Revert "Permit dump/reload of not-too-large >1GB tuples"

This reverts commit 4e01eca.
Per Tom Lane, changing the definition of StringInfoData amounts to an
ABI break, which is unacceptable in back branches.

Author: alvherre

src/backend/access/common/heaptuple.c

@@ -741,9 +741,7 @@ heap_form_tuple(TupleDesc tupleDescriptor,
 	 * Allocate and zero the space needed.  Note that the tuple body and
 	 * HeapTupleData management structure are allocated in one chunk.
 	 */
-	tuple = MemoryContextAllocExtended(CurrentMemoryContext,
-									   HEAPTUPLESIZE + len,
-									   MCXT_ALLOC_HUGE | MCXT_ALLOC_ZERO);
+	tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + len);
 	tuple->t_data = td = (HeapTupleHeader) ((char *) tuple + HEAPTUPLESIZE);
 
 	/*

src/backend/commands/copy.c

@@ -397,7 +397,7 @@ ReceiveCopyBegin(CopyState cstate)
 			pq_sendint(&buf, format, 2);		/* per-column formats */
 		pq_endmessage(&buf);
 		cstate->copy_dest = COPY_NEW_FE;
-		cstate->fe_msgbuf = makeLongStringInfo();
+		cstate->fe_msgbuf = makeStringInfo();
 	}
 	else if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 2)
 	{
@@ -1903,7 +1903,7 @@ CopyTo(CopyState cstate)
 	cstate->null_print_client = cstate->null_print;		/* default */
 
 	/* We use fe_msgbuf as a per-row buffer regardless of copy_dest */
-	cstate->fe_msgbuf = makeLongStringInfo();
+	cstate->fe_msgbuf = makeStringInfo();
 
 	/* Get info about the columns we need to process. */
 	cstate->out_functions = (FmgrInfo *) palloc(num_phys_attrs * sizeof(FmgrInfo));
@@ -2717,8 +2717,8 @@ BeginCopyFrom(Relation rel,
 	cstate->cur_attval = NULL;
 
 	/* Set up variables to avoid per-attribute overhead. */
-	initLongStringInfo(&cstate->attribute_buf);
-	initLongStringInfo(&cstate->line_buf);
+	initStringInfo(&cstate->attribute_buf);
+	initStringInfo(&cstate->line_buf);
 	cstate->line_buf_converted = false;
 	cstate->raw_buf = (char *) palloc(RAW_BUF_SIZE + 1);
 	cstate->raw_buf_index = cstate->raw_buf_len = 0;

src/backend/lib/stringinfo.c

@@ -4,8 +4,7 @@
  *
  * StringInfo provides an indefinitely-extensible string data type.
  * It can be used to buffer either ordinary C strings (null-terminated text)
- * or arbitrary binary data.  All storage is allocated with palloc() and
- * friends.
+ * or arbitrary binary data.  All storage is allocated with palloc().
  *
  * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
@@ -37,29 +36,11 @@ makeStringInfo(void)
 	return res;
 }
 
-/*
- * makeLongStringInfo
- *
- * Same as makeStringInfo, for larger strings.
- */
-StringInfo
-makeLongStringInfo(void)
-{
-	StringInfo	res;
-
-	res = (StringInfo) palloc(sizeof(StringInfoData));
-
-	initLongStringInfo(res);
-
-	return res;
-}
-
-
 /*
  * initStringInfo
  *
  * Initialize a StringInfoData struct (with previously undefined contents)
- * to describe an empty string; don't enable long strings yet.
+ * to describe an empty string.
  */
 void
 initStringInfo(StringInfo str)
@@ -68,22 +49,9 @@ initStringInfo(StringInfo str)
 
 	str->data = (char *) palloc(size);
 	str->maxlen = size;
-	str->long_ok = false;
 	resetStringInfo(str);
 }
 
-/*
- * initLongStringInfo
- *
- * Same as initStringInfo, plus enable long strings.
- */
-void
-initLongStringInfo(StringInfo str)
-{
-	initStringInfo(str);
-	str->long_ok = true;
-}
-
 /*
  * resetStringInfo
  *
@@ -174,7 +142,7 @@ appendStringInfoVA(StringInfo str, const char *fmt, va_list args)
 	/*
 	 * Return pvsnprintf's estimate of the space needed.  (Although this is
 	 * given as a size_t, we know it will fit in int because it's not more
-	 * than either MaxAllocSize or half an int's width.)
+	 * than MaxAllocSize.)
 	 */
 	return (int) nprinted;
 }
@@ -276,25 +244,15 @@ appendBinaryStringInfo(StringInfo str, const char *data, int datalen)
 void
 enlargeStringInfo(StringInfo str, int needed)
 {
-	Size		newlen;
-	Size		limit;
-
-	/*
-	 * Determine the upper size limit.  Because of overflow concerns outside
-	 * of this module, we limit ourselves to 4-byte signed integer range,
-	 * even for "long_ok" strings.
-	 */
-	limit = str->long_ok ?
-		(((Size) 1) << (sizeof(int32) * 8 - 1)) - 1 :
-		MaxAllocSize;
+	int			newlen;
 
 	/*
 	 * Guard against out-of-range "needed" values.  Without this, we can get
 	 * an overflow or infinite loop in the following.
 	 */
 	if (needed < 0)				/* should not happen */
 		elog(ERROR, "invalid string enlargement request size: %d", needed);
-	if (((Size) needed) >= (limit - (Size) str->len))
+	if (((Size) needed) >= (MaxAllocSize - (Size) str->len))
 		ereport(ERROR,
 				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 				 errmsg("out of memory"),
@@ -303,7 +261,7 @@ enlargeStringInfo(StringInfo str, int needed)
 
 	needed += str->len + 1;		/* total space required now */
 
-	/* Because of the above test, we now have needed <= limit */
+	/* Because of the above test, we now have needed <= MaxAllocSize */
 
 	if (needed <= str->maxlen)
 		return;					/* got enough space already */
@@ -318,14 +276,14 @@ enlargeStringInfo(StringInfo str, int needed)
 		newlen = 2 * newlen;
 
 	/*
-	 * Clamp to the limit in case we went past it.  Note we are assuming here
-	 * that limit <= INT_MAX/2, else the above loop could overflow.  We will
-	 * still have newlen >= needed.
+	 * Clamp to MaxAllocSize in case we went past it.  Note we are assuming
+	 * here that MaxAllocSize <= INT_MAX/2, else the above loop could
+	 * overflow.  We will still have newlen >= needed.
 	 */
-	if (newlen > limit)
-		newlen = limit;
+	if (newlen > (int) MaxAllocSize)
+		newlen = (int) MaxAllocSize;
 
-	str->data = (char *) repalloc_huge(str->data, (Size) newlen);
+	str->data = (char *) repalloc(str->data, newlen);
 
 	str->maxlen = newlen;
 }

src/include/lib/stringinfo.h

@@ -30,8 +30,6 @@
  *		cursor	is initialized to zero by makeStringInfo or initStringInfo,
  *				but is not otherwise touched by the stringinfo.c routines.
  *				Some routines use it to scan through a StringInfo.
- *		long_ok whether this StringInfo can allocate more than MaxAllocSize
- *				bytes (but still up to 2GB).
  *-------------------------
  */
 typedef struct StringInfoData
@@ -40,7 +38,6 @@ typedef struct StringInfoData
 	int			len;
 	int			maxlen;
 	int			cursor;
-	bool		long_ok;
 } StringInfoData;
 
 typedef StringInfoData *StringInfo;
@@ -49,11 +46,11 @@ typedef StringInfoData *StringInfo;
 /*------------------------
  * There are two ways to create a StringInfo object initially:
  *
- * StringInfo stringptr = makeStringInfo(); // or makeLongStringInfo();
+ * StringInfo stringptr = makeStringInfo();
  *		Both the StringInfoData and the data buffer are palloc'd.
  *
  * StringInfoData string;
- * initStringInfo(&string); // or initLongStringInfo();
+ * initStringInfo(&string);
  *		The data buffer is palloc'd but the StringInfoData is just local.
  *		This is the easiest approach for a StringInfo object that will
  *		only live as long as the current routine.
@@ -70,26 +67,21 @@ typedef StringInfoData *StringInfo;
 
 /*------------------------
  * makeStringInfo
- * makeLongStringInfo
- * Create an empty 'StringInfoData' & return a pointer to it.  The former
- * allows up to 1 GB in size, per palloc(); the latter allows up to 2 GB.
+ * Create an empty 'StringInfoData' & return a pointer to it.
  */
 extern StringInfo makeStringInfo(void);
-extern StringInfo makeLongStringInfo(void);
 
 /*------------------------
  * initStringInfo
- * initLongStringInfo
  * Initialize a StringInfoData struct (with previously undefined contents)
- * to describe an empty string.  Size limits as above.
+ * to describe an empty string.
  */
 extern void initStringInfo(StringInfo str);
-extern void initLongStringInfo(StringInfo str);
 
 /*------------------------
  * resetStringInfo
  * Clears the current content of the StringInfo, if any. The
- * StringInfo remains valid.  The long_ok flag is not reset.
+ * StringInfo remains valid.
  */
 extern void resetStringInfo(StringInfo str);