Page History

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After partition is received the historical rebalance must be initiated to load other cache updates.

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Catch-up temporary WAL

The swapped temporary storage will log all the cache updates to the temporary WAL storage (per each partition) for further applying them to the corresponding partition file. While the Demander is being receive partition files it must save sequentially all cache entries corresponding to the MOVING partition into a new temporary storage. These entries will be applied later one by one on the newly received cache partition file. All asynchronous operations will be enrolled to the end of temporary storage during storage reads until it becomes fully read. The file-based FIFO approach assumes to be used by this process.

The temporary storage is chosen to be WAL-based. The storage must support to:

• Unlimited number of WAL-files to store temporary data records;
• Iterating over stored data records during an asynchronous writer thread insert new records;
• WAL-per-partiton approach is need to be used;
• Write operations to storage must have higher priority over read operations;

Expected problems to be solved

• We must stop updating indexes on demander when the data is ready to be transferred from the supplier node. All async cache updates on demander must not cause the index update;
• The previous partition metadata page and all stored meta information must be destroyed in PageMemory and restored from the new partition file;

Preload entries from loaded partition file

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Apply partition on the fly

Catch-up temporary WAL

While the demander node is in the partition file transmission state it must save sequentially all cache entries corresponding to the MOVING partition into a new temporary storage. These entries will be applied later one by one on the newly received cache partition file. All asynchronous operations will be enrolled to the end of temporary storage during storage reads until it becomes fully read. The file-based FIFO approach assumes to be used by this process.

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