[Performance Branch] PlainTable to encode rows with seqID 0, value type using 1 internal byte.

Summary: In PlainTable, use one single byte to represent 8 bytes of internal bytes, if seqID = 0 and it is value type (which should be common for bottom most files). It is to save 7 bytes for uncompressed cases.

Test Plan: make all check

Reviewers: haobo, dhruba, kailiu

Reviewed By: haobo

CC: igor, leveldb

Differential Revision: https://reviews.facebook.net/D15489

table/block_based_table_factory.cc

@@ -20,15 +20,17 @@ namespace rocksdb {
 
 Status BlockBasedTableFactory::NewTableReader(
     const Options& options, const EnvOptions& soptions,
+    const InternalKeyComparator& internal_comparator,
     unique_ptr<RandomAccessFile>&& file, uint64_t file_size,
     unique_ptr<TableReader>* table_reader) const {
   return BlockBasedTable::Open(options, soptions, table_options_,
-                               std::move(file), file_size, table_reader);
+                               internal_comparator, std::move(file), file_size,
+                               table_reader);
 }
 
 TableBuilder* BlockBasedTableFactory::NewTableBuilder(
-    const Options& options, WritableFile* file,
-    CompressionType compression_type) const {
+    const Options& options, const InternalKeyComparator& internal_comparator,
+    WritableFile* file, CompressionType compression_type) const {
   auto flush_block_policy_factory = 
     table_options_.flush_block_policy_factory.get();
 
@@ -45,11 +47,9 @@ TableBuilder* BlockBasedTableFactory::NewTableBuilder(
                                           options.block_size_deviation);
   }
 
-  auto table_builder =  new BlockBasedTableBuilder(
-      options,
-      file,
-      flush_block_policy_factory,
-      compression_type);
+  auto table_builder =
+      new BlockBasedTableBuilder(options, internal_comparator, file,
+                                 flush_block_policy_factory, compression_type);
 
   // Delete flush_block_policy_factory only when it's just created from the
   // options.