prepare to alternative ordering. No-op yet

feodor · feodor · commit e33dac2fcdeb · 2016-05-17T17:21:01.000+03:00
diff --git a/rum.h b/rum.h
@@ -287,6 +287,7 @@ typedef struct RumOptions
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
 	bool		useFastUpdate;	/* use fast updates? */
+	bool		useAlternativeOrder;
 	int			orderByColumn;
 	int			addToColumn;
 } RumOptions;
@@ -302,6 +303,11 @@ typedef struct RumOptions
 #define RUM_SHARE	BUFFER_LOCK_SHARE
 #define RUM_EXCLUSIVE  BUFFER_LOCK_EXCLUSIVE
 
+typedef struct RumKey {
+	ItemPointerData		ipd;
+	bool				isNull;
+	Datum				addToCompare;
+} RumKey;
 
 /*
  * RumState: working data structure describing the index being worked on
@@ -310,6 +316,7 @@ typedef struct RumState
 {
 	Relation	index;
 	bool		oneCol;			/* true if single-column index */
+	bool		useAlternativeOrder;
 	AttrNumber	attrnOrderByColumn;
 	AttrNumber	attrnAddToColumn;
 
@@ -486,6 +493,7 @@ extern void checkLeafDataPage(RumState *rumstate, AttrNumber attrnum, Page page)
 
 /* rumdatapage.c */
 extern int rumCompareItemPointers(ItemPointer a, ItemPointer b);
+extern int compareRumKey(RumState *state, RumKey *a, RumKey *b);
 extern char *rumDataPageLeafWriteItemPointer(char *ptr, ItemPointer iptr, ItemPointer prev, bool addInfoIsNull);
 extern Pointer rumPlaceToDataPageLeaf(Pointer ptr, OffsetNumber attnum,
 	ItemPointer iptr, Datum addInfo, bool addInfoIsNull, ItemPointer prev,
diff --git a/rumdatapage.c b/rumdatapage.c
@@ -267,6 +267,42 @@ rumCompareItemPointers(ItemPointer a, ItemPointer b)
 	return (ba > bb) ? 1 : -1;
 }
 
+int
+compareRumKey(RumState *state, RumKey *a, RumKey *b)
+{
+
+	/* assume NULL is greate than any real value */
+	if (state->useAlternativeOrder)
+	{
+		if (a->isNull == false && b->isNull == false)
+		{
+			int res;
+			AttrNumber	attnum = state->attrnOrderByColumn;
+
+			res = DatumGetInt32(FunctionCall2Coll(
+									&state->compareFn[attnum - 1],
+									state->supportCollation[attnum - 1],
+									a->addToCompare, b->addToCompare));
+			if (res != 0)
+				return res;
+			/* fallback to ItemPointerCompare */
+		}
+		else if (a->isNull == true)
+		{
+			if (b->isNull == false)
+				return 1; 
+			/* fallback to ItemPointerCompare */
+		}
+		else
+		{
+			Assert(b->isNull == true);
+			return -1;
+		}
+	}
+
+	return rumCompareItemPointers(&a->ipd, &b->ipd);
+}
+
 /*
  * Merge two ordered arrays of itempointers, eliminating any duplicates.
  * Returns the number of items in the result.
diff --git a/rumutil.c b/rumutil.c
@@ -55,6 +55,9 @@ _PG_init(void)
 	add_string_reloption(rum_relopt_kind, "addto",
 						 "Column name to add a order by column",
 						 NULL, NULL);
+	add_bool_reloption(rum_relopt_kind, "use_alternative_order",
+					   "Use (addinfo, itempointer) order instead of just itempointer",
+					   false);
 }
 
 /*
@@ -158,7 +161,16 @@ initRumState(RumState *state, Relation index)
 
 		if (!(AttributeNumberIsValid(state->attrnOrderByColumn) &&
 			  AttributeNumberIsValid(state->attrnAddToColumn)))
-			elog(ERROR, "AddTo and OrderBy colums should be defined both");
+			elog(ERROR, "AddTo and OrderBy columns should be defined both");
+
+		if (options->useAlternativeOrder)
+		{
+			if (!(AttributeNumberIsValid(state->attrnOrderByColumn) &&
+				  AttributeNumberIsValid(state->attrnAddToColumn)))
+				elog(ERROR, "to use alternative ordering AddTo and OrderBy should be defined");
+
+			state->useAlternativeOrder = true;
+		}
 	}
 
 	for (i = 0; i < origTupdesc->natts; i++)
@@ -766,7 +778,8 @@ rumoptions(Datum reloptions, bool validate)
 	static const relopt_parse_elt tab[] = {
 		{"fastupdate", RELOPT_TYPE_BOOL, offsetof(RumOptions, useFastUpdate)},
 		{"orderby", RELOPT_TYPE_STRING, offsetof(RumOptions, orderByColumn)},
-		{"addto", RELOPT_TYPE_STRING, offsetof(RumOptions, addToColumn)}
+		{"addto", RELOPT_TYPE_STRING, offsetof(RumOptions, addToColumn)},
+		{"use_alternative_order", RELOPT_TYPE_BOOL, offsetof(RumOptions, useAlternativeOrder)}
 	};
 
 	options = parseRelOptions(reloptions, validate, rum_relopt_kind,
