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copy_chunk()

TimescaleDB allows you to copy existing chunks to a new location within a multi-node environment. This allows each data node to work both as a primary for some chunks and backup for others. If a data node fails, its chunks already exist on other nodes that can take over the responsibility of serving them.

warning

Experimental features could have bugs! They might not be backwards compatible, and could be removed in future releases. Use these features at your own risk, and do not use any experimental features in production.

Required arguments

NameTypeDescription
chunkREGCLASSName of chunk to be copied
source_nodeNAMEData node where the chunk currently resides
destination_nodeNAMEData node where the chunk is to be copied

Required settings

When copying a chunk, the destination data node needs a way to authenticate with the data node that holds the source chunk. It is currently recommended to use a password file on the data node.

The wal_level setting must also be set to logical or higher on data nodes from which chunks are copied. If you are copying or moving many chunks in parallel, you can increase max_wal_senders and max_replication_slots.

Failures

When a copy operation fails, it sometimes creates objects and metadata on the destination data node. It can also hold a replication slot open on the source data node. To clean up these objects and metadata, use cleanup_copy_chunk_operation.

Sample usage

CALL timescaledb_experimental.copy_chunk(‘_timescaledb_internal._dist_hyper_1_1_chunk’, ‘data_node_2’, ‘data_node_3’);

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