bool
compareDatum(Datum value1, Datum value2, Oid typeOid){
bool res = false;
switch(typeOid){
case 20:
case 21:
case 23:
{
res = datumIsEqual(value1, value2, true, (typeOid==20)? 8 : ((typeOid==21)? 2 : 4));
return res;
}
case 700:
case 701:
{
res = datumIsEqual(value1, value2, false, (typeOid==700)? 4 : 8 );
return res;
}
case 1042:
{
res = DirectFunctionCall2(bpchareq, value1, value2);
return res;
}
case 1043:
{
res = DirectFunctionCall2(texteq, value1, value2);
return res;
}
default:
return false;
}
}
/*
* Compare the tuple and slot and check if they have equal values.
*
* We use binary datum comparison which might return false negatives but
* that's the best we can do here as there may be multiple notions of
* equality for the data types and table columns don't specify which one
* to use.
*/
static bool
tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
{
Datum values[MaxTupleAttributeNumber];
bool isnull[MaxTupleAttributeNumber];
int attrnum;
Form_pg_attribute att;
heap_deform_tuple(tup, desc, values, isnull);
/* Check equality of the attributes. */
for (attrnum = 0; attrnum < desc->natts; attrnum++)
{
/*
* If one value is NULL and other is not, then they are certainly not
* equal
*/
if (isnull[attrnum] != slot->tts_isnull[attrnum])
return false;
/*
* If both are NULL, they can be considered equal.
*/
if (isnull[attrnum])
continue;
att = desc->attrs[attrnum];
if (!datumIsEqual(values[attrnum], slot->tts_values[attrnum],
att->attbyval, att->attlen))
return false;
}
return true;
}
/*
* UpdateTopnArray is a helper function for the unions and inserts. It takes
* given item and its frequency. If the item is not in the top-n array, it tries
* to insert new item. If there is place in the top-n array, it insert directly.
* Otherwise, it compares its frequency with the minimum of current items in the
* array and updates top-n array if new frequency is bigger.
*/
static ArrayType *
UpdateTopnArray(CmsTopn *cmsTopn, Datum candidateItem, TypeCacheEntry *itemTypeCacheEntry,
Frequency itemFrequency, bool *topnArrayUpdated)
{
ArrayType *currentTopnArray = TopnArray(cmsTopn);
ArrayType *updatedTopnArray = NULL;
int16 itemTypeLength = itemTypeCacheEntry->typlen;
bool itemTypeByValue = itemTypeCacheEntry->typbyval;
char itemTypeAlignment = itemTypeCacheEntry->typalign;
Frequency minOfNewTopnItems = MAX_FREQUENCY;
bool candidateAlreadyInArray = false;
int candidateIndex = -1;
int currentArrayLength = ARR_DIMS(currentTopnArray)[0];
if (currentArrayLength == 0)
{
Oid itemType = itemTypeCacheEntry->type_id;
if (itemTypeCacheEntry->typtype == TYPTYPE_COMPOSITE)
{
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("composite types are not supported")));
}
currentTopnArray = construct_empty_array(itemType);
}
/*
* If item frequency is smaller than min frequency of old top-n items,
* it cannot be in the top-n items and we insert it only if there is place.
* Otherwise, we need to check new minimum and whether it is in the top-n.
*/
if (itemFrequency <= cmsTopn->minFrequencyOfTopnItems)
{
if (currentArrayLength < cmsTopn->topnItemCount)
{
candidateIndex = currentArrayLength + 1;
minOfNewTopnItems = itemFrequency;
}
}
else
{
ArrayIterator iterator = array_create_iterator(currentTopnArray, 0);
Datum topnItem = 0;
int topnItemIndex = 1;
int minItemIndex = 1;
bool hasMoreItem = false;
bool isNull = false;
/*
* Find the top-n item with minimum frequency to replace it with candidate
* item.
*/
hasMoreItem = array_iterate(iterator, &topnItem, &isNull);
while (hasMoreItem)
{
Frequency topnItemFrequency = 0;
/* check if we already have this item in top-n array */
candidateAlreadyInArray = datumIsEqual(topnItem, candidateItem,
itemTypeByValue, itemTypeLength);
if (candidateAlreadyInArray)
{
minItemIndex = -1;
break;
}
/* keep track of minumum frequency item in the top-n array */
topnItemFrequency = CmsTopnEstimateItemFrequency(cmsTopn, topnItem,
itemTypeCacheEntry);
if (topnItemFrequency < minOfNewTopnItems)
{
minOfNewTopnItems = topnItemFrequency;
minItemIndex = topnItemIndex;
}
hasMoreItem = array_iterate(iterator, &topnItem, &isNull);
topnItemIndex++;
}
/* if new item is not in the top-n and there is place, insert the item */
if (!candidateAlreadyInArray && currentArrayLength < cmsTopn->topnItemCount)
{
minItemIndex = currentArrayLength + 1;
minOfNewTopnItems = Min(minOfNewTopnItems, itemFrequency);
}
candidateIndex = minItemIndex;
}
/*
* If it is not in the top-n structure and its frequency bigger than minimum
* put into top-n instead of the item which has minimum frequency. If it is
* in top-n or not frequent items, do not change anything.
*/
if (!candidateAlreadyInArray && minOfNewTopnItems <= itemFrequency)
{
updatedTopnArray = array_set(currentTopnArray, 1, &candidateIndex,
candidateItem, false, -1, itemTypeLength,
itemTypeByValue, itemTypeAlignment);
cmsTopn->minFrequencyOfTopnItems = minOfNewTopnItems;
*topnArrayUpdated = true;
}
else
{
updatedTopnArray = currentTopnArray;
*topnArrayUpdated = false;
}
return updatedTopnArray;
}
