ndb

ndb is a NoSQL schema-less database server for storage of structured entities with high performance, rich API, strong consistency for reads and queries (including ancestor queries), and efficient inserts/updates that scales to petabytes of data (big data) and unlimited rows.

It provides a linux-based server executable and client .so shared libraries.

Communication between the client and server happens over one of the following encoding formats:

• cbor (preferred - via libcbor go-codec libraries)
• msgpack (via lipmsgpack and go-codec libraries)
• simple (for testing purposes - via c_cpp/ code and go-codec libraries)

Installation

It only builds and runs on linux. It uses epoll internally to serve multiple connections in a very fast and performant way.

The datastore build depends on rocksdb, which also depends on some libraries:

leveldb:  depends on: snappy, tcmalloc
rocksdb   depends on: zlib, bzip2, snappy, gflags, tcmalloc
snappy:   depends on: tcmalloc
tcmalloc: depends on: libunwind

The easiest way to grab the dependencies is to install the libraries packaged and provided by your OS maintainers e.g. ubuntu.

sudo apt-get install libgflags-dev librocksdb-dev libzstd-dev libgtest-dev libgoogle-glog-dev

Note that libgtest-dev on ubuntu only install sources, so you have to build it appropriately.

sudo apt-get install cmake # install cmake
cd /usr/src/gtest
sudo cmake CMakeLists.txt
sudo make
sudo ln -s libgtest.a /usr/lib/
sudo ln -s libgtest_main.a /usr/lib/

It may be necessary to interact with libndb from within go. If so, that go program will depend on the shared library ndb which is currently only supported on linux. The go application MUST then be built on a linux machine. You will need to download the go installer there.

mkdir ~/opt && cd ~/opt
wget https://dl.google.com/go/go1.12.4.linux-amd64.tar.gz
tar xzf https://dl.google.com/go/go1.12.4.linux-amd64.tar.gz

Building

To build, the cc-common project should be available.

By default, it is a sibling folder to this ndb folder.

make clean all

If cc-common is in a different location, pass it during make.

make COMMON=/__where_cc_common_dir_is__ clean all

Possible errors and resolution

You might get an error of the form

libndb.so: undefined reference to `typeinfo for rocksdb::Logger'

This is because rocksdb is built in release mode without RTTI information, and rocksdb did not create a definition for the virtual constructor and methods in the Logger class.

To fix, you can either build rocksdb yourself, with the command like

# Build rocksdb static library
git clone https://github.com/facebook/rocksdb.git
make USE_RTTI=1 static_lib

# Build ndb using this one, running in the .../ndb directory
# (assuming rocksdb built into `.../rocks/db/dir`)
make ROCKSDBLIBDIR=.../rocks/db/dir all

OR

use the librocksdb-dev sharedlib but modify the /usr/include/rocksdb/env.h, find the class Logger declaration, and ensure that all public functions have =0 on their declaration, so that we can build against the shared lib which is built without RTTI.

FOr example, I mnade the changes below:

  virtual ~Logger() = 0;
  virtual Status Close() = 0;
  virtual void Logv(const InfoLogLevel log_level, const char* format, va_list ap) = 0;

See facebook/rocksdb#5208

Running

make server