Revert "Upgrade rocksdb crate (#17813)"

This reverts commit 1a51faa.

Cargo.toml

@@ -419,7 +419,7 @@ reqwest = { version = "0.11.20", default_features = false, features = [
   "rustls-tls",
 ] }
 roaring = "0.10.1"
-rocksdb = { version = "0.22.0", features = [
+rocksdb = { version = "0.21.0", features = [
   "snappy",
   "lz4",
   "zstd",

crates/typed-store/src/rocks/mod.rs

@@ -291,16 +291,16 @@ impl RocksDB {
         delegate_call!(self.multi_get_cf_opt(keys, readopts))
     }
 
-    pub fn batched_multi_get_cf_opt<'a, I, K>(
+    pub fn batched_multi_get_cf_opt<I, K>(
         &self,
         cf: &impl AsColumnFamilyRef,
         keys: I,
         sorted_input: bool,
         readopts: &ReadOptions,
     ) -> Vec<Result<Option<DBPinnableSlice<'_>>, Error>>
     where
-        K: AsRef<[u8]> + 'a + ?Sized,
-        I: IntoIterator<Item = &'a K>,
+        I: IntoIterator<Item = K>,
+        K: AsRef<[u8]>,
     {
         delegate_call!(self.batched_multi_get_cf_opt(cf, keys, sorted_input, readopts))
     }
@@ -932,7 +932,7 @@ impl<K, V> DBMap<K, V> {
             .rocksdb
             .batched_multi_get_cf_opt(
                 &self.cf(),
-                &(keys_bytes?),
+                keys_bytes?,
                 /*sorted_keys=*/ false,
                 &self.opts.readopts(),
             )
@@ -2372,6 +2372,13 @@ impl DBOptions {
 
         self
     }
+
+    // Optimize tables receiving significant deletions.
+    // TODO: revisit when intra-epoch pruning is enabled.
+    pub fn optimize_for_pruning(mut self) -> DBOptions {
+        self.options.set_min_write_buffer_number_to_merge(2);
+        self
+    }
 }
 
 /// Creates a default RocksDB option, to be used when RocksDB option is unspecified.