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

Index unique scan: is for the unique index scan, it is only applicable to the where condition is the target SQL of the equivalent query, because the scanning object is the unique index, only scan the index height of so many index blocks to stop, the index unique scan results return at most one record, index unique scan, scan index height-2 branch blocks, always scan only one leaf block.

Index range scan: index range scan, scan index height-2 branches fast, to scan N multi-leaf blocks, depending on where conditions, index range scan is single block read, because physical storage is discontiguous. Select * from test where id select / * + index_desc (test) * / * from test where object_id

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