RocksDB 5.4.5 release blog post

Summary:
5.4.5 release blog post.
Tag created at: https://github.com/facebook/rocksdb/releases/tag/rocksdb-5.4.5
Closes facebook#2378

Differential Revision: D5141648

Pulled By: sagar0

fbshipit-source-id: 43faadfbd7feb8bb01c3d56127ef3453e23dc28a

docs/_posts/2017-05-26-rocksdb-5-4-5-released.markdown

@@ -0,0 +1,39 @@
+---
+title: RocksDB 5.4.5 Released!
+layout: post
+author: sagar0
+category: blog
+---
+
+### Public API Change
+* Support dynamically changing `stats_dump_period_sec` option via SetDBOptions().
+* Added ReadOptions::max_skippable_internal_keys to set a threshold to fail a request as incomplete when too many keys are being skipped while using iterators.
+* DB::Get in place of std::string accepts PinnableSlice, which avoids the extra memcpy of value to std::string in most of cases.
+    * PinnableSlice releases the pinned resources that contain the value when it is destructed or when ::Reset() is called on it.
+    * The old API that accepts std::string, although discouraged, is still supported.
+* Replace Options::use_direct_writes with Options::use_direct_io_for_flush_and_compaction. See Direct IO wiki for details.
+
+### New Features
+* Memtable flush can be avoided during checkpoint creation if total log file size is smaller than a threshold specified by the user.
+* Introduce level-based L0->L0 compactions to reduce file count, so write delays are incurred less often.
+* (Experimental) Partitioning filters which creates an index on the partitions. The feature can be enabled by setting partition_filters when using kFullFilter. Currently the feature also requires two-level indexing to be enabled. Number of partitions is the same as the number of partitions for indexes, which is controlled by metadata_block_size.
+* DB::ResetStats() to reset internal stats.
+* Added CompactionEventListener and EventListener::OnFlushBegin interfaces.
+* Added DB::CreateColumnFamilie() and DB::DropColumnFamilies() to bulk create/drop column families.
+* Facility for cross-building RocksJava using Docker.
+
+### Bug Fixes
+* Fix WriteBatchWithIndex address use after scope error.
+* Fix WritableFile buffer size in direct IO.
+* Add prefetch to PosixRandomAccessFile in buffered io.
+* Fix PinnableSlice access invalid address when row cache is enabled.
+* Fix huge fallocate calls fail and make XFS unhappy.
+* Fix memory alignment with logical sector size.
+* Fix alignment in ReadaheadRandomAccessFile.
+* Fix bias with read amplification stats (READ_AMP_ESTIMATE_USEFUL_BYTES and READ_AMP_TOTAL_READ_BYTES).
+* Fix a manual / auto compaction data race.
+* Fix CentOS 5 cross-building of RocksJava.
+* Build and link with ZStd when creating the static RocksJava build.
+* Fix snprintf's usage to be cross-platform.
+* Fix build errors with blob DB.
+* Fix readamp test type inconsistency.