v.20.11Improvement

Allow Fetching Committed or Outdated Parts into Detached Directory for Migration

Official CH changelog text
Allow to fetch parts that are already committed or outdated in the current instance into the detached directory. It's useful when migrating tables from another cluster and having N to 1 shards mapping. It's also consistent with the current fetchPartition implementation. #16538 (Amos Bird).
Fetch parts that are already committed or outdated into the detached directory. This feature enables fetching data parts from the local instance that are not active, including committed or outdated parts, into the detached directory.

Why it matters

Facilitates table migration and shard mapping by allowing local fetching of parts that are not currently active. This solves the problem of migrating tables from another cluster with complex shard mappings (N to 1), ensuring consistency with the existing fetchPartition functionality and improving data management flexibility.

How to use it

Use the fetch parts functionality to retrieve committed or outdated parts from the current instance into the detached directory when migrating tables or working with shard mappings. This is consistent with the existing fetchPartition implementations, allowing seamless operations on local data parts.

Related resources

PreviousNext