Page (File architecture): Difference between revisions

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Note 1: FCT = 0, Table A = 1, Table B = 2, Table C = 3, Table D = 4, Table E = 5 and Table X = 6. Because of INCREASE and DECREASE  commands after the initial CREATE, the pages for a table may not be contiguous.   
Note 1: FCT = 0, Table A = 1, Table B = 2, Table C = 3, Table D = 4, Table E = 5 and Table X = 6. Because of INCREASE and DECREASE  commands after the initial CREATE, the pages for a table may not be contiguous.   


[[Category:File architecture and Management]]
[[Category:File architecture and management]]
[[Category:File architecture]]
[[Category:File architecture]]

Revision as of 13:04, 19 April 2013

A page is the underlying structure applied to the data-set(s) that comprise a Model 204 file.

All pages are 6184 bytes.

When a file is created, the pages in the file are formatted into:

  • 6144 bytes of 'usable' space (how the space is used depends on the page type)
  • a 40 byte page trailer


The page Trailer

The page trailer contains:

  • the file name. This is the name used in the Create process
  • the date / time when the page was last initialized.
  • the date / time the page was last written to the file
  • data used in the checkpoint process
  • the table that this page is part of (a numeric representation (see note 1))
  • the sequential page number within the table


Note 1: FCT = 0, Table A = 1, Table B = 2, Table C = 3, Table D = 4, Table E = 5 and Table X = 6. Because of INCREASE and DECREASE commands after the initial CREATE, the pages for a table may not be contiguous.