uCosminexus Service Platform, Basic Development Guide

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2.5.3 Releasing empty pages and empty segments

Release the empty pages and empty segments generated due to data deletion and restore them to unused status. Pre-conditions and method for releasing empty pages and empty segments is as follows:

Note
Release not only empty pages but empty segments as well without fail.
Organization of this subsection
(1) Pre-conditions
(2) Method for releasing

(1) Pre-conditions

Following conditions must be fulfilled for releasing empty pages and empty segments.

(2) Method for releasing

Method for releasing empty pages and empty segments is as follows: If password input is requested, enter " admin " as password.

  1. From [Start] menu of Windows, select [Cosminexus]-[Database console].
    Environment variables for operating the embedded database are set.
  2. Execute pdreclaim command to release the empty pages in use.
    Release the empty pages in use (pages in which data is not stored due to data deletion) and set those as unused pages.
    For details on pdreclaim command, see the "HiRDB Command Reference Guide".
    Execution format of pdreclaim command is as follows:
    For releasing empty pages, which are in use in table
     
    pdreclaim -u admin -k table -t all -o
     
    For releasing empty pages, which are in use in index
     
    pdreclaim -u admin -k index -t all
     
  3. Execute pdreclaim command to release empty segments in use.
    Release the empty segments (segments where in all pages are empty) that are in use and set those as unused segments.
    For details on pdreclaim command, see the "HiRDB Command Reference Guide".
    Execution format of pdreclaim command is as follows:
    For releasing empty segments, which are in use in table
     
    pdreclaim -u admin -k table -t all -o -j
     
    For releasing empty segments, which are in use in index
     
    pdreclaim -u admin -k table -t all -j
     
  4. Check whether the insufficiency of unused area has been removed.
    For checking method, see "2.5.1 Checking unused RD area".