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Apache Cassandra 1.1

Jonathan Ellis / @spyced

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• CQL3

• Global row + key caches

• Fine-grained data storage control

• Row level isolation

• Concurrent schema changes

• Off-heap cache works on Windows

• "Write survey mode"

• Hadoop improvements

• Stress tool

New features in 1.1

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Modern Cassandra, briefly• 0.7

• CREATE COLUMN FAMILY

• TTL

• Secondary (column) indexes

• 0.8• Counters

• Automatic memtable tuning

• 1.0• Compression

• Leveled compaction

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Global row + key caches• cassandra.yaml

• key_cache_size_in_mb (default 2)

• row_cache_size_in_mb (default 0)

• Also save periods

• Per-CF: caching=ALL|KEYS_ONLY*|ROWS_ONLY|NONE

• Old CF-level options are ignored• row_cache_size, key_cache_size

• save periods

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Data storage• Old:

• /var/lib/cassandra/data/Keyspace1/Standard1-hc-1-Data.db

• New:• /var/lib/cassandra/data/Keyspace1/Standard1/Keyspace1-

Standard1-hc-1-Data.db

• (Includes KS in !lename for easier bulk loading)

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Row-level isolation• Never see partial updates to a row

• We now have AID from ACID• C in ACID != C in CAP

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Concurrent schema changes• Fixes http://wiki.apache.org/cassandra/

FAQ#schema_disagreement

• Can still have temporary disagreements if you use a new CF before all nodes have it

• Also speeds up adding new nodes

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Off-heap cache on Windows• SerializingCacheProvider no longer requires JNA

• SCP is the default starting with 1.0, but falls back to CLHCP if JNA is not present in < 1.1

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Write survey mode• bin/cassandra -Dcassandra.write_survey=true

• Allows experimenting w/ compaction, compression, new versions*• isolate node to test reads

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Abortable compactions• nodetool stop <type>

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• (CQL2 is still default)

• Composite PK support• .. slice syntax removed

• ORDER BY syntax conforms to SQL

CQL3

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A simple exampleCREATE TABLE tweets (    tweet_id uuid PRIMARY KEY,    author varchar,    body varchar);

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Tweets

tweet_id

1790

1787

1778

author body

gwashingtonTo be prepared for war is one of the most

effectual means of preserving peace

jmadison All men having power ought to be distrusted to a certain degree

gmason

Those gentlemen, who will be elected senators, will fix themselves in the federal

town, and become citizens of that town more than of your state

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With clustering

CREATE TABLE timeline (    user_id varchar,    tweet_id uuid,    author varchar,    body varchar,    PRIMARY KEY (user_id, tweet_id));

partition keyclustered

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Timeline

user_id

jadams

jadams

ahamilton

ahamilton

tweet_id author body

1787 jmadison All men ...

1790 gwashington To be prepared ...

1778 gmason Those gentlemen ...

1790 gwashington To be prepared ...

clustered (within partition key)not

clustered

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Timeline, physical layout

jadams

ahamilton

(1787, author): jmadison

(1787, body):All men ...

(1790, author): gwashington

(1790, body): To be prepared ...

(1778, author): gmason

(1778, body): Those gentlemen ...

(1790, author): gwashington

(1790, body): To be prepared ...

Non-PK columns contain string literal of column name

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WITH COMPACT

CREATE TABLE timeline (    user_id varchar,    tweet_id uuid,    author varchar,    body varchar,    PRIMARY KEY (user_id, tweet_id, author))WITH COMPACT STORAGE;

• For backwards compatibilityAll but one column

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jadams

ahamilton

(1787, jmadison): All men ...

(1790, gwashington): To be prepared ...

(1778, gmason): Those gentlemen ...

(1790, gwashington): To be prepared ...

no “body” literal

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Earlier changes• (1.0.6) Allow CF names to be quali"ed by keyspace for

INSERT, ALTER, DELETE, TRUNCATE• INSERT INTO ks.cf (...) VALUES (...)

• (SELECT was done in 1.0.1)

• (1.0.4) ALTER CF attributes

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cqlsh• SOURCE and CAPTURE commands

• (1.0.8) DESCRIBE COLUMNFAMILIES

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The future is CQL (based)• cqlsh

• performance• prepared statements

• netty-based transport (CASSANDRA-2478)

• What does this mean for pycassa, Hector, et al?

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• 2I support*

• Wide row support*

• BulkOutputFormat

• (*Covered in updated WordCount)

Hadoop Integration

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Secondary Index supportIndexExpression expr = new IndexExpression( ByteBufferUtil.bytes("int4"), IndexOperator.EQ, ByteBufferUtil.bytes(0));

ConfigHelper.setInputRange( job.getConfiguration(),

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Wide row supportConfigHelper.setInputColumnFamily( job.getConfiguration(), KEYSPACE, COLUMN_FAMILY, true);

Also: PIG_WIDEROW_INPUT

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BulkOutputFormatjob.setOutputFormatClass( BulkOutputFormat.class);

• Compatible w/ CFOF + extra options

• OUTPUT_LOCATION

• BUFFER_SIZE_IN_MB

• STREAM_THROTTLE_MBITS

• (system default, 64, unlimited)

• Limitation: can’t stream to dead nodes ("x in 1.1.1?)

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Stress tool• tools/bin/stress*

• Insert, read, seq scan, indexed scan, multiget, counter add/get

• CQL

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Bonus: What’s new in C* 1.1.1• Incremental repair by token range

• Support for commitlog archiving and PITR

• Identify and blacklist corrupted SSTables from future compactions

• Open 1 sstableScanner per level for leveled compaction

• More CQL3 improvements (e.g. reversed clustering)

• "x re-creating Keyspaces/ColumnFamilies with the same name as dropped ones

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