Re: SSTable structure
The tricky thing with documenting the SS tables is that there are a lot of conditionals in the structure, so it makes for twisty reading. Just for fun, here's a terrible start I made once: https://github.com/mustardgrain/cassandra-notes/blob/master/SSTables.md On Mon, Mar 30, 2015, at 05:12 PM, Robert Coli wrote: On Mon, Mar 30, 2015 at 5:07 PM, daemeon reiydelle daeme...@gmail.com wrote: why? Then there are 2 places 2 maintain or get jira'ed for a discrepancy. If you are asserting that code is capable of documenting itself, we will just have to agree to disagree. =Rob
10,000s of column families/keyspaces
Hi all, I know it's an old topic, but I want to see if anything's changed on the number of column families that C* supports, either in 1.2.x or 2.x. For a number of reasons [1], we'd like to support multi-tenancy via separate column families. The problem is that there are around 5,000 tenants to support and each one needs a small handful of column families each. The last I heard C* supports 'a couple of hundred' column families before things start to bog down. What will it take for C* to support 50,000 column families? I'm about to dive into the code and run some tests, but I was curious about how to quantify the overhead of a column family. Is the reason performance? Memory? Does the off-heap work help here? Thanks, Kirk [1] The main three reasons: 1. ability to wholesale drop data for a given tenant via drop keyspace/drop CFs 2. ability to have divergent schema for each tenant (partially effected by DSE Solr integration) 3. secondary indexes per tenant (given requirement #2)
Re: read request distribution
Somewhat recently the Ownership column was changed to Effective Ownership. Previously the formula was essentially 100/nodes. Now it's 100*replication factor/nodes. So in previous releases of Cassandra it would be 100/12 = 8.33, now it would be closer to 25% (8.33*3 (assuming a replication factor of three)). Kirk On Mon, Nov 12, 2012, at 03:52 PM, Ananth Gundabattula wrote: Hi all, On an unrelated observation of the below readings, it looks like all the 3 nodes own 100% of the data. This confuses me a bit. We have a 12 node cluster with RF=3 but the effective ownership is shown as 8.33 % . So here is my question. How is the ownership calculated : Is Replica factor considered in the ownership calculation ? ( If yes , then 8.33 % ownership of a cluster seems wrong to me . If not 100% ownership for a node cluster seems wrong to me. Am I missing something in the calculation? Regards, Ananth On Fri, Nov 9, 2012 at 4:37 PM, Wei Zhu [1]wz1...@yahoo.com wrote: Hi All, I am doing a benchmark on a Cassandra. I have a three node cluster with RF=3. I generated 6M rows with sequence number from 1 to 6m, so the rows should be evenly distributed among the three nodes disregarding the replicates. I am doing a benchmark with read only requests, I generate read request for randomly generated keys from 1 to 6M. Oddly, nodetool cfstats, reports that one node has only half the requests as the other one and the third node sits in the middle. So the ratio is like 2:3:4. The node with the most read requests actually has the smallest latency and the one with the least read requests reports the largest latency. The difference is pretty big, the fastest is almost double the slowest. All three nodes have the exactly the same hardware and the data size on each node are the same since the RF is three and all of them have the complete data. I am using Hector as client and the random read request are in millions. I can't think of a reasonable explanation. Can someone please shed some lights? Thanks. -Wei References 1. mailto:wz1...@yahoo.com
Re: Data Modeling: Comments with Voting
Depending on your needs, you could simply duplicate the comments in two separate CFs with the column names including time in one and the vote in the other. If you allow for updates to the comments, that would pose some issues you'd need to solve at the app level. On 9/26/12 4:28 PM, Drew Kutcharian wrote: Hi Guys, Wondering what would be the best way to model a flat (no sub comments, i.e. twitter) comments list with support for voting (where I can sort by create time or votes) in Cassandra? To demonstrate: Sorted by create time: - comment 1 (5 votes) - comment 2 (1 votes) - comment 3 (no votes) - comment 4 (10 votes) Sorted by votes: - comment 4 (10 votes) - comment 1 (5 votes) - comment 2 (1 votes) - comment 3 (no votes) It's the sorted-by-votes that I'm having a bit of a trouble with. I'm looking for a roll-your-own approach and prefer not to use secondary indexes and CQL sorting. Thanks, Drew
Re: Batch update efficiency with composite key
I was aware of the read-then-write pattern for counters, but not secondary indexes. I'll have to take a look into that. Thanks. On 07/20/2012 02:32 AM, aaron morton wrote: I'm assuming the logical row is in a CQL 3 CF with composite PRIMARYKEY http://www.datastax.com/dev/blog/whats-new-in-cql-3-0 It will still be a no look write. The exception being secondary indexes and counters which include reads in the write path. Cheers - Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 20/07/2012, at 10:26 AM, Kirk True wrote: In Cassandra you don't read-then-write updates, you just write the updates. Sorry for being dense, but can you clarify a logical vs. physical row? Batching is useful for reducing round trips to the server. On 07/18/2012 06:18 AM, Leonid Ilyevsky wrote: I have a question about efficiency of updates to a CF with composite key. Let say I have 100 of logical rows to update, and they all belong to the same physical wide row. In my naïve understanding (correct me if I am wrong), in order to update a logical row, Cassandra has to retrieve the whole physical row, add columns to it, and put it back. So I put all my 100 updates in a batch and send it over. Would Cassandra be smart enough to recognize that they all belong to one physical row, retrieve it once, do all the updates and put it back once? Is my batch thing even relevant in this case? What happens if I just send updates one by one? I want to understand why I should use batches. I don’t really care about one timestamp for all records, I only care about efficiency. So I thought, I want to at least save on the number of remote calls, but I also wonder what happens on Cassandra side. This email, along with any attachments, is confidential and may be legally privileged or otherwise protected from disclosure. Any unauthorized dissemination, copying or use of the contents of this email is strictly prohibited and may be in violation of law. If you are not the intended recipient, any disclosure, copying, forwarding or distribution of this email is strictly prohibited and this email and any attachments should be deleted immediately. This email and any attachments do not constitute an offer to sell or a solicitation of an offer to purchase any interest in any investment vehicle sponsored by Moon Capital Management LP (“Moon Capital”). Moon Capital does not provide legal, accounting or tax advice. Any statement regarding legal, accounting or tax matters was not intended or written to be relied upon by any person as advice. Moon Capital does not waive confidentiality or privilege as a result of this email.
Re: Inability to drop column families
What does show schema show? Is the CF showing up? Are the data files for the CF on disk? If you poke around with the system CFs, is there any data still present? On 07/17/2012 02:54 PM, sj.climber wrote: Looking for ideas on how to diagnose this issue. I have installed v1.1.2 on a two-node cluster (the data files loaded, incidentally, were from an earlier v1.1.1 2-node setup). While initially I recall being able to create/drop column families, I am no longer able to. Let's say I have column family MyFamily in MyKeyspace. Using cassandra-cli, I issue: [default@unknown] use MyKeyspace; Authenticated to keyspace: MyKeyspace [default@galaxy_lookups] drop column family MyFamily; 27f5c6bc-8cf3-3671-94e6-9f905be28c35 Waiting for schema agreement... ... schemas agree across the cluster However, the column family is still there, either way using describe from within cassandra-cli, or through nodetool cfstats. Moreover, there are no errors in the Cassandra logs. Ideas on what to try next? Thanks! -- View this message in context: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Inability-to-drop-column-families-tp7581297.html Sent from the cassandra-u...@incubator.apache.org mailing list archive at Nabble.com.
Re: Replication factor - Consistency Questions
But isn't QUORUM on a 2-node cluster still 2 nodes? On 07/17/2012 11:50 PM, Jason Tang wrote: Yes, for ALL, it is not good for HA, and because we meet problem when use QUORAM, and current solution is switch Write:QUORAM / Read:QUORAM when got UnavailableException exception. 2012/7/18 Jay Parashar jparas...@itscape.com mailto:jparas...@itscape.com Thanks..but write ALL will fail for any downed nodes. I am thinking of QUORAM. *From:*Jason Tang [mailto:ares.t...@gmail.com mailto:ares.t...@gmail.com] *Sent:* Tuesday, July 17, 2012 8:24 PM *To:* user@cassandra.apache.org mailto:user@cassandra.apache.org *Subject:* Re: Replication factor - Consistency Questions Hi I am starting using Cassandra for not a long time, and also have problems in consistency. Here is some thinking. If you have Write:Any / Read:One, it will have consistency problem, and if you want to repair, check your schema, and check the parameter Read repair chance: http://wiki.apache.org/cassandra/StorageConfiguration And if you want to get consistency result, my suggestion is to have Write:ALL / Read:One, since for Cassandra, write is more faster then read. For performance impact, you need to test your traffic, and if your memory can not cache all your data, or your network is not fast enough, then yes, it will impact to write one more node. BRs 2012/7/18 Jay Parashar jparas...@itscape.com mailto:jparas...@itscape.com Hello all, There is a lot of material on Replication factor and Consistency level but I am a little confused by what is happening on my setup. (Cassandra 1.1.2). I would appreciate any answers. My Setup: A cluster of 2 nodes evenly balanced. My RF =2, Consistency Level; Write = ANY and Read = 1 I know that my consistency is Weak but since my RF = 2, I thought data would be just duplicated in both the nodes but sometimes, querying does not give me the correct (or gives partial) results. In other times, it gives me the right results Is the Read Repair going on after the first query? But as RF = 2, data is duplicated then why the repair? Note: My query is done a while after the Writes so data should have been in both the nodes. Or is this not the case (flushing not happening etc)? I am thinking of making the Write as 1 and Read as QUORAM so R + W RF (1 + 2 2) to give strong consistency. Will that affect performance a lot (generally speaking)? Thanks in advance Regards Jay
Re: Batch update efficiency with composite key
In Cassandra you don't read-then-write updates, you just write the updates. Sorry for being dense, but can you clarify a logical vs. physical row? Batching is useful for reducing round trips to the server. On 07/18/2012 06:18 AM, Leonid Ilyevsky wrote: I have a question about efficiency of updates to a CF with composite key. Let say I have 100 of logical rows to update, and they all belong to the same physical wide row. In my naïve understanding (correct me if I am wrong), in order to update a logical row, Cassandra has to retrieve the whole physical row, add columns to it, and put it back. So I put all my 100 updates in a batch and send it over. Would Cassandra be smart enough to recognize that they all belong to one physical row, retrieve it once, do all the updates and put it back once? Is my batch thing even relevant in this case? What happens if I just send updates one by one? I want to understand why I should use batches. I don't really care about one timestamp for all records, I only care about efficiency. So I thought, I want to at least save on the number of remote calls, but I also wonder what happens on Cassandra side. This email, along with any attachments, is confidential and may be legally privileged or otherwise protected from disclosure. Any unauthorized dissemination, copying or use of the contents of this email is strictly prohibited and may be in violation of law. If you are not the intended recipient, any disclosure, copying, forwarding or distribution of this email is strictly prohibited and this email and any attachments should be deleted immediately. This email and any attachments do not constitute an offer to sell or a solicitation of an offer to purchase any interest in any investment vehicle sponsored by Moon Capital Management LP (Moon Capital). Moon Capital does not provide legal, accounting or tax advice. Any statement regarding legal, accounting or tax matters was not intended or written to be relied upon by any person as advice. Moon Capital does not waive confidentiality or privilege as a result of this email.
Re: Errors with Cassandra 1.0.10, 1.1.0, 1.1.1-SNAPSHOT and 1.2.0-SNAPSHOT
Permissions problems on /var for the user running Cassandra? Sent from my iPhone On Jun 2, 2012, at 6:56 PM, Horacio G. de Oro hgde...@gmail.com wrote: Hi! While using Cassandra, I've seen this log messages when running some test cases (which insert lots of columns in 4 rows). I've tryied Cassandra 1.0.10, 1.1.0, 1.1.1-SNAPSHOT and 1.2.0-SNAPSHOT (built from git). I'm using the default configuration, Oracle jdk 1.6.0_32, Ubuntu 12.04 and pycassa. Since I'm very new to Cassandra (I'm just starting to learn it) I don't know if I'm doing something wrong, or maybe there are some bugs in the several versions of Cassandra I've tested. cassandra-1.0.10 - IOException: unable to mkdirs cassandra-1.1.0 - IOException: Unable to create directory cassandra-1.1.1-SNAPSHOT - IOException: Unable to create directory cassandra-1.2.0-SNAPSHOT - IOException: Unable to create directory - CLibrary.java (line 191) Unable to create hard link (...) command output: ln: failed to create hard link `(...)/lolog_tests-Logs_by_app-ia-3-Summary.db': File exists Thanks in advance! Horacio system-cassandra-1.0.10.log ERROR [MutationStage:1] 2012-06-02 20:37:41,115 AbstractCassandraDaemon.java (line 139) Fatal exception in thread Thread[MutationStage:1,5,main] java.io.IOError: java.io.IOException: unable to mkdirs /var/lib/cassandra/data/lolog_tests/snapshots/1338680261112-Logs_by_app at org.apache.cassandra.db.ColumnFamilyStore.snapshotWithoutFlush(ColumnFamilyStore.java:1433) at org.apache.cassandra.db.ColumnFamilyStore.snapshot(ColumnFamilyStore.java:1462) at org.apache.cassandra.db.ColumnFamilyStore.truncate(ColumnFamilyStore.java:1657) at org.apache.cassandra.db.TruncateVerbHandler.doVerb(TruncateVerbHandler.java:50) ERROR [MutationStage:11] 2012-06-02 20:37:55,730 AbstractCassandraDaemon.java (line 139) Fatal exception in thread Thread[MutationStage:11,5,main] java.io.IOError: java.io.IOException: unable to mkdirs /var/lib/cassandra/data/lolog_tests/snapshots/1338680275729-Logs_by_app at org.apache.cassandra.db.ColumnFamilyStore.snapshotWithoutFlush(ColumnFamilyStore.java:1433) at org.apache.cassandra.db.ColumnFamilyStore.snapshot(ColumnFamilyStore.java:1462) at org.apache.cassandra.db.ColumnFamilyStore.truncate(ColumnFamilyStore.java:1657) at org.apache.cassandra.db.TruncateVerbHandler.doVerb(TruncateVerbHandler.java:50) ERROR [MutationStage:19] 2012-06-02 20:37:57,395 AbstractCassandraDaemon.java (line 139) Fatal exception in thread Thread[MutationStage:19,5,main] java.io.IOError: java.io.IOException: unable to mkdirs /var/lib/cassandra/data/lolog_tests/snapshots/1338680277394-Logs_by_app at org.apache.cassandra.db.ColumnFamilyStore.snapshotWithoutFlush(ColumnFamilyStore.java:1433) at org.apache.cassandra.db.ColumnFamilyStore.snapshot(ColumnFamilyStore.java:1462) at org.apache.cassandra.db.ColumnFamilyStore.truncate(ColumnFamilyStore.java:1657) at org.apache.cassandra.db.TruncateVerbHandler.doVerb(TruncateVerbHandler.java:50) ERROR [MutationStage:20] 2012-06-02 20:41:26,666 AbstractCassandraDaemon.java (line 139) Fatal exception in thread Thread[MutationStage:20,5,main] java.io.IOError: java.io.IOException: unable to mkdirs /var/lib/cassandra/data/lolog_tests/snapshots/133868048-Logs_by_app at org.apache.cassandra.db.ColumnFamilyStore.snapshotWithoutFlush(ColumnFamilyStore.java:1433) at org.apache.cassandra.db.ColumnFamilyStore.snapshot(ColumnFamilyStore.java:1462) at org.apache.cassandra.db.ColumnFamilyStore.truncate(ColumnFamilyStore.java:1657) at org.apache.cassandra.db.TruncateVerbHandler.doVerb(TruncateVerbHandler.java:50) system-cassandra-1.1.0.log ERROR [MutationStage:1] 2012-06-02 20:45:15,609 AbstractCassandraDaemon.java (line 134) Exception in thread Thread[MutationStage:1,5,main] java.io.IOError: java.io.IOException: Unable to create directory /var/lib/cassandra/data/lolog_tests/Logs_by_app/snapshots/1338680715606-Logs_by_app at org.apache.cassandra.db.Directories.getOrCreate(Directories.java:384) at org.apache.cassandra.db.Directories.getSnapshotDirectory(Directories.java:186) at org.apache.cassandra.db.ColumnFamilyStore.snapshotWithoutFlush(ColumnFamilyStore.java:1440) at org.apache.cassandra.db.ColumnFamilyStore.snapshot(ColumnFamilyStore.java:1483) ERROR [MutationStage:9] 2012-06-02 20:45:30,728 AbstractCassandraDaemon.java (line 134) Exception in thread Thread[MutationStage:9,5,main] java.io.IOError: java.io.IOException: Unable to create directory
Re: How do I add a custom comparator class to a cassandra cluster ?
Disclaimer: I've never tried, but I'd imagine you can drop a JAR containing the class(es) into the lib directory and perform a rolling restart of the nodes. On 5/14/12 11:11 AM, Ertio Lew wrote: I need to add a custom comparator to a cluster, to sort columns in a certain customized fashion. How do I add the class to the cluster ?
Re: Two Random Ports in Private port range
Are these the dynamic JMX ports? Sent from my iPad On Apr 19, 2012, at 8:58 AM, W F amz...@gmail.com wrote: Hi All, I did a web search of the archives (hope I looked in the right place) and could not find a request like this. When Cassandra is running, it seems to create to random tcp listen ports. For example: 50378 and 58692, 49952, 52792. What are are these for and is there documentation regarding this? Sorry if this is already in the archive! Thanks ~A
Re: Stress test using Java-based stress utility
Have you checked the logs on the nodes to see if there are any errors? On 7/21/11 10:43 PM, Nilabja Banerjee wrote: Hi All, I am following this following link " http://www.datastax.com/docs/0.7/utilities/stress_java " for a stress test. I am getting this notification after running this command xxx.xxx.xxx.xx= my ip contrib/stress/bin/stress -d xxx.xxx.xxx.xx Created keyspaces. Sleeping 1s for propagation. total,interval_op_rate,interval_key_rate,avg_latency,elapsed_time Operation [44] retried 10 times - error inserting key 044 ((UnavailableException)) Operation [49] retried 10 times - error inserting key 049 ((UnavailableException)) Operation [7] retried 10 times - error inserting key 007 ((UnavailableException)) Operation [6] retried 10 times - error inserting key 006 ((UnavailableException)) Any idea why I am getting these things? Thank You -- Kirk True Founder, Principal Engineer Expert Engineering Firepower About us:
Re: 0.8.0 thrift api?
The best documentation (imo) for the Thrift API, is the cassandra.thrift file in the 'interface' subdirectory of the releas. Because cassandra.thrift is used to generate client bindings, it is always up to date, and usually well commented. The wiki lags behind, but sometimes will have more details on a specific topic. cheers, -kirk On Sat, Apr 23, 2011 at 11:38 AM, Michael Fortin mi...@m410.us wrote: Hi, Were can I find the thrift api documentation for 0.8? What's in the wiki is only for =7. I'm especially inserted in the new query and counter api's. That's accessible via thrift, right? Thanks, Mike -- ⑆gmail.com⑆necrobious⑈
Re: Embedding Cassandra in Java code w/o using ports
Not sure, but I've been playing with running cassandra in the same VM as an HTTP server for a pet project of mine, using a similar technique as the one found in the Solandra project. It does use ports on localhost, but hopefully gives you an idea of embedding cassandra (no clue if its a good idea or not yet, still playing with it myself). cheers, -kirk https://github.com/tjake/Solandra On Fri, Apr 1, 2011 at 9:07 PM, Bob Futrelle bob.futre...@gmail.com wrote: Connecting via CLI to local host with a port number has never been successful for me in Snow Leopard. No amount of reading suggestions and varying the approach has worked. So I'm going to talk to Cassandra via its API, from Java. But I noticed that in some code samples that call the API from Java, ports are also in play. In using Derby in Java I've never had to designate any ports. Is such a strategy available with Cassandra? - Bob Futrelle Northeastern U. -- ⑆gmail.com⑆necrobious⑈
