Hi
I have done some fun with Monetdb. i have created my own user define xmin function.
objective of that function is find minimum value from specific column.
I have writen some code as follow :
/****************************************************************************************/
/* Function Name : xmin */
/****************************************************************************************/
#define UI sht
#define UU unsigned short
#define UO sht
#include "impl_xmin.h"
#undef UI
#undef UU
#undef UO
#define UI int
#define UU unsigned short
#define UO int
#include "impl_xmin.h"
#undef UI
#undef UU
#undef UO
#define UI lng
#define UU unsigned short
#define UO lng
#include "impl_xmin.h"
#undef UI
#undef UU
#undef UO
#define UI dbl
#define UU unsigned short
#define UO dbl
#include "impl_xmin.h"
#undef UI
#undef UU
#undef UO
static str
UDFBATxmin_(BAT **ret, BAT *bone)
{
BAT *bres = NULL;
bit two_tail_sorted_unsigned = FALSE;
bit two_tail_revsorted_unsigned = FALSE;
BUN n;
str msg = NULL;
/* assert calling sanity */
assert(ret != NULL);
/* handle NULL pointer */
if (bone == NULL)
throw(MAL, "batudf.xmin", RUNTIME_OBJECT_MISSING);
n = BATcount(bone);
/* allocate result BAT */
switch (bone->ttype) {
case TYPE_sht:
bres = BATnew(TYPE_void, TYPE_sht, TOTALTHREAD);
break;
case TYPE_int:
bres = BATnew(TYPE_void, TYPE_int, TOTALTHREAD);
break;
case TYPE_lng:
bres = BATnew(TYPE_void, TYPE_lng, TOTALTHREAD);
break;
case TYPE_dbl:
bres = BATnew(TYPE_void, TYPE_dbl, TOTALTHREAD);
break;
default:
throw(MAL, "batudf.xmin","tails of input BATs must be one of {sht, int, lng, dbl}");
}
if (bres == NULL)
throw(MAL, "batudf.xmin", MAL_MALLOC_FAIL);
/* advice on sequential scan */
BATaccessBegin(bone, USE_TAIL, MMAP_SEQUENTIAL);
/* call type-specific core algorithm */
switch (bone->ttype) {
case TYPE_sht:
msg = UDFBATxmin_sht_sht ( bres, bone, n,&two_tail_sorted_unsigned, &two_tail_revsorted_unsigned );
break;
case TYPE_int:
msg = UDFBATxmin_int_int ( bres, bone, n,&two_tail_sorted_unsigned, &two_tail_revsorted_unsigned );
break;
case TYPE_lng:
msg = UDFBATxmin_lng_lng ( bres, bone, n,&two_tail_sorted_unsigned, &two_tail_revsorted_unsigned );
break;
case TYPE_dbl:
msg = UDFBATxmin_dbl_dbl ( bres, bone, n,&two_tail_sorted_unsigned, &two_tail_revsorted_unsigned );
break;
default:
BBPreleaseref(bres->batCacheid);
throw(MAL, "batudf.xmin","tails of input BATs must be one of {sht, int, lng, dbl}");
}
BATaccessEnd(bone, USE_TAIL, MMAP_SEQUENTIAL);
if (msg != MAL_SUCCEED) {
BBPreleaseref(bres->batCacheid);
} else {
/* set number of tuples in result BAT */
BATsetcount(bres, 1);
/* set result properties */
bres->hdense = TRUE; /* result head is dense */
BATseqbase(bres, bone->hseqbase); /* result head has same seqbase as input */
bres->hsorted = 1; /* result head is sorted */
bres->hrevsorted = (BATcount(bres) <= 1);
BATkey(bres, TRUE); /* result head is key (unique) */
/* Result tail is sorted, if the left/first input tail is
* sorted and key (unique), or if the left/first input tail is
* sorted and the second/right input tail is sorted and the
* second/right tail values are either all >= 0 or all < 0;
* otherwise, we cannot tell.
*/
if (BATtordered(bone)
&& (BATtkey(bone) || two_tail_sorted_unsigned))
bres->tsorted = 1;
else
bres->tsorted = (BATcount(bres) <= 1);
if (BATtrevordered(bone)
&& (BATtkey(bone) || two_tail_revsorted_unsigned))
bres->trevsorted = 1;
else
bres->trevsorted = (BATcount(bres) <= 1);
/* result tail is key (unique), iff both input tails are */
/*BATkey(BATmirror(bres), BATtkey(bone) || BATtkey(btwo));*/
*ret = bres;
}
return msg;
}
/* MAL wrapper */
str
UDFBATxmin(bat *ires, bat *ione)
{
// startTimer();
BAT *bres = NULL, *bone = NULL;
str msg = NULL;
/* assert calling sanity */
assert(ires != NULL && ione != NULL);
/* bat-id -> BAT-descriptor */
if ((bone = BATdescriptor(*ione)) == NULL)
throw(MAL, "batudf.xmin", RUNTIME_OBJECT_MISSING);
/* do the work */
msg = UDFBATxmin_ ( &bres, bone);
/* release input BAT-descriptors */
BBPreleaseref(bone->batCacheid);
if (msg == MAL_SUCCEED) {
/* register result BAT in buffer pool */
BBPkeepref((*ires = bres->batCacheid));
}
// printf("Total time Required to UDFBATmin = %lf",endTimer());
return msg;
}
/****************************************************************************************/
/* Function Name : impl_xmin.h */
/****************************************************************************************/
* impl_xmin.h
*
* Created on: 23-Nov-2012
* Author: swapnil
*/
/* concatenate two or five tokens */
#define U_CONCAT_2(a,b) a##b
#define U_CONCAT_5(a,b,c,d,e) a##b##c##d##e
/* function names, *_nil & TYPE_* macros */
#define UF(p,i,o,s) U_CONCAT_5(p,i,_,o,s)
#define UN(t) U_CONCAT_2(t,_nil)
#define UT(t) U_CONCAT_2(TYPE_,t)
static str
UF(UDFBATxmin_,UI,UO,) ( BAT *bres, BAT *bone, BUN n,
bit *two_tail_sorted_unsigned,
bit *two_tail_revsorted_unsigned )
{
UI *one = NULL;
UO *res = NULL;
BUN i;
/* assert calling sanity */
assert(bres != NULL && bone != NULL);
assert(BATcapacity(bres) >= 1);
assert(BATcount(bone) >= n);
assert(bone->ttype == UT(UI));
assert(bres->ttype == UT(UO));
/* get direct access to the tail arrays */
one = (UI*) Tloc(bone, BUNfirst(bone));
res = (UO*) Tloc(bres, BUNfirst(bres));
int loop;
startTimer();
res[0]=one[0];
for(loop=1;loop<n;loop++)
{
if(res[0]>one[loop])
res[0]=one[loop];
}
printf("Time for clReleaseMemObject = %lf\n",endTimer());
return MAL_SUCCEED;
}
/* undo local defines */
#undef UT
#undef UN
#undef UF
#undef U_CONCAT_5
#undef U_CONCAT_2
//*************************************************************************************************/
when i am executing following SQL statement then it will give result but it takes 10 to 13 seconds
I know where i am executing on single core of CPU but when i executing that above statement
then, I think it will taking data from disk because disk access indicator led blow when i executing
that above SQL statement. means, It was not using system main memory.
I will be wrong.
Can each time it is accessing BAT from disk or from main memory?
Can you test me Program ?
and Can you give me guidance for accessing BAT?
I hope you will give me proper guidance.
My SQL statement results are as follow
sql>select xmin(v1) from demo;
+---------+
| xmin_v1 |
+=========+
| 1 |
+---------+
1 tuple (3.2s)
sql>select xmin(v1) from demo;
+---------+
| xmin_v1 |
+=========+
| 1 |
+---------+
1 tuple (9.3s)
sql>select xmin(v1) from demo;
+---------+
| xmin_v1 |
+=========+
| 1 |
+---------+
1 tuple (14.3s)
sql>select xmin(v1) from demo;
+---------+
| xmin_v1 |
+=========+
| 1 |
+---------+
1 tuple (3.4s)
--
Regards,
Swapnil K. Joshi