[jira] [Comment Edited] (CASSANDRA-14013) Data loss in snapshots keyspace after service restart

["Benjamin Lerer (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-14013?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17226269#comment-17226269 ] 

Benjamin Lerer edited comment on CASSANDRA-14013 at 11/4/20, 4:52 PM:
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{quote}The current solution does not count on the fact that for example there might be also a snapshot / table called "snapshot" as well as "backups" for example - same for indexes and indexes in backups and snapshots. There might be also a snapshot called "snapshot" for a keyspace which is called "snapshot" and table which is called "snapshot" too and so on ... {quote}

[~stefan.miklosovic] I do not believe that tables or indexes named {{snapshot}} or {{backups}} are trully a problem because their corresponding directories will have different names.
The directory name for a table named {{snapshot}} is {{snapshot-<TableID>}} and the directory name for an index named {{snapshot}} is {{.snapshot}}.

The {{testKeyspaceTableParsing}} is incorrect because it assumes that a table named {{snapshot}} will result in a directory called {{snapshot}}.  



was (Author: blerer):
{quote}The current solution does not count on the fact that for example there might be also a snapshot / table called "snapshot" as well as "backups" for example - same for indexes and indexes in backups and snapshots. There might be also a snapshot called "snapshot" for a keyspace which is called "snapshot" and table which is called "snapshot" too and so on ... {quote}

[~stefan.miklosovic] I do not believe that tables or an indexes named {{snapshot}} or {{backups}} are trully a problem because their corresponding directories will have different names.
The directory name for a table named {{snapshot}} is {{snapshot-<TableID>}} and the directory name for an index named {{snapshot}} is {{.snapshot}}.

The {{testKeyspaceTableParsing}} is incorrect because it assumes that a table named {{snapshot}} will result in a directory called {{snapshot}}.  


> Data loss in snapshots keyspace after service restart
> -----------------------------------------------------
>
>                 Key: CASSANDRA-14013
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14013
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Legacy/Core
>            Reporter: Gregor Uhlenheuer
>            Assignee: Stefan Miklosovic
>            Priority: Normal
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> I am posting this bug in hope to discover the stupid mistake I am doing because I can't imagine a reasonable answer for the behavior I see right now :-)
> In short words, I do observe data loss in a keyspace called *snapshots* after restarting the Cassandra service. Say I do have 1000 records in a table called *snapshots.test_idx* then after restart the table has less entries or is even empty.
> My kind of "mysterious" observation is that it happens only in a keyspace called *snapshots*...
> h3. Steps to reproduce
> These steps to reproduce show the described behavior in "most" attempts (not every single time though).
> {code}
> # create keyspace
> CREATE KEYSPACE snapshots WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1};
> # create table
> CREATE TABLE snapshots.test_idx (key text, seqno bigint, primary key(key));
> # insert some test data
> INSERT INTO snapshots.test_idx (key,seqno) values ('key1', 1);
> ...
> INSERT INTO snapshots.test_idx (key,seqno) values ('key1000', 1000);
> # count entries
> SELECT count(*) FROM snapshots.test_idx;
> 1000
> # restart service
> kill <cassandra-pid>
> cassandra -f
> # count entries
> SELECT count(*) FROM snapshots.test_idx;
> 0
> {code}
> I hope someone can point me to the obvious mistake I am doing :-)
> This happened to me using both Cassandra 3.9 and 3.11.0



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