mariadb/mysql-test/suite/ndb/t/ndb_cache_multi2.test

-- source include/have_query_cache.inc
-- source include/have_multi_ndb.inc
-- source include/not_embedded.inc

--disable_warnings
drop table if exists t1, t2;
--enable_warnings


# Turn on and reset query cache on server1
connection server1;
echo == Connected to server1 ==;
set GLOBAL query_cache_type=on;
set GLOBAL query_cache_size=1355776;
set GLOBAL ndb_cache_check_time=1;
reset query cache;
flush status;

# Turn on and reset query cache on server2
connection server2;
echo == Connected to server2 ==;
set GLOBAL query_cache_type=on;
set GLOBAL query_cache_size=1355776;
set GLOBAL ndb_cache_check_time=1;
reset query cache;
flush status;

# Create test tables in NDB and load them into cache
# on server1
connection server1;
echo == Connected to server1 ==;
create table t1 (a int) engine=ndbcluster;
create table t2 (a int) engine=ndbcluster;
insert into t1 value (2);
insert into t2 value (3);
select * from t1;
# Run the check query once to load it into qc on server1
# See at the end of this test why we need to disable ps-protocol for
# this query (*)
--disable_ps_protocol
select a != 3 from t1;
--enable_ps_protocol
select * from t2;
show status like "Qcache_queries_in_cache";
show status like "Qcache_inserts";
show status like "Qcache_hits";


# Connect server2, load table in to cache, then update the table
connection server2;
echo == Connected to server2 ==;
show status like "Qcache_queries_in_cache";
show status like "Qcache_inserts";
show status like "Qcache_hits";
select * from t1;
show status like "Qcache_queries_in_cache";
show status like "Qcache_inserts";
show status like "Qcache_hits";
update t1 set a=3 where a=2;

# Connect to server1 and check that cache is invalidated
# and correct data is returned
connection server1;
echo == Connected to server1 ==;

# Loop and wait for max 10 seconds until query cache thread
# has invalidated the cache and the column a in t1 is equal to 3
let $retries=20;
while (`select a != 3 from t1`)
{
  dec $retries;
  if (!$retries)
  {
     The query_cache thread failed to invalidate query_cache in 10 seconds;
  }
  sleep 0.5;
}

# Select from t1 one last time for the result file
# Column a should be 3
select * from t1;

# There should now be three queries in the cache
show status like "Qcache_queries_in_cache";

drop table t1, t2;

# Turn off and reset query cache on server1 and server2
connection server1;
set GLOBAL query_cache_size=0;
set GLOBAL ndb_cache_check_time=0;
reset query cache;
flush status;
connection server2;
set GLOBAL query_cache_size=0;
set GLOBAL ndb_cache_check_time=0;
reset query cache;
flush status;

# (*) Why we need to execute the query in non-ps mode.
# The principle of this test is: two mysqlds connected to one cluster,
# both using their query cache. Queries are cached in server1
# ("select a!=3 from t1", "select * from t1"),
# table t1 is modified in server2, we want to see that this invalidates
# the query cache of server1. Invalidation with NDB works like this:
# when a query is found in the query cache, NDB is asked if the tables
# have changed. In this test, ha_ndbcluster calls NDB every millisecond
# to collect change information about tables.
# Due to this millisecond delay, there is need for a loop ("while...")
# in this test, which waits until a query1 ("select a!=3 from t1") is
# invalidated (which is equivalent to it returning
# up-to-date results), and then expects query2 ("select * from t1")
# to have been invalidated (see up-to-date results).
# But when enabling --ps-protocol in this test, the logic breaks,
# because query1 is still done via mysql_real_query() (see mysqltest.c:
# eval_expr() always uses mysql_real_query()). So, query1 returning
# up-to-date results is not a sign of it being invalidated in the cache,
# because it was NOT in the cache ("select a!=3 from t1" on line 39
# was done with prep stmts, while `select a!=3 from t1` is not,
# thus the second does not see the first in the cache). Thus, we may run
# query2 when cache still has not been invalidated.
# The solution is to make the initial "select a!=3 from t1" run
# as a normal query, this repairs the broken logic.
# But note, "select * from t1" is still using prepared statements
# which was the goal of this test with --ps-protocol.