Attached patch adds support of partial decompression for datums. It will be useful in many cases when extracting part of data is enough for big varlena structures.
It is especially useful for expanded datums, because it provides storage for partial results.
This isn't enough for anyone else to follow your thoughts and agree enough to commit.
Please explain the whole idea, starting from what problem you are trying to solve and how well this does it, why you did it this way and the other ways you tried/decided not to pursue. Thanks.
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Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
