mirror of https://github.com/citusdata/citus.git
Skip 2PC for readonly connections in a transaction (#4587)
* Skip 2PC for readonly connections in a transaction * Use ConnectionModifiedPlacement() function * Remove the second check of ConnectionModifiedPlacement() * Add order by to prevent flaky output * Test using pg_dist_transactionpull/4809/head
Naisila Puka
GitHub
parent
68a527ba17
commit
196064836c
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@ -20,6 +20,7 @@
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#include "distributed/connection_management.h"
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#include "distributed/listutils.h"
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#include "distributed/metadata_cache.h"
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#include "distributed/placement_connection.h"
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#include "distributed/remote_commands.h"
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#include "distributed/remote_transaction.h"
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#include "distributed/transaction_identifier.h"
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@ -782,9 +783,17 @@ CoordinatedRemoteTransactionsPrepare(void)
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continue;
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}
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/*
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* Check if any DML or DDL is executed over the connection on any
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* placement/table. If yes, we start preparing the transaction, otherwise
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* we skip prepare since the connection didn't perform any write (read-only)
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*/
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if (ConnectionModifiedPlacement(connection))
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{
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StartRemoteTransactionPrepare(connection);
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connectionList = lappend(connectionList, connection);
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}
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}
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bool raiseInterrupts = true;
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WaitForAllConnections(connectionList, raiseInterrupts);
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@ -798,6 +807,10 @@ CoordinatedRemoteTransactionsPrepare(void)
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if (transaction->transactionState != REMOTE_TRANS_PREPARING)
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{
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/*
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* Verify that the connection didn't modify any placement
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*/
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Assert(!ConnectionModifiedPlacement(connection));
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continue;
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}
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@ -331,6 +331,111 @@ SELECT count(*) FROM pg_dist_transaction;
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2
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(1 row)
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-- check that read-only participants skip prepare
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SET citus.shard_count TO 4;
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CREATE TABLE test_2pcskip (a int);
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SELECT create_distributed_table('test_2pcskip', 'a');
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create_distributed_table
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---------------------------------------------------------------------
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(1 row)
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INSERT INTO test_2pcskip SELECT i FROM generate_series(0, 5)i;
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SELECT recover_prepared_transactions();
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recover_prepared_transactions
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---------------------------------------------------------------------
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0
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(1 row)
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-- for the following test, ensure that 6 and 7 go to different shards on different workers
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SELECT count(DISTINCT nodeport) FROM pg_dist_shard_placement WHERE shardid IN (get_shard_id_for_distribution_column('test_2pcskip', 6),get_shard_id_for_distribution_column('test_2pcskip', 7));
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count
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---------------------------------------------------------------------
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2
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(1 row)
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-- only two of the connections will perform a write (INSERT)
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SET citus.force_max_query_parallelization TO ON;
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BEGIN;
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-- these inserts use two connections
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INSERT INTO test_2pcskip VALUES (6);
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INSERT INTO test_2pcskip VALUES (7);
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-- we know this will use more than two connections
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SELECT count(*) FROM test_2pcskip;
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count
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---------------------------------------------------------------------
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8
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(1 row)
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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count
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---------------------------------------------------------------------
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2
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(1 row)
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SELECT recover_prepared_transactions();
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recover_prepared_transactions
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---------------------------------------------------------------------
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0
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(1 row)
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-- only two of the connections will perform a write (INSERT)
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BEGIN;
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-- this insert uses two connections
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INSERT INTO test_2pcskip SELECT i FROM generate_series(6, 7)i;
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-- we know this will use more than two connections
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SELECT COUNT(*) FROM test_2pcskip;
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count
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---------------------------------------------------------------------
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10
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(1 row)
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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count
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---------------------------------------------------------------------
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2
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(1 row)
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-- check that reads from a reference table don't trigger 2PC
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-- despite repmodel being 2PC
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CREATE TABLE test_reference (b int);
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SELECT create_reference_table('test_reference');
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create_reference_table
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---------------------------------------------------------------------
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(1 row)
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INSERT INTO test_reference VALUES(1);
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INSERT INTO test_reference VALUES(2);
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SELECT recover_prepared_transactions();
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recover_prepared_transactions
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---------------------------------------------------------------------
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0
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(1 row)
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BEGIN;
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SELECT * FROM test_reference ORDER BY 1;
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b
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---------------------------------------------------------------------
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1
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2
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(2 rows)
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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count
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---------------------------------------------------------------------
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0
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(1 row)
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SELECT recover_prepared_transactions();
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recover_prepared_transactions
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---------------------------------------------------------------------
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0
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(1 row)
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-- Test whether auto-recovery runs
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ALTER SYSTEM SET citus.recover_2pc_interval TO 10;
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SELECT pg_reload_conf();
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@ -362,6 +467,8 @@ SELECT pg_reload_conf();
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DROP TABLE test_recovery_ref;
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DROP TABLE test_recovery;
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DROP TABLE test_recovery_single;
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DROP TABLE test_2pcskip;
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DROP TABLE test_reference;
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SELECT 1 FROM master_remove_node('localhost', :master_port);
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?column?
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---------------------------------------------------------------------
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@ -186,6 +186,52 @@ INSERT INTO test_recovery_single VALUES ('hello-2');
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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-- check that read-only participants skip prepare
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SET citus.shard_count TO 4;
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CREATE TABLE test_2pcskip (a int);
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SELECT create_distributed_table('test_2pcskip', 'a');
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INSERT INTO test_2pcskip SELECT i FROM generate_series(0, 5)i;
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SELECT recover_prepared_transactions();
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-- for the following test, ensure that 6 and 7 go to different shards on different workers
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SELECT count(DISTINCT nodeport) FROM pg_dist_shard_placement WHERE shardid IN (get_shard_id_for_distribution_column('test_2pcskip', 6),get_shard_id_for_distribution_column('test_2pcskip', 7));
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-- only two of the connections will perform a write (INSERT)
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SET citus.force_max_query_parallelization TO ON;
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BEGIN;
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-- these inserts use two connections
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INSERT INTO test_2pcskip VALUES (6);
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INSERT INTO test_2pcskip VALUES (7);
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-- we know this will use more than two connections
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SELECT count(*) FROM test_2pcskip;
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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SELECT recover_prepared_transactions();
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-- only two of the connections will perform a write (INSERT)
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BEGIN;
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-- this insert uses two connections
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INSERT INTO test_2pcskip SELECT i FROM generate_series(6, 7)i;
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-- we know this will use more than two connections
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SELECT COUNT(*) FROM test_2pcskip;
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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-- check that reads from a reference table don't trigger 2PC
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-- despite repmodel being 2PC
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CREATE TABLE test_reference (b int);
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SELECT create_reference_table('test_reference');
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INSERT INTO test_reference VALUES(1);
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INSERT INTO test_reference VALUES(2);
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SELECT recover_prepared_transactions();
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BEGIN;
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SELECT * FROM test_reference ORDER BY 1;
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COMMIT;
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SELECT count(*) FROM pg_dist_transaction;
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SELECT recover_prepared_transactions();
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-- Test whether auto-recovery runs
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ALTER SYSTEM SET citus.recover_2pc_interval TO 10;
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@ -200,5 +246,7 @@ SELECT pg_reload_conf();
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DROP TABLE test_recovery_ref;
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DROP TABLE test_recovery;
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DROP TABLE test_recovery_single;
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DROP TABLE test_2pcskip;
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DROP TABLE test_reference;
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SELECT 1 FROM master_remove_node('localhost', :master_port);
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