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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-05-04 12:15:05 +0000
commit46651ce6fe013220ed397add242004d764fc0153 (patch)
tree6e5299f990f88e60174a1d3ae6e48eedd2688b2b /src/tutorial/funcs.c
parentInitial commit. (diff)
downloadpostgresql-14-46651ce6fe013220ed397add242004d764fc0153.tar.xz
postgresql-14-46651ce6fe013220ed397add242004d764fc0153.zip
Adding upstream version 14.5.upstream/14.5upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/tutorial/funcs.c')
-rw-r--r--src/tutorial/funcs.c126
1 files changed, 126 insertions, 0 deletions
diff --git a/src/tutorial/funcs.c b/src/tutorial/funcs.c
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+++ b/src/tutorial/funcs.c
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+/* src/tutorial/funcs.c */
+
+/******************************************************************************
+ 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.
+*****************************************************************************/
+
+#include "postgres.h" /* general Postgres declarations */
+
+#include "executor/executor.h" /* for GetAttributeByName() */
+#include "utils/geo_decls.h" /* for point type */
+
+PG_MODULE_MAGIC;
+
+
+/* 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_PP(0);
+
+ /*
+ * VARSIZE_ANY_EXHDR is the size of the struct in bytes, minus the
+ * VARHDRSZ or VARHDRSZ_SHORT of its header. Construct the copy with a
+ * full-length header.
+ */
+ text *new_t = (text *) palloc(VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
+
+ SET_VARSIZE(new_t, VARSIZE_ANY_EXHDR(t) + VARHDRSZ);
+
+ /*
+ * VARDATA is a pointer to the data region of the new struct. The source
+ * could be a short datum, so retrieve its data through VARDATA_ANY.
+ */
+ memcpy((void *) VARDATA(new_t), /* destination */
+ (void *) VARDATA_ANY(t), /* source */
+ VARSIZE_ANY_EXHDR(t)); /* 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_PP(0);
+ text *arg2 = PG_GETARG_TEXT_PP(1);
+ int32 arg1_size = VARSIZE_ANY_EXHDR(arg1);
+ int32 arg2_size = VARSIZE_ANY_EXHDR(arg2);
+ 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_ANY(arg1), arg1_size);
+ memcpy(VARDATA(new_text) + arg1_size, VARDATA_ANY(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);
+}