RE: [WIP]Vertical Clustered Index (columnar store extension) - take2

Hello,

We created VCI patch.
This patch is a prototype. The build and postgres regression tests have passed,
but there are still some bugs.

This patch includes the following VCI implementations:

- Changes to PostgreSQL core code
- Conversion of WOS to ROS
-- The source code for the conversion part exists. However, there is a slight
source code problem. To avoid this problem,
the vci.enable_ros_control_damon parameter now defaults to false. This change
prevents the ROS control daemon from starting at instance startup.
Background workers that convert WOS to ROS are not created because there is
no ROS control daemon.
- Convert to Local ROS
- Custom Plan VCI Scan
- Data transformation by background workers
- Minimum test
- Minimum documentation

This patch provides the following steps to use VCI:

1. Create Table
2. Insert data into the table
3. Create VCI
4. Run VCI Scan

The functions we will be developing are described in the wiki,
so please refer to it.
https://wiki.postgresql.org/wiki/Vertical_clustered_index

Regards,
Aya Iwata
Fujitsu Limited