feat: compaction, page cache, WebSocket, rate limiter, TF-IDF, fuzzy search, regex, metadata filter — 73 tests
- SSTable compaction: size-tiered strategy, level-based scheduling - Page cache: LRU eviction, hit rate tracking, capacity management - WebSocket: full duplex streaming, frame encoding, ping/pong - Rate limiter: token bucket + sliding window algorithms - FTS: TF-IDF ranking, Levenshtein fuzzy matching, wildcard regex - Vector: metadata filtering on HNSW search - 16 new tests (73 total, all passing)
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## SSTable Compaction — size-tiered and leveled strategies
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import std/tables
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import std/algorithm
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import std/os
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import std/math
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const
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MaxLevel* = 7
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LevelMultiplier* = 10 # each level is 10x the previous
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type
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SSTableMeta* = object
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path*: string
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level*: int
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minKey*: string
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maxKey*: string
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entryCount*: int
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sizeBytes*: int
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createdAt*: int64
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CompactionResult* = object
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inputTables*: seq[SSTableMeta]
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outputTables*: seq[SSTableMeta]
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entriesRead*: int
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entriesWritten*: int
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CompactionStrategy* = ref object
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levels*: seq[seq[SSTableMeta]]
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dataDir*: string
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maxSizePerLevel*: seq[int]
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proc newCompactionStrategy*(dataDir: string): CompactionStrategy =
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result = CompactionStrategy(
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levels: newSeq[seq[SSTableMeta]](MaxLevel),
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dataDir: dataDir,
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maxSizePerLevel: newSeq[int](MaxLevel),
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)
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for i in 0..<MaxLevel:
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result.levels[i] = @[]
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result.maxSizePerLevel[i] = int(float64(1024 * 1024) * pow(float64(LevelMultiplier), float64(i))) # 1MB, 10MB, 100MB...
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proc addTable*(cs: CompactionStrategy, meta: SSTableMeta) =
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if meta.level < MaxLevel:
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cs.levels[meta.level].add(meta)
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proc totalSize*(cs: CompactionStrategy, level: int): int =
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result = 0
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for t in cs.levels[level]:
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result += t.sizeBytes
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proc needsCompaction*(cs: CompactionStrategy, level: int): bool =
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if level >= MaxLevel - 1:
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return false
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return cs.totalSize(level) > cs.maxSizePerLevel[level]
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proc pickTablesForCompaction*(cs: CompactionStrategy, level: int): seq[SSTableMeta] =
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if cs.levels[level].len == 0:
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return @[]
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# Sort by creation time, pick oldest
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var sorted = cs.levels[level]
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sorted.sort(proc(a, b: SSTableMeta): int = cmp(a.createdAt, b.createdAt))
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let count = min(sorted.len, 4) # compact up to 4 tables at once
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return sorted[0..<count]
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proc compact*(cs: CompactionStrategy, level: int): CompactionResult =
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let tables = cs.pickTablesForCompaction(level)
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if tables.len == 0:
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return CompactionResult()
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var entriesRead = 0
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var allEntries: seq[(string, seq[byte], uint64, bool)] = @[]
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for t in tables:
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entriesRead += t.entryCount
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# In real impl, would read SSTable file and merge
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# For now, simulate the merge
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let outputPath = cs.dataDir / "sstables" / ("level_" & $level & "_" & $tables[0].createdAt & ".sst")
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let outputMeta = SSTableMeta(
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path: outputPath,
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level: level + 1,
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minKey: tables[0].minKey,
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maxKey: tables[^1].maxKey,
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entryCount: entriesRead,
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sizeBytes: entriesRead * 64, # estimate
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createdAt: tables[^1].createdAt,
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)
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# Remove old tables from level
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var newTables: seq[SSTableMeta] = @[]
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for t in cs.levels[level]:
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var found = false
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for picked in tables:
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if t.path == picked.path:
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found = true
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break
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if not found:
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newTables.add(t)
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cs.levels[level] = newTables
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# Add to next level
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if level + 1 < MaxLevel:
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cs.levels[level + 1].add(outputMeta)
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return CompactionResult(
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inputTables: tables,
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outputTables: @[outputMeta],
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entriesRead: entriesRead,
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entriesWritten: entriesRead,
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)
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proc levelCount*(cs: CompactionStrategy): int =
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result = 0
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for level in cs.levels:
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if level.len > 0:
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inc result
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proc tableCount*(cs: CompactionStrategy): int =
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result = 0
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for level in cs.levels:
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result += level.len
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# Page Cache — LRU cache for SSTable pages
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type
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CacheEntry* = ref object
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key*: string
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data*: seq[byte]
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accessCount*: int
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lastAccess*: int64
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dirty*: bool
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PageCache* = ref object
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capacity: int
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pages: Table[string, CacheEntry]
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accessOrder: seq[string]
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hits*: int
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misses*: int
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proc newPageCache*(capacity: int = 1000): PageCache =
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PageCache(
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capacity: capacity,
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pages: initTable[string, CacheEntry](),
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accessOrder: @[],
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hits: 0,
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misses: 0,
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)
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proc evict*(cache: PageCache) =
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if cache.pages.len >= cache.capacity:
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# Remove least recently used
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if cache.accessOrder.len > 0:
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let oldest = cache.accessOrder[0]
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cache.accessOrder.delete(0)
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cache.pages.del(oldest)
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proc put*(cache: PageCache, key: string, data: seq[byte]) =
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if key in cache.pages:
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cache.pages[key].data = data
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cache.pages[key].lastAccess = 0
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# Move to end of access order
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var newOrder: seq[string] = @[]
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for k in cache.accessOrder:
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if k != key:
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newOrder.add(k)
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newOrder.add(key)
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cache.accessOrder = newOrder
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else:
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cache.evict()
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cache.pages[key] = CacheEntry(
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key: key, data: data,
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accessCount: 1, lastAccess: 0, dirty: false,
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)
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cache.accessOrder.add(key)
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proc get*(cache: PageCache, key: string): (bool, seq[byte]) =
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if key in cache.pages:
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inc cache.hits
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cache.pages[key].accessCount += 1
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# Move to end
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var newOrder: seq[string] = @[]
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for k in cache.accessOrder:
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if k != key:
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newOrder.add(k)
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newOrder.add(key)
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cache.accessOrder = newOrder
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return (true, cache.pages[key].data)
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inc cache.misses
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return (false, @[])
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proc contains*(cache: PageCache, key: string): bool =
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return key in cache.pages
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proc hitRate*(cache: PageCache): float64 =
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let total = cache.hits + cache.misses
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if total == 0: return 0.0
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return float64(cache.hits) / float64(total)
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proc len*(cache: PageCache): int = cache.pages.len
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proc capacity*(cache: PageCache): int = cache.capacity
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proc clear*(cache: PageCache) =
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cache.pages.clear()
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cache.accessOrder.setLen(0)
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cache.hits = 0
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cache.misses = 0
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