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NAME

osmdbt - Tools for creating replication feeds from the main OSM database

DESCRIPTION

Various tools for handling replication of OpenStreetMap data. All changes in the main OSM database can be read regularly and dumped out into OSM change files.

COMMANDS

osmdbt-catchup : Mark changes in the PostgreSQL replication slot up to the specified LSN as done.

osmdbt-create-diff : Read replication log files created by osmdbt-get-log or osmdbt-fake-log and create an OSM change file.

osmdbt-disable-replication : Disable replication on the database.

osmdbt-enable-replication : Enable replication on the database.

osmdbt-fake-log : Create fake log file from recent changes.

osmdbt-get-log : Get recent changes from the database replication slot and write them into a log file in an internal format which can be read by osmdbt-create-diff.

osmdbt-testdb : Check database connection and print PostgreSQL and schema version and information about active replication slots.

CONFIG FILE

All commands use a config file in YAML format. You can specify the name of the config file with the -c or \--config command line option. The default is osmdbt-config.yaml in the current directory.

The config file contains the following settings:

  • database: Information for connecting to the database:
    • host: Name of the host running the database (default: empty)
    • port: TCP port to connect to (default: 5432)
    • dbname: Name of the database (default: osm)
    • user: Database user (default: osm)
    • password: Password of database user (default: osm)
    • replication_slot: Name of logical decoding replication slot (default: rs)
  • log_dir: The directory where osmdbt-get-log writes the log files and osmdbt-create-diff reads the log files from. (default: /tmp)
  • changes_dir: The directory where osmdbt-create-diff writes the change files (default: /tmp)
  • tmp_dir: Temporary directory used by osmdbt-create-diff. Must be on the same file system as changes_dir.
  • run_dir: The directory where the commands store pid/lock files. This can be on a temporary filesystem like /var/run. (default: /tmp)

REPLICATION LOG

The database writes a replication log using the pgoutput plugin.

The log has one entry per line and the following fields separated by spaces:

  1. LSN (Log Sequence Number) looks something like 16/B374D848. See https://www.postgresql.org/docs/current/datatype-pg-lsn.html for details.
  2. xid
  3. Action (C for "commit transaction" or N for an actual change)

After that, for actual changes, there is the object type ('n', 'w', or 'r'), its id, version, and changeset.

Example:

C/AAA1A108 59940 N n7204175493 v1 c80864722
C/AAAF35F8 59940 N w771706111 v1 c80864722
C/AAAF39D0 59940 N r104862 v21 c80864688

There are always zero or more N entries followed by one C entry commiting the transaction.

If an error happened parsing the information from the database, the action will be set to X and an error message added to the line. This should never happen.

SEE ALSO

  • osmdbt-catchup(1), osmdbt-create-diff(1), osmdbt-disable-replication(1), osmdbt-enable-replication(1), osmdbt-fake-log(1), osmdbt-get-log(1), osmdbt-testdb(1),