From: Pavan Deolasee <pavan.deolasee@gmail.com>
Date: Thu, 3 Mar 2016 09:31:06 +0000 (+0530)
Subject: Avoid repeated palloc for query strings while handling multi-statement SQLs
X-Git-Tag: XL9_5_R1BETA2~41
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=8ea0a7aa1d0c4480517da7486c5bb5f95868c41a;p=postgres-xl.git

Avoid repeated palloc for query strings while handling multi-statement SQLs

We now only pass pointers until we have the complete query string. At that
point, we only required bytes and copy the query string
---

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 4593316fb9..c42e59a437 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -778,7 +778,8 @@ stmtmulti:	stmtmulti ';' stmt
 				{
 					if ($3 != NULL)
 					{
-						char *query = scanner_get_query(@3, -1, yyscanner);
+						char *query;
+						ListCell *last;
 						/*
 						 * Because of the way multi-commands are parsed by the
 						 * parser, when the earlier command was parsed and
@@ -787,12 +788,16 @@ stmtmulti:	stmtmulti ';' stmt
 						 * the ';' token, add '\0' at the corresponding offset
 						 * to get a separated command.
 						 */
-						if ($1->lastQuery)
-							$1->lastQuery[@2 - $1->offset] = '\0';
+						last = list_tail($1->queries);
+						query = palloc(@2 - $1->offset + 1);
+						memcpy(query, lfirst(last), @2 - $1->offset);
+						query[@2 - $1->offset] = '\0';
+
+						lfirst(last) = query;
+						query = scanner_get_query(@3, -1, yyscanner);
 						$1->offset = @2;
 						$1->parsetrees = lappend($1->parsetrees, $3);
-						$1->queries = lappend($1->queries, makeString(query));
-						$1->lastQuery = query;
+						$1->queries = lappend($1->queries, query);
 						$$ = $1;
 					}
 					else
@@ -804,7 +809,6 @@ stmtmulti:	stmtmulti ';' stmt
 					{
 						StmtMulti *n = (StmtMulti *) palloc0(sizeof (StmtMulti));
 						char *query = scanner_get_query(@1, -1, yyscanner);
-						n->lastQuery = query;
 
 						/*
 						 * Keep track of the offset where $1 started. We don't
@@ -825,7 +829,7 @@ stmtmulti:	stmtmulti ';' stmt
 						 * that resulted in the parsetree
 						 */
 						n->parsetrees = list_make1($1);
-						n->queries = list_make1(makeString(query));
+						n->queries = list_make1(query);
 						$$ = n;
 					}
 					else
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index 0d36717f4e..359ec9ca89 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -1557,8 +1557,6 @@ scanner_get_query(int start, int len, core_yyscan_t yyscanner)
 	else if (len + start > strlen(yyextra->query))
 		return NULL;
 
-	query = palloc0(len + 1);
-	memcpy(query, yyextra->query + start, len);
-	query[len] = '\0';
+	query = yyextra->query + start;
 	return query; 
 }
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 52dd180877..a7ee658a5d 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1176,7 +1176,7 @@ exec_simple_query(const char *query_string)
 	forboth(parsetree_item, parsetree_list, querysource_item, querysource_list)
 	{
 		Node	   *parsetree = (Node *) lfirst(parsetree_item);
-		char	   *querysource = ((Value *) lfirst(querysource_item))->val.str;
+		char	   *querysource = (char *) lfirst(querysource_item);
 		bool		snapshot_set = false;
 		const char *commandTag;
 		char		completionTag[COMPLETION_TAG_BUFSIZE];