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375369acd1
results with tuples as ordinary varlena Datums. This commit does not in itself do much for us, except eliminate the horrid memory leak associated with evaluation of whole-row variables. However, it lays the groundwork for allowing composite types as table columns, and perhaps some other useful features as well. Per my proposal of a few days ago.
134 lines
3.2 KiB
C
134 lines
3.2 KiB
C
/******************************************************************************
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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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NOTE: this file shows examples of "new style" function call conventions.
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See funcs.c for examples of "old style".
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*****************************************************************************/
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#include "postgres.h" /* general Postgres declarations */
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#include "fmgr.h" /* for argument/result macros */
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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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/* These prototypes just prevent possible warnings from gcc. */
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Datum add_one(PG_FUNCTION_ARGS);
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Datum add_one_float8(PG_FUNCTION_ARGS);
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Datum makepoint(PG_FUNCTION_ARGS);
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Datum copytext(PG_FUNCTION_ARGS);
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Datum concat_text(PG_FUNCTION_ARGS);
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Datum c_overpaid(PG_FUNCTION_ARGS);
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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_P(0);
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/*
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* VARSIZE is the total size of the struct in bytes.
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*/
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text *new_t = (text *) palloc(VARSIZE(t));
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VARATT_SIZEP(new_t) = VARSIZE(t);
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/*
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* VARDATA is a pointer to the data region of the struct.
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*/
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memcpy((void *) VARDATA(new_t), /* destination */
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(void *) VARDATA(t), /* source */
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VARSIZE(t) - VARHDRSZ); /* 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_P(0);
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text *arg2 = PG_GETARG_TEXT_P(1);
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int32 new_text_size = VARSIZE(arg1) + VARSIZE(arg2) - VARHDRSZ;
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text *new_text = (text *) palloc(new_text_size);
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memset((void *) new_text, 0, new_text_size);
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VARATT_SIZEP(new_text) = new_text_size;
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strncpy(VARDATA(new_text), VARDATA(arg1), VARSIZE(arg1) - VARHDRSZ);
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strncat(VARDATA(new_text), VARDATA(arg2), VARSIZE(arg2) - VARHDRSZ);
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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
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* salary
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*/
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PG_RETURN_BOOL(salary > limit);
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}
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