[jira] [Updated] (CASSANDRA-13924) Continuous/Infectious Repair
[ https://issues.apache.org/jira/browse/CASSANDRA-13924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] sankalp kohli updated CASSANDRA-13924: -- Description: eI've been working on a way to keep data consistent without scheduled/external/manual repair, because for large datasets repair is extremely expensive. The basic gist is to introduce a new kind of hint that keeps just the primary key of the mutation (indicating that PK needs repair) and is recorded on replicas instead of coordinators during write time. Then a periodic background task can issue read repairs to just the PKs that were mutated. The initial performance degradation of this approach is non trivial, but I believe that I can optimize it so that we are doing very little additional work (see below in the design doc for some proposed optimizations). My extremely rough proof of concept (uses a local table instead of HintStorage, etc) so far is [in a branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] and has a rough [design document|https://github.com/jolynch/cassandra/blob/continuous_repair/doc/source/architecture/continuous_repair.rst]. I'm working on getting benchmarks of the various optimizations, but I figured I should start this ticket before I got too deep into it. I believe this approach is particularly good for high read rate clusters requiring consistent low latency, and for clusters that mutate a relatively small proportion of their data (since you never have to read the whole dataset, just what's being mutated). I view this as something that works _with_ incremental repair to reduce work required because with this technique we could potentially flush repaired + unrepaired sstables directly from the memtable. I also see this as something that would be enabled or disabled per table since it is so use case specific (e.g. some tables don't need repair at all). I think this is somewhat of a hybrid approach based on incremental repair, ticklers (read all partitions @ ALL), mutation based repair (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I think it's worth talking about. If anyone has feedback on the idea, I'd love to chat about it. [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at NGCC; if you have time I'd love to continue that conversation here. was: I've been working on a way to keep data consistent without scheduled/external/manual repair, because for large datasets repair is extremely expensive. The basic gist is to introduce a new kind of hint that keeps just the primary key of the mutation (indicating that PK needs repair) and is recorded on replicas instead of coordinators during write time. Then a periodic background task can issue read repairs to just the PKs that were mutated. The initial performance degradation of this approach is non trivial, but I believe that I can optimize it so that we are doing very little additional work (see below in the design doc for some proposed optimizations). My extremely rough proof of concept (uses a local table instead of HintStorage, etc) so far is [in a branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] and has a rough [design document|https://github.com/jolynch/cassandra/blob/continuous_repair/doc/source/architecture/continuous_repair.rst]. I'm working on getting benchmarks of the various optimizations, but I figured I should start this ticket before I got too deep into it. I believe this approach is particularly good for high read rate clusters requiring consistent low latency, and for clusters that mutate a relatively small proportion of their data (since you never have to read the whole dataset, just what's being mutated). I view this as something that works _with_ incremental repair to reduce work required because with this technique we could potentially flush repaired + unrepaired sstables directly from the memtable. I also see this as something that would be enabled or disabled per table since it is so use case specific (e.g. some tables don't need repair at all). I think this is somewhat of a hybrid approach based on incremental repair, ticklers (read all partitions @ ALL), mutation based repair (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I think it's worth talking about. If anyone has feedback on the idea, I'd love to chat about it. [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at NGCC; if you have time I'd love to continue that conversation here. > Continuous/Infectious Repair > > > Key: CASSANDRA-13924 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13924 > Project: Cassandra > Issue Type: Improvement > Components: Repair >Reporter: Joseph Lynch >
[jira] [Updated] (CASSANDRA-13924) Continuous/Infectious Repair
[ https://issues.apache.org/jira/browse/CASSANDRA-13924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Jeff Jirsa updated CASSANDRA-13924: --- Labels: CommunityFeedbackRequested (was: ) > Continuous/Infectious Repair > > > Key: CASSANDRA-13924 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13924 > Project: Cassandra > Issue Type: Improvement > Components: Repair >Reporter: Joseph Lynch >Priority: Minor > Labels: CommunityFeedbackRequested > > I've been working on a way to keep data consistent without > scheduled/external/manual repair, because for large datasets repair is > extremely expensive. The basic gist is to introduce a new kind of hint that > keeps just the primary key of the mutation (indicating that PK needs repair) > and is recorded on replicas instead of coordinators during write time. Then a > periodic background task can issue read repairs to just the PKs that were > mutated. The initial performance degradation of this approach is non trivial, > but I believe that I can optimize it so that we are doing very little > additional work (see below in the design doc for some proposed optimizations). > My extremely rough proof of concept (uses a local table instead of > HintStorage, etc) so far is [in a > branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] > and has a rough [design > document|https://github.com/jolynch/cassandra/blob/continuous_repair/doc/source/architecture/continuous_repair.rst]. > I'm working on getting benchmarks of the various optimizations, but I > figured I should start this ticket before I got too deep into it. > I believe this approach is particularly good for high read rate clusters > requiring consistent low latency, and for clusters that mutate a relatively > small proportion of their data (since you never have to read the whole > dataset, just what's being mutated). I view this as something that works > _with_ incremental repair to reduce work required because with this technique > we could potentially flush repaired + unrepaired sstables directly from the > memtable. I also see this as something that would be enabled or disabled per > table since it is so use case specific (e.g. some tables don't need repair at > all). I think this is somewhat of a hybrid approach based on incremental > repair, ticklers (read all partitions @ ALL), mutation based repair > (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I > think it's worth talking about. > If anyone has feedback on the idea, I'd love to chat about it. > [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at > NGCC; if you have time I'd love to continue that conversation here. -- This message was sent by Atlassian JIRA (v6.4.14#64029) - To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org
[jira] [Updated] (CASSANDRA-13924) Continuous/Infectious Repair
[ https://issues.apache.org/jira/browse/CASSANDRA-13924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Joseph Lynch updated CASSANDRA-13924: - Description: I've been working on a way to keep data consistent without scheduled/external/manual repair, because for large datasets repair is extremely expensive. The basic gist is to introduce a new kind of hint that keeps just the primary key of the mutation (indicating that PK needs repair) and is recorded on replicas instead of coordinators during write time. Then a periodic background task can issue read repairs to just the PKs that were mutated. The initial performance degradation of this approach is non trivial, but I believe that I can optimize it so that we are doing very little additional work (see below in the design doc for some proposed optimizations). My extremely rough proof of concept (uses a local table instead of HintStorage, etc) so far is [in a branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] and has a rough [design document|https://github.com/jolynch/cassandra/blob/continuous_repair/doc/source/architecture/continuous_repair.rst. I'm working on getting benchmarks of the various optimizations, but I figured I should start this ticket before I got too deep into it. I believe this approach is particularly good for high read rate clusters requiring consistent low latency, and for clusters that mutate a relatively small proportion of their data (since you never have to read the whole dataset, just what's being mutated). I view this as something that works _with_ incremental repair to reduce work required because with this technique we could potentially flush repaired + unrepaired sstables directly from the memtable. I also see this as something that would be enabled or disabled per table since it is so use case specific (e.g. some tables don't need repair at all). I think this is somewhat of a hybrid approach based on incremental repair, ticklers (read all partitions @ ALL), mutation based repair (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I think it's worth talking about. If anyone has feedback on the idea, I'd love to chat about it. [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at NGCC; if you have time I'd love to continue that conversation here. was: I've been working on a way to keep data consistent without scheduled/external/manual repair, because for large datasets repair is extremely expensive. The basic gist is to introduce a new kind of hint that keeps just the primary key of the mutation (indicating that PK needs repair) and is recorded on replicas instead of coordinators during write time. Then a periodic background task can issue read repairs to just the PKs that were mutated. The initial performance degradation of this approach is non trivial, but I believe that I can optimize it so that we are doing very little additional work (see below in the design doc for some proposed optimizations). My extremely rough proof of concept (uses a local table instead of HintStorage, etc) so far is [in a branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] and has a rough [design document|https://github.com/jolynch/cassandra/blob/c597c0fc6415e00fa8db180be5034214d148822d/doc/source/architecture/continuous_repair.rst]. I'm working on getting benchmarks of the various optimizations, but I figured I should start this ticket before I got too deep into it. I believe this approach is particularly good for high read rate clusters requiring consistent low latency, and for clusters that mutate a relatively small proportion of their data (since you never have to read the whole dataset, just what's being mutated). I view this as something that works _with_ incremental repair to reduce work required because with this technique we could potentially flush repaired + unrepaired sstables directly from the memtable. I also see this as something that would be enabled or disabled per table since it is so use case specific (e.g. some tables don't need repair at all). I think this is somewhat of a hybrid approach based on incremental repair, ticklers (read all partitions @ ALL), mutation based repair (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I think it's worth talking about. If anyone has feedback on the idea, I'd love to chat about it. [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at NGCC; if you have time I'd love to continue that conversation here. > Continuous/Infectious Repair > > > Key: CASSANDRA-13924 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13924 > Project: Cassandra > Issue Type: Improvement > Components: Repair >Reporter: Joseph
[jira] [Updated] (CASSANDRA-13924) Continuous/Infectious Repair
[ https://issues.apache.org/jira/browse/CASSANDRA-13924?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Joseph Lynch updated CASSANDRA-13924: - Description: I've been working on a way to keep data consistent without scheduled/external/manual repair, because for large datasets repair is extremely expensive. The basic gist is to introduce a new kind of hint that keeps just the primary key of the mutation (indicating that PK needs repair) and is recorded on replicas instead of coordinators during write time. Then a periodic background task can issue read repairs to just the PKs that were mutated. The initial performance degradation of this approach is non trivial, but I believe that I can optimize it so that we are doing very little additional work (see below in the design doc for some proposed optimizations). My extremely rough proof of concept (uses a local table instead of HintStorage, etc) so far is [in a branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] and has a rough [design document|https://github.com/jolynch/cassandra/blob/continuous_repair/doc/source/architecture/continuous_repair.rst]. I'm working on getting benchmarks of the various optimizations, but I figured I should start this ticket before I got too deep into it. I believe this approach is particularly good for high read rate clusters requiring consistent low latency, and for clusters that mutate a relatively small proportion of their data (since you never have to read the whole dataset, just what's being mutated). I view this as something that works _with_ incremental repair to reduce work required because with this technique we could potentially flush repaired + unrepaired sstables directly from the memtable. I also see this as something that would be enabled or disabled per table since it is so use case specific (e.g. some tables don't need repair at all). I think this is somewhat of a hybrid approach based on incremental repair, ticklers (read all partitions @ ALL), mutation based repair (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I think it's worth talking about. If anyone has feedback on the idea, I'd love to chat about it. [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at NGCC; if you have time I'd love to continue that conversation here. was: I've been working on a way to keep data consistent without scheduled/external/manual repair, because for large datasets repair is extremely expensive. The basic gist is to introduce a new kind of hint that keeps just the primary key of the mutation (indicating that PK needs repair) and is recorded on replicas instead of coordinators during write time. Then a periodic background task can issue read repairs to just the PKs that were mutated. The initial performance degradation of this approach is non trivial, but I believe that I can optimize it so that we are doing very little additional work (see below in the design doc for some proposed optimizations). My extremely rough proof of concept (uses a local table instead of HintStorage, etc) so far is [in a branch|https://github.com/apache/cassandra/compare/cassandra-3.11...jolynch:continuous_repair] and has a rough [design document|https://github.com/jolynch/cassandra/blob/continuous_repair/doc/source/architecture/continuous_repair.rst. I'm working on getting benchmarks of the various optimizations, but I figured I should start this ticket before I got too deep into it. I believe this approach is particularly good for high read rate clusters requiring consistent low latency, and for clusters that mutate a relatively small proportion of their data (since you never have to read the whole dataset, just what's being mutated). I view this as something that works _with_ incremental repair to reduce work required because with this technique we could potentially flush repaired + unrepaired sstables directly from the memtable. I also see this as something that would be enabled or disabled per table since it is so use case specific (e.g. some tables don't need repair at all). I think this is somewhat of a hybrid approach based on incremental repair, ticklers (read all partitions @ ALL), mutation based repair (CASSANDRA-8911), and hinted handoff. There are lots of tradeoffs, but I think it's worth talking about. If anyone has feedback on the idea, I'd love to chat about it. [~bdeggleston], [~aweisberg] I chatted with you guys a bit about this at NGCC; if you have time I'd love to continue that conversation here. > Continuous/Infectious Repair > > > Key: CASSANDRA-13924 > URL: https://issues.apache.org/jira/browse/CASSANDRA-13924 > Project: Cassandra > Issue Type: Improvement > Components: Repair >Reporter: Joseph Lynch >Prio