How to clear /var directory data which purge action failed to delete the data

Resolving The Problem

1. Logon on the Platform HPC database.
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#psql -U hpcadmin -d hpcdb
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(Passwd is hpcadmin)

2. Run the following command to list the top size table.
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#SELECT nspname || '.' || relname AS "relation",
pg_size_pretty(pg_total_relation_size(C.oid)) AS "total_size"
FROM pg_class C
LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
WHERE nspname NOT IN ('pg_catalog', 'information_schema')
AND C.relkind <> 'i'
AND nspname !~ '^pg_toast'
ORDER BY pg_total_relation_size(C.oid) DESC
LIMIT 20;
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3. If we can see the outputs from the above steps has the similar information below, we can suppose the problem relates to such case.
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Table Name Size Last Report Size This report Growth
ci_server_snap           19 GB 20 GB 1GB
ci_netcard_snap          18 GB 18 GB 0GB
resource_metrics         3756 MB 5195 MB 1439MB
ci_disk_util             3544 MB 3544 MB 0MB
hpc_hw_resource_metrics  2803 MB 2957 MB 154MB
......
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4. Check the problematic tables partition status with the following sql command. We can see the problematic tables will not have the current date partition parts.
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#select * from pg_tables where tablename like 'ci_server_snap%';
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5. Backup the current hpc database.
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#pg_dump -U hpcadmin hpcdb > hpcbackup
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6. Drop the old data from the database
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#delete from ci_server_snap where time_stamp < '%';
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(please replace % to property time.)

7. Create new partition
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#select init_create_partitions();
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8. Free the disk.
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#vacuum full;
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(In this step, we need to make sure we have some free disk under the /var directory. The clear action needs the buffer space to free the disk)