mirror of https://github.com/postgres/postgres
b6b71b85bc | ||
---|---|---|
.. | ||
bench | ||
data | ||
expected | ||
sql | ||
Makefile | ||
README.intarray | ||
_int.h | ||
_int.sql.in | ||
_int_bool.c | ||
_int_gist.c | ||
_int_op.c | ||
_int_tool.c | ||
_intbig_gist.c |
README.intarray
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. Andrey Oktyabrski did a great work on adding new functions and operations. FUNCTIONS: int icount(int[]) - the number of elements in intarray test=# select icount('{1,2,3}'::int[]); icount -------- 3 (1 row) int[] sort(int[], 'asc' | 'desc') - sort intarray test=# select sort('{1,2,3}'::int[],'desc'); sort --------- {3,2,1} (1 row) int[] sort(int[]) - sort in ascending order int[] sort_asc(int[]),sort_desc(int[]) - shortcuts for sort int[] uniq(int[]) - returns unique elements test=# select uniq(sort('{1,2,3,2,1}'::int[])); uniq --------- {1,2,3} (1 row) int idx(int[], int item) - returns index of first intarray matching element to item, or '0' if matching failed. test=# select idx('{1,2,3,2,1}'::int[],2); idx ----- 2 (1 row) int[] subarray(int[],int START [, int LEN]) - returns part of intarray starting from element number START (from 1) and length LEN. test=# select subarray('{1,2,3,2,1}'::int[],2,3); subarray ---------- {2,3,2} (1 row) OPERATIONS: int[] && int[] - overlap - returns TRUE if arrays has at least one common elements. int[] @ int[] - contains - returns TRUE if left array contains right array int[] ~ int[] - contained - returns TRUE if left array is contained in right array # int[] - return the number of elements in array int[] + int - push element to array ( add to end of array) int[] + int[] - merge of arrays (right array added to the end of left one) int[] - int - remove entries matched by right argument from array int[] - int[] - remove right array from left int[] | int - returns intarray - union of arguments int[] | int[] - returns intarray as a union of two arrays int[] & int[] - returns intersection of arrays int[] @@ query_int - returns TRUE if array satisfies query (like '1&(2|3)') query_int ~~ int[] - -/- CHANGES: August 6, 2002 1. Reworked patch from Andrey Oktyabrski (ano@spider.ru) with functions: icount, sort, sort_asc, uniq, idx, subarray operations: #, +, -, |, & 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| +----------+-------+-------+--------+-------+