[Buildroot] [PATCH] package/systemd: needs glibc

Arnout Vandecappelle arnout at mind.be
Tue Dec 4 11:02:37 UTC 2018



On 04/12/2018 11:32, Nicolas Cavallari wrote:
>> select A.result_id from symbol_per_result A, symbol_per_result B
>> 	where A.result_id = B.result_id and
>> 	A.symbol_id = (select id from config_symbol where name = "BR2_INIT_SYSTEMD" and value = "y") and
>> 	B.symbol_id = (select id from config_symbol where name = "BR2_TOOLCHAIN_USES_UCLIBC" and value = "y");
>>
>> but that query itself already takes a significant amount of time to
>> complete:
>>
>> mysql> select A.result_id from symbol_per_result A, symbol_per_result B where A.result_id = B.result_id and A.symbol_id = (select id from config_symbol where name = "BR2_INIT_SYSTEMD" and value = "y") and B.symbol_id = (select id from config_symbol where name = "BR2_TOOLCHAIN_USES_UCLIBC" and value = "y");
>> Empty set (3 min 52.15 sec)
> an "explain extended select [...]" on this seems to says¹ that mysql browses
> every row of the table twice, because there is no index to use.
> 
> Adding an index on result_id helps:
> 
> MariaDB [brautobuild]> create index resid on symbol_per_result (result_id);
> 
> MariaDB [brautobuild]> select A.result_id from symbol_per_result A,
> symbol_per_result B where A.result_id = B.result_id and A.symbol_id = (select id
> from config_symbol where name = "BR2_INIT_SYSTEMD" and value = "y") and
> B.symbol_id = (select id from config_symbol where name =
> "BR2_TOOLCHAIN_USES_UCLIBC" and value = "y");
> Empty set (9.55 sec)

 Maybe it would be even better to make (result_id, symbol_id) the primary key of
symbol_per_result? Or do I misunderstand the implications of primary key?

 Regards,
 Arnout


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