feat: Implement delete operation for WAL based on local storage #1566
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jiacai2050
reviewed
Sep 9, 2024
jiacai2050
reviewed
Sep 9, 2024
jiacai2050
reviewed
Sep 9, 2024
jiacai2050
reviewed
Sep 9, 2024
jiacai2050
reviewed
Sep 9, 2024
…uired before acquiring the lock for a segment.
jiacai2050
reviewed
Sep 12, 2024
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| // Delete segments in all_segments | ||
| for (segment_id, _) in segments_to_remove.iter() { |
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segments_to_remove is Vec<(u64, Arc<...>)>, so there is no keys() for this type. Do I need to change it to a hashmap?
| drop(all_segments); | ||
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| // Delete segments on disk | ||
| for (_, segment) in segments_to_remove.iter() { |
| guard.mark_deleted(location.table_id, sequence_num); | ||
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| // Delete this segment if it is empty | ||
| if guard.is_empty() && guard.id != current_segment_id { |
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Since current segment may changed, the check here should be guard.id < current_segment_id.
| @@ -383,10 +465,13 @@ pub struct SegmentManager { | |||
| all_segments: Mutex<HashMap<u64, Arc<Mutex<Segment>>>>, | |||
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| /// Cache for opened segments | |||
| cache: Mutex<VecDeque<u64>>, | |||
| cache: Mutex<VecDeque<(u64, Arc<Mutex<Segment>>)>>, | |||
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The u64 in this tuple represents the segment ID. The reason for storing it is to determine if a segment exists in the cache without needing to acquire the lock for that segment. The newly added Arc<Mutex<Segment>> is to remove the original SegmentManager::get_segment method, which is redundant and may cause deadlock.
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Rationale
Currently the WAL based on the local disk does not support the delete function. This PR implements that functionality.
This is a follow-up task of #1552 and #1556.
Detailed Changes
For each
Segment, add a hashmap to record the minimum and maximum sequence numbers of all tables within that segment. Duringdeleteandwriteoperations, this hashmap will be updated. During read operations, logs will be filtered based on this hashmap.During the
deleteoperation, based on the aforementioned hashmap, if all logs of all tables in a read-only segment (a segment that is not currently being written to) are marked as deleted, the segment file will be physically deleted from the disk.Test Plan
Unit test, TSBS and running a script locally that repeatedly inserts data, forcibly kills, and restarts the database process to test persistence.