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Re: Commit is slow in Mysql 5.7
Posted by: Peter Brawley
Date: September 05, 2020 01:04PM

Innodb buffer pool is 4GB. How much RAM is there?

Is there swapping?

Are these relevant? ...

https://dev.mysql.com/doc/refman/5.7/en/innodb-change-buffer.html#innodb-change-buffer-maximum-size

https://www.percona.com/blog/2016/04/12/is-adaptive-hash-index-in-innodb-right-for-my-workload/

Slow Commit suggests input overload or big or complicated transactions. Let's see some Explain results for the Insert and Update queries.

Please ...

(i) post the result of ...

select engine,data,indexes,total
from (
  select 
    ifnull(engine,'TOTALS') as engine, 
    concat(data,' GB') as data, 
    concat(indexes,' GB') as indexes, 
    concat(tot,' GB') as total,
    if(engine is null,-1,tot) as ord
  from (
    select   
      engine,  
      round( sum(data_length)/1024/1024/1024, 2 ) as data,  
      round( sum(index_length)/1024/1024/1024, 2 ) as indexes,  
      round( sum(data_length+index_length)/1024/1024/1024, 2 ) as tot
    from information_schema.tables
    where engine is not null and engine not in('information_schema','performance_schema')
    group by engine with rollup
  ) sums
) list
order by list.ord desc;

(ii) post the results of running these queries in the mysql client program ...

show variables;

show global status;

select * from sys.memory_global_total;

select 
  substring_index(event_name,'/',2) as code_area, 
  sys.format_bytes( sum(current_alloc) ) as current_alloc 
from sys.x$memory_global_by_current_bytes 
group by substring_index(event_name,'/',2) 
order by sum(current_alloc) desc;

select 
  concat(format(a.num * 100.0 / b.num,2),"%") bufferpoolfullpct 
from 
  (select variable_value num from performance_schema.global_status
  where variable_name = 'innodb_buffer_pool_pages_data') a,
  (select variable_value num from performance_schema.global_status
  where variable_name = 'innodb_buffer_pool_pages_total') b;

... and look for runaway mem use in the results of ...

select * 
from performance_schema.memory_summary_global_by_event_name
where event_name like 'memory/performance_schema/%';

(iii) post the result of ...

free -m



Edited 1 time(s). Last edit at 09/05/2020 03:03PM by Peter Brawley.

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