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From:Xiang Fang Date:May 8 2009 5:25am
Subject:sub_select and evaluate_join_record continue increasing issue
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Hi all,

When I running a workload(olio) with MySQL 6.0 falcon engine, I find when time goes the
CPU utilization of MySQL server continue increasing to 100%, while the pressure from
client is almost same. I want to know why this issue is happened, so I collect functions
called number every 30 seconds. By looking the called number trend graph, please see the
detail data and graph in attached excel file. 

The following functions called number continue increasing during the run before the CPU
reach 100%.
IndexPage::findSupernode
Cach::fetchPage
evaluate_join_record
Dbb::handoffPage	
IndexPage::findNodeInBranch	
IndexRootPage::scanIndex	
IndexPage::findNodeInLeaf	
IndexRootPage::findRoot	
findLeaf	
StorageTable::indexScan	
sub_select	
StorageInterface::index_read	
Index::scanIndex	
join_read_key2	

The following functions called number are almost flat during the run before the CPU reach
100%, so we confirm the pressure from client is also same.
do_command	
dispatch_command	
do_select	
JOIN::exec	
msyql_parse	
mysql_execute_command	
mysql_select	
handle_select	
execute_sqlcom_select	
join_read_always_key	
IndexRootPage::positionIndex	
Index::positionIndex	
StorageInterface::index_first	
join_read_first	
handle_one_connection	

The following methods are not called.
Inversion::findRoot	
Sensitive_cursor::fetch	
sub_select_cache	
sub_select_sjm


From call stack, we know do_select will call sub_select, sub_select will call
evaluate_join_record and evaluate_join_record may call sub_select also (call loop).
Starting from sub_select, most of functions are increasing during time. Another
interesting thing is the do_select/sub_select ratio is higher to more than 100, and it
also continues increasing up to 180.

Does anyone have any clue for the sub_select or evaluate_join_record continue increasing
while the pressure is same? If you need more data, please let me know.

Thanks very much,
Xiang

Attachment: [application/vnd.ms-excel] function_count_summary.xls function_count_summary.xls
Thread
sub_select and evaluate_join_record continue increasing issue Xiang Fang8 May
  • Re: sub_select and evaluate_join_record continue increasing issueKristian Nielsen8 May