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Updates in Heaps

SQL:  update R  set F = val  where Condition

Analysis for updates is similar to that for deletion

  • scan all pages
  • replace any updated tuples   (within each page)
  • write affected pages to disk
Costupdate  =  br + bqw

Complication: new version of tuple larger than old version  (too big for page)

Solution:   delete, re-organise free space, then insert