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create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1(a int);
insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;
create table t10 (a int, b int, c int);
insert into t10
select
A.a + 1000*B.a,
A.a + 1000*B.a,
A.a + 1000*B.a
from t1 A, t0 B
order by A.a+1000*B.a;
#################################################################
## Try a basic example
flush status;
create table t21 as
select
sum(b) over (order by a rows between 2 preceding and 2 following) as SUM_B
from
t10;
select variable_name,
case when variable_value > 0 then 'WITH PASSES' else 'NO PASSES' end as result
from information_schema.session_status
where variable_name like 'Sort_merge_passes';
variable_name result
SORT_MERGE_PASSES NO PASSES
set sort_buffer_size=1024;
flush status;
create table t22 as
select
sum(b) over (order by a rows between 2 preceding and 2 following) as SUM_B
from
t10;
select variable_name,
case when variable_value > 0 then 'WITH PASSES' else 'NO PASSES' end as result
from information_schema.session_status
where variable_name like 'Sort_merge_passes';
variable_name result
SORT_MERGE_PASSES WITH PASSES
include/diff_tables.inc [t21, t22]
drop table t21, t22;
#################################################################
# Try many cursors
set sort_buffer_size=default;
flush status;
create table t21 as
select
sum(b) over (order by a rows between 2 preceding and 2 following) as SUM_B1,
sum(b) over (order by a rows between 5 preceding and 5 following) as SUM_B2,
sum(b) over (order by a rows between 20 preceding and 20 following) as SUM_B3
from
t10;
select variable_name,
case when variable_value > 0 then 'WITH PASSES' else 'NO PASSES' end as result
from information_schema.session_status
where variable_name like 'Sort_merge_passes';
variable_name result
SORT_MERGE_PASSES NO PASSES
set sort_buffer_size=1024;
flush status;
create table t22 as
select
sum(b) over (order by a rows between 2 preceding and 2 following) as SUM_B1,
sum(b) over (order by a rows between 5 preceding and 5 following) as SUM_B2,
sum(b) over (order by a rows between 20 preceding and 20 following) as SUM_B3
from
t10;
select variable_name,
case when variable_value > 0 then 'WITH PASSES' else 'NO PASSES' end as result
from information_schema.session_status
where variable_name like 'Sort_merge_passes';
variable_name result
SORT_MERGE_PASSES WITH PASSES
include/diff_tables.inc [t21, t22]
drop table t21, t22;
#################################################################
# Try having cursors pointing at different IO_CACHE pages
# in the IO_CACHE
set sort_buffer_size=default;
flush status;
create table t21 as
select
a,
sum(b) over (order by a range between 5000 preceding and 5000 following) as SUM_B1
from
t10;
select variable_name,
case when variable_value > 0 then 'WITH PASSES' else 'NO PASSES' end as result
from information_schema.session_status
where variable_name like 'Sort_merge_passes';
variable_name result
SORT_MERGE_PASSES NO PASSES
set sort_buffer_size=1024;
flush status;
create table t22 as
select
a,
sum(b) over (order by a range between 5000 preceding and 5000 following) as SUM_B1
from
t10;
select variable_name,
case when variable_value > 0 then 'WITH PASSES' else 'NO PASSES' end as result
from information_schema.session_status
where variable_name like 'Sort_merge_passes';
variable_name result
SORT_MERGE_PASSES WITH PASSES
include/diff_tables.inc [t21, t22]
drop table t21, t22;
#################################################################
drop table t10;
drop table t0,t1;
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