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Signed-off-by: Alex Chi <iskyzh@gmail.com>
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Alex Chi
2024-01-23 17:13:53 +08:00
parent 6520d8fcfc
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mini-lsm-book/src/week2-04-leveled.md
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@@ -99,7 +99,7 @@ L4: 202MB/200MB = 1.01
L5: 1.9GB/2GB = 0.95
```
L3 and L4 needs to be compacted, while L5 does not. And L3 has a larger ratio, and therefore we will produce a compaction task of L3 and L4.
L3 and L4 needs to be compacted with their lower level respectively, while L5 does not. And L3 has a larger ratio, and therefore we will produce a compaction task of L3 and L4. After the compaction is done, it is likely that we will schedule compactions of L4 and L5.
### Task 1.4: Select SST to Compact
@@ -160,6 +160,7 @@ The implementation should be similar to simple leveled compaction. Remember to c
* What is the peak storage usage for leveled compaction? Compared with universal compaction?
* Is it true that with a lower `level_size_multiplier`, you can always get a lower write amplification?
* What needs to be done if a user not using compaction at all decides to migrate to leveled compaction?
* Some people propose to do intra-L0 compaction (compact L0 tables and still put them in L0) before pushing them to lower layers. What might be the benefits of doing so? (Might be related: [PebblesDB SOSP'17](https://www.cs.utexas.edu/~rak/papers/sosp17-pebblesdb.pdf))
We do not provide reference answers to the questions, and feel free to discuss about them in the Discord community.