Storage Engine
The storage engine lives entirely in db/. It is a classic LSM-tree (Log-Structured Merge-tree) with a custom binary encoding layer.
Components at a glance
| Component | File(s) | Role |
|---|---|---|
| Binary encoding | cell.go | Typed value encoding for keys and values |
| Row/schema encoding | row.go | Multi-column key and value encoding |
| Write-Ahead Log | log.go, kv_entry.go | Crash-safe mutation log |
| Memtable | sorted_array.go | In-memory sorted key-value buffer |
| SSTables | sorted_file.go | Immutable on-disk sorted key-value files |
| Merge iterator | merge.go | Multi-level sorted merge |
| KV store | kv.go | LSM engine: transactions, compaction, cache |
| Metadata | metadata.go | Double-buffered SSTable version tracking |
| SQL layer | sql_parser.go, eval.go, table.go | SQL parsing, expression evaluation, table ops |
On-disk layout
For a data directory ./data, PallasDB creates:
SSTable filenames are sstable_<version> where version is a monotonically increasing uint64 tracked in the metadata.
Data flow summary
The sections below document each component in detail.