1 /* src/tutorial/funcs.c */
2
3 /******************************************************************************
4 These are user-defined functions that can be bound to a Postgres backend
5 and called by Postgres to execute SQL functions of the same name.
6
7 The calling format for these functions is defined by the CREATE FUNCTION
8 SQL statement that binds them to the backend.
9
10 NOTE: this file shows examples of "old style" function call conventions.
11 See funcs_new.c for examples of "new style".
12 *****************************************************************************/
13
14 #include "postgres.h" /* general Postgres declarations */
15
16 #include "executor/executor.h" /* for GetAttributeByName() */
17 #include "utils/geo_decls.h" /* for point type */
18
19 PG_MODULE_MAGIC;
20
21 /* These prototypes just prevent possible warnings from gcc. */
22
23 int add_one(int arg);
24 float8 *add_one_float8(float8 *arg);
25 Point *makepoint(Point *pointx, Point *pointy);
26 text *copytext(text *t);
27 text *concat_text(text *arg1, text *arg2);
28 bool c_overpaid(HeapTupleHeader t, /* the current instance of EMP */
29 int32 limit);
30
31
32 /* By Value */
33
34 int
add_one(int arg)35 add_one(int arg)
36 {
37 return arg + 1;
38 }
39
40 /* By Reference, Fixed Length */
41
42 float8 *
add_one_float8(float8 * arg)43 add_one_float8(float8 *arg)
44 {
45 float8 *result = (float8 *) palloc(sizeof(float8));
46
47 *result = *arg + 1.0;
48
49 return result;
50 }
51
52 Point *
makepoint(Point * pointx,Point * pointy)53 makepoint(Point *pointx, Point *pointy)
54 {
55 Point *new_point = (Point *) palloc(sizeof(Point));
56
57 new_point->x = pointx->x;
58 new_point->y = pointy->y;
59
60 return new_point;
61 }
62
63 /* By Reference, Variable Length */
64
65 text *
copytext(text * t)66 copytext(text *t)
67 {
68 /*
69 * VARSIZE is the total size of the struct in bytes.
70 */
71 text *new_t = (text *) palloc(VARSIZE(t));
72
73 SET_VARSIZE(new_t, VARSIZE(t));
74
75 /*
76 * VARDATA is a pointer to the data region of the struct.
77 */
78 memcpy((void *) VARDATA(new_t), /* destination */
79 (void *) VARDATA(t), /* source */
80 VARSIZE(t) - VARHDRSZ); /* how many bytes */
81 return new_t;
82 }
83
84 text *
concat_text(text * arg1,text * arg2)85 concat_text(text *arg1, text *arg2)
86 {
87 int32 arg1_size = VARSIZE(arg1) - VARHDRSZ;
88 int32 arg2_size = VARSIZE(arg2) - VARHDRSZ;
89 int32 new_text_size = arg1_size + arg2_size + VARHDRSZ;
90 text *new_text = (text *) palloc(new_text_size);
91
92 SET_VARSIZE(new_text, new_text_size);
93 memcpy(VARDATA(new_text), VARDATA(arg1), arg1_size);
94 memcpy(VARDATA(new_text) + arg1_size, VARDATA(arg2), arg2_size);
95 return new_text;
96 }
97
98 /* Composite types */
99
100 bool
c_overpaid(HeapTupleHeader t,int32 limit)101 c_overpaid(HeapTupleHeader t, /* the current instance of EMP */
102 int32 limit)
103 {
104 bool isnull;
105 int32 salary;
106
107 salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull));
108 if (isnull)
109 return false;
110 return salary > limit;
111 }
112