Each table has a different Guid — doing a hard link may work as long as the sstable dir’s guid is he same as the newly created table in the system schema.
-- Rahul Singh rahul.si...@anant.us Anant Corporation On Apr 19, 2018, 10:41 AM -0500, Kyrylo Lebediev <kyrylo_lebed...@epam.com>, wrote: > The table is too large to be copied fast/effectively , so I'd like to > leverage immutableness property of SSTables. > > My idea is to: > 1) create new empty table (NewTable) with the same structure as existing one > (OldTable) > 2) at some time run simultaneous 'nodetool snapshot -t ttt <keyspace> > OldTable' on all nodes -- this will create point in time state of OldTable > 3) on each node run: > for each file in OldTable ttt snapshot directory: > ln > ..../<keyspace>/OldTable-<uuid>/snapshots/ttt/<keyspace>_OldTable_xxxxxx > ...../<keyspace>/Newtable/<keyspace>_NewTable_xxxxx > then: > nodetool refresh <keyspace> NewTable > 4) nodetool repair NewTable > 5) Use OldTable and NewTable independently (Read/Write) > > Are there any issues with using hardlinks (ln) instead of copying (cp) in > this case? > > Thanks, > Kyrill > > From: Rahul Singh <rahul.xavier.si...@gmail.com> > Sent: Wednesday, April 18, 2018 2:07:17 AM > To: user@cassandra.apache.org > Subject: Re: copy from one table to another > > 1. Make a new table with the same schema. > For each node > 2. Shutdown node > 3. Copy data from Source sstable dir to new sstable dir. > > This will do what you want. > > -- > Rahul Singh > rahul.si...@anant.us > > Anant Corporation > > On Apr 16, 2018, 4:21 PM -0500, Kyrylo Lebediev <kyrylo_lebed...@epam.com>, > wrote: > > Thanks, Ali. > > I just need to copy a large table in production without actual copying by > > using hardlinks. After this both tables should be used independently (RW). > > Is this a supported way or not? > > > > Regards, > > Kyrill > > From: Ali Hubail <ali.hub...@petrolink.com> > > Sent: Monday, April 16, 2018 6:51:51 PM > > To: user@cassandra.apache.org > > Subject: Re: copy from one table to another > > > > If you want to copy a portion of the data to another table, you can also > > use sstable cql writer. It is more of an advanced feature and can be > > tricky, but doable. > > once you write the new sstables, you can then use the sstableloader to > > stream the new data into the new table. > > check this out: > > https://www.datastax.com/dev/blog/using-the-cassandra-bulk-loader-updated > > > > I have recently used this to clean up 500 GB worth of sstable data in order > > to purge tombstones that were mistakenly generated by the client. > > obviously this is not as fast as hardlinks + refresh, but it's much faster > > and more efficient than using cql to copy data accross the tables. > > take advantage of CQLSSTableWriter.builder.sorted() if you can, and utilize > > writetime if you have to. > > > > Ali Hubail > > > > Confidentiality warning: This message and any attachments are intended only > > for the persons to whom this message is addressed, are confidential, and > > may be privileged. If you are not the intended recipient, you are hereby > > notified that any review, retransmission, conversion to hard copy, copying, > > modification, circulation or other use of this message and any attachments > > is strictly prohibited. If you receive this message in error, please notify > > the sender immediately by return email, and delete this message and any > > attachments from your system. Petrolink International Limited its > > subsidiaries, holding companies and affiliates disclaims all responsibility > > from and accepts no liability whatsoever for the consequences of any > > unauthorized person acting, or refraining from acting, on any information > > contained in this message. For security purposes, staff training, to assist > > in resolving complaints and to improve our customer service, email > > communications may be monitored and telephone calls may be recorded. > > > > > > Kyrylo Lebediev <kyrylo_lebed...@epam.com> > > 04/16/2018 10:37 AM > > Please respond to > > user@cassandra.apache.org > > > > To > > "user@cassandra.apache.org" <user@cassandra.apache.org>, > > cc > > Subject > > Re: copy from one table to another > > > > > > > > > > > > Any issues if we: > > > > 1) create an new empty table with the same structure as the old one > > 2) create hardlinks ("ln without -s"): > > .../<newtable>-<newuuid>/<newkeyspacename>-<newtable>-* ---> > > .../<oldtable>-<olduuid>/<oldkeyspacename>-<oldtable>-* > > 3) run nodetool refresh -- newkeyspacename newtable > > > > and then query/modify both tables independently/simultaneously? > > > > In theory, as SSTables are immutable, this should work, but could there be > > some hidden issues? > > > > Regards, > > Kyrill > > > > From: Dmitry Saprykin <saprykin.dmi...@gmail.com> > > Sent: Sunday, April 8, 2018 7:33:03 PM > > To: user@cassandra.apache.org > > Subject: Re: copy from one table to another > > > > You can copy hardlinks to ALL SSTables from old to new table and then > > delete part of data you do not need in a new one. > > > > On Sun, Apr 8, 2018 at 10:20 AM, Nitan Kainth <nitankai...@gmail.com> wrote: > > If it for testing and you don’t need any specific data, just copy a set of > > sstables with all files of that sequence and move to target tables > > directory and rename it. > > > > Restart target node or run nodetool refresh > > > > Sent from my iPhone > > > > On Apr 8, 2018, at 4:15 AM, onmstester onmstester <onmstes...@zoho.com> > > wrote: > > > > Is there any way to copy some part of a table to another table in > > cassandra? A large amount of data should be copied so i don't want to fetch > > data to client and stream it back to cassandra using cql. > > > > Sent using Zoho Mail > > > > > >
