[sqlite] Is rowid the fastest?

[王庆刚]

hi,
     create a table using the following sql.
     CREATE TABLE t(x INTEGER PRIMARY KEY ASC, y, z);
  So the x is the alias of the rowid. Retrieving records by rowid around twice 
as fast as other indexs values.
  Because of the x is the alias of rowid, so retrieving records by x is also as 
fast as rowid. Is that right?

  In order to testing the efficiency. After I create index on t(x).
  And this give me a suprise, now I retrieve by x , I found that its is faster 
than its before.
  does retrieve by the rowid the fastest method? 
  Has creating index on t(x) anything influence to do with the rowid?

  best regards.