我是新的postgresql c函数,我开始下面的例子。Postgresql c函数返回一行2个文件
我想写一个简单的函数,它内部包含一个SQL并接收参数evaluete,并将两个字段分别作为2列的总和返回(现在更简单)。
下面的功能问题,检查通过
(get_call_result_type(fcinfo, &resultTypeId, &resultTupleDesc) != TYPEFUNC_COMPOSITE)
如果我删除此行中我得到1个整数结果从该查询
select * from pdc_imuanno(2012);
误差和从
select (a).* from pdc_imuanno(2012) a;
因为不是复合类型。
的问题是我怎么能为元组准备的模板,如果它不纠正这种
resultTupleDesc = CreateTemplateTupleDesc(2, false);
TupleDescInitEntry(resultTupleDesc, (AttrNumber) 1, "abp1", FLOAT4OID, -1, 0);
TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "abp2", FLOAT4OID, -1, 0);
在
get_call_result_type(fcinfo, &resultTypeId, &resultTupleDesc)
fcinfo是什么,从哪儿来
多?
源表:
CREATE TABLE imu.calcolo (
codfis character varying(16) NOT NULL,
anno integer NOT NULL,
abp1 numeric,
abp2 numeric,
CONSTRAINT imucalcolo_pkey PRIMARY KEY (codfis, anno)
)
WITH (OIDS=FALSE);
-------------------------------------------------------
#include "postgres.h"
#include "fmgr.h"
#include "catalog/pg_type.h"
#include "funcapi.h"
#include "executor/spi.h"
#include "lib/stringinfo.h"
#include "miscadmin.h"
#include <math.h>
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/numeric.h"
#include "access/htup_details.h"
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
PG_FUNCTION_INFO_V1(test_query);
Datum test_query(PG_FUNCTION_ARGS);
Datum
test_query(PG_FUNCTION_ARGS)
{
TupleDesc resultTupleDesc, tupledesc;
bool bisnull, cisnull;
Oid resultTypeId;
Datum retvals[2];
bool retnulls[2];
HeapTuple rettuple;
sprintf(query,"SELECT anno, abp1::real, abp2::real "
"FROM imu.calcolo WHERE anno = %d;",PG_GETARG_INT32(0));
int ret;
int proc;
float abp1 = 0;
float abp2 = 0;
SPI_connect();
ret = SPI_exec(query,0);
proc = SPI_processed;
if (ret > 0 && SPI_tuptable != NULL)
{
HeapTuple tuple;
tupledesc = SPI_tuptable->tupdesc;
SPITupleTable *tuptable = SPI_tuptable;
for (j = 0; j < proc; j++)
{
tuple = tuptable->vals[j];
abp1 += DatumGetFloat4(SPI_getbinval(tuple, tupledesc, 2, &bisnull));
abp2 += DatumGetFloat4(SPI_getbinval(tuple, tupledesc, 3, &cisnull));
}
}
resultTupleDesc = CreateTemplateTupleDesc(2, false);
TupleDescInitEntry(resultTupleDesc, (AttrNumber) 1, "abp1", FLOAT4OID, -1, 0);
TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "abp2", FLOAT4OID, -1, 0);
if (get_call_result_type(fcinfo, &resultTypeId, &resultTupleDesc) != TYPEFUNC_COMPOSITE) {
ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context that cannot accept type record")));
}
resultTupleDesc = BlessTupleDesc(resultTupleDesc);
SPI_finish();
retvals[0] = Float4GetDatum(abp1);
retvals[1] = Float4GetDatum(abp2);
retnulls[1] = bisnull;
retnulls[2] = cisnull;
rettuple = heap_form_tuple(resultTupleDesc, retvals, retnulls);
PG_RETURN_DATUM(HeapTupleGetDatum(rettuple));
}
创建功能:
CREATE FUNCTION pdc_imuanno(integer)
RETURNS float
AS 'pdc','test_query'
LANGUAGE C STABLE STRICT;
ALTER FUNCTION pdc_imuanno(integer) OWNER TO www;
查询:
select * from pdc_imuanno(2012);
好吧,我找到简单的和愚蠢的错误 我创建函数retunrning 1场,我希望看到回归2场。
在该创建SQL它的工作原理
CREATE FUNCTION pdc_imuanno(integer)
RETURNS TABLE(abp1 real, abp2 real)
AS 'pdc','test_query'
LANGUAGE C STABLE STRICT;
反正它的工作原理与行总结的数量有限,如果我延长了行号,在这一点上
rettuple = heap_form_tuple(resultTupleDesc, retvals, retnulls);
我想有崩溃 是值类型的一些错误
所以我查询表中的字段为numeric :: real,我将它们作为float4输出,并将它们输出为datum。
我的错误在哪里?
非常感谢您的帮助。
这在我的第一篇文章在StackOverflow。
卢卡
PostgreSQL的版本?请显示完整的可编译C文件。 –
我使用的PostgreSQL在Linux上是9.3。 –
看起来您将问题确定为函数签名与声明不匹配。我很高兴。如果您有后续问题,请发布新问题。链接回到这个上下文。包括你想要做什么的解释,而不仅仅是你的问题。 –