Re: Determining active sstables and table- dir

[kurt greaves]

In 2.2 it's cf_id from system.schema_columnfamilies. If it's not then
that's a bug. From 2.2 we stopped including table name in the SSTable name,
so whatever directory contains the SSTables is the active one. Conversely,
if you've dropped a table and re-added it, the directory without any
SSTables is the dropped table, and if you had auto_snapshot enabled it will
have a snapshots directory in there with a snapshot at the time of the drop.

On 27 April 2018 at 20:24, Carl Mueller 
wrote:

> IN cases where a table was dropped and re-added, there are now two table
> directories with different uuids with sstables.
>
> If you don't have knowledge of which one is active, how do you determine
> which is the active table directory? I have tried cf_id from
> system.schema_columnfamilies and that can work some of the time but have
> seen times cf_id != table-
>
> I have also seen situations where sstables that don't have the
> table/columnfamily are in the table dir and are clearly that active
> sstables (they compacted when I did a nodetool compact)
>
> Is there a way to get a running cassandra node's sstables for a given
> keyspace/table and what table- is active?
>
> This is in a 2.2.x environment that has probably churned a bit from 2.1.x
>

Re: Schema disagreement

[Gábor Auth]

Hi,

On Tue, May 1, 2018 at 10:27 PM Gábor Auth  wrote:

> One or two years ago I've tried the CDC feature but switched off... maybe
> is it a side effect of switched off CDC? How can I fix it? :)
>

Okay, I've worked out. Updated the schema of the affected keyspaces on the
new nodes with 'cdc=false' and everything is okay now.

I think, it is a strange bug around the CDC...

Bye,
Gábor Auth

Re: Schema disagreement

[Gábor Auth]

Hi,

On Tue, May 1, 2018 at 7:40 PM Gábor Auth  wrote:

> What can I do? Any suggestion? :(
>

Okay, I've diffed the good and the bad system_scheme tables. The only
difference is the `cdc` field in three keyspaces (in `tables` and `views`):
- the value of `cdc` field on the good node is `False`
- the value of `cdc` field on the bad node is `null`

The value of `cdc` field on the other keyspaces is `null`.

One or two years ago I've tried the CDC feature but switched off... maybe
is it a side effect of switched off CDC? How can I fix it? :)

Bye,
Gábor Auth

Re: Determining active sstables and table- dir

[Rahul Singh]

Schema column families is the most authoritative. You may have different data 
directories.

--
Rahul Singh
rahul.si...@anant.us

Anant Corporation

On Apr 27, 2018, 1:24 PM -0700, Carl Mueller , 
wrote:
> IN cases where a table was dropped and re-added, there are now two table 
> directories with different uuids with sstables.
>
> If you don't have knowledge of which one is active, how do you determine 
> which is the active table directory? I have tried cf_id from 
> system.schema_columnfamilies and that can work some of the time but have seen 
> times cf_id != table-
>
> I have also seen situations where sstables that don't have the 
> table/columnfamily are in the table dir and are clearly that active sstables 
> (they compacted when I did a nodetool compact)
>
> Is there a way to get a running cassandra node's sstables for a given 
> keyspace/table and what table- is active?
>
> This is in a 2.2.x environment that has probably churned a bit from 2.1.x

Re: Schema disagreement

[Gábor Auth]

Hi,

On Mon, Apr 30, 2018 at 11:11 PM Gábor Auth  wrote:

> On Mon, Apr 30, 2018 at 11:03 PM Ali Hubail 
> wrote:
>
>> What steps have you performed to add the new DC? Have you tried to follow
>> certain procedures like this?
>>
>> https://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsAddDCToCluster.html
>>
>
> Yes, exactly. :/
>

Okay, removed all new nodes (with `removenode`). Cleared all new node
(removed data and logs).

I did all the steps described in the link (again).

Same result:

Cluster Information:
   Name: cluster
   Snitch: org.apache.cassandra.locator.DynamicEndpointSnitch
   Partitioner: org.apache.cassandra.dht.Murmur3Partitioner
   Schema versions:
   5de14758-887d-38c1-9105-fc60649b0edf: [new, new, ...]

   f4ed784a-174a-38dd-a7e5-55ff6f3002b2: [old, old, ...]

The old nodes try to gossip their own schema:
DEBUG [InternalResponseStage:1] 2018-05-01 17:36:36,266
MigrationManager.java:572 - Gossiping my schema version
f4ed784a-174a-38dd-a7e5-55ff6f3002b2
DEBUG [InternalResponseStage:1] 2018-05-01 17:36:36,863
MigrationManager.java:572 - Gossiping my schema version
f4ed784a-174a-38dd-a7e5-55ff6f3002b2

The new nodes try to gossip their own schema:
DEBUG [InternalResponseStage:4] 2018-05-01 17:36:26,329
MigrationManager.java:572 - Gossiping my schema version
5de14758-887d-38c1-9105-fc60649b0edf
DEBUG [InternalResponseStage:4] 2018-05-01 17:36:27,595
MigrationManager.java:572 - Gossiping my schema version
5de14758-887d-38c1-9105-fc60649b0edf

What can I do? Any suggestion? :(

Bye,
Gábor Auth

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[Rich Bowen]

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Re: Does node add/remove requires all cluster nodes be present?

[Jinhua Luo]

Could you explain more?

When we add a new node, it should migrate data from other nodes, right?
What happens if other nodes are absent? For example, the cluster
consists of 3 nodes, but 2 nodes down, now we add the fourth new node,
what happens then?

2018-05-01 12:01 GMT+08:00 Jeff Jirsa :
> nodetool decommission streams data from the losing replica, so only that 
> instance has to be online (and decom should be preferred to removenode)
>
> If that instance is offline, you can use removenode, but you risk violating 
> consistency guarantees
>
> Adding nodes is similar - bootstrap streams from the losing range
>
> --
> Jeff Jirsa
>
>
>> On Apr 30, 2018, at 8:57 PM, Jinhua Luo  wrote:
>>
>> Hi All,
>>
>> When a new node added, due to the even distribution of the new tokens,
>> the current nodes of the ring should migrate data to this new node.
>>
>> So, does it requires all nodes be present? If not, then if some nodes
>> are down, then it will miss the data migration of those parts, how and
>> when to fix it? When those nodes come back?
>>
>> Similarly, the node removal would migrate its data to other nodes, so
>> it seems that all other nodes must be present, otherwise it would lost
>> data?
>>
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