Add index_type customization to BlockBasedOptions

src/db_options.rs

@@ -18,7 +18,7 @@ use std::mem;
 use libc::{self, c_int, c_uchar, c_uint, c_void, size_t, uint64_t};
 
 use ffi;
-use {BlockBasedOptions, DBCompactionStyle, DBCompressionType, DBRecoveryMode,
+use {BlockBasedOptions, BlockBasedIndexType, DBCompactionStyle, DBCompressionType, DBRecoveryMode,
      Options, WriteOptions};
 use compaction_filter::{self, CompactionFilterCallback, CompactionFilterFn, filter_callback};
 use comparator::{self, ComparatorCallback, CompareFn};
@@ -89,6 +89,24 @@ impl BlockBasedOptions {
             ffi::rocksdb_block_based_options_set_cache_index_and_filter_blocks(self.inner, v as u8);
         }
     }
+
+    /// Defines the index type to be used for SS-table lookups.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use rocksdb::{BlockBasedOptions, BlockBasedIndexType, Options};
+    ///
+    /// let mut opts = Options::default();
+    /// let mut block_opts = BlockBasedOptions::default();
+    /// block_opts.set_index_type(BlockBasedIndexType::HashSearch);
+    /// ```
+    pub fn set_index_type(&mut self, index_type: BlockBasedIndexType) {
+        let index = index_type as i32;
+        unsafe {
+            ffi::rocksdb_block_based_options_set_index_type(self.inner, index);
+        }
+    }
 }
 
 impl Default for BlockBasedOptions {

src/lib.rs

@@ -136,6 +136,20 @@ pub struct BlockBasedOptions {
     inner: *mut ffi::rocksdb_block_based_table_options_t,
 }
 
+/// Used by BlockBasedOptions::set_index_type.
+pub enum BlockBasedIndexType {
+    /// A space efficient index block that is optimized for
+    /// binary-search-based index.
+    BinarySearch,
+
+    /// The hash index, if enabled, will perform a hash lookup if
+    /// a prefix extractor has been provided through Options::set_prefix_extractor.
+    HashSearch,
+
+    /// A two-level index implementation. Both levels are binary search indexes.
+    TwoLevelIndexSearch,
+}
+
 /// Database-wide options around performance and behavior.
 ///
 /// Please read [the official tuning guide](https://github.com/facebook/rocksdb/wiki/RocksDB-Tuning-Guide), and most importantly, measure performance under realistic workloads with realistic hardware.