清单7中查询的谓词选择性较弱，因此需要对pdbxml表进行全表扫描。
The predicates in the query in Listing 7 are weakly selective so that a full table scan of the PDBXML table is required.
清单7中查询的谓词选择性较弱，因此需要对pdbxml表进行全表扫描。
The predicates in the query in Listing 7 are weakly selective so that a full table scan of the PDBXML table is required.
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