for rectangles with 0 distance

2016-09-09
==========
- (TZ) Added kNN queries support for rectangle data

2016-08-23
==========
- (TZ) Added v11, lots of API changes  

2015-10-28
==========
- (TZ) Added kNN-queries
- (TZ) Added (spherical) range queries
- (TZ) Numerous fixes, improvements, clean-up
- (TZ) Some API changes getDIM() -> getDim(), ...
- (TZ) Added PhTreeRevisited.pdf


2015-10-11
==========
- (TZ) Fixed possible NPE (in Critbit64COW) when using trees with k>6
- (TZ) Fixed memory waste in NodeEntries

2015-08-31
==========
- (TZ) Proper NoGC iterator for avoiding any object creation (+bug fix)
- (TZ) Changed iterator recursion to loops
- (TZ) Removed some old iterators and NV usage

2015-08-03
==========
- (TZ) PhQuery interface added. This allows resetting & reusing of query iterators.

2015-07-30
==========
- (TZ) Smaller NodeEntries + Avoid NodeEntry creation in some situations
- (TZ) Added experimental iterator that does not create new long[]...

2015-07-29
==========
- Added clear() method
- Fixed bug that prevented internal iterators from being reused (-> performance)
- Fixed another bug that caused queryAll to skip some matching keys.
       See TestIndexQueries.testBug64Neg_2() 
- Fixed bug that caused queryAll to skip some matching keys. 

2015-06-01
==========
- (TZ) Fixed bug that prevented internal iterators from being reused

2015-05-25
==========
- (TZ) Fixed another bug that caused queryAll to skip some matching keys.
       See TestIndexQueries.testBug64Neg_2() 

2015-05-24
==========
- (TZ) Fixed bug that caused queryAll to skip some matching keys.

2015-05-03
==========
- API change! Refactored the API for simplification and removal of old non-value API.
  
  
2015-03-03
==========
- Significantly reduced object creation during insert/update/delete/query. This should reduce
  GC problems.
- New queryAll() function that returns a list of results instead of an iterator. This should
  be faster especially for small expected result sets.