1 /* $PostgreSQL: pgsql/src/tutorial/funcs_new.c,v 1.13 2007/02/27 23:48:10 tgl Exp $ */
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.
7 The calling format for these functions is defined by the CREATE FUNCTION
8 SQL statement that binds them to the backend.
10 NOTE: this file shows examples of "new style" function call conventions.
11 See funcs.c for examples of "old style".
12 *****************************************************************************/
14 #include "postgres.h" /* general Postgres declarations */
16 #include "executor/executor.h" /* for GetAttributeByName() */
17 #include "utils/geo_decls.h" /* for point type */
22 /* These prototypes just prevent possible warnings from gcc. */
24 Datum add_one(PG_FUNCTION_ARGS);
25 Datum add_one_float8(PG_FUNCTION_ARGS);
26 Datum makepoint(PG_FUNCTION_ARGS);
27 Datum copytext(PG_FUNCTION_ARGS);
28 Datum concat_text(PG_FUNCTION_ARGS);
29 Datum c_overpaid(PG_FUNCTION_ARGS);
34 PG_FUNCTION_INFO_V1(add_one);
37 add_one(PG_FUNCTION_ARGS)
39 int32 arg = PG_GETARG_INT32(0);
41 PG_RETURN_INT32(arg + 1);
44 /* By Reference, Fixed Length */
46 PG_FUNCTION_INFO_V1(add_one_float8);
49 add_one_float8(PG_FUNCTION_ARGS)
51 /* The macros for FLOAT8 hide its pass-by-reference nature */
52 float8 arg = PG_GETARG_FLOAT8(0);
54 PG_RETURN_FLOAT8(arg + 1.0);
57 PG_FUNCTION_INFO_V1(makepoint);
60 makepoint(PG_FUNCTION_ARGS)
62 Point *pointx = PG_GETARG_POINT_P(0);
63 Point *pointy = PG_GETARG_POINT_P(1);
64 Point *new_point = (Point *) palloc(sizeof(Point));
66 new_point->x = pointx->x;
67 new_point->y = pointy->y;
69 PG_RETURN_POINT_P(new_point);
72 /* By Reference, Variable Length */
74 PG_FUNCTION_INFO_V1(copytext);
77 copytext(PG_FUNCTION_ARGS)
79 text *t = PG_GETARG_TEXT_P(0);
82 * VARSIZE is the total size of the struct in bytes.
84 text *new_t = (text *) palloc(VARSIZE(t));
86 SET_VARSIZE(new_t, VARSIZE(t));
89 * VARDATA is a pointer to the data region of the struct.
91 memcpy((void *) VARDATA(new_t), /* destination */
92 (void *) VARDATA(t), /* source */
93 VARSIZE(t) - VARHDRSZ); /* how many bytes */
94 PG_RETURN_TEXT_P(new_t);
97 PG_FUNCTION_INFO_V1(concat_text);
100 concat_text(PG_FUNCTION_ARGS)
102 text *arg1 = PG_GETARG_TEXT_P(0);
103 text *arg2 = PG_GETARG_TEXT_P(1);
104 int32 arg1_size = VARSIZE(arg1) - VARHDRSZ;
105 int32 arg2_size = VARSIZE(arg2) - VARHDRSZ;
106 int32 new_text_size = arg1_size + arg2_size + VARHDRSZ;
107 text *new_text = (text *) palloc(new_text_size);
109 SET_VARSIZE(new_text, new_text_size);
110 memcpy(VARDATA(new_text), VARDATA(arg1), arg1_size);
111 memcpy(VARDATA(new_text) + arg1_size, VARDATA(arg2), arg2_size);
112 PG_RETURN_TEXT_P(new_text);
115 /* Composite types */
117 PG_FUNCTION_INFO_V1(c_overpaid);
120 c_overpaid(PG_FUNCTION_ARGS)
122 HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(0);
123 int32 limit = PG_GETARG_INT32(1);
127 salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull));
129 PG_RETURN_BOOL(false);
132 * Alternatively, we might prefer to do PG_RETURN_NULL() for null salary
135 PG_RETURN_BOOL(salary > limit);