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Updated .gitignore and README

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tzaeschke committed Aug 31, 2015
1 parent 41c6ee6 commit 3014abb3c4263b44a67d7a4f33f65317e02e426a
Showing with 10 additions and 108 deletions.
  1. +4 −0 .gitignore
  2. +0 −36 README
  3. +6 −6 README.md
  4. +0 −66 TUNING.txt
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@@ -12,3 +12,7 @@
hs_err_pid*
/bin/
/target/
*.project
*.prefs
.classpath
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36 README

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# PH-tree
# PH-Tree
The PH-tree is a multi-dimensional indexing and storage structure.
By default it stores k-dimensional keys (points) consisting of k 64bit-integers. However, it can also be used
@@ -13,7 +13,7 @@ Contact:
{zaeschke,zimmerli,norrie)@inf.ethz.ch
# Main properties
# Main Properties
### Advantages
@@ -82,7 +82,7 @@ by 1,000,000 before casting the to (long) and adding them to the tree.
For updating the keys of entries (aka moving objects index), consider using ```update()```. This function
is about twice as fast for small displacements and at least as fast as a ```put()```/```remove()``` combo.
### Choose a type of query
### Choose a Type of Query
- ```queryExtent()```: Fastest option when traversing (almost) all of the tree
- ```query()```: Fastest option for for average result size > 50 (depending on data)
@@ -98,7 +98,7 @@ disadvantage that the entries need to be created and create load on the GC. Howe
provide easy access to the key, especially for SOLID keys.
### Data preprocessing
### Data Treprocessing
To improve speed, similar measures can be applied as suggested for MEMORY. For example it makes
sense to transform values into integers by multiplication with a constant.
@@ -108,9 +108,9 @@ or multiplying a constant such that the whole value domain falls into a single e
shift the values such that all values have the same exponent. It can also help to shift values
such that all values have a positive sign.
For heterogenous data (combination of floats, integers, boolean, ...) consider shifting the
For heterogeneous data (combination of floats, integers, boolean, ...) consider shifting the
values such that the min/max values in each dimension have a similar distance in the integer
representation. For example a 3D tree: [0...10][10..30][0..1000] multiply the first dimension by
representation. For example a 3D tree: `[0...10][10..30][0..1000]` multiply the first dimension by
100 and the second by 50, so that all dimensions have a range of about 1000.
The above is true if all dimension are queried with similar selectivity. If range queries in the
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