gbase8s自定义数据类型

1 如果为已知数据类型，可使用 distinct type 

CREATE DISTINCT TYPE birthday AS DATE;

2 未知数据类型 比如 现在想实现一个 描述 正方体体积的数据类型 volume（长，宽，高）

2.1  volume.h

typedef struct {
    int x;
    int y;
	int z;
} volume_t;

volume_t *volume_add(volume_t *a, volume_t *b);
volume_t *volume_comp(volume_t *a, volume_t *b);

2.2 volume.c

#include <string.h>
#include "volume.h"
#include "mi.h"

volume_t *volume_add(volume_t *a, volume_t *b) {
    volume_t *result = (volume_t *)mi_zalloc(sizeof(volume_t));
    result->x = a->x + b->x;
    result->y = a->y + b->y;
	result->z = a->z + b->z;
    return result;
}


mi_integer volume_comp(volume_t *a, volume_t *b) {
    if(a->x * a->y * a->z == b->x * b->y * b->z){
    return 1;
	}else{
	return 0;
	}
}


volume_t *volume_in(mi_lvarchar *input,MI_FPARAM* param)
{
    mi_lvarchar *result = NULL;
	volume_t *c = (volume_t *)mi_zalloc(sizeof(volume_t));
	mi_char* s = mi_lvarchar_to_string(input);
    mi_fp_setreturnisnull(param, 0, MI_TRUE);
    sscanf(s, "(%d,%d,%d)", &c->x, &c->y,&c->z);
    if (c == NULL) {
        char error_msg[] = "volume_input: volume_from_char failed!";
        mi_db_error_raise(NULL,MI_EXCEPTION, error_msg);
		return (mi_lvarchar *)NULL;
    }
	mi_fp_setreturnisnull(param, 0, MI_FALSE);
    return c;
}


mi_lvarchar *volume_out(volume_t *output,MI_FPARAM* param) {

    mi_lvarchar * var = NULL;
    mi_fp_setreturnisnull(param, 0, MI_TRUE);
    var = mi_new_var(sizeof(volume_t));
    if (var == (mi_lvarchar *)NULL) {
		char error_msg[] = "memory allocation failed";
        mi_db_error_raise(NULL, MI_EXCEPTION, error_msg);
    }
    sprintf(var,"(%d,%d,%d)", output->x, output->y,output->z);
    mi_fp_setreturnisnull(param, 0, MI_FALSE);
    return var;
}


mi_lvarchar *volume_send(volume_t *output,MI_FPARAM* param) {
	return volume_out(output,param);
}

volume_t *volume_rcv(mi_lvarchar *input,MI_FPARAM* param) {
	return volume_in(input,param);
}

volume_t *volume_import_txt(mi_lvarchar *input,MI_FPARAM* param) {
	return volume_in(input,param);
}

mi_lvarchar *volume_export_txt(volume_t *output,MI_FPARAM* param) {
	return volume_out(output,param);
}

volume_t *volume_import_bin(mi_lvarchar *input,MI_FPARAM* param) {
	return volume_in(input,param);
}

mi_lvarchar *volume_export_bin(volume_t *output,MI_FPARAM* param) {
	return volume_out(output,param);
}

mi_integer volume_comp(volume_t *a, volume_t *b) {
    if(a->x * a->y * a->z == b->x * b->y * b->z){
    return 1;
	}else{
	return 0;
	}
}


mi_integer volume_ncomp(volume_t *a, volume_t *b) {
    if(a->x * a->y * a->z == b->x * b->y * b->z){
    return 0;
	}else{
	return 1;
	}
}

2.3 创建数据类型

CREATE OPAQUE TYPE volume (
    INTERNALLENGTH = 12,
    ALIGNMENT = 4,
	CANNOTHASH
);

2.4 创建相关函数

create function volume_in(lvarchar) 
returns volume
with (handlesnulls)
external name '$GBASEDBTDIR/lib/volume.so(volume_in)'
language c;

create function volume_out(volume) 
returns lvarchar
with (handlesnulls)
external name '$GBASEDBTDIR/lib/volume.so(volume_out)'
language c;

create function volume_send(volume) 
returns lvarchar
external name '$GBASEDBTDIR/lib/volume.so(volume_send)'
language c;

create function volume_rcv(lvarchar) 
returns volume
external name '$GBASEDBTDIR/lib/volume.so(volume_rcv)'
language c;


create function volume_import_txt(lvarchar) 
returns volume
external name '$GBASEDBTDIR/lib/volume.so(volume_import_txt)'
language c;


create function volume_export_txt(volume) 
returns lvarchar
external name '$GBASEDBTDIR/lib/volume.so(volume_export_txt)'
language c;


create function volume_import_bin(lvarchar) 
returns volume
external name '$GBASEDBTDIR/lib/volume.so(volume_import_bin)'
language c;


create function volume_export_bin(volume) 
returns lvarchar
external name '$GBASEDBTDIR/lib/volume.so(volume_export_bin)'
language c;

create function volume_add(volume, volume) 
returns volume
external name '$GBASEDBTDIR/lib/volume.so(volume_add)'
language c;


create function volume_comp(volume, volume) 
returns int
external name '$GBASEDBTDIR/lib/volume.so(volume_comp)'
language c;

create function gbasedbt.compare(gbasedbt.volume, gbasedbt.volume)
returns integer
external name '$GBASEDBTDIR/lib/volume.so(volume_comp)' language c not variant;


create function gbasedbt.equal(gbasedbt.volume, gbasedbt.volume)
returns gbasedbt.boolean
external name '$GBASEDBTDIR/lib/volume.so(volume_comp)' language c not variant;


create function gbasedbt.notequal(gbasedbt.volume, gbasedbt.volume)
returns gbasedbt.boolean
external name '$GBASEDBTDIR/lib/volume.so(volume_ncomp)' language c not variant;


create function gbasedbt.volume_plus(gbasedbt.volume, gbasedbt.volume)
returns gbasedbt.volume with(not variant)
external name '$GBASEDBTDIR/lib/volume.so(volume_add)' language c ;

2.5 创建转换

create implicit cast(lvarchar as volume with gbasedbt.volume_in);
create implicit cast(volume as lvarchar with gbasedbt.volume_out);
create explicit cast(volume as sendrecv with gbasedbt.volume_send);
create implicit cast(sendrecv as volume with gbasedbt.volume_recv);
create implicit cast(impexp as volume with gbasedbt.volume_import_txt);
create explicit cast(volume as impexp with gbasedbt.volume_export_txt);
create implicit cast(impexpbin as volume with gbasedbt.volume_import_bin);
create explicit cast(volume as impexpbin with gbasedbt.volume_export_bin);

2.6 测试

create table t1(c1 volume);
insert into t1 values('(1,2,3)');
select volume_plus('(1,2,3)'::volume , '(1,2,3)'::volume) from dual;
create index idx_t1_c1 on t1(c1);
select * from t1;
Table created.

> 
1 row(s) inserted.

> 


(expression)  (2,4,6) 

1 row(s) retrieved.

> 
Index created.

> 



c1  (1,2,3) 

1 row(s) retrieved.

2.7 规则

gbase8s 要求必须实现 创建转换等组函数，其中还需要实现流支持函数以及存储支持函数，部分函数反编译出来看不太明白，舍弃了