oracle11g - Query performance issue in oracle -


i need improve query has more 8 joins , consumes lot of total tablespace.

following query:

select r.id, uc.contributor_full_name,s.code,        d.text, ucs.moderation_status, v.url   review r, user_contribution uc, user_contribution_status ucs,        video v, description d, video_description vd, location_video lv,        accommodation_video av, system s  r.user_contribution_id = ucs.user_contribution_id ,        uc.id = ucs.user_contribution_id ,        uc.system_id = s.id ,        r.accommodation_id = av.accommodation_id or        r.location_id = lv.location_id ,        av.video_id = v.id ,        lv.video_id = v.id ,        v.id = vd.video_id ,        vd.description_id = d.id;

is there better way write query?

with query it's possible oracle default whole lot of hash joins , full table scans, may or may not idea.

+1 post explain plan. until then, don't upvote answer!

i believe query equivalent this, , it's possible when @ explain plan you'll see oracle convert anyway:

select r.id       ,uc.contributor_full_name,s.code       ,d.text       ,ucs.moderation_status       ,v.url   review r join   user_contribution_status ucs on r.user_contribution_id = ucs.user_contribution_id join   user_contribution uc on uc.id = ucs.user_contribution_id join   system s on uc.system_id = s.id join   accommodation_video av on r.accommodation_id = av.accommodation_id join   video_description vd on v.id = vd.video_id join   description d on vd.description_id = d.id join   video v on av.video_id = v.id union select r.id       ,uc.contributor_full_name,s.code       ,d.text       ,ucs.moderation_status       ,v.url   review r join   user_contribution_status ucs on r.user_contribution_id = ucs.user_contribution_id join   user_contribution uc on uc.id = ucs.user_contribution_id join   system s on uc.system_id = s.id join   location_video lv on r.location_id = lv.location_id  join   video_description vd on v.id = vd.video_id join   description d on vd.description_id = d.id join   video v on lv.video_id = v.id;

warning: may have made assumptions constraints (e.g. pk, fk , not null) on of id columns, esp. regards accommodation_video , location_video. removed them subclauses assumption weren't necessary - assumption may wrong.


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