mirror of
https://github.com/postgres/postgres.git
synced 2025-06-25 01:02:05 +03:00
Postgres95 1.01 Distribution - Virgin Sources
This commit is contained in:
Marc G. Fournier
251
src/tutorial/complex.source
Normal file
251
src/tutorial/complex.source
Normal file
@ -0,0 +1,251 @@
|
||||
---------------------------------------------------------------------------
|
||||
--
|
||||
-- complex.sql-
|
||||
-- This file shows how to create a new user-defined type and how to
|
||||
-- use them.
|
||||
--
|
||||
--
|
||||
-- Copyright (c) 1994, Regents of the University of California
|
||||
--
|
||||
-- $Id: complex.source,v 1.1.1.1 1996/07/09 06:22:34 scrappy Exp $
|
||||
--
|
||||
---------------------------------------------------------------------------
|
||||
|
||||
-----------------------------
|
||||
-- Creating a new type:
|
||||
-- a user-defined type must have an input and an output function. They
|
||||
-- are user-defined C functions. We are going to create a new type
|
||||
-- called 'complex' which represents complex numbers.
|
||||
-----------------------------
|
||||
|
||||
-- Assume the user defined functions are in _OBJWD_/complex.so
|
||||
-- Look at $PWD/C-code/complex.c for the source.
|
||||
|
||||
-- the input function 'complex_in' takes a null-terminated string (the
|
||||
-- textual representation of the type) and turns it into the internal
|
||||
-- (in memory) representation. You will get a message telling you 'complex'
|
||||
-- does not exist yet but that's okay.
|
||||
|
||||
CREATE FUNCTION complex_in(opaque)
|
||||
RETURNS complex
|
||||
AS '_OBJWD_/complex.so'
|
||||
LANGUAGE 'c';
|
||||
|
||||
-- the output function 'complex_out' takes the internal representation and
|
||||
-- converts it into the textual representation.
|
||||
|
||||
CREATE FUNCTION complex_out(opaque)
|
||||
RETURNS opaque
|
||||
AS '_OBJWD_/complex.so'
|
||||
LANGUAGE 'c';
|
||||
|
||||
-- now, we can create the type. The internallength specifies the size of the
|
||||
-- memory block required to hold the type (we need two 8-byte doubles).
|
||||
|
||||
CREATE TYPE complex (
|
||||
internallength = 16,
|
||||
input = complex_in,
|
||||
output = complex_out
|
||||
);
|
||||
|
||||
|
||||
-----------------------------
|
||||
-- Using the new type:
|
||||
-- user-defined types can be use like ordinary built-in types.
|
||||
-----------------------------
|
||||
|
||||
-- eg. we can use it in a schema
|
||||
|
||||
CREATE TABLE test_complex (
|
||||
a complex,
|
||||
b complex
|
||||
);
|
||||
|
||||
-- data for user-defined type are just strings in the proper textual
|
||||
-- representation.
|
||||
|
||||
INSERT INTO test_complex VALUES ('(1.0, 2.5)', '(4.2, 3.55 )')
|
||||
INSERT INTO test_complex VALUES ('(33.0, 51.4)', '(100.42, 93.55)')
|
||||
|
||||
SELECT * FROM test_complex;
|
||||
|
||||
-----------------------------
|
||||
-- Creating an operator for the new type:
|
||||
-- Let's define an add operator for complex types. Since POSTGRES
|
||||
-- supports function overloading, we'll use + as the add operator.
|
||||
-- (Operators can be reused with different number and types of
|
||||
-- arguments.)
|
||||
-----------------------------
|
||||
|
||||
-- first, define a function complex_add (also in C-code/complex.c)
|
||||
CREATE FUNCTION complex_add(complex, complex)
|
||||
RETURNS complex
|
||||
AS '_OBJWD_/complex.so'
|
||||
LANGUAGE 'c';
|
||||
|
||||
-- we can now define the operator. We show a binary operator here but you
|
||||
-- can also define unary operators by omitting either of leftarg or rightarg.
|
||||
CREATE OPERATOR + (
|
||||
leftarg = complex,
|
||||
rightarg = complex,
|
||||
procedure = complex_add,
|
||||
commutator = +
|
||||
);
|
||||
|
||||
|
||||
SELECT (a + b) AS c FROM test_complex;
|
||||
|
||||
-- Occasionally, you may find it useful to cast the string to the desired
|
||||
-- type explicitly. :: denotes a type cast.
|
||||
|
||||
SELECT a + '(1.0,1.0)'::complex AS aa,
|
||||
b + '(1.0,1.0)'::complex AS bb
|
||||
FROM test_complex;
|
||||
|
||||
|
||||
-----------------------------
|
||||
-- Creating aggregate functions
|
||||
-- you can also define aggregate functions. The syntax is some what
|
||||
-- cryptic but the idea is to express the aggregate in terms of state
|
||||
-- transition functions.
|
||||
-----------------------------
|
||||
|
||||
CREATE AGGREGATE complex_sum (
|
||||
sfunc1 = complex_add,
|
||||
basetype = complex,
|
||||
stype1 = complex,
|
||||
initcond1 = '(0,0)'
|
||||
);
|
||||
|
||||
SELECT complex_sum(a) FROM test_complex;
|
||||
|
||||
|
||||
-------------------------------------------------------------------------------
|
||||
-- ATTENTION! ATTENTION! ATTENTION! --
|
||||
-- YOU MAY SKIP THE SECTION BELOW ON INTERFACING WITH INDICIES. YOU DON'T --
|
||||
-- NEED THE FOLLOWING IF YOU DON'T USE INDICIES WITH NEW DATA TYPES. --
|
||||
-------------------------------------------------------------------------------
|
||||
|
||||
SELECT 'READ ABOVE!' AS STOP;
|
||||
|
||||
-----------------------------
|
||||
-- Interfacing New Types with Indices:
|
||||
-- We cannot define a secondary index (eg. a B-tree) over the new type
|
||||
-- yet. We need to modify a few system catalogs to show POSTGRES how
|
||||
-- to use the new type. Unfortunately, there is no simple command to
|
||||
-- do this. Please bear with me.
|
||||
-----------------------------
|
||||
|
||||
-- first, define the required operators
|
||||
CREATE FUNCTION complex_abs_lt(complex, complex) RETURNS bool
|
||||
AS '_OBJWD_/complex.so' LANGUAGE 'c'
|
||||
CREATE FUNCTION complex_abs_le(complex, complex) RETURNS bool
|
||||
AS '_OBJWD_/complex.so' LANGUAGE 'c'
|
||||
CREATE FUNCTION complex_abs_eq(complex, complex) RETURNS bool
|
||||
AS '_OBJWD_/complex.so' LANGUAGE 'c'
|
||||
CREATE FUNCTION complex_abs_ge(complex, complex) RETURNS bool
|
||||
AS '_OBJWD_/complex.so' LANGUAGE 'c'
|
||||
CREATE FUNCTION complex_abs_gt(complex, complex) RETURNS bool
|
||||
AS '_OBJWD_/complex.so' LANGUAGE 'c';
|
||||
|
||||
-- the restrict and join selectivity functions are bogus (notice we only
|
||||
-- have intltsel, eqsel and intgtsel)
|
||||
CREATE OPERATOR < (
|
||||
leftarg = complex, rightarg = complex, procedure = complex_abs_lt,
|
||||
restrict = intltsel, join = intltjoinsel
|
||||
)
|
||||
CREATE OPERATOR <= (
|
||||
leftarg = complex, rightarg = complex, procedure = complex_abs_le,
|
||||
restrict = intltsel, join = intltjoinsel
|
||||
)
|
||||
CREATE OPERATOR = (
|
||||
leftarg = complex, rightarg = complex, procedure = complex_abs_eq,
|
||||
restrict = eqsel, join = eqjoinsel
|
||||
)
|
||||
CREATE OPERATOR >= (
|
||||
leftarg = complex, rightarg = complex, procedure = complex_abs_ge,
|
||||
restrict = intgtsel, join = intgtjoinsel
|
||||
)
|
||||
CREATE OPERATOR > (
|
||||
leftarg = complex, rightarg = complex, procedure = complex_abs_gt,
|
||||
restrict = intgtsel, join = intgtjoinsel
|
||||
);
|
||||
|
||||
INSERT INTO pg_opclass VALUES ('complex_abs_ops')
|
||||
|
||||
SELECT oid, opcname FROM pg_opclass WHERE opcname = 'complex_abs_ops';
|
||||
|
||||
SELECT o.oid AS opoid, o.oprname
|
||||
INTO TABLE complex_ops_tmp
|
||||
FROM pg_operator o, pg_type t
|
||||
WHERE o.oprleft = t.oid and o.oprright = t.oid
|
||||
and t.typname = 'complex';
|
||||
|
||||
-- make sure we have the right operators
|
||||
SELECT * from complex_ops_tmp;
|
||||
|
||||
INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy,
|
||||
amopselect, amopnpages)
|
||||
SELECT am.oid, opcl.oid, c.opoid, 1,
|
||||
'btreesel'::regproc, 'btreenpage'::regproc
|
||||
FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
|
||||
WHERE amname = 'btree' and opcname = 'complex_abs_ops'
|
||||
and c.oprname = '<';
|
||||
|
||||
INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy,
|
||||
amopselect, amopnpages)
|
||||
SELECT am.oid, opcl.oid, c.opoid, 2,
|
||||
'btreesel'::regproc, 'btreenpage'::regproc
|
||||
FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
|
||||
WHERE amname = 'btree' and opcname = 'complex_abs_ops'
|
||||
and c.oprname = '<=';
|
||||
|
||||
INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy,
|
||||
amopselect, amopnpages)
|
||||
SELECT am.oid, opcl.oid, c.opoid, 3,
|
||||
'btreesel'::regproc, 'btreenpage'::regproc
|
||||
FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
|
||||
WHERE amname = 'btree' and opcname = 'complex_abs_ops'
|
||||
and c.oprname = '=';
|
||||
|
||||
INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy,
|
||||
amopselect, amopnpages)
|
||||
SELECT am.oid, opcl.oid, c.opoid, 4,
|
||||
'btreesel'::regproc, 'btreenpage'::regproc
|
||||
FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
|
||||
WHERE amname = 'btree' and opcname = 'complex_abs_ops'
|
||||
and c.oprname = '>=';
|
||||
|
||||
INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy,
|
||||
amopselect, amopnpages)
|
||||
SELECT am.oid, opcl.oid, c.opoid, 5,
|
||||
'btreesel'::regproc, 'btreenpage'::regproc
|
||||
FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
|
||||
WHERE amname = 'btree' and opcname = 'complex_abs_ops'
|
||||
and c.oprname = '>';
|
||||
|
||||
DROP table complex_ops_tmp;
|
||||
|
||||
--
|
||||
CREATE FUNCTION complex_abs_cmp(complex, complex) RETURNS int4
|
||||
AS '_OBJWD_/complex.so' LANGUAGE 'c';
|
||||
|
||||
SELECT oid, proname FROM pg_proc WHERE proname = 'complex_abs_cmp';
|
||||
|
||||
INSERT INTO pg_amproc (amid, amopclaid, amproc, amprocnum)
|
||||
SELECT am.oid, opcl.oid, pro.oid, 1
|
||||
FROM pg_am am, pg_opclass opcl, pg_proc pro
|
||||
WHERE amname = 'btree' and opcname = 'complex_abs_ops'
|
||||
and proname = 'complex_abs_cmp';
|
||||
|
||||
-- now, we can define a btree index on complex types. First, let's populate
|
||||
-- the table (THIS DOESN'T ACTUALLY WORK. YOU NEED MANY MORE TUPLES.)
|
||||
INSERT INTO test_complex VALUES ('(56.0,-22.5)', '(-43.2,-0.07)')
|
||||
INSERT INTO test_complex VALUES ('(-91.9,33.6)', '(8.6,3.0)');
|
||||
|
||||
CREATE INDEX test_cplx_ind ON test_complex
|
||||
USING btree(a complex_abs_ops);
|
||||
|
||||
SELECT * from test_complex where a = '(56.0,-22.5)';
|
||||
SELECT * from test_complex where a < '(56.0,-22.5)';
|
||||
SELECT * from test_complex where a > '(56.0,-22.5)';
|
||||
Reference in New Issue
Block a user