extension with sequences. When executing the following command:
This behaviour is observed in PostgreSQL versions post v11 [1] , where sequences support in
used to work fine. However, this issue slipped through as we did not have any test cases to catch it.
Given the situation, I see two potential paths forward:
1/ Reintroduce Support for Sequences in pgstattuple: This would be a relatively small change. However, it's important to note that the purpose of
pgstattuple is to provide statistics like the number of tuples, dead tuples, and free space in a relation. Sequences, on the other hand, return only one value at a time and don’t have attributes like dead tuples. Therefore, the result for any sequence would consistently look something like this:
SELECT * FROM pgstattuple('serial');
table_len | tuple_count | tuple_len | tuple_percent | dead_tuple_count | dead_tuple_len | dead_tuple_percent | free_space | free_percent
-----------+-------------+-----------+---------------+------------------+----------------+--------------------+------------+--------------
8192 | 1 | 41 | 0.5 | 0 | 0 | 0 | 8104 | 98.93
(1 row)2/ Explicitly Block Sequence Support in pgstattuple: We could align sequences with other unsupported objects, such as foreign tables, by providing a more explicit error message. For instance:
SELECT * FROM pgstattuple('x');
ERROR: cannot get tuple-level statistics for relation "x"
DETAIL: This operation is not supported for foreign tables.This approach would ensure that the error handling for sequences is consistent with how other unsupported objects are handled.
Personally, I lean towards the second approach, as it promotes consistency and clarity. However, I would greatly appreciate the community's feedback and suggestions on the best way to proceed.
Based on the feedback received, I will work on the appropriate patch.
