Re: Duplicates columns which are backed by LIST collection types
If data was TTL'ed & tombstoned, shouldn't select be returning just 3 elements from the list column ? Thanks, Murali On Thu, Oct 24, 2019 at 12:03 PM ZAIDI, ASAD wrote: > Guess TTL’ed data is lurking around? If so , you can try get rid of > tombstones (by reducing gc_grace_seconds to zero? ) and let compaction take > care of tombstone before sstable migration. Do keep an eye on hinted > handoffs because of zero’ed gc_grace_second property. > > > > > > *From:* Muralikrishna Gutha [mailto:muralikgu...@gmail.com] > *Sent:* Thursday, October 24, 2019 10:39 AM > *To:* user@cassandra.apache.org > *Subject:* Re: Duplicates columns which are backed by LIST collection > types > > > > Thanks, List datatype has been in-use for this table almost over a few > years now and never had issues. We ran into this issue recently when we did > the keyspace migration. > > > > Thanks, > > Murali > > > > On Thu, Oct 24, 2019 at 11:36 AM ZAIDI, ASAD wrote: > > Have you chosen correct datatype to begin with, if you don’t want > duplicates? > > > > Generally speaking: > > > > A set and a list both represent multiple values but do so differently. > > A set doesn’t save ordering and values are sorted in ascending order. No > duplicates are allowed. > > > > A list saves ordering where you append or prepend the value into the list. > A list allows duplicates. > > > > > > > > *From:* Muralikrishna Gutha [mailto:muralikgu...@gmail.com] > *Sent:* Thursday, October 24, 2019 10:27 AM > *To:* user@cassandra.apache.org > *Cc:* Muralikrishna Gutha > *Subject:* Duplicates columns which are backed by LIST collection types > > > > Hello Guys, > > > > We started noticing strange behavior after we migrated one keyspace from > existing cluster to new cluster. > > > > We expanded our source cluster from 18 node to 36 nodes and Didn't run > "nodetool cleanup". > > We took sstable backups on source cluster and restored which has duplicate > data and restored (sstableloader) it on to new cluster. Apparently > applications started seeing duplicate data mostly on list backed columns. > Below is sstable2json output for one of the list backed columns. > > > > Clustering Column1:Clustering Column2:mods (List collection type > > ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233 > > > > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b050eac811e9ab2729ea208ce219","eb25d0b13a6611e980b22102e728a233",1570648383445000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b051eac811e9ab2729ea208ce219","eb26bb113a6611e980b22102e728a233",1570648383445000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b052eac811e9ab2729ea208ce219","a4fcf1f1eac811e99664732b9302ab46",1570648383445000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973560ead811e98bf68711844fec13","eb25d0b13a6611e980b22102e728a233",1570654999478000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973561ead811e98bf68711844fec13","eb26bb113a6611e980b22102e728a233",1570654999478000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973562ead811e98bf68711844fec13","a4fcf1f1eac811e99664732b9302ab46",1570654999478000], > > > > Below is the select statement i would expect Cassandra to return data with > latest timestamp rather it returns duplicate values. > > > > select mods from keyspace.table where partition_key ='1117302' and > type='ModifierList' and id=eb26e221-3a66-11e9-80b2-2102e728a233; > > > > [image: image.png] > > > > Any help or guidance is greatly appreciated. > > > > -- > > Thanks & Regards > Murali K Gutha > > > > > -- > > Thanks & Regards > Murali K Gutha > -- Thanks & Regards Murali K Gutha
RE: Duplicates columns which are backed by LIST collection types
Guess TTL’ed data is lurking around? If so , you can try get rid of tombstones (by reducing gc_grace_seconds to zero? ) and let compaction take care of tombstone before sstable migration. Do keep an eye on hinted handoffs because of zero’ed gc_grace_second property. From: Muralikrishna Gutha [mailto:muralikgu...@gmail.com] Sent: Thursday, October 24, 2019 10:39 AM To: user@cassandra.apache.org Subject: Re: Duplicates columns which are backed by LIST collection types Thanks, List datatype has been in-use for this table almost over a few years now and never had issues. We ran into this issue recently when we did the keyspace migration. Thanks, Murali On Thu, Oct 24, 2019 at 11:36 AM ZAIDI, ASAD mailto:az1...@att.com>> wrote: Have you chosen correct datatype to begin with, if you don’t want duplicates? Generally speaking: A set and a list both represent multiple values but do so differently. A set doesn’t save ordering and values are sorted in ascending order. No duplicates are allowed. A list saves ordering where you append or prepend the value into the list. A list allows duplicates. From: Muralikrishna Gutha [mailto:muralikgu...@gmail.com<mailto:muralikgu...@gmail.com>] Sent: Thursday, October 24, 2019 10:27 AM To: user@cassandra.apache.org<mailto:user@cassandra.apache.org> Cc: Muralikrishna Gutha mailto:muralikgu...@gmail.com>> Subject: Duplicates columns which are backed by LIST collection types Hello Guys, We started noticing strange behavior after we migrated one keyspace from existing cluster to new cluster. We expanded our source cluster from 18 node to 36 nodes and Didn't run "nodetool cleanup". We took sstable backups on source cluster and restored which has duplicate data and restored (sstableloader) it on to new cluster. Apparently applications started seeing duplicate data mostly on list backed columns. Below is sstable2json output for one of the list backed columns. Clustering Column1:Clustering Column2:mods (List collection type ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233 ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b050eac811e9ab2729ea208ce219","eb25d0b13a6611e980b22102e728a233",1570648383445000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b051eac811e9ab2729ea208ce219","eb26bb113a6611e980b22102e728a233",1570648383445000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b052eac811e9ab2729ea208ce219","a4fcf1f1eac811e99664732b9302ab46",1570648383445000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973560ead811e98bf68711844fec13","eb25d0b13a6611e980b22102e728a233",1570654999478000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973561ead811e98bf68711844fec13","eb26bb113a6611e980b22102e728a233",1570654999478000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973562ead811e98bf68711844fec13","a4fcf1f1eac811e99664732b9302ab46",1570654999478000], Below is the select statement i would expect Cassandra to return data with latest timestamp rather it returns duplicate values. select mods from keyspace.table where partition_key ='1117302' and type='ModifierList' and id=eb26e221-3a66-11e9-80b2-2102e728a233; [image.png] Any help or guidance is greatly appreciated. -- Thanks & Regards Murali K Gutha -- Thanks & Regards Murali K Gutha
Re: Duplicates columns which are backed by LIST collection types
Thanks, List datatype has been in-use for this table almost over a few years now and never had issues. We ran into this issue recently when we did the keyspace migration. Thanks, Murali On Thu, Oct 24, 2019 at 11:36 AM ZAIDI, ASAD wrote: > Have you chosen correct datatype to begin with, if you don’t want > duplicates? > > > > Generally speaking: > > > > A set and a list both represent multiple values but do so differently. > > A set doesn’t save ordering and values are sorted in ascending order. No > duplicates are allowed. > > > > A list saves ordering where you append or prepend the value into the list. > A list allows duplicates. > > > > > > > > *From:* Muralikrishna Gutha [mailto:muralikgu...@gmail.com] > *Sent:* Thursday, October 24, 2019 10:27 AM > *To:* user@cassandra.apache.org > *Cc:* Muralikrishna Gutha > *Subject:* Duplicates columns which are backed by LIST collection types > > > > Hello Guys, > > > > We started noticing strange behavior after we migrated one keyspace from > existing cluster to new cluster. > > > > We expanded our source cluster from 18 node to 36 nodes and Didn't run > "nodetool cleanup". > > We took sstable backups on source cluster and restored which has duplicate > data and restored (sstableloader) it on to new cluster. Apparently > applications started seeing duplicate data mostly on list backed columns. > Below is sstable2json output for one of the list backed columns. > > > > Clustering Column1:Clustering Column2:mods (List collection type > > ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233 > > > > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b050eac811e9ab2729ea208ce219","eb25d0b13a6611e980b22102e728a233",1570648383445000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b051eac811e9ab2729ea208ce219","eb26bb113a6611e980b22102e728a233",1570648383445000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b052eac811e9ab2729ea208ce219","a4fcf1f1eac811e99664732b9302ab46",1570648383445000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973560ead811e98bf68711844fec13","eb25d0b13a6611e980b22102e728a233",1570654999478000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973561ead811e98bf68711844fec13","eb26bb113a6611e980b22102e728a233",1570654999478000], > > > ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973562ead811e98bf68711844fec13","a4fcf1f1eac811e99664732b9302ab46",1570654999478000], > > > > Below is the select statement i would expect Cassandra to return data with > latest timestamp rather it returns duplicate values. > > > > select mods from keyspace.table where partition_key ='1117302' and > type='ModifierList' and id=eb26e221-3a66-11e9-80b2-2102e728a233; > > > > [image: image.png] > > > > Any help or guidance is greatly appreciated. > > > > -- > > Thanks & Regards > Murali K Gutha > -- Thanks & Regards Murali K Gutha
RE: Duplicates columns which are backed by LIST collection types
Have you chosen correct datatype to begin with, if you don’t want duplicates? Generally speaking: A set and a list both represent multiple values but do so differently. A set doesn’t save ordering and values are sorted in ascending order. No duplicates are allowed. A list saves ordering where you append or prepend the value into the list. A list allows duplicates. From: Muralikrishna Gutha [mailto:muralikgu...@gmail.com] Sent: Thursday, October 24, 2019 10:27 AM To: user@cassandra.apache.org Cc: Muralikrishna Gutha Subject: Duplicates columns which are backed by LIST collection types Hello Guys, We started noticing strange behavior after we migrated one keyspace from existing cluster to new cluster. We expanded our source cluster from 18 node to 36 nodes and Didn't run "nodetool cleanup". We took sstable backups on source cluster and restored which has duplicate data and restored (sstableloader) it on to new cluster. Apparently applications started seeing duplicate data mostly on list backed columns. Below is sstable2json output for one of the list backed columns. Clustering Column1:Clustering Column2:mods (List collection type ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233 ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b050eac811e9ab2729ea208ce219","eb25d0b13a6611e980b22102e728a233",1570648383445000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b051eac811e9ab2729ea208ce219","eb26bb113a6611e980b22102e728a233",1570648383445000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:d120b052eac811e9ab2729ea208ce219","a4fcf1f1eac811e99664732b9302ab46",1570648383445000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973560ead811e98bf68711844fec13","eb25d0b13a6611e980b22102e728a233",1570654999478000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973561ead811e98bf68711844fec13","eb26bb113a6611e980b22102e728a233",1570654999478000], ["ModifierList:eb26e221-3a66-11e9-80b2-2102e728a233:mods:38973562ead811e98bf68711844fec13","a4fcf1f1eac811e99664732b9302ab46",1570654999478000], Below is the select statement i would expect Cassandra to return data with latest timestamp rather it returns duplicate values. select mods from keyspace.table where partition_key ='1117302' and type='ModifierList' and id=eb26e221-3a66-11e9-80b2-2102e728a233; [image.png] Any help or guidance is greatly appreciated. -- Thanks & Regards Murali K Gutha
