Changing snitch from PropertyFile to Gossip

Is it possible to do this without down time i.e. run in mixed mode while doing a rolling upgrade?

Thrift row cache in Cassandra 2.1

clarify it, would be appreciated. Thanks, AJ

Backups, Snapshots, SSTable Data Files, Compaction

Hi, I am working on a backup strategy and am trying to understand what is going on in the data directory. I notice that after a write to a CF and then flush, a new set of data files are created with an index number incremented in their names, such as: Initially: Users-e-1-Filter.db Users-e-

Re: Backups, Snapshots, SSTable Data Files, Compaction

On 6/6/2011 11:25 PM, Benjamin Coverston wrote: Currently, my data dir has about 16 sets. I thought that compaction (with nodetool) would clean-up these files, but it doesn't. Neither does cleanup or repair. You're not even talking about snapshots using nodetool snapshot yet. Also nodetool

Re: Backups, Snapshots, SSTable Data Files, Compaction

On 6/7/2011 2:29 AM, Maki Watanabe wrote: You can find useful information in: http://www.datastax.com/docs/0.8/operations/scheduled_tasks sstables are immutable. Once it written to disk, it won't be updated. When you take snapshot, the tool makes hard links to sstable files. After certain time,

CLI set command returns null

Ver 0.8.0. Please help. I don't know what I'm doing wrong. One simple keyspace with one simple CF with one simple column. I've tried two simple tutorials. Is there a common newbie mistake I could be making??? Thanks in advance! [default@Keyspace1] describe keyspace; Keyspace: Keyspace1:

Re: Backups, Snapshots, SSTable Data Files, Compaction

Thanks to everyone who responded thus far. On 6/7/2011 10:16 AM, Benjamin Coverston wrote: Not to say that there aren't workloads where having many TB/Node doesn't work, but if you're planning to read from the data you're writing you do want to ensure that your working set is stored in memory

Re: CLI set command returns null

andra.cli.CliClient.executeCLIStatement(CliClient.java:292) at org.apache.cassandra.cli.CliMain.processStatement(CliMain.java:217) at org.apache.cassandra.cli.CliMain.main(CliMain.java:345) [default@Keyspace1] On 6/7/2011 12:27 PM, Jonathan Ellis wrote: try running cli with --debug On Tue, Jun 7, 2011 a

Re: CLI set command returns null, ver 0.8.0

assandra.cli.CliMain.main(CliMain.java:345) [default@Keyspace1] Granted, there are no rows in the CF yet (see probs below), but this exception seems to be during the parsing stage. I've check everything else, AFAIK, so I'm at a loss. Much obliged. On 6/7/2011 12:44 PM, AJ wrote: The

Re: Multiple large disks in server - setup considerations

On 6/7/2011 9:32 PM, Edward Capriolo wrote: I do not like large disk set-ups. I think they end up not being economical. Most low latency use cases want high RAM to DISK ratio. Two machines with 32GB RAM is usually less expensive then one machine with 64GB ram. For a machine with 1TB drive

Misc Performance Questions

Is there a performance hit when dropping a CF? What if it contains .5 TB of data? If not, is there a quick and painless way to drop a large amount of data w/minimal perf hit? Is there a performance hit running multiple keyspaces on a cluster versus only one keyspace given a constant total

Re: Misc Performance Questions

Thank you Richard! On 6/8/2011 2:57 AM, Richard Low wrote: There is however a difference in running multiple column families versus putting everything in the same column family and separating them with e.g. a key prefix. E.g. if you have a large data set and a small one, it will be quicker to

Re: CLI set command returns null, ver 0.8.0

45) [default@Keyspace1] What does "comparators do not match" mean? Thanks, Mike On 6/8/2011 4:37 PM, aaron morton wrote: Can you provide the cli script to create the schema and info on how many nodes you have. Thanks - Aaron Morton Freelance Cassandra Developer @aaro

Ideas for Big Data Support

[Please feel free to correct me on anything or suggest other workarounds that could be employed now to help.] Hello, This is purely theoretical, as I don't have a big working cluster yet and am still in the planning stages, but from what I understand, while Cass scales well horizontally, EACH

Re: Ideas for Big Data Support

On 6/9/2011 8:40 AM, Edward Capriolo wrote: Some of these things are challenges, and a few are being worked on in one way or another. 1) Dynamic snitch was implemented to determine slow acting nodes and re-balance load. 2) You can budget bootstrap with rsync, as long as you know what dat

Consistency Levels and Replication with Down Nodes

The O'Reilly book on Cass says this about READ consistency level ALL: "Query all nodes. Wait for all nodes to respond, and return to the client the record with the most recent timestamp. Then, if necessary, perfrom a read repair in the background. If any nodes fail or respond, fail the read o

Where is the Overview Documentation on Counters?

I can't find any that gives an overview of their purpose/benefits/etc, only how to code them. I can only guess that they are more efficient for some reason but don't know exactly why or exactly what conditions I would choose to use them over a regular column. Thanks!

Re: SSL & Streaming

Performance-wise, I think it would be better to just let the client encrypt sensitive data before storing it, versus encrypting all traffic all the time. If individual values are encrypted, then they don't have to be encrypted/decrypted during transit between nodes during the initial updates a

Docs: "Why do deleted keys show up during range scans?"

http://wiki.apache.org/cassandra/FAQ#range_ghosts "So to special case leaving out result entries for deletions, we would have to check the entire rest of the row to make sure there is no undeleted data anywhere else either (in which case leaving the key out would be an error)." The above doe

Re: Docs: "Why do deleted keys show up during range scans?"

On 6/13/2011 7:03 AM, Stephen Connolly wrote: It returns the set of columns for the set of rows... how do you determine the difference between a completely empty row and a row that just does not have any of the matching columns? I would expect it to not return anything (no row at all) for both

Re: Docs: "Why do deleted keys show up during range scans?"

On 6/13/2011 9:25 AM, Stephen Connolly wrote: On 13 June 2011 16:14, AJ wrote: On 6/13/2011 7:03 AM, Stephen Connolly wrote: It returns the set of columns for the set of rows... how do you determine the difference between a completely empty row and a row that just does not have any of the

Re: Docs: "Why do deleted keys show up during range scans?"

On 6/13/2011 10:14 AM, Stephen Connolly wrote: store the query inverted. that way empty -> deleted I don't know what that means... get the other columns? Can you elaborate? Is there docs for this or is this a hack/workaround? the tombstones are stored for each column that had data IIRC.

Is this the proper use of OPP?

I'm just becoming aware of the restrictions of using an OPP as compared to Random. Please let me know if I understand this correctly. First off, if using the OPP only for an increased performance of range queries, then it will probably be very hard to predict if you will end up with hotspots

Re: Is this the proper use of OPP?

ou to this article, it does a good job describing OPP and pretty much answers the specific questions you asked. http://ria101.wordpress.com/2010/02/22/cassandra-randompartitioner-vs-orderpreservingpartitioner/ -Eric On Mon, Jun 13, 2011 at 5:06 PM, AJ wrote: I'm just becoming aware of the

Where is my data?

Is there an official deterministic formula to compute the various subsets of a given cluster that comprises a complete set of data (redundant rows ok)? IOW, if multiple nodes become unavailable one at a time, at what point can I say <100% of my data is available? Obviously, the method would h

Docs: Token Selection

This http://wiki.apache.org/cassandra/Operations#Token_selection says: "With NetworkTopologyStrategy, you should calculate the tokens the nodes in each DC independantly." and gives the example: DC1 node 1 = 0 node 2 = 85070591730234615865843651857942052864 DC2 node 3 = 1 node 4 = 8507059173

Re: Docs: "Why do deleted keys show up during range scans?"

ted which matches every column, so in effect it is deleting the columns, not the whole row. A row key will not be forgotten/deleted until there are no columns or tombstones which reference it. Until there are no references to that row key in any SSTables you can still get that key back from the AP

Re: Docs: Token Selection

.5 -> 0) Node2 Owns 50% (Ranges 0 -> 1 & 1 -> 8..4) DC2 Node1 Owns 50% (Ranges 8..5 -> 0 & 0 -> 1) Node2 Owns 50% (Ranges 1 -> 8..4 & 8..4 -> 8..5) Regards, On Tue, Jun 14, 2011 at 3:47 PM, AJ <mailto:a...@dude.podzone.net>> wrote:

Re: New web client & future API

Nice interface... and someone has good taste in music. BTW, I'm new to web programming, what did you use for the web components? JSF, JavaScript, something else? On 6/14/2011 7:42 AM, Markus Wiesenbacher | Codefreun.de wrote: Hi, what is the future API for Cassandra? Thrift, Avro, CQL? I

Re: Where is my data?

Thanks On 6/15/2011 3:20 AM, Sylvain Lebresne wrote: You can use the thrift call describe_ring(). It will returns a map that associate to each range of the ring who is a replica. Once any range has all it's endpoint unavailable, that range of the data is unavailable. -- Sylvain

Re: cascading failures due to memory

Sasha, Did you ever nail down the cause of this problem? On 5/31/2011 4:01 AM, Sasha Dolgy wrote: hi everyone, the current nodes i have deployed (4) have all been working fine, with not a lot of data ... more reads than writes at the moment. as i had monitoring disabled, when one node's OS ki

Re: Forcing Cassandra to free up some space

In regards to cleaning-up old sstable files, I posed this question before as I noticed after taking a snapshot, the older files (pre-compaction) shared no links with the snapshots. Therefore, (if the Cass snapshot functionality is working correctly) those older files can be manually deleted.

Re: Docs: Token Selection

On 6/15/2011 12:14 PM, Vijay wrote: Correction "The problem in the above approach is you have 2 nodes between 12 to 4 in DC1 but from 4 to 12 you just have 1" should be "The problem in the above approach is you have 1 node between 0-4 (25%) and and one node covering the rest which is 4

Re: Docs: Token Selection

les if it helps DC1 Node 1 : token 0 DC1 Node 2 : token 8.. DC2 Node 1 : token 4.. DC2 Node 1 : token 12.. or DC1 Node 1 : token 0 DC1 Node 2 : token 1.. DC2 Node 1 : token 8.. DC2 Node 1 : token 7.. Regards, On Wed, Jun 15, 2011 at 12:28 PM, AJ <mailto:a...@dude.podzone.net>> w

Re: Docs: Token Selection

ou are doing the right thing... Regards, On Wed, Jun 15, 2011 at 2:34 PM, AJ <mailto:a...@dude.podzone.net>> wrote: Vijay, thank you for your thoughtful reply. Will Cass complain if I don't setup my tokens like in the examples? On 6/15/2011 2:41 PM, Vijay wrote:

Re: Docs: Token Selection

LOL, I feel Eric's pain. This double-ring thing can throw you for a loop since, like I said, there is only one place it is documented and it is only *implied*, so one is not sure he is interpreting it correctly. Even the source for NTS doesn't mention this. Thanks for everyone's help on this

Re: Docs: Token Selection

n 6/16/2011 7:21 AM, Eric tamme wrote: AJ, sorry I seemed to miss the original email on this thread. As Aaron said, when computing tokens for multiple data centers, you should compute them independently for each data center - as if it were its own Cassandra cluster. You can have "overlapping&

Propose new ConsistencyLevel.ALL_AVAIL for reads

Good morning all. Hypothetical Setup: 1 data center RF = 3 Total nodes > 3 Problem: Suppose I need maximum consistency for one critical operation; thus I specify CL = ALL for reads. However, this will fail if only 1 replica endpoint is down. I don't see why this fail is necessary all of the

Re: Propose new ConsistencyLevel.ALL_AVAIL for reads

On 6/16/2011 10:05 AM, Ryan King wrote: I don't think this buys you anything that you can't get with quorum reads and writes. -ryan QUORUM <= ALL_AVAIL <= ALL == RF

Re: Propose new ConsistencyLevel.ALL_AVAIL for reads

On 6/16/2011 10:58 AM, Dan Hendry wrote: I think this would add a lot of complexity behind the scenes and be conceptually confusing, particularly for new users. I'm not so sure about this. Cass is already somewhat sophisticated and I don't see how this could trip-up anyone who can already gras

Re: Propose new ConsistencyLevel.ALL_AVAIL for reads

On 6/16/2011 2:37 PM, Ryan King wrote: On Thu, Jun 16, 2011 at 1:05 PM, AJ wrote: The Cassandra consistency model is pretty elegant and this type of approach breaks that elegance in many ways. It would also only really be useful when the value has a high probability of being updated

Re: Propose new ConsistencyLevel.ALL_AVAIL for reads

UPDATE to my suggestion is below. On 6/16/2011 5:50 PM, Ryan King wrote: On Thu, Jun 16, 2011 at 2:12 PM, AJ wrote: On 6/16/2011 2:37 PM, Ryan King wrote: On Thu, Jun 16, 2011 at 1:05 PM, AJwrote: The Cassandra consistency model is pretty elegant and this type of approach breaks that

Re: Propose new ConsistencyLevel.ALL_AVAIL for reads

On 6/16/2011 7:56 PM, Dan Hendry wrote: How would your solution deal with complete network partitions? A node being 'down' does not actually mean it is dead, just that it is unreachable from whatever is making the decision to mark it 'down'. Following from Ryan's example, consider nodes A, B,

Re: Propose new ConsistencyLevel.ALL_AVAIL for reads

On 6/16/2011 9:36 PM, Dan Hendry wrote: "Help me out here. I'm trying to visualize a situation where the clients can access all the C* nodes but the nodes can't access each other. I don't see how that can happen on a regular ethernet subnet in one data center. Well, I"m sure there is a case

Re: Docs: Token Selection

On 6/16/2011 9:45 PM, aaron morton wrote: But, I'm thinking about using OldNetworkTopStrat. NetworkTopologyStrategy is where it's at. Oh yeah? It didn't look like it would serve my requirements. I want 2 full production geo-diverse data centers with each serving as a failover for the other

Re: Docs: Token Selection

, etc.? On 6/17/2011 12:20 AM, Jonathan Ellis wrote: Replication location is determined by the row key, not the location of the client that inserted it. (Otherwise, without knowing what DC a row was inserted in, you couldn't look it up to read it!) On Fri, Jun 17, 2011 at 12:20 AM, AJ wr

Re: Docs: Token Selection

On 6/17/2011 7:26 AM, William Oberman wrote: I haven't done it yet, but when I researched how to make geo-diverse/failover DCs, I figured I'd have to do something like RF=6, strategy = {DC1=3, DC2=3}, and LOCAL_QUORUM for reads/writes. This gives you an "ack" after 2 local nodes do the read/wr

Re: Docs: Token Selection

+1 Yes, that is what I'm talking about Eric. Maybe I could write my own strategy, I dunno. I'll have to understand more first. On 6/17/2011 10:37 AM, Sasha Dolgy wrote: +1 for this if it is possible... On Fri, Jun 17, 2011 at 6:31 PM, Eric tamme wrote: What I don't like about NTS is I wou

Re: Docs: Token Selection

On 6/17/2011 10:31 AM, Eric tamme wrote: What I don't like about NTS is I would have to have more replicas than I need. {DC1=2, DC2=2}, RF=4 would be the minimum. If I felt that 2 local replicas was insufficient, I'd have to move up to RF=6 which seems like a waste... I'm predicting data in the

Re: Docs: Token Selection

Hi Jeremiah, can you give more details? Thanks On 6/17/2011 10:49 AM, Jeremiah Jordan wrote: Run two Cassandra clusters... -Original Message- From: Eric tamme [mailto:eta...@gmail.com] Sent: Friday, June 17, 2011 11:31 AM To: user@cassandra.apache.org Subject: Re: Docs: Token Selection

Re: Docs: Token Selection

On 6/17/2011 12:33 PM, Eric tamme wrote: As i said previously, trying to build make cassandra treat things differently based on some kind of persistent locality set it maintains in memory .. or whatever .. sounds like you will be absolutely undermining the core principles of how cassandra works.

Re: Docs: Token Selection

On 6/17/2011 12:32 PM, Jeremiah Jordan wrote: Run two clusters, one which has {DC1:2, DC2:1} and one which is {DC1:1,DC2:2}. You can't have both in the same cluster, otherwise it isn't possible to tell where the data got written when you want to read it. For a given key "XYZ" you must b

Re: Docs: Token Selection

t have multiple keyspaces ... Hey! I think you're on to something Sasha! Placement strat and RF are both defined per ks. I'll let that stew for a while in my brain. Thanks! On Fri, Jun 17, 2011 at 9:23 PM, AJ wrote: On 6/17/2011 12:32 PM, Jeremiah Jordan wrote: Run two clust

Storing Accounting Data

Is C* suitable for storing customer account (financial) data, as well as billing, payroll, etc? This is a new company so migration is not an issue... starting from scratch. Thanks!

Re: Storing Accounting Data

limit the number of databases - Stephen --- Sent from my Android phone, so random spelling mistakes, random nonsense words and other nonsense are a direct result of using swype to type on the screen On 21 Jun 2011 18:30, "AJ" <mailto:a...@dude.podzone.net>> wrote:

Re: Storing Accounting Data

un 21, 2011 at 2:03 PM, AJ <mailto:a...@dude.podzone.net>> wrote: On 6/21/2011 2:50 PM, Stephen Connolly wrote: how important are things like transactional consistency for you? would you have issues if only one side of a transfer was recorded? Right. Both of those

Re: Storing Accounting Data

And I was thinking of using JTA for transaction processing. I have no experience with it but on the surface it looks like it should work. On 6/21/2011 3:31 PM, AJ wrote: What's the best accepted way to handle that 100% in the client? Retries? On 6/21/2011 3:14 PM, Anand Somani wrote

Re: Storing Accounting Data

On 6/21/2011 3:14 PM, Anand Somani wrote: Not sure if it is that simple, a quorum can fail with writes happening on some nodes (there is no rollback). Also there is no concept of atomic compare-and-swap. Good points. I suppose what I need is for the client to implement the part of ACID tha

Re: Storing Accounting Data

l more than I want to do. But, I just rediscovered Dominic's Cages <http://code.google.com/p/cages/>. Has anyone tried it? --- Sent from my Android phone, so random spelling mistakes, random nonsense words and other nonsense are a direct result of using swype to type on the scre

Re: Atomicity Strategies

On 4/9/2011 7:52 PM, aaron morton wrote: My understanding of what they did with locking (based on the examples) was to achieve a level of transaction isolation http://en.wikipedia.org/wiki/Isolation_(database_systems) I think the

Re: No Transactions: An Example

I think Sasha's idea is worth studying more. Here is a supporting read referenced in the O'Reilly Cassandra book that talks about alternatives to 2-phase commit and synchronous transactions: http://www.eaipatterns.com/ramblings/18_starbucks.html If it can be done without locks and the busines

NTS Replication Strategy - only replicating to a subset of data centers

I'm just double-checking, but when using NTS, is it required to specify ALL the data centers in the strategy_options attribute? IOW, I do NOT want replication to ALL data centers; only a two of the three. So, if my property file snitch describes all of the existing data centers and nodes as:

Re: Atomicity Strategies

Thanks Aaron! On 6/22/2011 5:25 PM, aaron morton wrote: Atomic on a single machine yes. - Aaron Morton Freelance Cassandra Developer @aaronmorton http://www.thelastpickle.com On 23 Jun 2011, at 09:42, AJ wrote: On 4/9/2011 7:52 PM, aaron morton wrote: My understanding of

Is LOCAL_QUORUM as strong as QUORUM?

Quorum read/writes guarantees consistency. But, when a keyspace spans multiple data centers, does local quorum read/writes also guarantee consistency? I'm thinking maybe not if two data centers get partitioned. Thanks!

Re: Is LOCAL_QUORUM as strong as QUORUM?

On 6/22/2011 5:56 PM, mcasandra wrote: LOCAL_QUORUM gurantees consistency in the local data center only. Other replica nodes in the same DC and other DC not part of the QUORUM will be eventually consistent. If you want to ensure consistency accross DCs you can use EACH_QUORUM but keep in mind the

Re: Is LOCAL_QUORUM as strong as QUORUM?

On 6/22/2011 6:50 PM, AJ wrote: On 6/22/2011 5:56 PM, mcasandra wrote: LOCAL_QUORUM gurantees consistency in the local data center only. Other replica nodes in the same DC and other DC not part of the QUORUM will be eventually consistent. If you want to ensure consistency accross DCs you can

Re: Is LOCAL_QUORUM as strong as QUORUM?

On 6/22/2011 8:20 PM, mcasandra wrote: Well it depends on the requirements. If you use any combination of CL with EACH_QUORUM it means you are accepting the fact that you are ok if one of the DC is down. And in your scenario you care more about DCs being consistent even if writes were to fail. Al

Re: Storing files in blob into Cassandra

On 6/22/2011 1:07 AM, Damien Picard wrote: Hi, I have to store some files (Images, documents, etc.) for my users in a webapp. I use Cassandra for all of my data and I would like to know if this is a good idea to store these files into blob on a Cassandra CF ? Is there some contraindications, o

Re: No Transactions: An Example

On 6/23/2011 7:37 AM, Trevor Smith wrote: AJ, Thanks for your input. I don't fully follow though how this would work with a bank scenario. Could you explain in more detail? Thanks. Trevor I don't know yet. I'll be researching that. My working procedure is to figure out

Re: Storing files in blob into Cassandra

On 6/22/2011 11:43 PM, Sasha Dolgy wrote: maybe you want to spend a few minutes reading about Haystack over at facebook to give you some ideas... https://www.facebook.com/note.php?note_id=76191543919 Not saying what they've done is the right way... just sayin' Thanks for the tip Sasha; will d

Cassandra ACID

Can any Cassandra contributors/guru's confirm my understanding of Cassandra's degree of support for the ACID properties? I provide official references when known. Please let me know if I missed some good official documentation. *Atomicity* All individual writes are atomic at the row level.

Concurrency: Does C* support a Happened-Before relation between processes' writes?

Sorry, I know this is long-winded but I just want to make sure before I go through the trouble to implement this since it's not something that can be reliably tested and requires in-depth knowledge about C* internals. But, this ultimately deals with concurrency control so anyone interested in

Re: Concurrency: Does C* support a Happened-Before relation between processes' writes?

On 6/24/2011 2:09 PM, Jim Newsham wrote: On 6/24/2011 9:28 AM, Yang wrote: without a clear description of your pseudo-code, it's difficult to say whether it will work. but I think it can work fine as an election/agreement protocol, which you can use as a lock to some degree, but this requires

Re: Concurrency: Does C* support a Happened-Before relation between processes' writes?

On 6/24/2011 2:27 PM, Jonathan Ellis wrote: Might be able to do it with http://en.wikipedia.org/wiki/Lamport%27s_bakery_algorithm. "It is remarkable that this algorithm is not built on top of some lower level "atomic" operation, e.g. compare-and-swap." I've been meaning to get back to reading t

Re: Cassandra ACID

in cassandra.yaml. For "some" performance improvement with "some" cost in durability you can specify "commitlog_sync: periodic". See discussion below for more details. Refs: Plenty + this thread. On 6/24/2011 1:46 PM, Jim Newsham wrote: On 6/23/2011 8:55 PM, AJ wr

Re: Concurrency: Does C* support a Happened-Before relation between processes' writes?

On 6/24/2011 2:27 PM, Jonathan Ellis wrote: Might be able to do it with http://en.wikipedia.org/wiki/Lamport%27s_bakery_algorithm. "It is remarkable that this algorithm is not built on top of some lower level "atomic" operation, e.g. compare-and-swap." This looks like it may work. Jonathan, h

Re: Concurrency: Does C* support a Happened-Before relation between processes' writes?

On 6/25/2011 8:24 AM, Edward Capriolo wrote: I played around with the bakery algorithm and had ok success the challenges are most implementations assume an n size array of fixed clients and when you get it working it turns out to be a good number of cassandra ops to acquire your bakery lock. I

Sharing Cassandra with Solandra

where say that you have to run Solandra on every C* node in the ring. I'm not sure if I interpreted that correctly. Also, what's the index size to data size ratio to expect (ballpark)? How does it perform? Any caveats? Thanks! aj

Re: Auto compaction to be staggered ?

the same in my *Ideas for Big Data Support* thread, "5.) Postponed Major Compactions: The option to postpone auto-triggered major compactions until a pre-defined time of day or week or until staff can do it manually. " aj

Re: Clock skew

I'm curious, do you think the sleep is required even in a non-virtualized environment? Is it only needed when implementing some kind of lock? Does the type of lock make a difference? Thanks! aj (the other one) On 6/28/2011 11:31 AM, Dominic Williams wrote: Hi, yes you are correct, a

Re: Sharing Cassandra with Solandra

On 6/27/2011 3:39 PM, David Strauss wrote: On Mon, 2011-06-27 at 15:06 -0600, AJ wrote: Would anyone care to talk about their experiences with using Solandra along side another application that uses Cassandra (also on the same node)? I'm curious about any resource contention issu

Re: No Transactions: An Example

o large as to be a significant perf hit. A note about the updates. You have to make sure the clean-up process processes the updates in order and only 1 time. If you can't guarantee these, then you'll have to make sure your updates are idempotent and commutative. Oh yeah, and you must use QUORUM read/writes, of course. Any critiques? aj

Re: Meaning of 'nodetool repair has to run within GCGraceSeconds'

It would be helpful if this was automated some how.

Re: Cassandra ACID

mit log. However, this requires "commitlog_sync: batch" in cassandra.yaml. For "some" performance improvement with "some" cost in durability you can specify "commitlog_sync: periodic". See discussion below for more details. Refs: Plenty + this thread

Strong Consistency with ONE read/writes

Is this possible? All reads and writes for a given key will always go to the same node from a client. It seems the only thing needed is to allow the clients to compute which node is the closes replica for the given key using the same algorithm C* uses. When the first replica receives the wri

Re: Strong Consistency with ONE read/writes

I'm saying I will make my clients forward the C* requests to the first replica instead of forwarding to a random node. -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. Will Oberman wrote: Sent from my iPhone On Jul 1, 2011, at 9:53 PM, AJ wrote: > Is this

Re: Strong Consistency with ONE read/writes

slaves can take-over as master, so you still have high availability. I'm not saying it's easy and I'm only coming at this from a customer request point of view. The question is, would this be useful if it could be added to Cass's bag of tricks? Cass is already a hybrid.

Re: Strong Consistency with ONE read/writes

On 7/2/2011 6:03 AM, William Oberman wrote: Ok, I see the "you happen to choose the 'right' node" idea, but it sounds like you want to solve "C* problems" in the client, and they already wrote that complicated code to make clients simple. You're talking about reimplementing key<->node mapping

Re: Strong Consistency with ONE read/writes

te_pending" flag on any column value would probably make this work. But, I'll think more on this later. aj On 7/2/2011 10:55 AM, Yang wrote: there is a JIRA completed in 0.7.x that "Prefers" a certain node in snitch, so this does roughly what you want MOST of the time

Re: Strong Consistency with ONE read/writes

. On Jul 3, 2011, at 5:20 PM, AJ <mailto:a...@dude.podzone.net>> wrote: Yang, How would you deal with the problem when the 1st node responds success but then crashes before completely forwarding any replicas? Then, after switching to the next primary, a read would return stale

Re: Strong Consistency with ONE read/writes

27;t sound any different than a TWO write. I'm trying to save a hop (+ 1 data xfer) by ack'ing immediately after the primary successfully writes, i.e., ONE write. On Jul 3, 2011 11:20 AM, "AJ" <mailto:a...@dude.podzone.net>> wrote: > Yang, > > How would you

Re: Strong Consistency with ONE read/writes

ting. The point of the placeholders is to handle the crash case that I talked about... "like" a WAL does. But, C* will propagate the value to N-1 eventually anyways, 'cause that's just what it does anyways :-) will On Sun, Jul 3, 2011 at 7:47 PM, AJ <mailto:a...@dude.

Re: Strong Consistency with ONE read/writes

We seem to be having a fundamental misunderstanding. Thanks for your comments. aj On 7/3/2011 8:28 PM, William Oberman wrote: I'm using cassandra as a tool, like a black box with a certain contract to the world. Without modifying the "core", C* will send the updates to all re

Command Request: rename a column

quick and could even be made atomic (per node) as I suspect it would mostly entail only reference updates. Has anything like this been discussed before? Seems like such a natural operation for a hash-table-like data store. aj

Re: Command Request: rename a column

On 7/8/2011 2:18 AM, Sylvain Lebresne wrote: On Fri, Jul 8, 2011 at 9:22 AM, AJ wrote: I think it would be really cool to be able to rename a column, or, more generally, a move command to move data from one column to another in the same CF without the client having to read and resend the

Feature Request: Multi-key Mapping

s) indexes and better suited for range queries. Of course, some indirection would be needed to avoid the naive solution of simply duplicating values. Maybe Unix inodes is the best analogy here. aj

Re: Strong Consistency with ONE read/writes

replicated to any other replica node. But, then again, you also say that the leader does not forward replicas in your idea; so it's not real clear. I'm still trying to figure out how to make this work with normal Cass operation. aj On 7/11/2011 3:48 PM, Yang wrote: I'm n

Anyone using Facebook's flashcache?

. Do any Cass developers have any thoughts on this and whether or not it would be helpful considering Cass' architecture and operation? Links: http://www.facebook.com/note.php?note_id=388112370932 https://github.com/facebook/flashcache/wiki aj

Re: Anyone using Facebook's flashcache?

On 7/12/2011 10:19 AM, Peter Schuller wrote: Do any Cass developers have any thoughts on this and whether or not it would be helpful considering Cass' architecture and operation? A well-functioning L2 cache should definitely be very useful with Cassandra for read-intensive workloads where the re

Re: Anyone using Facebook's flashcache?

ot; the ssd by reading in (and discarding) the top 25% (250/1000GB) of the usual hot data. aj

  1   2   >