1 /* src/tutorial/funcs_new.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 "new style" function call conventions.
11 See funcs.c for examples of "old 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
22 /* By Value */
23
24 PG_FUNCTION_INFO_V1(add_one);
25
26 Datum
add_one(PG_FUNCTION_ARGS)27 add_one(PG_FUNCTION_ARGS)
28 {
29 int32 arg = PG_GETARG_INT32(0);
30
31 PG_RETURN_INT32(arg + 1);
32 }
33
34 /* By Reference, Fixed Length */
35
36 PG_FUNCTION_INFO_V1(add_one_float8);
37
38 Datum
add_one_float8(PG_FUNCTION_ARGS)39 add_one_float8(PG_FUNCTION_ARGS)
40 {
41 /* The macros for FLOAT8 hide its pass-by-reference nature */
42 float8 arg = PG_GETARG_FLOAT8(0);
43
44 PG_RETURN_FLOAT8(arg + 1.0);
45 }
46
47 PG_FUNCTION_INFO_V1(makepoint);
48
49 Datum
makepoint(PG_FUNCTION_ARGS)50 makepoint(PG_FUNCTION_ARGS)
51 {
52 Point *pointx = PG_GETARG_POINT_P(0);
53 Point *pointy = PG_GETARG_POINT_P(1);
54 Point *new_point = (Point *) palloc(sizeof(Point));
55
56 new_point->x = pointx->x;
57 new_point->y = pointy->y;
58
59 PG_RETURN_POINT_P(new_point);
60 }
61
62 /* By Reference, Variable Length */
63
64 PG_FUNCTION_INFO_V1(copytext);
65
66 Datum
copytext(PG_FUNCTION_ARGS)67 copytext(PG_FUNCTION_ARGS)
68 {
69 text *t = PG_GETARG_TEXT_PP(0);
70
71 /*
72 * VARSIZE_ANY_EXHDR is the size of the struct in bytes, minus the
73 * VARHDRSZ or VARHDRSZ_SHORT of its header. Construct the copy with a
74 * full-length header.
75 */
76 text *new_t = (text *) palloc(VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
77
78 SET_VARSIZE(new_t, VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
79
80 /*
81 * VARDATA is a pointer to the data region of the new struct. The source
82 * could be a short datum, so retrieve its data through VARDATA_ANY.
83 */
84 memcpy((void *) VARDATA(new_t), /* destination */
85 (void *) VARDATA_ANY(t), /* source */
86 VARSIZE_ANY_EXHDR(t)); /* how many bytes */
87 PG_RETURN_TEXT_P(new_t);
88 }
89
90 PG_FUNCTION_INFO_V1(concat_text);
91
92 Datum
concat_text(PG_FUNCTION_ARGS)93 concat_text(PG_FUNCTION_ARGS)
94 {
95 text *arg1 = PG_GETARG_TEXT_PP(0);
96 text *arg2 = PG_GETARG_TEXT_PP(1);
97 int32 arg1_size = VARSIZE_ANY_EXHDR(arg1);
98 int32 arg2_size = VARSIZE_ANY_EXHDR(arg2);
99 int32 new_text_size = arg1_size + arg2_size + VARHDRSZ;
100 text *new_text = (text *) palloc(new_text_size);
101
102 SET_VARSIZE(new_text, new_text_size);
103 memcpy(VARDATA(new_text), VARDATA_ANY(arg1), arg1_size);
104 memcpy(VARDATA(new_text) + arg1_size, VARDATA_ANY(arg2), arg2_size);
105 PG_RETURN_TEXT_P(new_text);
106 }
107
108 /* Composite types */
109
110 PG_FUNCTION_INFO_V1(c_overpaid);
111
112 Datum
c_overpaid(PG_FUNCTION_ARGS)113 c_overpaid(PG_FUNCTION_ARGS)
114 {
115 HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(0);
116 int32 limit = PG_GETARG_INT32(1);
117 bool isnull;
118 int32 salary;
119
120 salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull));
121 if (isnull)
122 PG_RETURN_BOOL(false);
123
124 /*
125 * Alternatively, we might prefer to do PG_RETURN_NULL() for null salary
126 */
127
128 PG_RETURN_BOOL(salary > limit);
129 }
130