FTP Replicator PostgreSQL Database

PostgreSQL is used to hold the status information for Replication. The Database name is specified in the Python configuration. There needs to be an instance of this database on both LOCAL and REMOTE locations.

Transmission Log

This is a PostgreSQL table ‘transmissionlog’ which holds the files that have been previously transmitted. It is used to indicate the files that are about to be transmitted. The currents timestamp can be checked against the last edit time on a file to indicate whether a file needs to be retransmitted.

It has the following structure:-

Field	Type	Holds
Filename	Text	Fully pathed filename.
currentts	Timestamp without time zone	Last time file was modified.
Newts	Timestamp without time zone	Latest time file was modified.
action	Character(1)	Action (A=Addition, U=Update).
locale	Character(1)	Owner of the field (by default R=Remote, L=Local)

Status

This is a PostgreSQL table which holds the status of the current run for a location.

Field	Type	Holds
running	Bool	Whether a Run is running.
runnumber	Integer	The current/last run number.
status	Text	The status of the current run.
currentts	Timestamp without time zone	Timestamp of action.
exitstatus	Integer	The exit status of the last entity.
nextprocess	Text	The next entity to be run with its full parameter set.
commmode	Text	The communication mode being used, sync or async.

The status field is the name of the last part run, used to ensure that if L1->L2->L3 is the order, we do not run L1->L3 and assume we’re fine. This also contains the fact that a process is currently running ‘L2 running’.

The nextprocess field holds what entity is to be run next when the current finishes with the full parameter set it would use. This is necessary when running in Asynchronous mode to get the call that a REMOTE entity would have used.

PostgreSQL Configuration

In the pg_hba.conf file the authentication method for local connections needs to be trust, e.g.

Example

host all all 127.0.0.1/32 trust

Where 127.0.0.1/32 means all connections originating from the PostgreSQL server itself.