Slow performance of query [duplicate] - sqlite

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Closed 11 years ago.
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Slow Performance of Sql Query
Hi,
I have asked the performance of query and i tried to simplyfy it.but still it not works.I am adding my query below.Please can you simplify it more effectively
select
r.parent_itemid f_id,
parent_item.name f_name,
parent_item.typeid f_typeid,
parent_item.ownerid f_ownerid,
parent_item.created f_created,
parent_item.modifiedby f_modifiedby,
parent_item.modified f_modified,
pt.name f_tname,
child_item.id i_id,
t.name i_tname,
child_item.typeid i_typeid,
child_item.name i_name,
child_item.ownerid i_ownerid,
child_item.created i_created,
child_item.modifiedby i_modifiedby,
child_item.modified i_modified,
r.ordinal i_ordinal
from
item child_item,
type t,
relation r,
item parent_item,
type pt
where
r.child_itemid = child_item.id and
t.id=child_item.typeid and
parent_item.id = r.parent_itemid and
pt.id = parent_item.typeid
and parent_item.id in (
select
itemid
from
permission
where
itemid=parent_item.id and
(holder_itemid in (10,100) and level > 0) )
order by
r.parent_itemid,
r.relation_typeid,
r.ordinal
Thanks you
regards
jennie

Answer 1

You don't need the correlated subquery on the permissions. Any other problems need to be fixed by checking the indexes indexes on the join fields (like item.child_itemid ) & filter fields (like permission.holder_itemid) will help the performance of your query
select
r.parent_itemid f_id,
parent_item.name f_name,
parent_item.typeid f_typeid,
parent_item.ownerid f_ownerid,
parent_item.created f_created,
parent_item.modifiedby f_modifiedby,
parent_item.modified f_modified,
pt.name f_tname,
child_item.id i_id,
t.name i_tname,
child_item.typeid i_typeid,
child_item.name i_name,
child_item.ownerid i_ownerid,
child_item.created i_created,
child_item.modifiedby i_modifiedby,
child_item.modified i_modified,
r.ordinal i_ordinal
from
item child_item,
type t,
relation r,
item parent_item,
type pt,
permission p
where
r.child_itemid = child_item.id
and t.id=child_item.typeid
and parent_item.id = r.parent_itemid
and pt.id = parent_item.typeid
and parent_item.id = p.itemid
and p.holder_itemid in (10, 100)
and p.level > 0
order by
r.parent_itemid,
r.relation_typeid,
r.ordinal

Answer 2

Try removing the subquery, something like:
select
r.parent_itemid f_id,
parent_item.name f_name,
parent_item.typeid f_typeid,
parent_item.ownerid f_ownerid,
parent_item.created f_created,
parent_item.modifiedby f_modifiedby,
parent_item.modified f_modified,
pt.name f_tname,
child_item.id i_id,
t.name i_tname,
child_item.typeid i_typeid,
child_item.name i_name,
child_item.ownerid i_ownerid,
child_item.created i_created,
child_item.modifiedby i_modifiedby,
child_item.modified i_modified,
r.ordinal i_ordinal
from
item child_item,
type t,
relation r,
item parent_item,
type pt,
permission perm /* <<< added this line <<< */
where
r.child_itemid = child_item.id and
t.id=child_item.typeid and
parent_item.id = r.parent_itemid and
pt.id = parent_item.typeid
and parent_item.id = perm.itemid /* <<< modified this line <<< */
and perm.itemid = parent_item.id /* <<< copied these 2 lines from the subquery <<< */
and (perm.holder_itemid in (10,100) and perm.level > 0) ) /* <<< */
order by
r.parent_itemid,
r.relation_typeid,
r.ordinal
Give it a try, and see if it works and makes any difference.