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Re: MySQL8
Posted by: Peter Brawley
Date: June 06, 2021 09:59AM

The most common causes are inefficient queries, incorrect tuning of the server, too much load for available resources, in that order.

RAM settings need to be tailored to load & resources. MySQL 8.0.what? What is innodb_buffer_pool_size? How much RAM does the machine have, how much is used by other processes?

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

(iv) turn on the slow query log, optimise the queries it identifies.

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June 04, 2021 03:07AM
Re: MySQL8
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June 06, 2021 09:59AM


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