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

diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 2fb2a312710e02e58ae9350558a93a419d0a2b30..194f3b380a1e0ef05db8af1a5528f059c03bab0f 100644 (file)
--- a/src/backend/commands/copy.c
+++ b/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;
@@ -2929,72 +2928,87 @@ 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;
 
-                       end_ptr = cur_ptr;
-                       if (cur_ptr >= line_end_ptr)
-                               break;
-                       c = *cur_ptr++;
-                       /* unquoted field delimiter */
-                       if (c == delimc && !in_quote)
-                       {
-                               found_delim = true;
-                               break;
-                       }
-                       /* start of quoted field (or part of field) */
-                       if (c == quotec && !in_quote)
+                       /* Not in quote */
+                       for (;;)
                        {
-                               saw_quote = true;
-                               in_quote = true;
-                               continue;
+                               end_ptr = cur_ptr;
+                               if (cur_ptr >= line_end_ptr)
+                                       goto endfield;
+                               c = *cur_ptr++;
+                               /* unquoted field delimiter */
+                               if (c == delimc)
+                               {
+                                       found_delim = true;
+                                       goto endfield;
+                               }
+                               /* start of quoted field (or part of field) */
+                               if (c == quotec)
+                               {
+                                       saw_quote = true;
+                                       break;
+                               }
+                               /* Add c to output string */
+                               *output_ptr++ = c;
                        }
-                       /* escape within a quoted field */
-                       if (c == escapec && in_quote)
+
+                       /* In quote */
+                       for (;;)
                        {
-                               /*
-                                * peek at the next char if available, and escape it if it is
-                                * an escape char or a quote char
-                                */
-                               if (cur_ptr < line_end_ptr)
-                               {
-                                       char            nextc = *cur_ptr;
+                               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++;
 
-                                       if (nextc == escapec || nextc == quotec)
+                               /* escape within a quoted field */
+                               if (c == escapec)
+                               {
+                                       /*
+                                        * peek at the next char if available, and escape it if it is
+                                        * an escape char or a quote char
+                                        */
+                                       if (cur_ptr < line_end_ptr)
                                        {
-                                               *output_ptr++ = nextc;
-                                               cur_ptr++;
-                                               continue;
+                                               char            nextc = *cur_ptr;
+
+                                               if (nextc == escapec || nextc == quotec)
+                                               {
+                                                       *output_ptr++ = nextc;
+                                                       cur_ptr++;
+                                                       continue;
+                                               }
                                        }
                                }
-                       }
+                               /*
+                                * 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)
+                                       break;
 
-                       /*
-                        * 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;
+                               /* Add c to output string */
+                               *output_ptr++ = c;
                        }
-
-                       /* 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 &&