Merge pull request #30 from Congyuwang/load_latest_options

Automatically Load latest options

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "RocksDict"
-version = "0.3.0"
+version = "0.3.3"
 edition = "2021"
 description = "Rocksdb Python Binding"
 
@@ -13,7 +13,10 @@ crate-type = ["cdylib"]
 [dependencies]
 rocksdb = { git = "https://github.com/Congyuwang/rust-rocksdb", branch = "rocksdict" }
 librocksdb-sys = { git = "https://github.com/Congyuwang/rust-rocksdb", branch = "rocksdict" }
-ahash = "0.8.1"
+pyo3-log = "0.7.0"
+log = "0.4"
+serde = { version = "1", features = ["derive"] }
+serde_json = "1.0.87"
 num-bigint = "^0.4.3"
 libc = "0.2.112"
 

README.md

@@ -98,6 +98,65 @@ db.close()
 Rdict.destroy(PATH_TO_ROCKSDB)
 ```
 
+## New Feature Since v0.3.3
+
+Loading Options from RocksDict Path.
+
+### Load Options and add A New ColumnFamily
+```python
+from rocksdict import Options, Rdict
+path = str("./rocksdict_path")
+
+opts, cols = Options.load_latest(path)
+opts.create_missing_column_families(True)
+cols["bytes"] = Options()
+self.test_dict = Rdict(path, options=opts, column_families=cols)
+```
+
+### Reopening RocksDB Reads DB Options Automatically
+
+```python
+import shutil
+
+from rocksdict import Rdict, Options, SliceTransform, PlainTableFactoryOptions
+import os
+
+def db_options():
+    opt = Options()
+    # create table
+    opt.create_if_missing(True)
+    # config to more jobs
+    opt.set_max_background_jobs(os.cpu_count())
+    # configure mem-table to a large value (256 MB)
+    opt.set_write_buffer_size(0x10000000)
+    opt.set_level_zero_file_num_compaction_trigger(4)
+    # configure l0 and l1 size, let them have the same size (1 GB)
+    opt.set_max_bytes_for_level_base(0x40000000)
+    # 256 MB file size
+    opt.set_target_file_size_base(0x10000000)
+    # use a smaller compaction multiplier
+    opt.set_max_bytes_for_level_multiplier(4.0)
+    # use 8-byte prefix (2 ^ 64 is far enough for transaction counts)
+    opt.set_prefix_extractor(SliceTransform.create_max_len_prefix(8))
+    # set to plain-table for better performance
+    opt.set_plain_table_factory(PlainTableFactoryOptions())
+    return opt
+
+
+# create DB
+db = Rdict("./some_path", db_options())
+db[0] = 1
+db.close()
+
+# automatic reloading all options on reopening
+db = Rdict("./some_path")
+assert db[0] == 1
+
+# destroy
+db.close()
+shutil.rmtree("./some_path")
+```
+
 ## More Examples on BatchWrite, SstFileWrite, Snapshot, RocksDB Options, and etc.
 
 Go to [example](https://github.com/Congyuwang/RocksDict/tree/main/examples) folder.