Clarification on pg_basebackup

PostgreSQL 9.3

Would someone be able to clarify if one should use the –X option with pg_basebackup when your intention is to include all WAL files created?  There are two scenarios.  The first scenario listed below makes sense using the –X option.  Bus scenario #2 has me a little confused.  I don’t want to cause any issues when restoring.

1)      Use pg_basebackup for a fully standalone restorable snapshot of the database using the –X parameter.  When a failure occurs you restore the database to that exact point in time.

2)      You restore from a pg_basebackup and you also apply all of the WAL files since the last pg_basebackup.  Do you want to use the –X option when doing the pg_basebackup if your intention is to have all of the WAL files since you backed up last?  Or does it matter.  Would PostgreSQL just ignore the duplicate WAL files that were created by the –X option during the pg_basebackup? 

Thanks for your clarification.  This is a hard scenario to test.

Thanks,

Lance Campbell

Software Architect

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