| /* $PostgreSQL: pgsql/src/tutorial/funcs_new.c,v 1.13 2007/02/27 23:48:10 tgl Exp $ */ |
| |
| /****************************************************************************** |
| These are user-defined functions that can be bound to a Postgres backend |
| and called by Postgres to execute SQL functions of the same name. |
| |
| The calling format for these functions is defined by the CREATE FUNCTION |
| SQL statement that binds them to the backend. |
| |
| NOTE: this file shows examples of "new style" function call conventions. |
| See funcs.c for examples of "old style". |
| *****************************************************************************/ |
| |
| #include "postgres.h" /* general Postgres declarations */ |
| |
| #include "executor/executor.h" /* for GetAttributeByName() */ |
| #include "utils/geo_decls.h" /* for point type */ |
| |
| |
| PG_MODULE_MAGIC; |
| |
| /* These prototypes just prevent possible warnings from gcc. */ |
| |
| Datum add_one(PG_FUNCTION_ARGS); |
| Datum add_one_float8(PG_FUNCTION_ARGS); |
| Datum makepoint(PG_FUNCTION_ARGS); |
| Datum copytext(PG_FUNCTION_ARGS); |
| Datum concat_text(PG_FUNCTION_ARGS); |
| Datum c_overpaid(PG_FUNCTION_ARGS); |
| |
| |
| /* By Value */ |
| |
| PG_FUNCTION_INFO_V1(add_one); |
| |
| Datum |
| add_one(PG_FUNCTION_ARGS) |
| { |
| int32 arg = PG_GETARG_INT32(0); |
| |
| PG_RETURN_INT32(arg + 1); |
| } |
| |
| /* By Reference, Fixed Length */ |
| |
| PG_FUNCTION_INFO_V1(add_one_float8); |
| |
| Datum |
| add_one_float8(PG_FUNCTION_ARGS) |
| { |
| /* The macros for FLOAT8 hide its pass-by-reference nature */ |
| float8 arg = PG_GETARG_FLOAT8(0); |
| |
| PG_RETURN_FLOAT8(arg + 1.0); |
| } |
| |
| PG_FUNCTION_INFO_V1(makepoint); |
| |
| Datum |
| makepoint(PG_FUNCTION_ARGS) |
| { |
| Point *pointx = PG_GETARG_POINT_P(0); |
| Point *pointy = PG_GETARG_POINT_P(1); |
| Point *new_point = (Point *) palloc(sizeof(Point)); |
| |
| new_point->x = pointx->x; |
| new_point->y = pointy->y; |
| |
| PG_RETURN_POINT_P(new_point); |
| } |
| |
| /* By Reference, Variable Length */ |
| |
| PG_FUNCTION_INFO_V1(copytext); |
| |
| Datum |
| copytext(PG_FUNCTION_ARGS) |
| { |
| text *t = PG_GETARG_TEXT_P(0); |
| |
| /* |
| * VARSIZE is the total size of the struct in bytes. |
| */ |
| text *new_t = (text *) palloc(VARSIZE(t)); |
| |
| SET_VARSIZE(new_t, VARSIZE(t)); |
| |
| /* |
| * VARDATA is a pointer to the data region of the struct. |
| */ |
| memcpy((void *) VARDATA(new_t), /* destination */ |
| (void *) VARDATA(t), /* source */ |
| VARSIZE(t) - VARHDRSZ); /* how many bytes */ |
| PG_RETURN_TEXT_P(new_t); |
| } |
| |
| PG_FUNCTION_INFO_V1(concat_text); |
| |
| Datum |
| concat_text(PG_FUNCTION_ARGS) |
| { |
| text *arg1 = PG_GETARG_TEXT_P(0); |
| text *arg2 = PG_GETARG_TEXT_P(1); |
| int32 arg1_size = VARSIZE(arg1) - VARHDRSZ; |
| int32 arg2_size = VARSIZE(arg2) - VARHDRSZ; |
| int32 new_text_size = arg1_size + arg2_size + VARHDRSZ; |
| text *new_text = (text *) palloc(new_text_size); |
| |
| SET_VARSIZE(new_text, new_text_size); |
| memcpy(VARDATA(new_text), VARDATA(arg1), arg1_size); |
| memcpy(VARDATA(new_text) + arg1_size, VARDATA(arg2), arg2_size); |
| PG_RETURN_TEXT_P(new_text); |
| } |
| |
| /* Composite types */ |
| |
| PG_FUNCTION_INFO_V1(c_overpaid); |
| |
| Datum |
| c_overpaid(PG_FUNCTION_ARGS) |
| { |
| HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(0); |
| int32 limit = PG_GETARG_INT32(1); |
| bool isnull; |
| int32 salary; |
| |
| salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull)); |
| if (isnull) |
| PG_RETURN_BOOL(false); |
| |
| /* |
| * Alternatively, we might prefer to do PG_RETURN_NULL() for null salary |
| */ |
| |
| PG_RETURN_BOOL(salary > limit); |
| } |