[GitHub] [iceberg] wypoon commented on issue #6042: Add delete file information to partitions table

[GitBox <gi...@apache.org>]

wypoon commented on issue #6042:
URL: https://github.com/apache/iceberg/issues/6042#issuecomment-1316220819

   I'm trying to understand the proposed behavior.
   To go back to @ajantha-bhat's example: Suppose you have a partition `{A}` with `record_count`=6 and `file_count`=2 (3 records in each file). Suppose you now delete 3 records in one file. I understand that `pos_delete_file_count` will be 1 and `pos_delete_record_count` will be 3. But what about `record_count` and `file_count`? Will `file_count` be 3 (is it supposed to be the total number of data files, including delete files)? And `record_count`? When is it possible to correctly compute the `record_count` using metadata alone (without applying delete files)?
   
   Another example: Suppose you have two partitions `{A}` and `{B}`. Let's say `record_count`=1000 and `file_count`=1 for partition `{B}`. Suppose you rename `B` to `C` (using an `UPDATE <table> SET <partition column> = 'C' where <partition column = 'B'` where we use merge-on-read, resulting in 1 delete file and 1 new pure data file). If you do a `SELECT * FROM <table>.partitions` currently, you will get an entry for each of `{A}`, `{B}` and `{C}`. What should the behavior be (should there be an entry for `{B}` and if so, what should be shown for it? and for `{C}`?)?


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