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

Hi.

Here is the latest set of VCI patches.

Summary of changes:
A recent master commit [1] introduced a new flag to allow bgworkers to
be terminated for database-related commands. The VCI main patch is now
setting that flag so that "vci:ROS control worker(slot=%d)" bgworkers
are interruptible.

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[1] https://github.com/postgres/postgres/commit/f1e251be80a05cb66191d5ea48f2cdc3acff72b5

Kind Regards,
Peter Smith.
Fujitsu Australia