1SET @def_var= @@session.transaction_prealloc_size; 2SET SESSION transaction_prealloc_size=1024*1024*1024*1; 3SHOW PROCESSLIST; 4Id User Host db Command Time State Info Progress 5<Id> root <Host> test Query <Time> <State> SHOW PROCESSLIST 0.000 6SET SESSION transaction_prealloc_size=1024*1024*1024*2; 7SHOW PROCESSLIST; 8Id User Host db Command Time State Info Progress 9<Id> root <Host> test Query <Time> <State> SHOW PROCESSLIST 0.000 10SET SESSION transaction_prealloc_size=1024*1024*1024*3; 11SHOW PROCESSLIST; 12Id User Host db Command Time State Info Progress 13<Id> root <Host> test Query <Time> <State> SHOW PROCESSLIST 0.000 14SET SESSION transaction_prealloc_size=1024*1024*1024*4; 15SHOW PROCESSLIST; 16Id User Host db Command Time State Info Progress 17<Id> root <Host> test Query <Time> <State> SHOW PROCESSLIST 0.000 18SET SESSION transaction_prealloc_size=1024*1024*1024*5; 19SHOW PROCESSLIST; 20Id User Host db Command Time State Info Progress 21<Id> root <Host> test Query <Time> <State> SHOW PROCESSLIST 0.000 22