/* Remaining fields are invalid when conn is NULL: */
int xact_depth; /* 0 = no xact open, 1 = main xact open, 2 =
* one level of subxact open, etc */
- bool xact_read_only; /* xact r/o state */
bool have_prep_stmt; /* have we prepared any stmts in this xact? */
bool have_error; /* have any subxacts aborted in this xact? */
bool changing_xact_state; /* xact state change in process */
/* tracks whether any work is needed in callback functions */
static bool xact_got_connection = false;
-/*
- * tracks the nesting level of the topmost read-only transaction determined
- * by GetTopReadOnlyTransactionNestLevel()
- */
-static int top_read_only_level = 0;
-
/* custom wait event values, retrieved from shared memory */
static uint32 pgfdw_we_cleanup_result = 0;
static uint32 pgfdw_we_connect = 0;
/* Reset all transient state fields, to be sure all are clean */
entry->xact_depth = 0;
- entry->xact_read_only = false;
entry->have_prep_stmt = false;
entry->have_error = false;
entry->changing_xact_state = false;
* those scans. A disadvantage is that we can't provide sane emulation of
* READ COMMITTED behavior --- it would be nice if we had some other way to
* control which remote queries share a snapshot.
- *
- * Note also that we always start the remote transaction with the same
- * read/write and deferrable properties as the local transaction, and start
- * the remote subtransaction with the same read/write property as the local
- * subtransaction.
*/
static void
begin_remote_xact(ConnCacheEntry *entry)
{
int curlevel = GetCurrentTransactionNestLevel();
- /*
- * Set the nesting level of the topmost read-only transaction if the
- * current transaction is read-only and we haven't yet. Once it's set,
- * it's retained until that transaction is committed/aborted, and then
- * reset (see pgfdw_xact_callback and pgfdw_subxact_callback).
- */
- if (XactReadOnly)
- {
- if (top_read_only_level == 0)
- top_read_only_level = GetTopReadOnlyTransactionNestLevel();
- Assert(top_read_only_level > 0);
- }
- else
- Assert(top_read_only_level == 0);
-
- /*
- * Start main transaction if we haven't yet; otherwise, change the
- * already-started remote transaction/subtransaction to read-only if the
- * local transaction/subtransaction have been done so after starting them
- * and we haven't yet.
- */
+ /* Start main transaction if we haven't yet */
if (entry->xact_depth <= 0)
{
- StringInfoData sql;
- bool ro = (top_read_only_level == 1);
+ const char *sql;
elog(DEBUG3, "starting remote transaction on connection %p",
entry->conn);
- initStringInfo(&sql);
- appendStringInfoString(&sql, "START TRANSACTION ISOLATION LEVEL ");
if (IsolationIsSerializable())
- appendStringInfoString(&sql, "SERIALIZABLE");
+ sql = "START TRANSACTION ISOLATION LEVEL SERIALIZABLE";
else
- appendStringInfoString(&sql, "REPEATABLE READ");
- if (ro)
- appendStringInfoString(&sql, " READ ONLY");
- if (XactDeferrable)
- appendStringInfoString(&sql, " DEFERRABLE");
+ sql = "START TRANSACTION ISOLATION LEVEL REPEATABLE READ";
entry->changing_xact_state = true;
- do_sql_command(entry->conn, sql.data);
+ do_sql_command(entry->conn, sql);
entry->xact_depth = 1;
- if (ro)
- {
- Assert(!entry->xact_read_only);
- entry->xact_read_only = true;
- }
entry->changing_xact_state = false;
}
- else if (!entry->xact_read_only)
- {
- Assert(top_read_only_level == 0 ||
- entry->xact_depth <= top_read_only_level);
- if (entry->xact_depth == top_read_only_level)
- {
- entry->changing_xact_state = true;
- do_sql_command(entry->conn, "SET transaction_read_only = on");
- entry->xact_read_only = true;
- entry->changing_xact_state = false;
- }
- }
- else
- Assert(top_read_only_level > 0 &&
- entry->xact_depth >= top_read_only_level);
/*
* If we're in a subtransaction, stack up savepoints to match our level.
*/
while (entry->xact_depth < curlevel)
{
- StringInfoData sql;
- bool ro = (entry->xact_depth + 1 == top_read_only_level);
+ char sql[64];
- initStringInfo(&sql);
- appendStringInfo(&sql, "SAVEPOINT s%d", entry->xact_depth + 1);
- if (ro)
- appendStringInfoString(&sql, "; SET transaction_read_only = on");
+ snprintf(sql, sizeof(sql), "SAVEPOINT s%d", entry->xact_depth + 1);
entry->changing_xact_state = true;
- do_sql_command(entry->conn, sql.data);
+ do_sql_command(entry->conn, sql);
entry->xact_depth++;
- if (ro)
- {
- Assert(!entry->xact_read_only);
- entry->xact_read_only = true;
- }
entry->changing_xact_state = false;
}
}
/* Also reset cursor numbering for next transaction */
cursor_number = 0;
-
- /* Likewise for top_read_only_level */
- top_read_only_level = 0;
}
/*
false);
}
}
-
- /* If in the topmost read-only transaction, reset top_read_only_level */
- if (curlevel == top_read_only_level)
- top_read_only_level = 0;
}
/*
/* Reset state to show we're out of a transaction */
entry->xact_depth = 0;
- /* Reset xact r/o state */
- entry->xact_read_only = false;
-
/*
* If the connection isn't in a good idle state, it is marked as
* invalid or keep_connections option of its server is disabled, then
{
/* Reset state to show we're out of a subtransaction */
entry->xact_depth--;
-
- /* If in the topmost read-only transaction, reset xact r/o state */
- if (entry->xact_depth + 1 == top_read_only_level)
- entry->xact_read_only = false;
}
}
DROP FOREIGN TABLE remote_application_name;
DROP VIEW my_application_name;
-- ===================================================================
--- test read-only and/or deferrable transactions
--- ===================================================================
-CREATE TABLE loct (f1 int, f2 text);
-CREATE FUNCTION locf() RETURNS SETOF loct LANGUAGE SQL AS
- 'UPDATE public.loct SET f2 = f2 || f2 RETURNING *';
-CREATE VIEW locv AS SELECT t.* FROM locf() t;
-CREATE FOREIGN TABLE remt (f1 int, f2 text)
- SERVER loopback OPTIONS (table_name 'locv');
-CREATE FOREIGN TABLE remt2 (f1 int, f2 text)
- SERVER loopback2 OPTIONS (table_name 'locv');
-INSERT INTO loct VALUES (1, 'foo'), (2, 'bar');
-START TRANSACTION READ ONLY;
-SAVEPOINT s;
-SELECT * FROM remt; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SELECT * FROM remt; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK;
-START TRANSACTION;
-SAVEPOINT s;
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK;
-START TRANSACTION;
-SAVEPOINT s;
-SELECT * FROM remt; -- should work
- f1 | f2
-----+--------
- 1 | foofoo
- 2 | barbar
-(2 rows)
-
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SELECT * FROM remt; -- should work
- f1 | f2
-----+--------
- 1 | foofoo
- 2 | barbar
-(2 rows)
-
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK;
-START TRANSACTION;
-SAVEPOINT s;
-SELECT * FROM remt; -- should work
- f1 | f2
-----+--------
- 1 | foofoo
- 2 | barbar
-(2 rows)
-
-SET transaction_read_only = on;
-SELECT * FROM remt2; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SELECT * FROM remt; -- should work
- f1 | f2
-----+--------
- 1 | foofoo
- 2 | barbar
-(2 rows)
-
-SET transaction_read_only = on;
-SELECT * FROM remt2; -- should fail
-ERROR: cannot execute UPDATE in a read-only transaction
-CONTEXT: SQL function "locf" statement 1
-remote SQL command: SELECT f1, f2 FROM public.locv
-ROLLBACK;
-DROP FOREIGN TABLE remt;
-CREATE FOREIGN TABLE remt (f1 int, f2 text)
- SERVER loopback OPTIONS (table_name 'loct');
-START TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY;
-SELECT * FROM remt;
- f1 | f2
-----+-----
- 1 | foo
- 2 | bar
-(2 rows)
-
-COMMIT;
-START TRANSACTION ISOLATION LEVEL SERIALIZABLE DEFERRABLE;
-SELECT * FROM remt;
- f1 | f2
-----+-----
- 1 | foo
- 2 | bar
-(2 rows)
-
-COMMIT;
-START TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE;
-SELECT * FROM remt;
- f1 | f2
-----+-----
- 1 | foo
- 2 | bar
-(2 rows)
-
-COMMIT;
--- Clean up
-DROP FOREIGN TABLE remt;
-DROP FOREIGN TABLE remt2;
-DROP VIEW locv;
-DROP FUNCTION locf();
-DROP TABLE loct;
--- ===================================================================
-- test parallel commit and parallel abort
-- ===================================================================
ALTER SERVER loopback OPTIONS (ADD parallel_commit 'true');
DROP FOREIGN TABLE remote_application_name;
DROP VIEW my_application_name;
--- ===================================================================
--- test read-only and/or deferrable transactions
--- ===================================================================
-CREATE TABLE loct (f1 int, f2 text);
-CREATE FUNCTION locf() RETURNS SETOF loct LANGUAGE SQL AS
- 'UPDATE public.loct SET f2 = f2 || f2 RETURNING *';
-CREATE VIEW locv AS SELECT t.* FROM locf() t;
-CREATE FOREIGN TABLE remt (f1 int, f2 text)
- SERVER loopback OPTIONS (table_name 'locv');
-CREATE FOREIGN TABLE remt2 (f1 int, f2 text)
- SERVER loopback2 OPTIONS (table_name 'locv');
-INSERT INTO loct VALUES (1, 'foo'), (2, 'bar');
-
-START TRANSACTION READ ONLY;
-SAVEPOINT s;
-SELECT * FROM remt; -- should fail
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SELECT * FROM remt; -- should fail
-ROLLBACK;
-
-START TRANSACTION;
-SAVEPOINT s;
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ROLLBACK;
-
-START TRANSACTION;
-SAVEPOINT s;
-SELECT * FROM remt; -- should work
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SELECT * FROM remt; -- should work
-SET transaction_read_only = on;
-SELECT * FROM remt; -- should fail
-ROLLBACK;
-
-START TRANSACTION;
-SAVEPOINT s;
-SELECT * FROM remt; -- should work
-SET transaction_read_only = on;
-SELECT * FROM remt2; -- should fail
-ROLLBACK TO s;
-RELEASE SAVEPOINT s;
-SELECT * FROM remt; -- should work
-SET transaction_read_only = on;
-SELECT * FROM remt2; -- should fail
-ROLLBACK;
-
-DROP FOREIGN TABLE remt;
-CREATE FOREIGN TABLE remt (f1 int, f2 text)
- SERVER loopback OPTIONS (table_name 'loct');
-
-START TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY;
-SELECT * FROM remt;
-COMMIT;
-
-START TRANSACTION ISOLATION LEVEL SERIALIZABLE DEFERRABLE;
-SELECT * FROM remt;
-COMMIT;
-
-START TRANSACTION ISOLATION LEVEL SERIALIZABLE READ ONLY DEFERRABLE;
-SELECT * FROM remt;
-COMMIT;
-
--- Clean up
-DROP FOREIGN TABLE remt;
-DROP FOREIGN TABLE remt2;
-DROP VIEW locv;
-DROP FUNCTION locf();
-DROP TABLE loct;
-
-- ===================================================================
-- test parallel commit and parallel abort
-- ===================================================================
<productname>PostgreSQL</productname> release might modify these rules.
</para>
- <para>
- The remote transaction is opened in the same read/write mode as the local
- transaction: if the local transaction is <literal>READ ONLY</literal>,
- the remote transaction is opened in <literal>READ ONLY</literal> mode,
- otherwise it is opened in <literal>READ WRITE</literal> mode.
- (This rule is also applied to remote and local subtransactions.)
- </para>
-
- <para>
- The remote transaction is also opened in the same deferrable mode as the
- local transaction: if the local transaction is <literal>DEFERRABLE</literal>,
- the remote transaction is opened in <literal>DEFERRABLE</literal> mode,
- otherwise it is opened in <literal>NOT DEFERRABLE</literal> mode.
- </para>
-
<para>
Note that it is currently not supported by
<filename>postgres_fdw</filename> to prepare the remote transaction for
return CurrentTransactionState->startedInRecovery;
}
-/*
- * GetTopReadOnlyTransactionNestLevel
- *
- * Note: this will return zero when not inside any transaction or when neither
- * a top-level transaction nor subtransactions are read-only, one when the
- * top-level transaction is read-only, two when one level of subtransaction is
- * read-only, etc.
- *
- * Note: subtransactions of the topmost read-only transaction are also
- * read-only, because they inherit read-only mode from the transaction, and
- * thus can't change to read-write mode. See check_transaction_read_only().
- */
-int
-GetTopReadOnlyTransactionNestLevel(void)
-{
- TransactionState s = CurrentTransactionState;
-
- if (!XactReadOnly)
- return 0;
- while (s->nestingLevel > 1)
- {
- if (!s->prevXactReadOnly)
- return s->nestingLevel;
- s = s->parent;
- }
- return s->nestingLevel;
-}
-
/*
* EnterParallelMode
*/
extern void SetCurrentStatementStartTimestamp(void);
extern int GetCurrentTransactionNestLevel(void);
extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
-extern int GetTopReadOnlyTransactionNestLevel(void);
extern void CommandCounterIncrement(void);
extern void ForceSyncCommit(void);
extern void StartTransactionCommand(void);
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