max_replica_delay_for_distributed_queries_test.sql

gistfile1.txt

-- SERVER A
create table test_r(a Int64) Engine=ReplicatedMergeTree('/clickhouse/{cluster}/tables/{table}','{replica}') order by a;
insert into  test_r select number from numbers(1e6);
create table test_d as test_r Engine=Distributed('replicated', dw,test_r);

select count() from test_r;
1000000

select count() from test_d;
1000000

system stop REPLICATED sends test_r;  -- artificially stop replication to emulate replication lag
system stop FETCHES test_r;


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-- SERVER B
create table test_r(a Int64) Engine=ReplicatedMergeTree('/clickhouse/{cluster}/tables/{table}','{replica}') order by a;
select count() from test_r;
0    -- replication does not work (stop REPLICATED sends)

create table test_d as test_r Engine=Distributed('replicated', dw,test_r);
select count() from test_d;
0    -- incorrect result because max_replica_delay_for_distributed_queries = 300, and replication lag is less < 300

set max_replica_delay_for_distributed_queries=10;
select count() from test_d;
1000000 -- correct result max_replica_delay_for_distributed_queries=10