ING_DB

WEGA/contrib/ingres/dbs/src/access/replace.c

@@ -0,0 +1,182 @@
+# include	"gen.h"
+# include	"../h/dbs.h"
+# include	"../h/access.h"
+
+# define	SAMETUP		0
+# define	SAMEKEYS	1
+# define	DIFFTUP		2
+
+/*
+**	AAam_replace - replace an already existing tuple
+**
+**	AAam_replace will replace the tuple specified by TID
+**	with the new tuple. An attempt is made to not
+**	move the tuple if at all possible.
+**
+**	Three separate conditions are delt with. If the
+**	new tuple is the same as the old tuple, a return
+**	of zero occures and the page is not changed.
+**
+**	If the keys(if any) are the same and the canonical
+**	tuple lengths are the same, then the new tuple will
+**	be placed in the same location.
+**
+**	If the lengths or the keys are different, then the
+**	tuple is deleted and the new tuple inserted
+**
+**	Checkdups specifies whether to check for duplicates.
+**	If the new tuple is a duplicate of one already there,
+**	then the tuple at TID is deleted
+**	returns:
+**		<0  fatal error
+**		 0  ok
+**		 1  new tuple was duplicate of returned tid
+**		 2  tuple not found, already deleted (TID invalid)
+**
+**		If AAam_replace returns 1 then tid is set to the
+**		duplicate tuple. This is necessary for updating
+**		secondary indices.
+*/
+AAam_replace(d, tid, tuple, checkdups)
+register DESC			*d;
+register struct tup_id		*tid;
+char				*tuple;
+int				checkdups;
+{
+	register int			i;
+	register int			same;
+	register int			need;
+	register int			len;
+	register int			oldlength;
+	char				*new;
+	char				*old;
+	char				*oldt;
+	struct tup_id			primtid;
+	long				primpage;
+	char				oldtuple[MAXTUP];
+	extern char			*AAgetint_tuple();
+
+#	ifdef xATR1
+	if (AAtTfp(95, 0, "REPLACE: %.14s,", d->reldum.relid))
+	{
+		AAdumptid(tid);
+		printf("REPLACE: ");
+		AAprtup(d, tuple);
+	}
+#	endif
+
+	/* make tuple canonical */
+	need = AAcanonical(d, tuple);
+
+	/* if heap, no dup checking */
+	if (abs(ctoi(d->reldum.relspec)) == M_HEAP)
+		checkdups = FALSE;
+
+	if (i = AAgetpage(d, tid))
+		return (i);	/* fatal error */
+
+	/* check if tid exists */
+	if (i = AAinvalid(tid))
+		return (i);	/* already deleted or AAinvalid */
+
+	oldt = AAgetint_tuple(d, tid, oldtuple);
+	oldlength = AAtup_len(tid);
+
+	/* check whether tuples are the same, different lengths, different keys */
+	same = DIFFTUP;	/* assume diff lengths or keys */
+	if (oldlength == need)
+	{
+		/* same size. check for same domains */
+		same = SAMETUP;	/* assume identical */
+		new = tuple;
+		old = oldt;
+		for (i = 1; i <= d->reldum.relatts; i++)
+		{
+			len = ctou(d->relfrml[i]);
+			if (AAicompare(new, old, d->relfrmt[i], len))
+			{
+				if (d->relxtra[i])
+				{
+					same = DIFFTUP;
+					break;
+				}
+				same = SAMEKEYS;
+			}
+			old += len;
+			new += len;
+		}
+	}
+
+#	ifdef xATR2
+	AAtTfp(95, 1, "REPLACE: same=%d\n", same);
+#	endif
+
+	switch (same)
+	{
+	  case SAMETUP:		/* new tuple same as old tuple */
+		i = 1;	/* flag as duplicate */
+		/* though character strings may compare equal,
+		**  they can look different, so if they do look different
+		**  go ahead and do the replace using AAput_tuple.  */
+		if (!AAbequal(tuple, oldt, d->reldum.relwid))
+			goto puttuple;
+		break;
+
+	  case SAMEKEYS:	/* keys the same, lengths the same, tuples different */
+		if (checkdups)
+		{
+			/* This is either an ISAM or HASH file. If mainpg
+			** is non-zero, then the primary page = mainpg - 1.
+			** Otherwise, "find" must be called to determine
+			** the primary page
+			*/
+			if (AAcc_head->mainpg)
+			{
+				primpage = AAcc_head->mainpg - 1;
+				AAstuff_page(&primtid, &primpage);
+			}
+			else
+			{
+				if (i = AAam_find(d, FULLKEY, &primtid, &primtid, tuple))
+					return (i);	/* fatal error */
+				if (i = AAgetpage(d, tid))	/* restore page for tuple */
+					return (i);
+			}
+
+			if (i = AAscan_dups(d, &primtid, tuple))
+			{
+				if (i == 1)
+				{
+					AAdel_tuple(tid, oldlength);	/* tuple a duplicate */
+					d->reladds--;
+					/* copy tid of duplicate tuple */
+					AAbmove(&primtid, tid, sizeof(primtid));
+				}
+				break;
+			}
+		}
+		goto puttuple;
+
+	  case DIFFTUP:		/* keys different or lengths different */
+		AAdel_tuple(tid, oldlength);
+
+		/* find where to put tuple */
+		if (i = AAfindbest(d, tid, tuple, need, checkdups))
+		{
+			d->reladds--;
+			break;
+		}
+
+		/* place new tuple in page */
+puttuple:
+		AAput_tuple(tid, AAcctuple, need);
+		i = 0;
+	}
+
+#	ifdef xATR1
+	if (AAtTfp(95, 2, "REPLACE: rets %d,", i))
+		AAdumptid(tid);
+#	endif
+
+	return (i);
+}