Improve efficiency of attribute scanning in CopyReadAttributesCSV.

The loop is split into two parts, inside quotes, and outside quotes, saving some instructions in both parts.

Heikki Linnakangas

src/backend/commands/copy.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.295 2008/01/01 19:45:48 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.296 2008/03/08 01:16:26 adunstan Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2913,7 +2913,6 @@ CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
 	for (;;)
 	{
 		bool		found_delim = false;
-		bool		in_quote = false;
 		bool		saw_quote = false;
 		char	   *start_ptr;
 		char	   *end_ptr;
@@ -2929,30 +2928,53 @@ CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
 		start_ptr = cur_ptr;
 		fieldvals[fieldno] = output_ptr;
 
-		/* Scan data for field */
+		/* Scan data for field,
+		 *
+		 * The loop starts in "not quote" mode and then toggles between 
+		 * that and "in quote" mode. 
+		 * The loop exits normally if it is in "not quote" mode and a
+		 * delimiter or line end is seen.
+		 */
 		for (;;)
 		{
 			char		c;
 
+			/* Not in quote */
+			for (;;)
+			{
 				end_ptr = cur_ptr;
 				if (cur_ptr >= line_end_ptr)
-				break;
+					goto endfield;
 				c = *cur_ptr++;
 				/* unquoted field delimiter */
-			if (c == delimc && !in_quote)
+				if (c == delimc)
 				{
 					found_delim = true;
-				break;
+					goto endfield;
 				}
 				/* start of quoted field (or part of field) */
-			if (c == quotec && !in_quote)
+				if (c == quotec)
 				{
 					saw_quote = true;
-				in_quote = true;
-				continue;
+					break;
+				}
+				/* Add c to output string */
+				*output_ptr++ = c;
 			}
+
+			/* In quote */
+			for (;;)
+			{
+				end_ptr = cur_ptr;
+				if (cur_ptr >= line_end_ptr)
+					ereport(ERROR,
+							(errcode(ERRCODE_BAD_COPY_FILE_FORMAT),
+							 errmsg("unterminated CSV quoted field")));
+
+				c = *cur_ptr++;
+
 				/* escape within a quoted field */
-			if (c == escapec && in_quote)
+				if (c == escapec)
 				{
 					/*
 					 * peek at the next char if available, and escape it if it is
@@ -2970,31 +2992,23 @@ CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
 						}
 					}
 				}
-
 				/*
 				 * end of quoted field. Must do this test after testing for escape
 				 * in case quote char and escape char are the same (which is the
 				 * common case).
 				 */
-			if (c == quotec && in_quote)
-			{
-				in_quote = false;
-				continue;
-			}
+				if (c == quotec)
+					break;
 
 				/* Add c to output string */
 				*output_ptr++ = c;
 			}
+		}
+	endfield:
 
 		/* Terminate attribute value in output area */
 		*output_ptr++ = '\0';
 
-		/* Shouldn't still be in quote mode */
-		if (in_quote)
-			ereport(ERROR,
-					(errcode(ERRCODE_BAD_COPY_FILE_FORMAT),
-					 errmsg("unterminated CSV quoted field")));
-
 		/* Check whether raw input matched null marker */
 		input_len = end_ptr - start_ptr;
 		if (!saw_quote && input_len == cstate->null_print_len &&