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drop table if exists t1;
set @@session.max_heap_table_size=16*1024*1024*24;
create temporary table t1 (a int not null, b int, c varchar(400), d varchar(400), primary key (a), key (b)) engine=MEMORY comment="testing heaps";
show table status like "t1";
Session Schema Name Type Engine Version Rows Avg_row_length Table_size Auto_increment
# test t1 TEMPORARY MEMORY # # # # #
insert into t1 values (1,1,'012',NULL), (2,2,'0123456789',NULL), (3,3,'012345678901234567890123456789',NULL), (4,4,NULL,'0123456789012345678901234567890123456789012345678901234567890123456789');
select * from t1;
a b c d
1 1 012 NULL
2 2 0123456789 NULL
3 3 012345678901234567890123456789 NULL
4 4 NULL 0123456789012345678901234567890123456789012345678901234567890123456789
delete from t1 where a = 3;
select * from t1;
a b c d
1 1 012 NULL
2 2 0123456789 NULL
4 4 NULL 0123456789012345678901234567890123456789012345678901234567890123456789
insert into t1 values (5,5,NULL,'0123'), (6,6,NULL,'0123');
select * from t1;
a b c d
1 1 012 NULL
2 2 0123456789 NULL
5 5 NULL 0123
4 4 NULL 0123456789012345678901234567890123456789012345678901234567890123456789
6 6 NULL 0123
update t1 set c = '012345678901234567890123456789' where a = 2;
select * from t1;
a b c d
1 1 012 NULL
2 2 012345678901234567890123456789 NULL
5 5 NULL 0123
4 4 NULL 0123456789012345678901234567890123456789012345678901234567890123456789
6 6 NULL 0123
update t1 set c = '0123456789' where a = 2;
select * from t1;
a b c d
1 1 012 NULL
2 2 0123456789 NULL
5 5 NULL 0123
4 4 NULL 0123456789012345678901234567890123456789012345678901234567890123456789
6 6 NULL 0123
insert into t1 values (7,7,'0123',NULL), (8,8,'0123',NULL);
select * from t1;
a b c d
1 1 012 NULL
2 2 0123456789 NULL
5 5 NULL 0123
4 4 NULL 0123456789012345678901234567890123456789012345678901234567890123456789
6 6 NULL 0123
7 7 0123 NULL
8 8 0123 NULL
delete from t1;
select * from t1;
a b c d
select count(*) from t1;
count(*)
10001
insert into t1 values (100000,100000,NULL,'0123'), (100000,100000,NULL,'0123');
ERROR 23000: Duplicate entry '100000' for key 'PRIMARY'
show table status like "t1";
Session Schema Name Type Engine Version Rows Avg_row_length Table_size Auto_increment
# test t1 TEMPORARY MEMORY # # # # #
select count(*) from t1;
count(*)
10002
set @@session.max_heap_table_size=default;
drop table t1;
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