diff --git a/doc/src/sgml/ref/begin.sgml b/doc/src/sgml/ref/begin.sgml
index bf1195f5277..741d8aa997a 100644
--- a/doc/src/sgml/ref/begin.sgml
+++ b/doc/src/sgml/ref/begin.sgml
@@ -1,5 +1,5 @@
@@ -20,9 +20,12 @@ PostgreSQL documentation
-BEGIN [ WORK | TRANSACTION ]
- [ ISOLATION LEVEL { READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE } ]
- [ READ WRITE | READ ONLY ]
+BEGIN [ WORK | TRANSACTION ] [ transaction_mode [, ...] ]
+
+where transaction_mode is one of:
+
+ ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
+ READ WRITE | READ ONLY
@@ -101,8 +104,13 @@ BEGIN [ WORK | TRANSACTION ]
Issuing BEGIN when already inside a transaction block will
provoke a warning message. The state of the transaction is not affected.
To nest transactions within a transaction block, use savepoints
- (See
- for more information).
+ (see ).
+
+
+
+ For reasons of backwards compatibility, the commas between successive
+ transaction_modes may be
+ omitted.
@@ -123,15 +131,10 @@ BEGIN;
BEGIN is a PostgreSQL
- language extension. There is no explicit BEGIN
- command in the SQL standard; transaction initiation is
- always implicit and it terminates either with a
- COMMIT or ROLLBACK statement.
-
-
-
- Other relational database systems may offer an autocommit feature
- as a convenience.
+ language extension. It is equivalent to the SQL-standard command
+ , which see for additional
+ compatibility information.
diff --git a/doc/src/sgml/ref/set_transaction.sgml b/doc/src/sgml/ref/set_transaction.sgml
index ef6dea1ac18..50a89088250 100644
--- a/doc/src/sgml/ref/set_transaction.sgml
+++ b/doc/src/sgml/ref/set_transaction.sgml
@@ -1,4 +1,4 @@
-
+
SET TRANSACTION
@@ -16,13 +16,13 @@
-SET TRANSACTION
- [ ISOLATION LEVEL { READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE } ]
- [ READ WRITE | READ ONLY ]
+SET TRANSACTION transaction_mode [, ...]
+SET SESSION CHARACTERISTICS AS TRANSACTION transaction_mode [, ...]
-SET SESSION CHARACTERISTICS AS TRANSACTION
- [ ISOLATION LEVEL { READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE } ]
- [ READ WRITE | READ ONLY ]
+where transaction_mode is one of:
+
+ ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
+ READ WRITE | READ ONLY
@@ -34,7 +34,7 @@ SET SESSION CHARACTERISTICS AS TRANSACTION
characteristics of the current transaction. It has no effect on any
subsequent transactions. SET SESSION
CHARACTERISTICS sets the default transaction
- characteristics for each transaction of a session. SET
+ characteristics for subsequent transactions of a session. SET
TRANSACTION can override it for an individual
transaction.
@@ -47,7 +47,7 @@ SET SESSION CHARACTERISTICS AS TRANSACTION
The isolation level of a transaction determines what data the
- transaction can see when other transactions are running concurrently.
+ transaction can see when other transactions are running concurrently:
@@ -64,28 +64,35 @@ SET SESSION CHARACTERISTICS AS TRANSACTION
SERIALIZABLE
- The current transaction can only see rows committed before
- first query or data-modification statement was executed in this transaction.
+ All statements of the current transaction can only see rows committed
+ before the first query or data-modification statement was executed in
+ this transaction.
Intuitively, serializable means that two concurrent
transactions will leave the database in the same state as if
- the two has been executed strictly after one another in either
- order.
+ the two had been executed strictly one after the other (in one
+ order or the other).
- The level READ UNCOMMITTED is mapped to
- READ COMMITTED, the level REPEATABLE
- READ is mapped to SERIALIZABLE, The
- transaction isolation level cannot be set after the first query or
+ The SQL standard defines two additional levels, READ
+ UNCOMMITTED and REPEATABLE READ.
+ In PostgreSQL READ
+ UNCOMMITTED is treated as
+ READ COMMITTED, while REPEATABLE
+ READ is treated as SERIALIZABLE.
+
+
+
+ The transaction isolation level cannot be changed after the first query or
data-modification statement (SELECT,
INSERT, DELETE,
- UPDATE, FETCH,
+ UPDATE, FETCH, or
COPY) of a transaction has been executed. See
for more information about transaction
isolation and concurrency control.
@@ -112,13 +119,27 @@ SET SESSION CHARACTERISTICS AS TRANSACTION
Notes
- The session default transaction isolation level can also be set
- with the command
-
-SET default_transaction_isolation = 'value'
-
- and in the configuration file. Consult for more
- information.
+ If SET TRANSACTION is executed without a prior
+ START TRANSACTION or BEGIN,
+ it will appear to have no effect, since the transaction will immediately
+ end.
+
+
+
+ It is possible to dispense with SET TRANSACTION by
+ instead specifying the desired transaction_modes in
+ START TRANSACTION.
+
+
+
+ The session default transaction modes can also be set by setting the
+ configuration parameters
+ and .
+ (In fact SET SESSION CHARACTERISTICS is just a
+ verbose equivalent for setting these variables with SET.)
+ This allows them to be set in the configuration file. Consult for more information.
@@ -131,7 +152,7 @@ SET default_transaction_isolation = 'value'
isolation level in the standard; in
PostgreSQL the default is ordinarily
READ COMMITTED, but you can change it as
- described above. Because of multiversion concurrency control, the
+ mentioned above. Because of multiversion concurrency control, the
SERIALIZABLE level is not truly
serializable. See for details.
@@ -139,7 +160,15 @@ SET default_transaction_isolation = 'value'
In the SQL standard, there is one other transaction characteristic
that can be set with these commands: the size of the diagnostics
- area. This concept is only for use in embedded SQL.
+ area. This concept is specific to embedded SQL, and therefore is
+ not implemented in the PostgreSQL server.
+
+
+
+ The SQL standard requires commas between successive transaction_modes, but for historical
+ reasons PostgreSQL allows the commas to be
+ omitted.
diff --git a/doc/src/sgml/ref/start_transaction.sgml b/doc/src/sgml/ref/start_transaction.sgml
index 1a7bc363ce7..823bd991953 100644
--- a/doc/src/sgml/ref/start_transaction.sgml
+++ b/doc/src/sgml/ref/start_transaction.sgml
@@ -1,5 +1,5 @@
@@ -20,9 +20,12 @@ PostgreSQL documentation
-START TRANSACTION
- [ ISOLATION LEVEL { READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE } ]
- [ READ WRITE | READ ONLY ]
+START TRANSACTION [ transaction_mode [, ...] ]
+
+where transaction_mode is one of:
+
+ ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
+ READ WRITE | READ ONLY
@@ -30,10 +33,10 @@ START TRANSACTION
Description
- This command begins a new transaction. If the isolation level or
+ This command begins a new transaction block. If the isolation level or
read/write mode is specified, the new transaction has those
characteristics, as if was executed. It is the same
+ endterm="sql-set-transaction-title"> was executed. This is the same
as the command.
@@ -52,8 +55,25 @@ START TRANSACTION
Compatibility
- This command conforms to the SQL standard; but see also the
- compatibility section of START TRANSACTION
+ to start a transaction block: any SQL command implicitly begins a block.
+ PostgreSQL's behavior can be seen as implicitly
+ issuing a COMMIT after each command that does not
+ follow START TRANSACTION (or BEGIN),
+ and it is therefore often called autocommit.
+ Other relational database systems may offer an autocommit feature
+ as a convenience.
+
+
+
+ The SQL standard requires commas between successive transaction_modes, but for historical
+ reasons PostgreSQL allows the commas to be
+ omitted.
+
+
+
+ See also the compatibility section of .
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 6a27714b05e..e8bc3cf5ade 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.470 2004/08/12 19:12:21 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.471 2004/08/12 21:00:28 tgl Exp $
*
* HISTORY
* AUTHOR DATE MAJOR EVENT
@@ -161,11 +161,11 @@ static void doNegateFloat(Value *v);
%type opt_drop_behavior
-%type createdb_opt_list copy_opt_list
-%type createdb_opt_item copy_opt_item
+%type createdb_opt_list copy_opt_list transaction_mode_list
+%type createdb_opt_item copy_opt_item transaction_mode_item
%type opt_lock lock_type cast_context
-%type opt_force opt_or_replace transaction_access_mode
+%type opt_force opt_or_replace
opt_grant_grant_option opt_revoke_grant_option
opt_nowait
@@ -222,7 +222,7 @@ static void doNegateFloat(Value *v);
target_list update_target_list insert_column_list
insert_target_list def_list indirection opt_indirection
group_clause TriggerFuncArgs select_limit
- opt_select_limit opclass_item_list transaction_mode_list
+ opt_select_limit opclass_item_list
transaction_mode_list_or_empty
TableFuncElementList
prep_type_clause prep_type_list
@@ -4021,27 +4021,26 @@ opt_transaction: WORK {}
| /*EMPTY*/ {}
;
-transaction_mode_list:
+transaction_mode_item:
ISOLATION LEVEL iso_level
- { $$ = list_make1(makeDefElem("transaction_isolation",
- makeStringConst($3, NULL))); }
- | transaction_access_mode
- { $$ = list_make1(makeDefElem("transaction_read_only",
- makeIntConst($1))); }
- | ISOLATION LEVEL iso_level transaction_access_mode
- {
- $$ = list_make2(makeDefElem("transaction_isolation",
- makeStringConst($3, NULL)),
- makeDefElem("transaction_read_only",
- makeIntConst($4)));
- }
- | transaction_access_mode ISOLATION LEVEL iso_level
- {
- $$ = list_make2(makeDefElem("transaction_read_only",
- makeIntConst($1)),
- makeDefElem("transaction_isolation",
- makeStringConst($4, NULL)));
- }
+ { $$ = makeDefElem("transaction_isolation",
+ makeStringConst($3, NULL)); }
+ | READ ONLY
+ { $$ = makeDefElem("transaction_read_only",
+ makeIntConst(TRUE)); }
+ | READ WRITE
+ { $$ = makeDefElem("transaction_read_only",
+ makeIntConst(FALSE)); }
+ ;
+
+/* Syntax with commas is SQL-spec, without commas is Postgres historical */
+transaction_mode_list:
+ transaction_mode_item
+ { $$ = list_make1($1); }
+ | transaction_mode_list ',' transaction_mode_item
+ { $$ = lappend($1, $3); }
+ | transaction_mode_list transaction_mode_item
+ { $$ = lappend($1, $2); }
;
transaction_mode_list_or_empty:
@@ -4050,11 +4049,6 @@ transaction_mode_list_or_empty:
{ $$ = NIL; }
;
-transaction_access_mode:
- READ ONLY { $$ = TRUE; }
- | READ WRITE { $$ = FALSE; }
- ;
-
/*****************************************************************************
*
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 89ac4843ba8..0fff253a61c 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.224 2004/08/12 19:12:21 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/utility.c,v 1.225 2004/08/12 21:00:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -333,23 +333,21 @@ ProcessUtility(Node *parsetree,
case TRANS_STMT_BEGIN:
case TRANS_STMT_START:
{
+ ListCell *lc;
+
BeginTransactionBlock();
-
- if (stmt->options)
+ foreach(lc, stmt->options)
{
- ListCell *head;
+ DefElem *item = (DefElem *) lfirst(lc);
- foreach(head, stmt->options)
- {
- DefElem *item = (DefElem *) lfirst(head);
-
- if (strcmp(item->defname, "transaction_isolation") == 0)
- SetPGVariable("transaction_isolation",
- list_make1(item->arg), false);
- else if (strcmp(item->defname, "transaction_read_only") == 0)
- SetPGVariable("transaction_read_only",
- list_make1(item->arg), false);
- }
+ if (strcmp(item->defname, "transaction_isolation") == 0)
+ SetPGVariable("transaction_isolation",
+ list_make1(item->arg),
+ false);
+ else if (strcmp(item->defname, "transaction_read_only") == 0)
+ SetPGVariable("transaction_read_only",
+ list_make1(item->arg),
+ false);
}
}
break;