Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.sai.msu.su/~megera/postgres/gist/code/7.1/README.rtree_box_gist Дата изменения: Sun Jan 14 18:18:12 2001 Дата индексирования: Sat Dec 22 08:06:54 2007 Кодировка:

This is R-Tree implementation using GiST for boxes.
Code (for PG95) are taken from http://s2k-ftp.cs.berkeley.edu:8000/gist/pggist/
and sligtly changed according to new version of GiST (7.1)

All work was done by Teodor Sigaev (teodor@stack.net) and Oleg Bartunov
(oleg@sai.msu.su). See http://www.sai.msu.su/~megera/postgres/gist
for additional information.

INSTALLATION:

gmake
gmake install
-- load functions
psql < box.sql

REGRESSION TEST:

gmake installcheck

EXAMPLE USAGE:

create table boxtmp (b box);
-- create index
create index bix on boxtmp using gist (b gist_box_ops);
-- query
select * from boxtmp where b && '(1000,1000,0,0)'::box;


BENCHMARKS:

subdirectory bench contains benchmark suite.
Prerequisities: perl, DBI, DBD:Pg, Time::HiRes

cd ./bench
1. createdb TEST
2. psql TEST < ../box.sql
3. ./create_test.pl | psql TEST
-- change $NUM - number of rows in test dataset
4. ./bench.pl - perl script to benchmark queries.
Run script without arguments to see available options.

a)test without GiST index, using built-in R-Tree
./bench.pl -d TEST
b)test R-Tree using GiST index
./bench.pl -d TEST -g


RESULTS:

1. One interesting thing is that insertion time for built-in R-Tree is
about 8 times more than ones for GiST implementation of R-Tree !!!
2. Postmaster requires much more memory for built-in R-Tree
3. Search time depends on dataset. In our case we got:
+------------+-----------+--------------+
|Number boxes|R-tree, sec|R-tree using |
| | | GiST, sec |
+------------+-----------+--------------+
| 10| 0.002| 0.002|
+------------+-----------+--------------+
| 100| 0.002| 0.002|
+------------+-----------+--------------+
| 1000| 0.002| 0.002|
+------------+-----------+--------------+
| 10000| 0.015| 0.025|
+------------+-----------+--------------+
| 20000| 0.029| 0.048|
+------------+-----------+--------------+
| 40000| 0.055| 0.092|
+------------+-----------+--------------+
| 80000| 0.113| 0.178|
+------------+-----------+--------------+
| 160000| 0.338| 0.337|
+------------+-----------+--------------+
| 320000| 0.674| 0.673|
+------------+-----------+--------------+