How can I optimize this MySQL query, select rows that are NOT IN another table -

-

i have query:

select *  (     select         ign,         max(aktualizacja) wywalony,         datediff(curdate(),max(aktualizacja)) wywalony_dni_temu     dump_armijny     group ign ) ign not in (     select distinct ign     dump_armijny     aktualizacja =     (         select max(aktualizacja)         dump_armijny     ) ) order wywalony desc

but takes ~2 seconds on 13k rows table, , grows fast, how can optimize it?

here query:

select a.* (select ign, max(aktualizacja) wywalony,               datediff(curdate(), max(aktualizacja)) wywalony_dni_temu       dump_armijny       group ign      ) ign not in (select distinct ign                   dump_armijny                   aktualizacja = (select max(aktualizacja)                                         dump_armijny                                        )                  ) order wywalony desc;

typically not exists more optimized not in , select distinct unnecessary in in subquery anyway. write query this:

select ign, max(aktualizacja) wywalony,         datediff(curdate(), max(aktualizacja)) wywalony_dni_temu dump_armijny not exists (select 1                    dump_armijny a2 join                         (select max(aktualizacja) maxa dump_armijny) m                         on aktualizacja = m.maxa                    a.ign = a2.ign                  ) group ign order wywalony desc;

it bit hard follow logic of query, think same as:

select ign, max(aktualizacja) wywalony,         datediff(curdate(), max(aktualizacja)) wywalony_dni_temu dump_armijny join      (select max(aktualizacja) maxa dump_armijny) m group ign having wywalony <> m.maxa order wywalony;

in case, should define indexes. "must-have" dump_armijny(aktualizacja). not exists version, want dump_armijny(ign, aktualizacja).


Comments

Post a Comment

Popular posts from this blog

python - How to create jsonb index using GIN on SQLAlchemy? -

-
here's current code creating index jsonb. index("mytable_data_idx_id_key", mytable.data['id'].astext, postgresql_using='gin') but got error. sqlalchemy.exc.programmingerror: (psycopg2.programmingerror) data type text has no default operator class access method "gin" hint: must specify operator class index or define default operator class data type. [sql: "create index event_data_idx_id_key on event using gin ((data ->> 'id'))"] is there way create index on sqlalchemy? the postgresql specific sqlalchemy docs @ http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html#operator-classes mention postgresql_ops dictionary provide "operator class" used postgresql, , provide example illustrating use: index('my_index', my_table.c.id, my_table.c.data, postgresql_ops={ 'data': 'text_pattern_ops', ...
Read more

PHP DOM loadHTML() method unusual warning -

-
i had following code works fine on localhost: $document = new domdocument(); $document->loadhtml($p_result); $form = $document->getelementsbytagname('form')->item(0); // code continues using $form variable after same code updated on outside server, loadhtml() failed , issued warning. warning: domdocument::loadhtml() expects parameter 1 valid path, string given in path/name/to/script.php returned null instead of object code pretty gets fatal error. note contents of $p_result absolutely same on outside server , on localhost. but why displays kind of warning , why not work? doesn't loadhtml() expects argument 1 string in first place? why method expects parameter 1 valid path ? just make clear i'm not calling loadhtmlfile() , i'm calling loadhtml() . thanks. you're affected one of php bugs . issue present in php 5.6.8 , 5.6.9. have affected php version on server, , bug-free version on localhost. the bug forbids null ...
Read more

c# - TransactionScope not rolling back although no complete() is called -

-
i'm using transactionscope rollback transaction fail bool errorreported = false; action<importerrorlog> newerrorcallback = e => { errorreported = true; errorcallback(e); }; using (var transaction = new transactionscope()) { foreach (importtaskdefinition task in taskdefinition) { loader.load(streamfile, newerrorcallback, task.destinationtable, processingtaskid); } if (!errorreported) transaction.complete(); } i'm sure there no transactionscope started ahead or after code. i'm using entity framework insert in db. regardless state of errorreported transaction never rolled in case of error. what missing ? transactionscope sets transaction.current . that's does. wants transacted must @ property. i believe ef each time connection opened reason. probably, connection open when scope installed. open connection inside of scope or enlist manually. ef has nasty "design decision": default opens ...
Read more