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query_histogram.c
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query_histogram.c
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#include <stdio.h>
#include <math.h>
#include <string.h>
#include <sys/time.h>
#include <unistd.h>
#include "postgres.h"
#include "queryhist.h"
#include "fmgr.h"
#include "funcapi.h"
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
PG_FUNCTION_INFO_V1(query_histogram);
PG_FUNCTION_INFO_V1(query_histogram_reset);
PG_FUNCTION_INFO_V1(query_histogram_get_reset);
Datum query_histogram(PG_FUNCTION_ARGS);
Datum query_histogram_reset(PG_FUNCTION_ARGS);
Datum query_histogram_get_reset(PG_FUNCTION_ARGS);
Datum
query_histogram(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
TupleDesc tupdesc;
AttInMetadata *attinmeta;
histogram_data* data;
/* init on the first call */
if (SRF_IS_FIRSTCALL()) {
MemoryContext oldcontext;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
data = query_hist_get_data(PG_GETARG_BOOL(0));
/* init (open file, etc.), maybe read all the data in memory
* so that the file is not kept open for a long time */
funcctx->user_fctx = data;
funcctx->max_calls = data->bins_count;
if (data->bins_count > 0) {
funcctx->max_calls = data->bins_count + 1;
}
/* Build a tuple descriptor for our result type */
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("function returning record called in context "
"that cannot accept type record")));
/*
* generate attribute metadata needed later to produce tuples from raw
* C strings
*/
attinmeta = TupleDescGetAttInMetadata(tupdesc);
funcctx->attinmeta = attinmeta;
funcctx->tuple_desc = tupdesc;
/* switch back to the old context */
MemoryContextSwitchTo(oldcontext);
}
/* init the context */
funcctx = SRF_PERCALL_SETUP();
/* check if we have more data */
if (funcctx->max_calls > funcctx->call_cntr)
{
HeapTuple tuple;
Datum result;
Datum values[6];
bool nulls[6];
int binIdx;
binIdx = funcctx->call_cntr;
data = (histogram_data*)funcctx->user_fctx;
memset(nulls, 0, sizeof(nulls));
if (data->histogram_type == HISTOGRAM_LINEAR) {
values[0] = UInt32GetDatum(binIdx * data->bins_width);
if (funcctx->max_calls - 1 == funcctx->call_cntr) {
values[1] = UInt32GetDatum(0);
nulls[1] = TRUE;
} else {
values[1] = UInt32GetDatum((binIdx+1)* data->bins_width);
}
} else {
if (funcctx->call_cntr == 0) {
values[0] = UInt32GetDatum(0);
} else {
values[0] = UInt32GetDatum(pow(2,binIdx-1) * data->bins_width);
}
if (funcctx->max_calls - 1 == funcctx->call_cntr) {
values[1] = UInt32GetDatum(0);
nulls[1] = TRUE;
} else {
values[1] = UInt32GetDatum(pow(2,binIdx) * data->bins_width);
}
}
values[2] = Int64GetDatum(data->count_data[binIdx]);
if (data->total_count > 0) {
values[3] = Float4GetDatum(100.0*data->count_data[binIdx] / data->total_count);
} else {
values[3] = Float4GetDatum(0);
}
values[4] = Float8GetDatum(data->time_data[binIdx]);
if (data->total_time > 0) {
values[5] = Float4GetDatum(100*data->time_data[binIdx] / data->total_time);
} else {
values[5] = Float4GetDatum(0);
}
/* Build and return the tuple. */
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
/* make the tuple into a datum */
result = HeapTupleGetDatum(tuple);
/* Here we want to return another item: */
SRF_RETURN_NEXT(funcctx, result);
}
else
{
/* Here we are done returning items and just need to clean up: */
SRF_RETURN_DONE(funcctx);
}
}
Datum
query_histogram_reset(PG_FUNCTION_ARGS)
{
query_hist_reset(false);
PG_RETURN_VOID();
}
Datum
query_histogram_get_reset(PG_FUNCTION_ARGS)
{
PG_RETURN_TIMESTAMP(get_hist_last_reset());
}