Php versions – Not found column _block_number in block

I am using ClickHouse version v24.6.1.4609-stable.

I have a database with only one SRMT table, and a corresponding Buffer table. Partitions are by month.

I have a cron job to delete rows which runs nightly, and just started to fail yesterday.

I was able to isolate a problematic ALTER TABLE statement:

ALTER TABLE event_performances
 DELETE
 WHERE is_deleted = 1 
 AND event_timestamp = '2022-03-03 05:00:00'
 SETTINGS mutations_sync=2, alter_sync=2;

(There are 12 rows in the event_performances table that meet the criteria and should be deleted.)

The error message I get is

Code 341 : UNFINISHED
Mutation 0000000419 failed to finish, error: 'Not found column _block_number in block.
There are only columns: client_id, event_id, event_type,
[... lots of column names redacted],
event_timestamp, version, is_deleted'.

To be clear, the list of column names are the actual visible column names in my table, without any of the ClickHouse columns beginning with underscore.

I get the same error message when I run my query in the web client, and when I run it via PHP.

The similar query with earlier dates returns OK, that the ALTER succeeded.

I am at a loss of where to go from here; I don’t understand what the _block_number column is doing here.

When I query for the mutations, I get rows like

0000000774  n*****  event_performances  0000000774  DELETE WHERE (is_deleted = 1) AND (event_timestamp = '2022-03-03 05:00:00') AND (delivery_id = 17869469)    2024-11-21 08:10:40 ["202105","202106","202107","202108","202109","202110","202111","202112","202201","202202","202203","202204","202205","202206","202207","202208","202209","202210","202211","202212","202301","202302","202303","202304","202305","202306","202307","202308","202309","202310","202311","202312","202401","202402","202403","202404","202405","202406","202407","202408","202409","202410","202411"]    ["781","775","778","787","784","788","792","799","809","815","840","839","840","846","874","882","920","960","959","939","969","965","975","989","1057","1077","1083","1153","1171","1207","1262","1338","1369","1461","1475","1569","1569","1653","1758","1940","2309","3204","17696"] ["202203_0_707_10_840"] 1   0   0       1970-01-01 00:00:00 

I understand that there are fields called block_numbers, but I don’t know that those are related to _block_number.

Running the query SELECT * FROM "parts_columns" where partition_id = '202203' yields 157 rows, but I don’t know enough to read the results intelligently.

How do I fix my issue? How can I get the ALTER TABLE to succeed?