Shulou(Shulou.com)06/01 Report--

Analysis:

Since the optimizer cannot judge or obtain the statistical information of the remote table, the original execution plan defaults to pull the remote table (regardless of size) to the local reconnection mode.

In this way, the situation will be slow if the remote table is large, and the query like the above will take more than 1 minute.

The original SQL statement:

Select Wb.*, (Select Wi.Nextarrivedate From Mbs7_Oms.Xs_Warearriveinfo@Dc.Moonbasadb.Com Wi Where Wi.Warecode = Wb.Warecode) As Nextarrivedate From Mbs7_Crm.Wi_Warebase@Dc.Moonbasadb.Com Wb-here the remote table is larger Inner Join (Select Wa.Stylecode) Max (Wa.Warecode) As Warecode From Mbs7_Crm.Wi_Warebase@Dc.Moonbasadb.Com Wa Inner Join (Select Stylecode From Dc_Support.Kh_Visitpage Vis Where Vis.Cuscode =: B1 And Vis.Addtime > = Trunc (Sysdate-31) And Vis.Addtime < Trunc (Sysdate-30) And Rownum = Trunc (Sysdate-31) And Vis.Addtime < Trunc (Sysdate-30) And Rownum

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