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: email@example.com 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 firstname.lastname@example.org To "email@example.com" <firstname.lastname@example.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: email@example.com 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<mailto: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<mailto: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<https://www.zoho.com/mail/>