Rearrange coding in COPY so that expansible string buffer for data being

read is reused for successive attributes, instead of being deleted and
recreated from scratch for each value read in.  This reduces palloc/pfree
overhead a lot.  COPY IN still seems to be noticeably slower than it was
in 6.5 --- we need to figure out why.  This change takes care of the only
major performance loss I can see in copy.c itself, so the performance
problem is at a lower level somewhere.

src/backend/commands/copy.c

@@ -6,7 +6,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.95 2000/01/14 22:11:33 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/copy.c,v 1.96 2000/01/16 21:37:50 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -66,6 +66,21 @@ static int	CountTuples(Relation relation);
 static int	lineno;
 static bool	fe_eof;
 
+/*
+ * These static variables are used to avoid incurring overhead for each
+ * attribute processed.  attribute_buf is reused on each CopyReadAttribute
+ * call to hold the string being read in.  Under normal use it will soon
+ * grow to a suitable size, and then we will avoid palloc/pfree overhead
+ * for subsequent attributes.  Note that CopyReadAttribute returns a pointer
+ * to attribute_buf's data buffer!
+ * encoding, if needed, can be set once at the start of the copy operation.
+ */
+static StringInfoData	attribute_buf;
+#ifdef MULTIBYTE
+static int				encoding;
+#endif
+
+
 /*
  * Internal communications functions
  */
@@ -276,6 +291,14 @@ DoCopy(char *relname, bool binary, bool oids, bool from, bool pipe,
 			 "directly to or from a file.  Anyone can COPY to stdout or "
 			 "from stdin.  Psql's \\copy command also works for anyone.");
 
+	/*
+	 * Set up variables to avoid per-attribute overhead.
+	 */
+	initStringInfo(&attribute_buf);
+#ifdef MULTIBYTE
+	encoding = pg_get_client_encoding();
+#endif
+
 	if (from)
 	{							/* copy from file to database */
 		if (rel->rd_rel->relkind == RELKIND_SEQUENCE)
@@ -337,6 +360,7 @@ DoCopy(char *relname, bool binary, bool oids, bool from, bool pipe,
 		}
 		CopyTo(rel, binary, oids, fp, delim, null_print);
 	}
+
 	if (!pipe)
 	{
 		FreeFile(fp);
@@ -348,6 +372,7 @@ DoCopy(char *relname, bool binary, bool oids, bool from, bool pipe,
 		if (IsUnderPostmaster)
 			pq_endcopyout(false);
 	}
+	pfree(attribute_buf.data);
 
 	/*
 	 * Close the relation.  If reading, we can release the AccessShareLock
@@ -717,7 +742,6 @@ CopyFrom(Relation rel, bool binary, bool oids, FILE *fp, char *delim, char *null
 					loaded_oid = oidin(string);
 					if (loaded_oid < BootstrapObjectIdData)
 						elog(ERROR, "COPY TEXT: Invalid Oid. line: %d", lineno);
-					pfree(string);
 				}
 			}
 			for (i = 0; i < attr_count && !done; i++)
@@ -727,8 +751,6 @@ CopyFrom(Relation rel, bool binary, bool oids, FILE *fp, char *delim, char *null
 				{
 					values[i] = PointerGetDatum(NULL);
 					nulls[i] = 'n';
-					if (string)
-						pfree(string);
 				}
 				else if (string == NULL)
 					done = 1;
@@ -745,7 +767,6 @@ CopyFrom(Relation rel, bool binary, bool oids, FILE *fp, char *delim, char *null
 					if (!PointerIsValid(values[i]) &&
 						!(rel->rd_att->attrs[i]->attbyval))
 						elog(ERROR, "copy from line %d: Bad file format", lineno);
-					pfree(string);
 				}
 			}
 			if (!done)
@@ -1115,9 +1136,10 @@ CopyReadNewline(FILE *fp, int *newline)
 /*
  * Read the value of a single attribute.
  *
- * Result is either a palloc'd string, or NULL (if EOF or a null attribute).
- * *isnull is set true if a null attribute, else false.
+ * Result is either a string, or NULL (if EOF or a null attribute).
+ * Note that the caller should not pfree the string!
  *
+ * *isnull is set true if a null attribute, else false.
  * delim is the string of acceptable delimiter characters(s).
  * *newline remembers whether we've seen a newline ending this tuple.
  * null_print says how NULL values are represented
@@ -1126,19 +1148,20 @@ CopyReadNewline(FILE *fp, int *newline)
 static char *
 CopyReadAttribute(FILE *fp, bool *isnull, char *delim, int *newline, char *null_print)
 {
-	StringInfoData	attribute_buf;
 	char		c;
 #ifdef MULTIBYTE
 	int			mblen;
-	int			encoding;
 	unsigned char s[2];
 	char	   *cvt;
 	int			j;
 
-	encoding = pg_get_client_encoding();
 	s[1] = 0;
 #endif
 
+	/* reset attribute_buf to empty */
+	attribute_buf.len = 0;
+	attribute_buf.data[0] = '\0';
+
 	/* if last delimiter was a newline return a NULL attribute */
 	if (*newline)
 	{
@@ -1148,8 +1171,6 @@ CopyReadAttribute(FILE *fp, bool *isnull, char *delim, int *newline, char *null_
 
 	*isnull = (bool) false;		/* set default */
 
-	initStringInfo(&attribute_buf);
-
 	if (CopyGetEof(fp))
 		goto endOfFile;
 
@@ -1265,17 +1286,20 @@ CopyReadAttribute(FILE *fp, bool *isnull, char *delim, int *newline, char *null_
 									   attribute_buf.len);
 	if (cvt != attribute_buf.data)
 	{
-		pfree(attribute_buf.data);
-		return cvt;
+		/* transfer converted data back to attribute_buf */
+		attribute_buf.len = 0;
+		attribute_buf.data[0] = '\0';
+		appendBinaryStringInfo(&attribute_buf, cvt, strlen(cvt));
+		pfree(cvt);
 	}
 #endif
+
     if (strcmp(attribute_buf.data, null_print)==0)
         *isnull = true;
 
 	return attribute_buf.data;
 
 endOfFile:
-	pfree(attribute_buf.data);
 	return NULL;
 }
 
@@ -1286,13 +1310,11 @@ CopyAttributeOut(FILE *fp, char *server_string, char *delim)
 	char		c;
 #ifdef MULTIBYTE
 	char	   *string_start;
-	int			encoding;
 	int			mblen;
 	int			i;
 #endif
 
 #ifdef MULTIBYTE
-	encoding = pg_get_client_encoding();
 	string = (char *) pg_server_to_client((unsigned char *) server_string,
 										  strlen(server_string));
 	string_start = string;