pgpool2.git / summary / log / commit / refs

commit    b5f26de7d67278db695e1be8f0c426e59b8a050b
Author:   Tatsuo Ishii <ishii@postgresql.org>
Date:     Sat Nov 17 10:12:40 2012 +0000

    Fix bug with query cache returning incorrect data in some cases when a
    persistent table and temp table have same name.
    
    Here is a sequence to trigger the bug:
    1) CREATE TABLE t1(i int);	-- create a persistent table
    2) INSERT INTO t1 VALUES(1);
    3) SELECT * FROM t1;		-- query cache entry created
    4) CREATE TEMP TABLE t1(i int);	-- create a temp table
    5) SELECT * FROM t1;		-- query cache entry mistakenly created!
    
    Problem is #3 creates relcache entry for t1, and #5 incorrecly uses it
    and believes that temp table t1 is not a temp table. To solve the
    problem, new function discard_temp_table_relcache() added and it gets
    called in ReadyforQuery if CREATE TEMP TABLE executed to discard
    relcache for temp table info.


 pool_proto_modules.c | 31 +++++++++++++++++++++++--------
 pool_select_walker.c | 27 ++++++++++++++++++++-------
 pool_select_walker.h |  1 +
 3 files changed, 44 insertions(+), 15 deletions(-)

diff --git a/pool_proto_modules.c b/pool_proto_modules.c
index ed186a647..2fd2a1d8c 100644
--- a/pool_proto_modules.c
+++ b/pool_proto_modules.c
@@ -1724,15 +1724,30 @@ POOL_STATUS ReadyForQuery(POOL_CONNECTION *frontend,
 						return POOL_END;
 				}
 
-				/*
-				 * If the query was not READ SELECT, and we are in an
-				 * explicit transaction, remember that we had a write
-				 * query in this transaction.
-				 */
-				else if (!is_select_query(node, query) &&
-						 TSTATE(backend, MASTER_SLAVE ? PRIMARY_NODE_ID : REAL_MASTER_NODE_ID) == 'T')
+				else if (!is_select_query(node, query))
 				{
-					pool_set_writing_transaction();
+					/*
+					 * If the query was not READ SELECT, and we are in an
+					 * explicit transaction, remember that we had a write
+					 * query in this transaction.
+					 */
+					if (TSTATE(backend, MASTER_SLAVE ? PRIMARY_NODE_ID : REAL_MASTER_NODE_ID) == 'T')
+					{
+						pool_set_writing_transaction();
+					}
+
+					/*
+					 * If the query was CREATE TEMP TABLE, discard
+					 * temp table relcache because we might have had
+					 * persistent table relation cache which has table
+					 * name as the tem table.
+					 */
+					if (IsA(node, CreateStmt))
+					{
+						CreateStmt *create_table_stmt = (CreateStmt *)node;
+						if (create_table_stmt->relation->istemp)
+							discard_temp_table_relcache();
+					}
 				}
 			}
 
diff --git a/pool_select_walker.c b/pool_select_walker.c
index 8a2e23222..1f16d0d1f 100644
--- a/pool_select_walker.c
+++ b/pool_select_walker.c
@@ -493,6 +493,8 @@ static bool is_system_catalog(char *table_name)
  * Judge the table used in a query represented by node is a temporary
  * table or not.
  */
+static POOL_RELCACHE *is_temp_table_relcache;
+
 static bool is_temp_table(char *table_name)
 {
 /*
@@ -520,7 +522,6 @@ static bool is_temp_table(char *table_name)
 	int hasrelistemp;
 	bool result;
 	static POOL_RELCACHE *hasrelistemp_cache;
-	static POOL_RELCACHE *relcache;
 	char *query;
 	POOL_CONNECTION_POOL *backend;
 
@@ -555,12 +556,12 @@ static bool is_temp_table(char *table_name)
 	/*
 	 * If relcache does not exist, create it.
 	 */
-	if (!relcache)
+	if (!is_temp_table_relcache)
 	{
-		relcache = pool_create_relcache(pool_config->relcache_size, query,
-										int_register_func, int_unregister_func,
-										true);
-		if (relcache == NULL)
+		is_temp_table_relcache = pool_create_relcache(pool_config->relcache_size, query,
+													  int_register_func, int_unregister_func,
+													  true);
+		if (is_temp_table_relcache == NULL)
 		{
 			pool_error("is_temp_table: pool_create_relcache error");
 			return false;
@@ -570,10 +571,22 @@ static bool is_temp_table(char *table_name)
 	/*
 	 * Search relcache.
 	 */
-	result = pool_search_relcache(relcache, backend, table_name)==0?false:true;
+	result = pool_search_relcache(is_temp_table_relcache, backend, table_name)==0?false:true;
 	return result;
 }
 
+/*
+ * Discard relcache used by is_temp_table_relcache().
+ */
+void discard_temp_table_relcache(void)
+{
+	if (is_temp_table_relcache)
+	{
+		pool_discard_relcache(is_temp_table_relcache);
+		is_temp_table_relcache = NULL;
+	}
+}
+
 /*
  * Judge the table used in a query represented by node is a unlogged
  * table or not.
diff --git a/pool_select_walker.h b/pool_select_walker.h
index 5bf8afc28..3e6555b77 100644
--- a/pool_select_walker.h
+++ b/pool_select_walker.h
@@ -51,6 +51,7 @@ extern bool pool_has_function_call(Node *node);
 extern bool pool_has_non_immutable_function_call(Node *node);
 extern bool pool_has_system_catalog(Node *node);
 extern bool pool_has_temp_table(Node *node);
+extern void discard_temp_table_relcache(void);
 extern bool pool_has_unlogged_table(Node *node);
 extern bool pool_has_view(Node *node);
 extern bool pool_has_insertinto_or_locking_clause(Node *node);


[parent: ece0f8ffafcf]