Add unsorted decompressed chunk path even if we have sorted ones #6879
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The unsorted paths are better for hash aggregation, but currently in this case we are only going to add sorted paths.
Add ANALYZE. To keep the desired MergeAppend plans, we also have to add a LIMIT everywhere so that the MergeAppend is chosen based on its lower startup cost. Otherwise the plain Sort over Append will be chosen because for small tables its cost is less.
Add ANALYZE after compression. The plan changes are expected, SeqScans are preferred over IndexScans and Sort over MergeAppend for small tables.
We would add extra Sort nodes when adjusting the children of space partitioning MergeAppend under ChunkAppend. This is not needed because MergeAppend plans add the required Sort themselves, and in general no adjustment seems to be required for the MergeAppend children specifically there.
Currently we use the cheapest path before final aggregation for this (i.e. Append over individual chunks), but it does not consider the cost of a Sort that might be required before aggregation. To account for this, use instead the child path of the cheapest final aggregated path.
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The unsorted paths are better for hash aggregation, but currently if we're doing aggregation and we can push down the sort, we are only going to add sorted paths.
Fixes #6836