127 lines
3.0 KiB
C
127 lines
3.0 KiB
C
/* src/tutorial/funcs.c */
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/******************************************************************************
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These are user-defined functions that can be bound to a Postgres backend
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and called by Postgres to execute SQL functions of the same name.
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The calling format for these functions is defined by the CREATE FUNCTION
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SQL statement that binds them to the backend.
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*****************************************************************************/
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#include "postgres.h" /* general Postgres declarations */
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#include "executor/executor.h" /* for GetAttributeByName() */
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#include "utils/geo_decls.h" /* for point type */
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PG_MODULE_MAGIC;
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/* By Value */
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PG_FUNCTION_INFO_V1(add_one);
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Datum
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add_one(PG_FUNCTION_ARGS)
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{
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int32 arg = PG_GETARG_INT32(0);
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PG_RETURN_INT32(arg + 1);
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}
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/* By Reference, Fixed Length */
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PG_FUNCTION_INFO_V1(add_one_float8);
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Datum
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add_one_float8(PG_FUNCTION_ARGS)
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{
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/* The macros for FLOAT8 hide its pass-by-reference nature */
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float8 arg = PG_GETARG_FLOAT8(0);
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PG_RETURN_FLOAT8(arg + 1.0);
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}
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PG_FUNCTION_INFO_V1(makepoint);
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Datum
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makepoint(PG_FUNCTION_ARGS)
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{
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Point *pointx = PG_GETARG_POINT_P(0);
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Point *pointy = PG_GETARG_POINT_P(1);
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Point *new_point = (Point *) palloc(sizeof(Point));
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new_point->x = pointx->x;
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new_point->y = pointy->y;
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PG_RETURN_POINT_P(new_point);
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}
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/* By Reference, Variable Length */
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PG_FUNCTION_INFO_V1(copytext);
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Datum
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copytext(PG_FUNCTION_ARGS)
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{
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text *t = PG_GETARG_TEXT_PP(0);
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/*
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* VARSIZE_ANY_EXHDR is the size of the struct in bytes, minus the
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* VARHDRSZ or VARHDRSZ_SHORT of its header. Construct the copy with a
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* full-length header.
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*/
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text *new_t = (text *) palloc(VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
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SET_VARSIZE(new_t, VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
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/*
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* VARDATA is a pointer to the data region of the new struct. The source
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* could be a short datum, so retrieve its data through VARDATA_ANY.
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*/
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memcpy(VARDATA(new_t), /* destination */
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VARDATA_ANY(t), /* source */
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VARSIZE_ANY_EXHDR(t)); /* how many bytes */
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PG_RETURN_TEXT_P(new_t);
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}
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PG_FUNCTION_INFO_V1(concat_text);
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Datum
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concat_text(PG_FUNCTION_ARGS)
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{
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text *arg1 = PG_GETARG_TEXT_PP(0);
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text *arg2 = PG_GETARG_TEXT_PP(1);
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int32 arg1_size = VARSIZE_ANY_EXHDR(arg1);
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int32 arg2_size = VARSIZE_ANY_EXHDR(arg2);
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int32 new_text_size = arg1_size + arg2_size + VARHDRSZ;
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text *new_text = (text *) palloc(new_text_size);
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SET_VARSIZE(new_text, new_text_size);
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memcpy(VARDATA(new_text), VARDATA_ANY(arg1), arg1_size);
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memcpy(VARDATA(new_text) + arg1_size, VARDATA_ANY(arg2), arg2_size);
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PG_RETURN_TEXT_P(new_text);
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}
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/* Composite types */
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PG_FUNCTION_INFO_V1(c_overpaid);
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Datum
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c_overpaid(PG_FUNCTION_ARGS)
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{
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HeapTupleHeader t = PG_GETARG_HEAPTUPLEHEADER(0);
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int32 limit = PG_GETARG_INT32(1);
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bool isnull;
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int32 salary;
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salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull));
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if (isnull)
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PG_RETURN_BOOL(false);
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/*
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* Alternatively, we might prefer to do PG_RETURN_NULL() for null salary
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*/
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PG_RETURN_BOOL(salary > limit);
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}
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