• # explain

    Posté par . En réponse au message performances de JOIN / EXISTS sur postgres. Évalué à 1.

    Bon, je viens de faire un explain sur la requete, mais j'avoue ne pas tout comprendre ;

    "Nested Loop Semi Join (cost=8.30..638694661.54 rows=22164 width=4) (actual time=302.577..732235.774 rows=31863 loops=1)"
" -> Seq Scan on mixiuser (cost=0.00..874903.36 rows=52453936 width=4) (actual time=32.473..211619.619 rows=52049079 loops=1)"
" -> Bitmap Heap Scan on email (cost=8.30..85.48 rows=20 width=8) (actual time=0.007..0.007 rows=0 loops=52049079)"
" Recheck Cond: ((mixiuser.id = target_id) OR (mixiuser.id = source_id))"
" -> BitmapOr (cost=8.30..8.30 rows=20 width=0) (actual time=0.005..0.005 rows=0 loops=52049079)"
" -> Bitmap Index Scan on ix_email_target_id (cost=0.00..4.11 rows=6 width=0) (actual time=0.002..0.002 rows=0 loops=52049079)"
" Index Cond: (mixiuser.id = target_id)"
" -> Bitmap Index Scan on ix_email_source_id (cost=0.00..4.18 rows=14 width=0) (actual time=0.002..0.002 rows=0 loops=52049079)"
" Index Cond: (mixiuser.id = source_id)"
"Total runtime: 732339.279 ms"