postgresql: Looking at the detail of wal file.

Using pg_xlogdump to look at the contents of a wal file.

root@photon-machine [ /storage/archive/vpostgres ]#  /opt/vmware/vpostgres/9.6/bin/pg_xlogdump 00000001000000020000002E
/opt/vmware/vpostgres/9.6/bin/pg_xlogdump /storage/archive/vpostgres/00000001000000020000002

postgresql: Purging WAL files with pg_archivecleanup in VC Appliance.

Purging wall files with pg_archivecleanup in VC Appliance. 
Essentially, this is similar to "rm" except, it detects dependency of WAL files and subsequent  WAL files.
The following -n flag provide information of what else to be removed if WAL file 0000000100000002000000EA is removed.
Note: watch out for space right after pg_xlog



root@photon-machine [ /storage/db/vpostgres/pg_xlog ]# /opt/vmware/vpostgres/9.6/bin/pg_archivecleanup -n /storage/db/vpostgres/pg_xlog/ 0000000100000002000000EA
/storage/db/vpostgres/pg_xlog//0000000100000002000000E6
/storage/db/vpostgres/pg_xlog//0000000100000002000000E9
/storage/db/vpostgres/pg_xlog//0000000100000002000000E8
/storage/db/vpostgres/pg_xlog//0000000100000002000000E7

Another example of deletion on different WAL file. The WAL file of 0000000100000002000000E6 will no longer in pg_xlog once deleted.


root@photon-machine [ /storage/db/vpostgres/pg_xlog ]# /opt/vmware/vpostgres/9.6/bin/pg_archivecleanup -d /storage/db/vpostgres/pg_xlog/ 0000000100000002000000E7
pg_archivecleanup: keep WAL file "/storage/db/vpostgres/pg_xlog//0000000100000002000000E7" and later
pg_archivecleanup: removing file "/storage/db/vpostgres/pg_xlog//0000000100000002000000E6"