From 6f37e267cd081bbf70e877b825a7c18b4510eee2 Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Sun, 10 Jun 2018 18:46:01 +0900 Subject: [PATCH 3/4] postgres_fdw supports atomic commit APIs. --- contrib/postgres_fdw/connection.c | 534 ++++++++++++++++++------ contrib/postgres_fdw/expected/postgres_fdw.out | 387 +++++++++++++++++- contrib/postgres_fdw/option.c | 5 +- contrib/postgres_fdw/postgres_fdw.c | 60 +++- contrib/postgres_fdw/postgres_fdw.h | 10 +- contrib/postgres_fdw/sql/postgres_fdw.sql | 151 +++++++- doc/src/sgml/postgres-fdw.sgml | 37 ++ 7 files changed, 1040 insertions(+), 144 deletions(-) diff --git a/contrib/postgres_fdw/connection.c b/contrib/postgres_fdw/connection.c index fe4893a..9c0fa9a 100644 --- a/contrib/postgres_fdw/connection.c +++ b/contrib/postgres_fdw/connection.c @@ -15,8 +15,11 @@ #include "postgres_fdw.h" #include "access/htup_details.h" -#include "catalog/pg_user_mapping.h" #include "access/xact.h" +#include "catalog/pg_user_mapping.h" +#include "commands/defrem.h" +#include "foreign/fdwapi.h" +#include "foreign/fdwxact.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "pgstat.h" @@ -56,6 +59,7 @@ typedef struct ConnCacheEntry bool have_error; /* have any subxacts aborted in this xact? */ bool changing_xact_state; /* xact state change in process */ bool invalidated; /* true if reconnect is pending */ + bool am_participant_of_ac; /* true if fdwxact code control the transaction */ uint32 server_hashvalue; /* hash value of foreign server OID */ uint32 mapping_hashvalue; /* hash value of user mapping OID */ } ConnCacheEntry; @@ -78,7 +82,7 @@ static void disconnect_pg_server(ConnCacheEntry *entry); static void check_conn_params(const char **keywords, const char **values, UserMapping *user); static void configure_remote_session(PGconn *conn); static void do_sql_command(PGconn *conn, const char *sql); -static void begin_remote_xact(ConnCacheEntry *entry); +static void begin_remote_xact(ConnCacheEntry *entry, Oid serverid, Oid userid); static void pgfdw_xact_callback(XactEvent event, void *arg); static void pgfdw_subxact_callback(SubXactEvent event, SubTransactionId mySubid, @@ -91,20 +95,14 @@ static bool pgfdw_exec_cleanup_query(PGconn *conn, const char *query, bool ignore_errors); static bool pgfdw_get_cleanup_result(PGconn *conn, TimestampTz endtime, PGresult **result); - - -/* - * Get a PGconn which can be used to execute queries on the remote PostgreSQL - * server with the user's authorization. A new connection is established - * if we don't already have a suitable one, and a transaction is opened at - * the right subtransaction nesting depth if we didn't do that already. - * - * will_prep_stmt must be true if caller intends to create any prepared - * statements. Since those don't go away automatically at transaction end - * (not even on error), we need this flag to cue manual cleanup. - */ -PGconn * -GetConnection(UserMapping *user, bool will_prep_stmt) +static bool pgfdw_commit_transaction(ConnCacheEntry *entry); +static bool pgfdw_rollback_transaction(ConnCacheEntry *entry); +static void pgfdw_cleanup_after_transaction(ConnCacheEntry *entry); +static ConnCacheEntry *GetConnectionState(Oid umid, bool will_prep_stmt, + bool start_transaction); + +static ConnCacheEntry * +GetConnectionState(Oid umid, bool will_prep_stmt, bool start_transaction) { bool found; ConnCacheEntry *entry; @@ -136,11 +134,8 @@ GetConnection(UserMapping *user, bool will_prep_stmt) pgfdw_inval_callback, (Datum) 0); } - /* Set flag that we did GetConnection during the current transaction */ - xact_got_connection = true; - /* Create hash key for the entry. Assume no pad bytes in key struct */ - key = user->umid; + key = umid; /* * Find or create cached entry for requested connection. @@ -182,6 +177,7 @@ GetConnection(UserMapping *user, bool will_prep_stmt) */ if (entry->conn == NULL) { + UserMapping *user = GetUserMappingByOid(umid); ForeignServer *server = GetForeignServer(user->serverid); /* Reset all transient state fields, to be sure all are clean */ @@ -190,6 +186,7 @@ GetConnection(UserMapping *user, bool will_prep_stmt) entry->have_error = false; entry->changing_xact_state = false; entry->invalidated = false; + entry->am_participant_of_ac = false; entry->server_hashvalue = GetSysCacheHashValue1(FOREIGNSERVEROID, ObjectIdGetDatum(server->serverid)); @@ -200,6 +197,15 @@ GetConnection(UserMapping *user, bool will_prep_stmt) /* Now try to make the connection */ entry->conn = connect_pg_server(server, user); + Assert(entry->conn); + + if (!entry->conn) + { + elog(DEBUG3, "attempt to connection to server \"%s\" by postgres_fdw failed", + server->servername); + return NULL; + } + elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\" (user mapping oid %u, userid %u)", entry->conn, server->servername, user->umid, user->userid); } @@ -207,16 +213,46 @@ GetConnection(UserMapping *user, bool will_prep_stmt) /* * Start a new transaction or subtransaction if needed. */ - begin_remote_xact(entry); + if (start_transaction) + { + UserMapping *user = GetUserMappingByOid(umid); + + begin_remote_xact(entry, user->serverid, user->userid); + + /* Set flag that we did GetConnection during the current transaction */ + xact_got_connection = true; + } /* Remember if caller will prepare statements */ entry->have_prep_stmt |= will_prep_stmt; + return entry; +} + +/* + * Get a PGconn which can be used to execute queries on the remote PostgreSQL + * server with the user's authorization. A new connection is established + * if we don't already have a suitable one, and a transaction is opened at + * the right subtransaction nesting depth if we didn't do that already. + * + * will_prep_stmt must be true if caller intends to create any prepared + * statements. Since those don't go away automatically at transaction end + * (not even on error), we need this flag to cue manual cleanup. + */ +PGconn * +GetConnection(Oid umid, bool will_prep_stmt, bool start_transaction) +{ + ConnCacheEntry *entry; + + entry = GetConnectionState(umid, will_prep_stmt, start_transaction); + return entry->conn; } /* * Connect to remote server using specified server and user mapping properties. + * If the attempt to connect fails, and the caller can handle connection failure + * (connection_error_ok = true) return NULL, throw error otherwise. */ static PGconn * connect_pg_server(ForeignServer *server, UserMapping *user) @@ -265,11 +301,22 @@ connect_pg_server(ForeignServer *server, UserMapping *user) conn = PQconnectdbParams(keywords, values, false); if (!conn || PQstatus(conn) != CONNECTION_OK) + { + char *connmessage; + int msglen; + + /* libpq typically appends a newline, strip that */ + connmessage = pstrdup(PQerrorMessage(conn)); + msglen = strlen(connmessage); + if (msglen > 0 && connmessage[msglen - 1] == '\n') + connmessage[msglen - 1] = '\0'; + ereport(ERROR, (errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION), errmsg("could not connect to server \"%s\"", server->servername), errdetail_internal("%s", pchomp(PQerrorMessage(conn))))); + } /* * Check that non-superuser has used password to establish connection; @@ -414,15 +461,24 @@ do_sql_command(PGconn *conn, const char *sql) * control which remote queries share a snapshot. */ static void -begin_remote_xact(ConnCacheEntry *entry) +begin_remote_xact(ConnCacheEntry *entry, Oid serverid, Oid userid) { int curlevel = GetCurrentTransactionNestLevel(); + ForeignServer *server = GetForeignServer(serverid); /* Start main transaction if we haven't yet */ if (entry->xact_depth <= 0) { const char *sql; + /* Register the new foreign server if enabled */ + if (server_uses_twophase_commit(server)) + { + /* Register foreign server with auto-generated identifer */ + FdwXactRegisterForeignTransaction(serverid, userid, NULL); + entry->am_participant_of_ac = true; + } + elog(DEBUG3, "starting remote transaction on connection %p", entry->conn); @@ -650,12 +706,11 @@ static void pgfdw_xact_callback(XactEvent event, void *arg) { HASH_SEQ_STATUS scan; - ConnCacheEntry *entry; + ConnCacheEntry *entry; - /* Quick exit if no connections were touched in this transaction. */ + /* Quick exit if no connections were touched in this transaction */ if (!xact_got_connection) return; - /* * Scan all connection cache entries to find open remote transactions, and * close them. @@ -663,17 +718,20 @@ pgfdw_xact_callback(XactEvent event, void *arg) hash_seq_init(&scan, ConnectionHash); while ((entry = (ConnCacheEntry *) hash_seq_search(&scan))) { - PGresult *res; - /* Ignore cache entry if no open connection right now */ if (entry->conn == NULL) continue; + /* + * Foreign transactions participating to atomic commit are ended + * by two-phase commit APIs. Ignore them. + */ + if (entry->am_participant_of_ac) + continue; + /* If it has an open remote transaction, try to close it */ if (entry->xact_depth > 0) { - bool abort_cleanup_failure = false; - elog(DEBUG3, "closing remote transaction on connection %p", entry->conn); @@ -681,40 +739,7 @@ pgfdw_xact_callback(XactEvent event, void *arg) { case XACT_EVENT_PARALLEL_PRE_COMMIT: case XACT_EVENT_PRE_COMMIT: - - /* - * If abort cleanup previously failed for this connection, - * we can't issue any more commands against it. - */ - pgfdw_reject_incomplete_xact_state_change(entry); - - /* Commit all remote transactions during pre-commit */ - entry->changing_xact_state = true; - do_sql_command(entry->conn, "COMMIT TRANSACTION"); - entry->changing_xact_state = false; - - /* - * If there were any errors in subtransactions, and we - * made prepared statements, do a DEALLOCATE ALL to make - * sure we get rid of all prepared statements. This is - * annoying and not terribly bulletproof, but it's - * probably not worth trying harder. - * - * DEALLOCATE ALL only exists in 8.3 and later, so this - * constrains how old a server postgres_fdw can - * communicate with. We intentionally ignore errors in - * the DEALLOCATE, so that we can hobble along to some - * extent with older servers (leaking prepared statements - * as we go; but we don't really support update operations - * pre-8.3 anyway). - */ - if (entry->have_prep_stmt && entry->have_error) - { - res = PQexec(entry->conn, "DEALLOCATE ALL"); - PQclear(res); - } - entry->have_prep_stmt = false; - entry->have_error = false; + pgfdw_commit_transaction(entry); break; case XACT_EVENT_PRE_PREPARE: @@ -739,66 +764,7 @@ pgfdw_xact_callback(XactEvent event, void *arg) break; case XACT_EVENT_PARALLEL_ABORT: case XACT_EVENT_ABORT: - - /* - * Don't try to clean up the connection if we're already - * in error recursion trouble. - */ - if (in_error_recursion_trouble()) - entry->changing_xact_state = true; - - /* - * If connection is already unsalvageable, don't touch it - * further. - */ - if (entry->changing_xact_state) - break; - - /* - * Mark this connection as in the process of changing - * transaction state. - */ - entry->changing_xact_state = true; - - /* Assume we might have lost track of prepared statements */ - entry->have_error = true; - - /* - * If a command has been submitted to the remote server by - * using an asynchronous execution function, the command - * might not have yet completed. Check to see if a - * command is still being processed by the remote server, - * and if so, request cancellation of the command. - */ - if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE && - !pgfdw_cancel_query(entry->conn)) - { - /* Unable to cancel running query. */ - abort_cleanup_failure = true; - } - else if (!pgfdw_exec_cleanup_query(entry->conn, - "ABORT TRANSACTION", - false)) - { - /* Unable to abort remote transaction. */ - abort_cleanup_failure = true; - } - else if (entry->have_prep_stmt && entry->have_error && - !pgfdw_exec_cleanup_query(entry->conn, - "DEALLOCATE ALL", - true)) - { - /* Trouble clearing prepared statements. */ - abort_cleanup_failure = true; - } - else - { - entry->have_prep_stmt = false; - entry->have_error = false; - } - - /* Disarm changing_xact_state if it all worked. */ - entry->changing_xact_state = abort_cleanup_failure; + pgfdw_rollback_transaction(entry); break; } } @@ -1193,3 +1159,325 @@ exit: ; *result = last_res; return timed_out; } + +/* + * The function prepares transaction on foreign server. This function + * is called only at the pre-commit phase of the local transaction. Since + * we should have the connection to the server that we are interested in + * we don't use serverid and userid that are necessary to get user mapping + * that is the key of the connection cache. + */ +bool +postgresPrepareForeignTransaction(ForeignTransaction *foreign_xact) +{ + ConnCacheEntry *entry = NULL; + bool result = false; + PGresult *res; + StringInfo command; + + entry = hash_search(ConnectionHash, &(foreign_xact->usermapping->umid), + HASH_FIND, NULL); + + if (!entry->conn) + return false; + + pgfdw_reject_incomplete_xact_state_change(entry); + + command = makeStringInfo(); + appendStringInfo(command, "PREPARE TRANSACTION '%s'", foreign_xact->fx_id); + + /* Do commit foreign transaction */ + entry->changing_xact_state = true; + res = pgfdw_exec_query(entry->conn, command->data); + entry->changing_xact_state = false; + + if (PQresultStatus(res) == PGRES_COMMAND_OK) + result = true; + + if (result) + elog(DEBUG1, "prepared foreign transaction on server %u with ID %s", + foreign_xact->server->serverid, foreign_xact->fx_id); + + if (entry->have_prep_stmt && entry->have_error) + { + res = PQexec(entry->conn, "DEALLOCATE ALL"); + PQclear(res); + } + + entry->have_prep_stmt = false; + entry->have_error = false; + + pgfdw_cleanup_after_transaction(entry); + + return result; +} + +/* + * The function commits the transactionon foreign server. This + * function is called both at the pre-commit phase of the local transaction + * when committing and at the end of the local transaction when aborting. + * Since we should the connections to the server that involved with the local + * transaction we don't use serverid and userid that are necessary to get + * user mapping that is the key of connection cache. + */ +bool +postgresCommitForeignTransaction(ForeignTransaction *foreign_xact) +{ + ConnCacheEntry *entry = NULL; + bool result = false; + + entry = hash_search(ConnectionHash, &(foreign_xact->usermapping->umid), + HASH_FIND, NULL); + + result = pgfdw_commit_transaction(entry); + + return result; +} + +/* + * The function rollbacks the transactionon foreign server. This + * function is called both at the pre-commit phase of the local transaction + * when committing and at the end of the local transaction when aborting. + * Since we should the connections to the server that involved with the local + * transaction we don't use serverid and userid that are necessary to get + * user mapping that is the key of connection cache. + */ +bool +postgresRollbackForeignTransaction(ForeignTransaction *foreign_xact) +{ + ConnCacheEntry *entry = NULL; + bool ret; + + entry = hash_search(ConnectionHash, &(foreign_xact->usermapping->umid), + HASH_FIND, NULL); + + /* Rollback a remote transaction */ + ret = pgfdw_rollback_transaction(entry); + + return ret; +} + +bool +postgresResolveForeignTransaction(ForeignTransaction *foreign_xact, bool is_commit) +{ + ConnCacheEntry *entry = NULL; + StringInfo command; + bool result; + PGresult *res; + + entry = GetConnectionState(foreign_xact->usermapping->umid, + false, false); + + if (!entry->conn) + return false; + + command = makeStringInfo(); + appendStringInfo(command, "%s PREPARED '%s'", + is_commit ? "COMMIT" : "ROLLBACK", + foreign_xact->fx_id); + + res = pgfdw_exec_query(entry->conn, command->data); + + if (PQresultStatus(res) != PGRES_COMMAND_OK) + { + int sqlstate; + char *diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE); + + /* + * The command failed, raise a warning to log the reason of failure. + * We may not be in a transaction here, so raising error doesn't + * help. Even if we are in a transaction, it would be the resolver + * transaction, which will get aborted on raising error, thus + * delaying resolution of other prepared foreign transactions. + */ + pgfdw_report_error(WARNING, res, entry->conn, false, command->data); + + if (diag_sqlstate) + { + sqlstate = MAKE_SQLSTATE(diag_sqlstate[0], + diag_sqlstate[1], + diag_sqlstate[2], + diag_sqlstate[3], + diag_sqlstate[4]); + } + else + sqlstate = ERRCODE_CONNECTION_FAILURE; + + /* + * If we tried to COMMIT/ABORT a prepared transaction and the prepared + * transaction was missing on the foreign server, it was probably + * resolved by some other means. Anyway, it should be considered as resolved. + */ + result = (sqlstate == ERRCODE_UNDEFINED_OBJECT); + } + else + result = true; + + elog(DEBUG1, "%s prepared foreign transaction on server %u with ID %s", + is_commit ? "commit" : "rollback", foreign_xact->server->serverid, + foreign_xact->fx_id); + + /* Cleanup transaction status */ + pgfdw_cleanup_after_transaction(entry); + + return result; +} +/* Cleanup at main-transaction end */ +static void +pgfdw_cleanup_after_transaction(ConnCacheEntry *entry) +{ + /* Reset state to show we're out of a transaction */ + entry->xact_depth = 0; + entry->am_participant_of_ac = false; + + /* + * If the connection isn't in a good idle state, discard it to + * recover. Next GetConnection will open a new connection. + */ + if (PQstatus(entry->conn) != CONNECTION_OK || + PQtransactionStatus(entry->conn) != PQTRANS_IDLE || + entry->changing_xact_state) + { + elog(DEBUG3, "discarding connection %p", entry->conn); + disconnect_pg_server(entry); + } + + /* + * Regardless of the event type, we can now mark ourselves as out of the + * transaction. + */ + xact_got_connection = false; + + /* Also reset cursor numbering for next transaction */ + cursor_number = 0; +} + +static bool +pgfdw_rollback_transaction(ConnCacheEntry *entry) +{ + bool abort_cleanup_failure = false; + + /* + * In rollback local transaction, if we don't the connection + * it means any transaction started. So we can ragard it as + * success. + */ + if (!entry || !entry->conn) + return true; + + /* + * Don't try to clean up the connection if we're already + * in error recursion trouble. + */ + if (in_error_recursion_trouble()) + entry->changing_xact_state = true; + + /* + * If connection is already unsalvageable, don't touch it + * further. + */ + if (entry->changing_xact_state) + return true; + + /* + * Mark this connection as in the process of changing + * transaction state. + */ + entry->changing_xact_state = true; + + /* Assume we might have lost track of prepared statements */ + entry->have_error = true; + + /* + * If a command has been submitted to the remote server by + * using an asynchronous execution function, the command + * might not have yet completed. Check to see if a + * command is still being processed by the remote server, + * and if so, request cancellation of the command. + */ + if (PQtransactionStatus(entry->conn) == PQTRANS_ACTIVE && + !pgfdw_cancel_query(entry->conn)) + { + /* Unable to cancel running query. */ + abort_cleanup_failure = true; + } + else if (!pgfdw_exec_cleanup_query(entry->conn, + "ABORT TRANSACTION", + false)) + { + /* Unable to abort remote transaction. */ + abort_cleanup_failure = true; + } + else if (entry->have_prep_stmt && entry->have_error && + !pgfdw_exec_cleanup_query(entry->conn, + "DEALLOCATE ALL", + true)) + { + /* Trouble clearing prepared statements. */ + abort_cleanup_failure = true; + } + else + { + entry->have_prep_stmt = false; + entry->have_error = false; + } + + /* Disarm changing_xact_state if it all worked. */ + entry->changing_xact_state = abort_cleanup_failure; + + /* Cleanup transaction status */ + pgfdw_cleanup_after_transaction(entry); + + return !abort_cleanup_failure; +} + +static bool +pgfdw_commit_transaction(ConnCacheEntry *entry) +{ + PGresult *res; + bool result = false; + + if (!entry || !entry->conn) + return false; + + /* + * If abort cleanup previously failed for this connection, + * we can't issue any more commands against it. + */ + pgfdw_reject_incomplete_xact_state_change(entry); + + entry->changing_xact_state = true; + res = pgfdw_exec_query(entry->conn, "COMMIT TRANSACTION"); + entry->changing_xact_state = false; + + if (PQresultStatus(res) == PGRES_COMMAND_OK) + result = true; + + /* + * If there were any errors in subtransactions, and we + * made prepared statements, do a DEALLOCATE ALL to make + * sure we get rid of all prepared statements. This is + * annoying and not terribly bulletproof, but it's + * probably not worth trying harder. + * + * DEALLOCATE ALL only exists in 8.3 and later, so this + * constrains how old a server postgres_fdw can + * communicate with. We intentionally ignore errors in + * the DEALLOCATE, so that we can hobble along to some + * extent with older servers (leaking prepared statements + * as we go; but we don't really support update operations + * pre-8.3 anyway). + */ + if (entry->have_prep_stmt && entry->have_error) + { + res = PQexec(entry->conn, "DEALLOCATE ALL"); + PQclear(res); + } + entry->have_prep_stmt = false; + entry->have_error = false; + + /* Cleanup transaction status */ + pgfdw_cleanup_after_transaction(entry); + + return result; +} diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index cf4863c..b6a91a9 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -13,12 +13,17 @@ DO $d$ OPTIONS (dbname '$$||current_database()||$$', port '$$||current_setting('port')||$$' )$$; + EXECUTE $$CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname '$$||current_database()||$$', + port '$$||current_setting('port')||$$' + )$$; END; $d$; CREATE USER MAPPING FOR public SERVER testserver1 OPTIONS (user 'value', password 'value'); CREATE USER MAPPING FOR CURRENT_USER SERVER loopback; CREATE USER MAPPING FOR CURRENT_USER SERVER loopback2; +CREATE USER MAPPING FOR CURRENT_USER SERVER loopback3; -- =================================================================== -- create objects used through FDW loopback server -- =================================================================== @@ -52,6 +57,13 @@ CREATE TABLE "S 1"."T 4" ( c3 text, CONSTRAINT t4_pkey PRIMARY KEY (c1) ); +CREATE TABLE "S 1"."T 5" ( + c1 int NOT NULL +); +CREATE TABLE "S 1"."T 6" ( + c1 int NOT NULL, + CONSTRAINT t6_pkey PRIMARY KEY (c1) +); -- Disable autovacuum for these tables to avoid unexpected effects of that ALTER TABLE "S 1"."T 1" SET (autovacuum_enabled = 'false'); ALTER TABLE "S 1"."T 2" SET (autovacuum_enabled = 'false'); @@ -87,6 +99,7 @@ ANALYZE "S 1"."T 1"; ANALYZE "S 1"."T 2"; ANALYZE "S 1"."T 3"; ANALYZE "S 1"."T 4"; +ANALYZE "S 1"."T 5"; -- =================================================================== -- create foreign tables -- =================================================================== @@ -129,6 +142,15 @@ CREATE FOREIGN TABLE ft6 ( c2 int NOT NULL, c3 text ) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 4'); +CREATE FOREIGN TABLE ft7_twophase ( + c1 int NOT NULL +) SERVER loopback OPTIONS (schema_name 'S 1', table_name 'T 5'); +CREATE FOREIGN TABLE ft8_twophase ( + c1 int NOT NULL +) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 5'); +CREATE FOREIGN TABLE ft9_not_twophase ( + c1 int NOT NULL +) SERVER loopback3 OPTIONS (schema_name 'S 1', table_name 'T 5'); -- A table with oids. CREATE FOREIGN TABLE doesn't support the -- WITH OIDS option, but ALTER does. CREATE FOREIGN TABLE ft_pg_type ( @@ -185,16 +207,19 @@ ALTER FOREIGN TABLE ft2 OPTIONS (schema_name 'S 1', table_name 'T 1'); ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (column_name 'C 1'); ALTER FOREIGN TABLE ft2 ALTER COLUMN c1 OPTIONS (column_name 'C 1'); \det+ - List of foreign tables - Schema | Table | Server | FDW options | Description ---------+------------+-----------+--------------------------------------------------+------------- - public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') | - public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') | - public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') | - public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') | - public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') | - public | ft_pg_type | loopback | (schema_name 'pg_catalog', table_name 'pg_type') | -(6 rows) + List of foreign tables + Schema | Table | Server | FDW options | Description +--------+------------------+-----------+--------------------------------------------------+------------- + public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') | + public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') | + public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') | + public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') | + public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') | + public | ft7_twophase | loopback | (schema_name 'S 1', table_name 'T 5') | + public | ft8_twophase | loopback2 | (schema_name 'S 1', table_name 'T 5') | + public | ft9_not_twophase | loopback3 | (schema_name 'S 1', table_name 'T 5') | + public | ft_pg_type | loopback | (schema_name 'pg_catalog', table_name 'pg_type') | +(9 rows) -- Test that alteration of server options causes reconnection -- Remote's errors might be non-English, so hide them to ensure stable results @@ -8485,3 +8510,345 @@ SELECT b, avg(a), max(a), count(*) FROM pagg_tab GROUP BY b HAVING sum(a) < 700 -- Clean-up RESET enable_partitionwise_aggregate; +-- =================================================================== +-- test atomic commit across foreign servers +-- =================================================================== +ALTER SERVER loopback OPTIONS(ADD two_phase_commit 'on'); +ALTER SERVER loopback2 OPTIONS(ADD two_phase_commit 'on'); +ALTER SERVER loopback3 OPTIONS(ADD two_phase_commit 'off'); +\det+ + List of foreign tables + Schema | Table | Server | FDW options | Description +--------+------------------+-----------+-------------------------------------------------------------------+------------- + public | fpagg_tab_p1 | loopback | (table_name 'pagg_tab_p1') | + public | fpagg_tab_p2 | loopback | (table_name 'pagg_tab_p2') | + public | fpagg_tab_p3 | loopback | (table_name 'pagg_tab_p3') | + public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') | + public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1', use_remote_estimate 'true') | + public | ft3 | loopback | (table_name 'loct3', use_remote_estimate 'true') | + public | ft4 | loopback | (schema_name 'S 1', table_name 'T 3') | + public | ft5 | loopback | (schema_name 'S 1', table_name 'T 4') | + public | ft6 | loopback2 | (schema_name 'S 1', table_name 'T 4') | + public | ft7_twophase | loopback | (schema_name 'S 1', table_name 'T 5') | + public | ft8_twophase | loopback2 | (schema_name 'S 1', table_name 'T 5') | + public | ft9_not_twophase | loopback3 | (schema_name 'S 1', table_name 'T 5') | + public | ft_pg_type | loopback | (schema_name 'pg_catalog', table_name 'pg_type') | + public | ftprt1_p1 | loopback | (table_name 'fprt1_p1', use_remote_estimate 'true') | + public | ftprt1_p2 | loopback | (table_name 'fprt1_p2') | + public | ftprt2_p1 | loopback | (table_name 'fprt2_p1', use_remote_estimate 'true') | + public | ftprt2_p2 | loopback | (table_name 'fprt2_p2', use_remote_estimate 'true') | + public | rem1 | loopback | (table_name 'loc1') | + public | rem2 | loopback | (table_name 'loc2') | +(19 rows) + +-- Check two_phase_commit setting +SELECT srvname FROM pg_foreign_server WHERE 'two_phase_commit=on' = ANY(srvoptions) or 'two_phase_commit=off' = ANY(srvoptions); + srvname +----------- + loopback + loopback2 + loopback3 +(3 rows) + +-- Enable atomic commit +SET foreign_twophase_commit TO on; +-- Modify one 2PC-capable server then commit and rollback. +BEGIN; +INSERT INTO ft7_twophase VALUES(1); +COMMIT; +SELECT * FROM ft7_twophase; + c1 +---- + 1 +(1 row) + +BEGIN; +INSERT INTO ft7_twophase VALUES(1); +ROLLBACK; +SELECT * FROM ft7_twophase; + c1 +---- + 1 +(1 row) + +-- Modify two 2PC-capable servers then commit and rollback. +-- This requires to use 2PC when commit. +BEGIN; +INSERT INTO ft7_twophase VALUES(2); +INSERT INTO ft8_twophase VALUES(2); +COMMIT; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 +(3 rows) + +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 +(3 rows) + +BEGIN; +INSERT INTO ft7_twophase VALUES(3); +INSERT INTO ft8_twophase VALUES(3); +ROLLBACK; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 +(3 rows) + +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 +(3 rows) + +-- Modify both local data and 2PC-capable server then commit and rollback. +BEGIN; +INSERT INTO ft7_twophase VALUES(4); +INSERT INTO "S 1"."T 6" VALUES (4); +COMMIT; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +SELECT * FROM "S 1"."T 6"; + c1 +---- + 4 +(1 row) + +BEGIN; +INSERT INTO ft7_twophase VALUES(5); +INSERT INTO "S 1"."T 6" VALUES (5); +ROLLBACK; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +SELECT * FROM "S 1"."T 6"; + c1 +---- + 4 +(1 row) + +-- Modify foreign server and raise an error +BEGIN; +INSERT INTO ft7_twophase VALUES(8); +INSERT INTO ft8_twophase VALUES(NULL); -- violation +ERROR: null value in column "c1" violates not-null constraint +DETAIL: Failing row contains (null). +CONTEXT: remote SQL command: INSERT INTO "S 1"."T 5"(c1) VALUES ($1) +ROLLBACK; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +-- Rollback foreign transaction that involves both 2PC-capable +-- and 2PC-non-capable foreign servers. +BEGIN; +INSERT INTO ft8_twophase VALUES(7); +INSERT INTO ft9_not_twophase VALUES(7); +ROLLBACK; +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +SELECT * FROM ft9_not_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +-- Fails, cannot commit the distributed transaction if 2PC-non-capable +-- server involved in. +BEGIN; +INSERT INTO ft8_twophase VALUES(6); +INSERT INTO ft9_not_twophase VALUES(6); +COMMIT; -- error +ERROR: cannot COMMIT a distributed transaction that has operated on foreign server that doesn't support atomic commit +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +SELECT * FROM ft9_not_twophase; + c1 +---- + 1 + 2 + 2 + 4 +(4 rows) + +-- Disables atomic commit, and success the same case as above. +SET foreign_twophase_commit TO off; +BEGIN; +INSERT INTO ft8_twophase VALUES(6); +INSERT INTO ft9_not_twophase VALUES(6); +COMMIT; -- success +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 +(5 rows) + +SELECT * FROM ft9_not_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 +(5 rows) + +-- Enable atomic commit, again. +SET foreign_twophase_commit TO on; +-- Commit and rollback foreign transactions that are part of +-- prepare transaction. +BEGIN; +INSERT INTO ft7_twophase VALUES(9); +INSERT INTO ft8_twophase VALUES(9); +PREPARE TRANSACTION 'gx1'; +COMMIT PREPARED 'gx1'; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 + 6 + 9 + 9 +(8 rows) + +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 + 6 + 9 + 9 +(8 rows) + +BEGIN; +INSERT INTO ft7_twophase VALUES(10); +INSERT INTO ft8_twophase VALUES(10); +PREPARE TRANSACTION 'gx1'; +ROLLBACK PREPARED 'gx1'; +SELECT * FROM ft7_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 + 6 + 9 + 9 +(8 rows) + +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 + 6 + 9 + 9 +(8 rows) + +-- Fails, cannot prepare the transaction if non-supporeted +-- server involved in. +BEGIN; +INSERT INTO ft8_twophase VALUES(11); +INSERT INTO ft9_not_twophase VALUES(11); +PREPARE TRANSACTION 'gx1'; -- error +ERROR: cannot prepare a transaction that modified remote tables +SELECT * FROM ft8_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 + 6 + 9 + 9 +(8 rows) + +SELECT * FROM ft9_not_twophase; + c1 +---- + 1 + 2 + 2 + 4 + 6 + 6 + 9 + 9 +(8 rows) + diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c index 6854f1b..1f45b1c 100644 --- a/contrib/postgres_fdw/option.c +++ b/contrib/postgres_fdw/option.c @@ -108,7 +108,8 @@ postgres_fdw_validator(PG_FUNCTION_ARGS) * Validate option value, when we can do so without any context. */ if (strcmp(def->defname, "use_remote_estimate") == 0 || - strcmp(def->defname, "updatable") == 0) + strcmp(def->defname, "updatable") == 0 || + strcmp(def->defname, "two_phase_commit") == 0) { /* these accept only boolean values */ (void) defGetBoolean(def); @@ -177,6 +178,8 @@ InitPgFdwOptions(void) /* fetch_size is available on both server and table */ {"fetch_size", ForeignServerRelationId, false}, {"fetch_size", ForeignTableRelationId, false}, + /* two phase commit support */ + {"two_phase_commit", ForeignServerRelationId, false}, {NULL, InvalidOid, false} }; diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c index 78b0f43..28bd246 100644 --- a/contrib/postgres_fdw/postgres_fdw.c +++ b/contrib/postgres_fdw/postgres_fdw.c @@ -14,6 +14,7 @@ #include "postgres_fdw.h" +#include "access/xact.h" #include "access/htup_details.h" #include "access/sysattr.h" #include "catalog/pg_class.h" @@ -21,6 +22,7 @@ #include "commands/explain.h" #include "commands/vacuum.h" #include "foreign/fdwapi.h" +#include "foreign/fdwxact.h" #include "funcapi.h" #include "miscadmin.h" #include "nodes/makefuncs.h" @@ -358,6 +360,7 @@ static void postgresGetForeignUpperPaths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *output_rel, void *extra); +static bool postgresIsTwoPhaseCommitEnabled(Oid serverid); /* * Helper functions @@ -451,7 +454,6 @@ static void merge_fdw_options(PgFdwRelationInfo *fpinfo, const PgFdwRelationInfo *fpinfo_o, const PgFdwRelationInfo *fpinfo_i); - /* * Foreign-data wrapper handler function: return a struct with pointers * to my callback routines. @@ -505,10 +507,29 @@ postgres_fdw_handler(PG_FUNCTION_ARGS) /* Support functions for upper relation push-down */ routine->GetForeignUpperPaths = postgresGetForeignUpperPaths; + /* Support functions for foreign transactions */ + routine->PrepareForeignTransaction = postgresPrepareForeignTransaction; + routine->CommitForeignTransaction = postgresCommitForeignTransaction; + routine->RollbackForeignTransaction = postgresRollbackForeignTransaction; + routine->ResolveForeignTransaction = postgresResolveForeignTransaction; + routine->IsTwoPhaseCommitEnabled = postgresIsTwoPhaseCommitEnabled; + PG_RETURN_POINTER(routine); } /* + * postgresIsTwoPhaseCommitEnabled + */ +static bool +postgresIsTwoPhaseCommitEnabled(Oid serverid) +{ + ForeignServer *server = GetForeignServer(serverid); + + + return server_uses_twophase_commit(server); +} + +/* * postgresGetForeignRelSize * Estimate # of rows and width of the result of the scan * @@ -1355,7 +1376,7 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags) * Get connection to the foreign server. Connection manager will * establish new connection if necessary. */ - fsstate->conn = GetConnection(user, false); + fsstate->conn = GetConnection(user->umid, false, true); /* Assign a unique ID for my cursor */ fsstate->cursor_number = GetCursorNumber(fsstate->conn); @@ -2400,7 +2421,7 @@ postgresBeginDirectModify(ForeignScanState *node, int eflags) * Get connection to the foreign server. Connection manager will * establish new connection if necessary. */ - dmstate->conn = GetConnection(user, false); + dmstate->conn = GetConnection(user->umid, false, true); /* Update the foreign-join-related fields. */ if (fsplan->scan.scanrelid == 0) @@ -2697,7 +2718,7 @@ estimate_path_cost_size(PlannerInfo *root, &retrieved_attrs, NULL); /* Get the remote estimate */ - conn = GetConnection(fpinfo->user, false); + conn = GetConnection(fpinfo->user->umid, false, true); get_remote_estimate(sql.data, conn, &rows, &width, &startup_cost, &total_cost); ReleaseConnection(conn); @@ -3314,7 +3335,7 @@ create_foreign_modify(EState *estate, user = GetUserMapping(userid, table->serverid); /* Open connection; report that we'll create a prepared statement. */ - fmstate->conn = GetConnection(user, true); + fmstate->conn = GetConnection(user->umid, true, true); fmstate->p_name = NULL; /* prepared statement not made yet */ /* Set up remote query information. */ @@ -4101,7 +4122,7 @@ postgresAnalyzeForeignTable(Relation relation, */ table = GetForeignTable(RelationGetRelid(relation)); user = GetUserMapping(relation->rd_rel->relowner, table->serverid); - conn = GetConnection(user, false); + conn = GetConnection(user->umid, false, true); /* * Construct command to get page count for relation. @@ -4191,7 +4212,7 @@ postgresAcquireSampleRowsFunc(Relation relation, int elevel, table = GetForeignTable(RelationGetRelid(relation)); server = GetForeignServer(table->serverid); user = GetUserMapping(relation->rd_rel->relowner, table->serverid); - conn = GetConnection(user, false); + conn = GetConnection(user->umid, false, true); /* * Construct cursor that retrieves whole rows from remote. @@ -4414,7 +4435,7 @@ postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid) */ server = GetForeignServer(serverOid); mapping = GetUserMapping(GetUserId(), server->serverid); - conn = GetConnection(mapping, false); + conn = GetConnection(mapping->umid, false, true); /* Don't attempt to import collation if remote server hasn't got it */ if (PQserverVersion(conn) < 90100) @@ -5795,3 +5816,26 @@ find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel) /* We didn't find any suitable equivalence class expression */ return NULL; } + +/* + * server_uses_twophase_commit + * Returns true if the foreign server is configured to support 2PC. + */ +bool +server_uses_twophase_commit(ForeignServer *server) +{ + ListCell *lc; + + /* Check the options for two phase compliance */ + foreach(lc, server->options) + { + DefElem *d = (DefElem *) lfirst(lc); + + if (strcmp(d->defname, "two_phase_commit") == 0) + { + return defGetBoolean(d); + } + } + /* By default a server is not 2PC compliant */ + return false; +} diff --git a/contrib/postgres_fdw/postgres_fdw.h b/contrib/postgres_fdw/postgres_fdw.h index a5d4011..585cf3e 100644 --- a/contrib/postgres_fdw/postgres_fdw.h +++ b/contrib/postgres_fdw/postgres_fdw.h @@ -13,6 +13,7 @@ #ifndef POSTGRES_FDW_H #define POSTGRES_FDW_H +#include "foreign/fdwxact.h" #include "foreign/foreign.h" #include "lib/stringinfo.h" #include "nodes/relation.h" @@ -115,7 +116,8 @@ extern int set_transmission_modes(void); extern void reset_transmission_modes(int nestlevel); /* in connection.c */ -extern PGconn *GetConnection(UserMapping *user, bool will_prep_stmt); +extern PGconn *GetConnection(Oid umid, bool will_prep_stmt, bool start_transaction); +extern PGconn *GetExistingConnection(Oid umid); extern void ReleaseConnection(PGconn *conn); extern unsigned int GetCursorNumber(PGconn *conn); extern unsigned int GetPrepStmtNumber(PGconn *conn); @@ -123,6 +125,11 @@ extern PGresult *pgfdw_get_result(PGconn *conn, const char *query); extern PGresult *pgfdw_exec_query(PGconn *conn, const char *query); extern void pgfdw_report_error(int elevel, PGresult *res, PGconn *conn, bool clear, const char *sql); +extern bool postgresPrepareForeignTransaction(ForeignTransaction *foreign_xact); +extern bool postgresCommitForeignTransaction(ForeignTransaction *foreign_xact); +extern bool postgresRollbackForeignTransaction(ForeignTransaction *foriegn_xact); +extern bool postgresResolveForeignTransaction(ForeignTransaction *foreign_xact, + bool is_commit); /* in option.c */ extern int ExtractConnectionOptions(List *defelems, @@ -179,6 +186,7 @@ extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, List *remote_conds, List *pathkeys, bool is_subquery, List **retrieved_attrs, List **params_list); extern const char *get_jointype_name(JoinType jointype); +extern bool server_uses_twophase_commit(ForeignServer *server); /* in shippable.c */ extern bool is_builtin(Oid objectId); diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index cdfd9c9..3dd82a1 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -15,6 +15,10 @@ DO $d$ OPTIONS (dbname '$$||current_database()||$$', port '$$||current_setting('port')||$$' )$$; + EXECUTE $$CREATE SERVER loopback3 FOREIGN DATA WRAPPER postgres_fdw + OPTIONS (dbname '$$||current_database()||$$', + port '$$||current_setting('port')||$$' + )$$; END; $d$; @@ -22,6 +26,7 @@ CREATE USER MAPPING FOR public SERVER testserver1 OPTIONS (user 'value', password 'value'); CREATE USER MAPPING FOR CURRENT_USER SERVER loopback; CREATE USER MAPPING FOR CURRENT_USER SERVER loopback2; +CREATE USER MAPPING FOR CURRENT_USER SERVER loopback3; -- =================================================================== -- create objects used through FDW loopback server @@ -56,6 +61,14 @@ CREATE TABLE "S 1"."T 4" ( c3 text, CONSTRAINT t4_pkey PRIMARY KEY (c1) ); +CREATE TABLE "S 1"."T 5" ( + c1 int NOT NULL +); + +CREATE TABLE "S 1"."T 6" ( + c1 int NOT NULL, + CONSTRAINT t6_pkey PRIMARY KEY (c1) +); -- Disable autovacuum for these tables to avoid unexpected effects of that ALTER TABLE "S 1"."T 1" SET (autovacuum_enabled = 'false'); @@ -94,6 +107,7 @@ ANALYZE "S 1"."T 1"; ANALYZE "S 1"."T 2"; ANALYZE "S 1"."T 3"; ANALYZE "S 1"."T 4"; +ANALYZE "S 1"."T 5"; -- =================================================================== -- create foreign tables @@ -142,6 +156,19 @@ CREATE FOREIGN TABLE ft6 ( c3 text ) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 4'); +CREATE FOREIGN TABLE ft7_twophase ( + c1 int NOT NULL +) SERVER loopback OPTIONS (schema_name 'S 1', table_name 'T 5'); + +CREATE FOREIGN TABLE ft8_twophase ( + c1 int NOT NULL +) SERVER loopback2 OPTIONS (schema_name 'S 1', table_name 'T 5'); + +CREATE FOREIGN TABLE ft9_not_twophase ( + c1 int NOT NULL +) SERVER loopback3 OPTIONS (schema_name 'S 1', table_name 'T 5'); + + -- A table with oids. CREATE FOREIGN TABLE doesn't support the -- WITH OIDS option, but ALTER does. CREATE FOREIGN TABLE ft_pg_type ( @@ -2251,7 +2278,6 @@ SELECT t1.a, t1.phv, t2.b, t2.phv FROM (SELECT 't1_phv' phv, * FROM fprt1 WHERE RESET enable_partitionwise_join; - -- =================================================================== -- test partitionwise aggregates -- =================================================================== @@ -2301,3 +2327,126 @@ SELECT b, avg(a), max(a), count(*) FROM pagg_tab GROUP BY b HAVING sum(a) < 700 -- Clean-up RESET enable_partitionwise_aggregate; + +-- =================================================================== +-- test atomic commit across foreign servers +-- =================================================================== + +ALTER SERVER loopback OPTIONS(ADD two_phase_commit 'on'); +ALTER SERVER loopback2 OPTIONS(ADD two_phase_commit 'on'); +ALTER SERVER loopback3 OPTIONS(ADD two_phase_commit 'off'); + +\det+ + +-- Check two_phase_commit setting +SELECT srvname FROM pg_foreign_server WHERE 'two_phase_commit=on' = ANY(srvoptions) or 'two_phase_commit=off' = ANY(srvoptions); + +-- Enable atomic commit +SET foreign_twophase_commit TO on; + +-- Modify one 2PC-capable server then commit and rollback. +BEGIN; +INSERT INTO ft7_twophase VALUES(1); +COMMIT; +SELECT * FROM ft7_twophase; + +BEGIN; +INSERT INTO ft7_twophase VALUES(1); +ROLLBACK; +SELECT * FROM ft7_twophase; + +-- Modify two 2PC-capable servers then commit and rollback. +-- This requires to use 2PC when commit. +BEGIN; +INSERT INTO ft7_twophase VALUES(2); +INSERT INTO ft8_twophase VALUES(2); +COMMIT; +SELECT * FROM ft7_twophase; +SELECT * FROM ft8_twophase; + +BEGIN; +INSERT INTO ft7_twophase VALUES(3); +INSERT INTO ft8_twophase VALUES(3); +ROLLBACK; +SELECT * FROM ft7_twophase; +SELECT * FROM ft8_twophase; + +-- Modify both local data and 2PC-capable server then commit and rollback. +BEGIN; +INSERT INTO ft7_twophase VALUES(4); +INSERT INTO "S 1"."T 6" VALUES (4); +COMMIT; +SELECT * FROM ft7_twophase; +SELECT * FROM "S 1"."T 6"; + +BEGIN; +INSERT INTO ft7_twophase VALUES(5); +INSERT INTO "S 1"."T 6" VALUES (5); +ROLLBACK; +SELECT * FROM ft7_twophase; +SELECT * FROM "S 1"."T 6"; + +-- Modify foreign server and raise an error +BEGIN; +INSERT INTO ft7_twophase VALUES(8); +INSERT INTO ft8_twophase VALUES(NULL); -- violation +ROLLBACK; +SELECT * FROM ft7_twophase; +SELECT * FROM ft8_twophase; + +-- Rollback foreign transaction that involves both 2PC-capable +-- and 2PC-non-capable foreign servers. +BEGIN; +INSERT INTO ft8_twophase VALUES(7); +INSERT INTO ft9_not_twophase VALUES(7); +ROLLBACK; +SELECT * FROM ft8_twophase; +SELECT * FROM ft9_not_twophase; + +-- Fails, cannot commit the distributed transaction if 2PC-non-capable +-- server involved in. +BEGIN; +INSERT INTO ft8_twophase VALUES(6); +INSERT INTO ft9_not_twophase VALUES(6); +COMMIT; -- error +SELECT * FROM ft8_twophase; +SELECT * FROM ft9_not_twophase; + +-- Disables atomic commit, and success the same case as above. +SET foreign_twophase_commit TO off; +BEGIN; +INSERT INTO ft8_twophase VALUES(6); +INSERT INTO ft9_not_twophase VALUES(6); +COMMIT; -- success +SELECT * FROM ft8_twophase; +SELECT * FROM ft9_not_twophase; + +-- Enable atomic commit, again. +SET foreign_twophase_commit TO on; + +-- Commit and rollback foreign transactions that are part of +-- prepare transaction. +BEGIN; +INSERT INTO ft7_twophase VALUES(9); +INSERT INTO ft8_twophase VALUES(9); +PREPARE TRANSACTION 'gx1'; +COMMIT PREPARED 'gx1'; +SELECT * FROM ft7_twophase; +SELECT * FROM ft8_twophase; + +BEGIN; +INSERT INTO ft7_twophase VALUES(10); +INSERT INTO ft8_twophase VALUES(10); +PREPARE TRANSACTION 'gx1'; +ROLLBACK PREPARED 'gx1'; +SELECT * FROM ft7_twophase; +SELECT * FROM ft8_twophase; + +-- Fails, cannot prepare the transaction if non-supporeted +-- server involved in. +BEGIN; +INSERT INTO ft8_twophase VALUES(11); +INSERT INTO ft9_not_twophase VALUES(11); +PREPARE TRANSACTION 'gx1'; -- error +SELECT * FROM ft8_twophase; +SELECT * FROM ft9_not_twophase; diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml index 54b5e98..f4a9ff5 100644 --- a/doc/src/sgml/postgres-fdw.sgml +++ b/doc/src/sgml/postgres-fdw.sgml @@ -436,6 +436,43 @@ + + + Transaction Management Options + + + By default, if the transaction involves with multiple remote server, + each transaction on remote server is committed or aborted independently. + Some of transactions may fail to commit on remote server while other + transactions commit successfully. This may be overridden using + following option: + + + + + + two_phase_commit + + + This option controls whether postgres_fdw allows + to use two-phase-commit when transaction commits. This option can + only be specified for foreign servers, not per-table. + The default is false. + + + + If this option is enabled, postgres_fdw prepares + transaction on remote server and PostgreSQL + keeps track of the distributed transaction. + must be set more + than 1 on local server and + must set to more than 1 on remote server. + + + + + + -- 1.7.1