message: Mention Ninja
  Now that we all are using it.
  [ci skip]
diff: @@ -39,23 +39,26 @@ GPORCA uses the following library:
  [GP-XERCES is available here](https://github.com/greenplum-db/gp-xerces). The GP-XERCES README
  gives instructions for building and installing.
  -## Build GPORCA
  +## Build and install GPORCA
  +
  +ORCA is built with [CMake](https://cmake.org), so any build system supported by
  +CMake can be used. The team uses [Ninja](https://ninja-build.org) because it's
  +really really fast and convenient.
  Go into `gporca` directory:
  ```
  mkdir build
  cd build
  -cmake ../
  -make
  -sudo make install
  +cmake -GNinja ../
  +ninja install
  ```
  <a name="test"></a>
  ## Test GPORCA
  To run all GPORCA tests, simply use the `ctest` command from the build directory
  -after `make` finishes.
  +after build finishes.
  ```
  ctest
  @@ -169,17 +172,17 @@ Here are few build flavors:
  ```
  # debug build
  -cmake -D CMAKE_BUILD_TYPE=DEBUG ../
  +cmake -GNinja -D CMAKE_BUILD_TYPE=DEBUG ../
  ```
  ```
  # release build with debug info
  -cmake -D CMAKE_BUILD_TYPE=RelWithDebInfo ../
  +cmake -GNinja -D CMAKE_BUILD_TYPE=RelWithDebInfo ../
  ```
  ```
  # release build
  -cmake -D CMAKE_BUILD_TYPE=RELEASE ../
  +cmake -GNinja -D CMAKE_BUILD_TYPE=RELEASE ../
  ```
  ## Explicitly Specifying GP-Xerces For Build
  @@ -200,7 +203,7 @@ However, to use the current build scripts in GPDB, Xerces with the gp_xerces
  patch will need to be placed on the /usr path.
  ```
  -cmake -D XERCES_INCLUDE_DIR=/opt/gp_xerces/include -D XERCES_LIBRARY=/opt/gp_xerces/lib/libxerces-c.so ..
  +cmake -GNinja -D XERCES_INCLUDE_DIR=/opt/gp_xerces/include -D XERCES_LIBRARY=/opt/gp_xerces/lib/libxerces-c.so ..
  ```
  Again, on Mac OS X, the library name will end with `.dylib` instead of `.so`.
  @@ -233,13 +236,13 @@ Toolchain files for building 32 or 64-bit x86 libraries are located in the cmake
  directory. Here is an example of building for 32-bit x86:
  ```
  -cmake -D CMAKE_TOOLCHAIN_FILE=../cmake/i386.toolchain.cmake ../
  +cmake -GNinja -D CMAKE_TOOLCHAIN_FILE=../cmake/i386.toolchain.cmake ../
  ```
  And for 64-bit x86:
  ```
  -cmake -D CMAKE_TOOLCHAIN_FILE=../cmake/x86_64.toolchain.cmake ../
  +cmake -GNinja -D CMAKE_TOOLCHAIN_FILE=../cmake/x86_64.toolchain.cmake ../
  ```
  ## How to speed-up the build (or debug it)
  @@ -277,7 +280,7 @@ GPORCA has four libraries:
  By default, GPORCA will be installed under /usr/local. You can change this by
  setting CMAKE_INSTALL_PREFIX when running cmake, for example:
  ```
  -cmake -D CMAKE_INSTALL_PREFIX=/home/user/gporca ../
  +cmake -GNinja -D CMAKE_INSTALL_PREFIX=/home/user/gporca ../
  ```
  By default, the header files are located in:
  