304 lines
10 KiB
Plaintext
304 lines
10 KiB
Plaintext
---------------------------------------------------------------------------
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--
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-- complex.sql-
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-- This file shows how to create a new user-defined type and how to
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-- use this new type.
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--
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--
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-- Copyright (c) 1994, Regents of the University of California
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--
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-- $Id: complex.source,v 1.8 2000/07/17 03:05:41 tgl Exp $
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--
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---------------------------------------------------------------------------
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-----------------------------
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-- Creating a new type:
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-- a user-defined type must have an input and an output function. They
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-- are user-defined C functions. We are going to create a new type
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-- called 'complex' which represents complex numbers.
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-----------------------------
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-- Assume the user defined functions are in _OBJWD_/complex_DLSUFFIX_
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-- Look at $PWD/complex.c for the source.
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-- the input function 'complex_in' takes a null-terminated string (the
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-- textual representation of the type) and turns it into the internal
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-- (in memory) representation. You will get a message telling you 'complex'
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-- does not exist yet but that's okay.
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CREATE FUNCTION complex_in(opaque)
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RETURNS complex
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AS '_OBJWD_/complex_DLSUFFIX_'
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LANGUAGE 'c';
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-- the output function 'complex_out' takes the internal representation and
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-- converts it into the textual representation.
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CREATE FUNCTION complex_out(opaque)
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RETURNS opaque
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AS '_OBJWD_/complex_DLSUFFIX_'
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LANGUAGE 'c';
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-- now, we can create the type. The internallength specifies the size of the
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-- memory block required to hold the type (we need two 8-byte doubles).
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CREATE TYPE complex (
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internallength = 16,
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input = complex_in,
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output = complex_out
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);
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-----------------------------
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-- Using the new type:
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-- user-defined types can be use like ordinary built-in types.
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-----------------------------
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-- eg. we can use it in a schema
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CREATE TABLE test_complex (
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a complex,
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b complex
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);
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-- data for user-defined type are just strings in the proper textual
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-- representation.
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INSERT INTO test_complex VALUES ('(1.0, 2.5)', '(4.2, 3.55 )');
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INSERT INTO test_complex VALUES ('(33.0, 51.4)', '(100.42, 93.55)');
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SELECT * FROM test_complex;
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-----------------------------
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-- Creating an operator for the new type:
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-- Let's define an add operator for complex types. Since POSTGRES
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-- supports function overloading, we'll use + as the add operator.
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-- (Operators can be reused with different number and types of
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-- arguments.)
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-----------------------------
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-- first, define a function complex_add (also in complex.c)
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CREATE FUNCTION complex_add(complex, complex)
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RETURNS complex
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AS '_OBJWD_/complex_DLSUFFIX_'
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LANGUAGE 'c';
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-- we can now define the operator. We show a binary operator here but you
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-- can also define unary operators by omitting either of leftarg or rightarg.
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CREATE OPERATOR + (
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leftarg = complex,
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rightarg = complex,
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procedure = complex_add,
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commutator = +
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);
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SELECT (a + b) AS c FROM test_complex;
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-- Occasionally, you may find it useful to cast the string to the desired
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-- type explicitly. :: denotes a type cast.
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SELECT a + '(1.0,1.0)'::complex AS aa,
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b + '(1.0,1.0)'::complex AS bb
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FROM test_complex;
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-----------------------------
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-- Creating aggregate functions
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-- you can also define aggregate functions. The syntax is somewhat
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-- cryptic but the idea is to express the aggregate in terms of state
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-- transition functions.
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-----------------------------
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CREATE AGGREGATE complex_sum (
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sfunc = complex_add,
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basetype = complex,
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stype = complex,
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initcond = '(0,0)'
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);
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SELECT complex_sum(a) FROM test_complex;
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-------------------------------------------------------------------------------
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-- ATTENTION! ATTENTION! ATTENTION! --
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-- YOU MAY SKIP THE SECTION BELOW ON INTERFACING WITH INDICES. YOU DON'T --
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-- NEED THE FOLLOWING IF YOU DON'T USE INDICES WITH NEW DATA TYPES. --
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-------------------------------------------------------------------------------
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SELECT 'READ ABOVE!' AS STOP;
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-----------------------------
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-- Interfacing New Types with Indices:
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-- We cannot define a secondary index (eg. a B-tree) over the new type
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-- yet. We need to modify a few system catalogs to show POSTGRES how
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-- to use the new type. Unfortunately, there is no simple command to
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-- do this. Please bear with me.
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-----------------------------
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-- first, define the required operators
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CREATE FUNCTION complex_abs_lt(complex, complex) RETURNS bool
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AS '_OBJWD_/complex_DLSUFFIX_' LANGUAGE 'c';
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CREATE FUNCTION complex_abs_le(complex, complex) RETURNS bool
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AS '_OBJWD_/complex_DLSUFFIX_' LANGUAGE 'c';
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CREATE FUNCTION complex_abs_eq(complex, complex) RETURNS bool
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AS '_OBJWD_/complex_DLSUFFIX_' LANGUAGE 'c';
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CREATE FUNCTION complex_abs_ge(complex, complex) RETURNS bool
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AS '_OBJWD_/complex_DLSUFFIX_' LANGUAGE 'c';
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CREATE FUNCTION complex_abs_gt(complex, complex) RETURNS bool
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AS '_OBJWD_/complex_DLSUFFIX_' LANGUAGE 'c';
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CREATE OPERATOR < (
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leftarg = complex, rightarg = complex, procedure = complex_abs_lt,
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restrict = scalarltsel, join = scalarltjoinsel
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);
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CREATE OPERATOR <= (
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leftarg = complex, rightarg = complex, procedure = complex_abs_le,
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restrict = scalarltsel, join = scalarltjoinsel
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);
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CREATE OPERATOR = (
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leftarg = complex, rightarg = complex, procedure = complex_abs_eq,
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restrict = eqsel, join = eqjoinsel
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);
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CREATE OPERATOR >= (
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leftarg = complex, rightarg = complex, procedure = complex_abs_ge,
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restrict = scalargtsel, join = scalargtjoinsel
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);
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CREATE OPERATOR > (
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leftarg = complex, rightarg = complex, procedure = complex_abs_gt,
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restrict = scalargtsel, join = scalargtjoinsel
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);
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INSERT INTO pg_opclass (opcname, opcdeftype)
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SELECT 'complex_abs_ops', oid FROM pg_type WHERE typname = 'complex';
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SELECT oid, opcname, opcdeftype
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FROM pg_opclass WHERE opcname = 'complex_abs_ops';
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SELECT o.oid AS opoid, o.oprname
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INTO TABLE complex_ops_tmp
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FROM pg_operator o, pg_type t
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WHERE o.oprleft = t.oid and o.oprright = t.oid
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and t.typname = 'complex';
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-- make sure we have the right operators
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SELECT * from complex_ops_tmp;
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INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy)
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SELECT am.oid, opcl.oid, c.opoid, 1
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '<';
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INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy)
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SELECT am.oid, opcl.oid, c.opoid, 2
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '<=';
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INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy)
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SELECT am.oid, opcl.oid, c.opoid, 3
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '=';
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INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy)
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SELECT am.oid, opcl.oid, c.opoid, 4
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '>=';
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INSERT INTO pg_amop (amopid, amopclaid, amopopr, amopstrategy)
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SELECT am.oid, opcl.oid, c.opoid, 5
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '>';
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--
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CREATE FUNCTION complex_abs_cmp(complex, complex) RETURNS int4
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AS '_OBJWD_/complex_DLSUFFIX_' LANGUAGE 'c';
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SELECT oid, proname FROM pg_proc WHERE proname = 'complex_abs_cmp';
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INSERT INTO pg_amproc (amid, amopclaid, amproc, amprocnum)
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SELECT am.oid, opcl.oid, pro.oid, 1
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FROM pg_am am, pg_opclass opcl, pg_proc pro
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and proname = 'complex_abs_cmp';
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-- now, we can define a btree index on complex types. First, let's populate
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-- the table. Note that postgres needs many more tuples to start using the
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-- btree index during selects.
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INSERT INTO test_complex VALUES ('(56.0,-22.5)', '(-43.2,-0.07)');
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INSERT INTO test_complex VALUES ('(-91.9,33.6)', '(8.6,3.0)');
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CREATE INDEX test_cplx_ind ON test_complex
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USING btree(a complex_abs_ops);
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SELECT * from test_complex where a = '(56.0,-22.5)';
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SELECT * from test_complex where a < '(56.0,-22.5)';
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SELECT * from test_complex where a > '(56.0,-22.5)';
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DELETE FROM pg_amop where (amopid, amopclaid, amopopr, amopstrategy)
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= (
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SELECT am.oid, opcl.oid, c.opoid, 1
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '<');
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DELETE FROM pg_amop where (amopid, amopclaid, amopopr, amopstrategy)
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= (
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SELECT am.oid, opcl.oid, c.opoid, 2
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '<=');
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DELETE FROM pg_amop where (amopid, amopclaid, amopopr, amopstrategy)
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= (
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SELECT am.oid, opcl.oid, c.opoid, 3
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '=');
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DELETE FROM pg_amop where (amopid, amopclaid, amopopr, amopstrategy)
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= (
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SELECT am.oid, opcl.oid, c.opoid, 4
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '>=');
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DELETE FROM pg_amop where (amopid, amopclaid, amopopr, amopstrategy)
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= (
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SELECT am.oid, opcl.oid, c.opoid, 5
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FROM pg_am am, pg_opclass opcl, complex_ops_tmp c
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and c.oprname = '>');
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DELETE FROM pg_amproc where (amid, amopclaid, amproc, amprocnum)
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= (
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SELECT am.oid, opcl.oid, pro.oid, 1
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FROM pg_am am, pg_opclass opcl, pg_proc pro
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WHERE amname = 'btree' and opcname = 'complex_abs_ops'
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and proname = 'complex_abs_cmp');
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DELETE FROM pg_opclass WHERE opcname = 'complex_abs_ops';
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DROP FUNCTION complex_in(opaque);
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DROP FUNCTION complex_out(opaque);
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DROP FUNCTION complex_add(complex, complex);
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DROP FUNCTION complex_abs_lt(complex, complex);
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DROP FUNCTION complex_abs_le(complex, complex);
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DROP FUNCTION complex_abs_eq(complex, complex);
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DROP FUNCTION complex_abs_ge(complex, complex);
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DROP FUNCTION complex_abs_gt(complex, complex);
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DROP FUNCTION complex_abs_cmp(complex, complex);
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DROP OPERATOR + (complex, complex);
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DROP OPERATOR < (complex, complex);
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DROP OPERATOR <= (complex, complex);
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DROP OPERATOR = (complex, complex);
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DROP OPERATOR >= (complex, complex);
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DROP OPERATOR > (complex, complex);
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DROP AGGREGATE complex_sum complex;
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DROP TYPE complex;
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DROP TABLE test_complex, complex_ops_tmp;
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