This pull request optimizes history indexing by splitting a single large
database
batch into multiple smaller chunks.
Originally, the indexer will resolve a batch of state histories and
commit all
corresponding index entries atomically together with the indexing
marker.
While indexing more state histories in a single batch improves
efficiency, excessively
large batches can cause significant memory issues.
To mitigate this, the pull request splits the mega-batch into several
smaller batches
and flushes them independently during indexing. However, this introduces
a potential
inconsistency that some index entries may be flushed while the indexing
marker is not,
and an unclean shutdown may leave the database in a partially updated
state.
This can corrupt index data.
To address this, head truncation is introduced. After a restart, any
excessive index
entries beyond the expected indexing marker are removed, ensuring the
index remains
consistent after an unclean shutdown.
This change introduces an iterator for the history index in the pathdb.
It provides sequential access to historical entries, enabling efficient
scanning and future features built on top of historical state traversal.
