A typo, even though they are debug message I am interested in knowing their meaning since they happen very often.
Thanks Jon for the video, that is helpful, our data is partitioned by other metrics and not time, its clustered by a timestamp, our biggest partition is ~8MB. Since we are using TWCS with 7 days window each week data should be in its own bucket sstable, dare I ask, is there a way to manually remove \‘archive’ very old time buckets at one point by removing those sstables or that could break things? From: Jon Haddad <j...@jonhaddad.com> Sent: Thursday, May 23, 2024 5:43 PM To: user@cassandra.apache.org Cc: Bowen Song <bo...@bso.ng> Subject: Re: TWCS Log Warning As an aside, if you're not putting a TTL on your data, it's a good idea to be proactive and use multiple tables. For example, one per month or year. This allows you the flexibility to delete your data by dropping old tables. Storing old data in Cassandra is expensive. Once you get to a certain point it becomes far more cost effective to offload your old data to an object store and keep your Cassandra cluster to a minimum size. I gave a talk on this topic on my YT channel: https://www.youtube.com/live/Ysfi3V2KQtU Jon On Thu, May 23, 2024 at 7:35 AM Bowen Song via user <user@cassandra.apache.org<mailto:user@cassandra.apache.org>> wrote: As the log level name "DEBUG" suggested, these are debug messages, not warnings. Is there any reason made you believe that these messages are warnings? On 23/05/2024 11:10, Isaeed Mohanna wrote: Hi I have a big table (~220GB reported by used space live by tablestats) with time series data that uses TWCS with the following settings compaction = {'class': 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy', 'compaction_window_size': '7', 'compaction_window_unit': 'DAYS', 'max_threshold': '32', 'min_threshold': '4'} The table does not have a TTL configured since we need the data, it now has ~450 sstables, I have had this setup for several years and so far I am satisfied with the performance, we mostly read\write data from the previous several months. Requests for earlier data occur but not in the quantities and performance is less critical then. I have recently noticed reoccurring warning in the Cassandra log file and I wanted to ask about their meaning and wither I need to do something about it DEBUG [CompactionExecutor:356242] 2024-05-23 09:01:59,655 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables DEBUG [CompactionExecutor:356242] 2024-05-23 09:01:59,655 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables DEBUG [CompactionExecutor:356243] 2024-05-23 09:02:59,655 TimeWindowCompactionStrategy.java:122 - TWCS expired check sufficiently far in the past, checking for fully expired SSTables DEBUG [CompactionExecutor:356243] 2024-05-23 09:02:59,658 TimeWindowCompactionStrategy.java:122 - TWCS expired check sufficiently far in the past, checking for fully expired SSTables DEBUG [CompactionExecutor:356242] 2024-05-23 09:03:59,655 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables DEBUG [CompactionExecutor:356242] 2024-05-23 09:03:59,656 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables DEBUG [CompactionExecutor:356245] 2024-05-23 09:05:00,490 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables DEBUG [CompactionExecutor:356245] 2024-05-23 09:05:00,490 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables DEBUG [CompactionExecutor:356244] 2024-05-23 09:06:00,490 TimeWindowCompactionStrategy.java:129 - TWCS skipping check for fully expired SSTables The debug messages above appear in one of my Cassandra nodes every several minutes, I have a 4 node cluster with RF=3. Is there anything I need to do about those messages or its safe to ignore them Thank you for the help
