difference between checkpoint_segments and wal_keep_segments in postgres configuration file

[Raghavendra Rao J S V]

I am not clear the difference between  checkpoint_segments and
wal_keep_segments .

I would like to now below things. Please explain.Thanks in advance.


   - Difference  between *checkpoint_segments *and *wal_keep_segments *
   value
   - Role  of  *checkpoint_segments *and *wal_keep_segments *
   - Which one should has higher value.

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Regards,
Raghavendra Rao J S V