4.2 KiB
id | title |
---|---|
metadata-migration | Metadata Migration |
If you have been running an evaluation Druid cluster using the built-in Derby metadata storage and wish to migrate to a more production-capable metadata store such as MySQL or PostgreSQL, this document describes the necessary steps.
Shut down cluster services
To ensure a clean migration, shut down the non-coordinator services to ensure that metadata state will not change as you do the migration.
When migrating from Derby, the coordinator processes will still need to be up initially, as they host the Derby database.
Exporting metadata
Druid provides an Export Metadata Tool for exporting metadata from Derby into CSV files which can then be imported into your new metadata store.
The tool also provides options for rewriting the deep storage locations of segments; this is useful for deep storage migration.
Run the export-metadata
tool on your existing cluster, and save the CSV files it generates. After a successful export, you can shut down the coordinator.
Initializing the new metadata store
Create database
Before importing the existing cluster metadata, you will need to set up the new metadata store.
The MySQL extension and PostgreSQL extension docs have instructions for initial database setup.
Update configuration
Update your Druid runtime properties with the new metadata configuration.
Create Druid tables
Druid provides a metadata-init
tool for creating Druid's metadata tables. After initializing the Druid database, you can run the commands shown below from the root of the Druid package to initialize the tables.
In the example commands below:
lib
is the Druid lib directoryextensions
is the Druid extensions directorybase
corresponds to the value ofdruid.metadata.storage.tables.base
in the configuration,druid
by default.- The
--connectURI
parameter corresponds to the value ofdruid.metadata.storage.connector.connectURI
. - The
--user
parameter corresponds to the value ofdruid.metadata.storage.connector.user
. - The
--password
parameter corresponds to the value ofdruid.metadata.storage.connector.password
.
MySQL
cd ${DRUID_ROOT}
java -classpath "lib/*" -Dlog4j.configurationFile=conf/druid/cluster/_common/log4j2.xml -Ddruid.extensions.directory="extensions" -Ddruid.extensions.loadList="[\"mysql-metadata-storage\"]" -Ddruid.metadata.storage.type=mysql -Ddruid.node.type=metadata-init org.apache.druid.cli.Main tools metadata-init --connectURI="<mysql-uri>" --user <user> --password <pass> --base druid
PostgreSQL
cd ${DRUID_ROOT}
java -classpath "lib/*" -Dlog4j.configurationFile=conf/druid/cluster/_common/log4j2.xml -Ddruid.extensions.directory="extensions" -Ddruid.extensions.loadList="[\"postgresql-metadata-storage\"]" -Ddruid.metadata.storage.type=postgresql -Ddruid.node.type=metadata-init org.apache.druid.cli.Main tools metadata-init --connectURI="<postgresql-uri>" --user <user> --password <pass> --base druid
Import metadata
After initializing the tables, please refer to the import commands for your target database.
Restart cluster
After importing the metadata successfully, you can now restart your cluster.