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Sender: Todd Nine <todd@spidertracks.co.nz>
Subject: Input on difficult migration issue from 0.7.4 to 0.8.2
From: Todd Nine <todd@spidertracks.com>
To: "user@cassandra.apache.org" <user@cassandra.apache.org>
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Date: Wed, 03 Aug 2011 13:06:32 +1200
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Hi all,
  I seem to have backed myself into a corner and I cannot easily upgrade
from a custom 0.7.4 installation to the default 0.8.2.  Any help I could
get would be greatly appreciated.  Below is an outline of the problem.

Current installation:
0.7.4 with Ed Anuff's custom composite comparators.
https://github.com/riptano/hector-composite/commit/74407df3ef97c3fa90eae9f68d84b50be3d9938e
CF Comprator Type : "DynamicComposite"


New installation:
0.8.2 with Casasndra's native DynamicComposite column time.
CF Comparator Type:
"DynamicComposite(a=>AsciiType,b=>BytesType,i=>IntegerType,x=>LexicalUUIDType,l=>LongType,t=>TimeUUIDType,s=>UTF8Type,u=>UUIDType,A=>AsciiType(reversed=true),B=>BytesType(reversed=true),I=>IntegerType(reversed=true),X=>LexicalUUIDType(reversed=true),L=>LongType(reversed=true),T=>TimeUUIDType(reversed=true),S=>UTF8Type(reversed=true),U=>UUIDType(reversed=true))"


I cannot simply upgrade Cassandra, this fails because the comparator is
incorrectly defined for version 0.8.1 and on.  My issue is that the
column family definition has changed, the bytes that are stored are
compatible, I simply need to re-define the CF and migrate the column
data over. 


Initially I was thinking I could perform a read from the rows and
columns from a single 0.7 node, then insert them into the 0.8 cluster,
however I cannot have 2 different versions of the thrift API running in
the same java JVM due to namespace conflicts.


Idea is to perform the following steps, if anyone has any better
suggestions, they would be greatly appreciated.

1. Back up all my CFs that use the dynamic composite, and copy the
SSTable out of my Keyspace's data directory to tmp
2. Drop all CFs that use dynamic composite
3. Re-create the CFs with the new comparator definition
4. Using an external program directly read the 0.7 SSTables (without
starting the cassandra daemon) and insert the rows and columns into the
0.8 cluster via thrift.


Can anyone point me at a good example for reading rows and columns
directly from the SSTables without using the thrift api?

Thanks,
Todd

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Hi all,<BR>
&nbsp; I seem to have backed myself into a corner and I cannot easily upgrade from a custom 0.7.4 installation to the default 0.8.2.&nbsp; Any help I could get would be greatly appreciated.&nbsp; Below is an outline of the problem.<BR>
<BR>
Current installation:<BR>
0.7.4 with Ed Anuff's custom composite comparators.&nbsp; <A HREF="https://github.com/riptano/hector-composite/commit/74407df3ef97c3fa90eae9f68d84b50be3d9938e">https://github.com/riptano/hector-composite/commit/74407df3ef97c3fa90eae9f68d84b50be3d9938e</A><BR>
CF Comprator Type : &quot;DynamicComposite&quot;<BR>
<BR>
<BR>
New installation:<BR>
0.8.2 with Casasndra's native DynamicComposite column time.<BR>
CF Comparator Type: &quot;DynamicComposite(a=&gt;AsciiType,b=&gt;BytesType,i=&gt;IntegerType,x=&gt;LexicalUUIDType,l=&gt;LongType,t=&gt;TimeUUIDType,s=&gt;UTF8Type,u=&gt;UUIDType,A=&gt;AsciiType(reversed=true),B=&gt;BytesType(reversed=true),I=&gt;IntegerType(reversed=true),X=&gt;LexicalUUIDType(reversed=true),L=&gt;LongType(reversed=true),T=&gt;TimeUUIDType(reversed=true),S=&gt;UTF8Type(reversed=true),U=&gt;UUIDType(reversed=true))&quot;<BR>
<BR>
<BR>
I cannot simply upgrade Cassandra, this fails because the comparator is incorrectly defined for version 0.8.1 and on.&nbsp; My issue is that the column family definition has changed, the bytes that are stored are compatible, I simply need to re-define the CF and migrate the column data over. <BR>
<BR>
<BR>
Initially I was thinking I could perform a read from the rows and columns from a single 0.7 node, then insert them into the 0.8 cluster, however I cannot have 2 different versions of the thrift API running in the same java JVM due to namespace conflicts.<BR>
<BR>
<BR>
Idea is to perform the following steps, if anyone has any better suggestions, they would be greatly appreciated.<BR>
<BR>
1. Back up all my CFs that use the dynamic composite, and copy the SSTable out of my Keyspace's data directory to tmp<BR>
2. Drop all CFs that use dynamic composite<BR>
3. Re-create the CFs with the new comparator definition<BR>
4. Using an external program directly read the 0.7 SSTables (without starting the cassandra daemon) and insert the rows and columns into the 0.8 cluster via thrift.<BR>
<BR>
<BR>
Can anyone point me at a good example for reading rows and columns directly from the SSTables without using the thrift api?<BR>
<BR>
Thanks,<BR>
Todd
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