Snapshot summary should contain default values

[homar]

Currently snapshot summary, which is a map, contains particular values only if they were affected by changes in that snapshot.
These pieces of information would be easier to use and more feasible if they were always present there and had default values.
For example DELETED_RECORDS_PROP, ADDED_POS_DELETES_PROP, REMOVED_POS_DELETES_PROP, ADDED_EQ_DELETES_PROP etc. could be set to 0 by default.

[findepi]

For example DELETED_RECORDS_PROP, ADDED_POS_DELETES_PROP, REMOVED_POS_DELETES_PROP, ADDED_EQ_DELETES_PROP etc. could be set to 0 by default.

At least for snapshots created with table.newDelete()....commit().

This is needed in Trino to reliably provide number of deleted rows to the user, also when delete happens to delete no files.
(Related discussion trinodb/trino#12136 (comment))

[homar]

I made a pr for this #4660

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[github-actions]

This issue has been closed because it has not received any activity in the last 14 days since being marked as 'stale'