mirror of https://github.com/postgres/postgres
101 lines
3.2 KiB
Plaintext
101 lines
3.2 KiB
Plaintext
This is an implementation of RD-tree data structure using GiST interface
|
|
of PostgreSQL. It has built-in lossy compression.
|
|
|
|
Current implementation provides index support for one-dimensional array of
|
|
int4's - gist__int_ops, suitable for small and medium size of arrays (used on
|
|
default), and gist__intbig_ops for indexing large arrays (we use superimposed
|
|
signature with length of 4096 bits to represent sets).
|
|
|
|
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.
|
|
|
|
CHANGES:
|
|
|
|
October 1, 2001
|
|
1. Change search method in array to binary
|
|
September 28, 2001
|
|
1. gist__int_ops now is without lossy
|
|
2. add sort entry in picksplit
|
|
September 21, 2001
|
|
1. Added support for boolean query (indexable operator @@, looks like
|
|
a @@ '1|(2&3)', perfomance is better in any case )
|
|
2. Done some small optimizations
|
|
March 19, 2001
|
|
1. Added support for toastable keys
|
|
2. Improved split algorithm for intbig (selection speedup is about 30%)
|
|
|
|
INSTALLATION:
|
|
|
|
gmake
|
|
gmake install
|
|
-- load functions
|
|
psql <database> < _int.sql
|
|
|
|
REGRESSION TEST:
|
|
|
|
gmake installcheck
|
|
|
|
EXAMPLE USAGE:
|
|
|
|
create table message (mid int not null,sections int[]);
|
|
create table message_section_map (mid int not null,sid int not null);
|
|
|
|
-- create indices
|
|
CREATE unique index message_key on message ( mid );
|
|
CREATE unique index message_section_map_key2 on message_section_map (sid, mid );
|
|
CREATE INDEX message_rdtree_idx on message using gist ( sections gist__int_ops);
|
|
|
|
-- select some messages with section in 1 OR 2 - OVERLAP operator
|
|
select message.mid from message where message.sections && '{1,2}';
|
|
|
|
-- select messages contains in sections 1 AND 2 - CONTAINS operator
|
|
select message.mid from message where message.sections @ '{1,2}';
|
|
-- the same, CONTAINED operator
|
|
select message.mid from message where '{1,2}' ~ message.sections;
|
|
|
|
BENCHMARK:
|
|
|
|
subdirectory bench contains benchmark suite.
|
|
cd ./bench
|
|
1. createdb TEST
|
|
2. psql TEST < ../_int.sql
|
|
3. ./create_test.pl | psql TEST
|
|
4. ./bench.pl - perl script to benchmark queries, supports OR, AND queries
|
|
with/without RD-Tree. Run script without arguments to
|
|
see availbale options.
|
|
|
|
a)test without RD-Tree (OR)
|
|
./bench.pl -d TEST -s 1,2 -v
|
|
b)test with RD-Tree
|
|
./bench.pl -d TEST -s 1,2 -v -r
|
|
|
|
BENCHMARKS:
|
|
|
|
Size of table <message>: 200000
|
|
Size of table <message_section_map>: 268538
|
|
|
|
Distribution of messages by sections:
|
|
|
|
section 0: 73899 messages
|
|
section 1: 16298 messages
|
|
section 50: 1241 messages
|
|
section 99: 705 messages
|
|
|
|
old - without RD-Tree support,
|
|
new - with RD-Tree
|
|
|
|
+----------+---------------+----------------+
|
|
|Search set|OR, time in sec|AND, time in sec|
|
|
| +-------+-------+--------+-------+
|
|
| | old | new | old | new |
|
|
+----------+-------+-------+--------+-------+
|
|
| 1| 1.427| 0.215| -| -|
|
|
+----------+-------+-------+--------+-------+
|
|
| 99| 1.029| 0.018| -| -|
|
|
+----------+-------+-------+--------+-------+
|
|
| 1,2| 1.829| 0.334| 5.654| 0.042|
|
|
+----------+-------+-------+--------+-------+
|
|
| 1,2,50,60| 2.057| 0.359| 5.044| 0.007|
|
|
+----------+-------+-------+--------+-------+
|