Replace Prefetch Logic in BlockBasedTableIterator with IODispatcher. #14255
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krhancoc
commented
Jan 23, 2026
| multi_scan_status_ = FilterAndPinCachedBlocks( | ||
| scan_block_handles, multiscan_opts, &block_indices_to_read, | ||
| &pinned_data_blocks_guard, &prefetched_max_idx); | ||
| // Calculate prefetch_max_idx (enforces max_prefetch_size) |
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This will eventually be replaced by pushing this into the IO Dispatcher. I didn't want to add semantic changes into IODispatcher in this diff.
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This diff introduces the IODispatcher into the BlockBasedTableIterator. This replaces much of the prefetch logic with the logic found in IODispatcher.
Test Plan:
I ran the following benchmark, %change is within noise tolerance. There shouldn't be any large performance improvement with this change, more so there should also not be any performance degradation.
MultiScan Benchmark: Current Branch vs Main
Configuration:
Results:
│ Mode │ Main (ops/sec) │ Current (ops/sec) │ Change │
│ Sync │ 8,901 │ 9,032 │ +1.5% │
│ Async │ 11,297 │ 11,947 │ +5.8% │