org.apache.cassandra.db

Class DefsTables

java.lang.Object

org.apache.cassandra.db.DefsTables

public class DefsTables
extends java.lang.Object

SCHEMA_{KEYSPACES, COLUMNFAMILIES, COLUMNS}_CF are used to store Keyspace/ColumnFamily attributes to make schema load/distribution easy, it replaces old mechanism when local migrations where serialized, stored in system.Migrations and used for schema distribution. SCHEMA_KEYSPACES_CF layout: ascii => json_serialized_value ... Where is a name of keyspace e.g. "ks". SCHEMA_COLUMNFAMILIES_CF layout: composite(ascii, ascii) => json_serialized_value Where is a name of keyspace e.g. "ks"., first component of the column name is name of the ColumnFamily, last component is the name of the ColumnFamily attribute. SCHEMA_COLUMNS_CF layout: composite(ascii, ascii, ascii) => json_serialized value Where is a name of keyspace e.g. "ks". Column names where made composite to support 3-level nesting which represents following structure: "ColumnFamily name":"column name":"column attribute" => "value" Example of schema (using CLI): schema_keyspaces ---------------- RowKey: ks => (column=durable_writes, value=true, timestamp=1327061028312185000) => (column=name, value="ks", timestamp=1327061028312185000) => (column=replication_factor, value=0, timestamp=1327061028312185000) => (column=strategy_class, value="org.apache.cassandra.locator.NetworkTopologyStrategy", timestamp=1327061028312185000) => (column=strategy_options, value={"datacenter1":"1"}, timestamp=1327061028312185000) schema_columnfamilies --------------------- RowKey: ks => (column=cf:bloom_filter_fp_chance, value=0.0, timestamp=1327061105833119000) => (column=cf:caching, value="NONE", timestamp=1327061105833119000) => (column=cf:column_type, value="Standard", timestamp=1327061105833119000) => (column=cf:comment, value="ColumnFamily", timestamp=1327061105833119000) => (column=cf:default_validation_class, value="org.apache.cassandra.db.marshal.BytesType", timestamp=1327061105833119000) => (column=cf:gc_grace_seconds, value=864000, timestamp=1327061105833119000) => (column=cf:id, value=1000, timestamp=1327061105833119000) => (column=cf:key_alias, value="S0VZ", timestamp=1327061105833119000) ... part of the output omitted. schema_columns -------------- RowKey: ks => (column=cf:c:index_name, value=null, timestamp=1327061105833119000) => (column=cf:c:index_options, value=null, timestamp=1327061105833119000) => (column=cf:c:index_type, value=null, timestamp=1327061105833119000) => (column=cf:c:name, value="aGVsbG8=", timestamp=1327061105833119000) => (column=cf:c:validation_class, value="org.apache.cassandra.db.marshal.AsciiType", timestamp=1327061105833119000)

Constructor Summary

Constructors

Constructor and Description
DefsTables()

Method Summary

Methods

Modifier and Type	Method and Description
static java.util.Collection<KSMetaData>	loadFromKeyspace() Load keyspace definitions for the system keyspace (system.SCHEMA_KEYSPACES_CF)
static void	mergeSchema(java.util.Collection<RowMutation> mutations) Merge remote schema in form of row mutations with local and mutate ks/cf metadata objects (which also involves fs operations on add/drop ks/cf)
static java.nio.ByteBuffer	searchComposite(java.lang.String name, boolean start)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DefsTables

public DefsTables()

Method Detail

loadFromKeyspace

public static java.util.Collection<KSMetaData> loadFromKeyspace()

Load keyspace definitions for the system keyspace (system.SCHEMA_KEYSPACES_CF)

Returns:

Collection of found keyspace definitions

searchComposite

public static java.nio.ByteBuffer searchComposite(java.lang.String name,
                                  boolean start)

mergeSchema

public static void mergeSchema(java.util.Collection<RowMutation> mutations)
                        throws ConfigurationException,
                               java.io.IOException

Merge remote schema in form of row mutations with local and mutate ks/cf metadata objects (which also involves fs operations on add/drop ks/cf)

Parameters:

mutations - the schema changes to apply

Throws:

ConfigurationException - If one of metadata attributes has invalid value

java.io.IOException - If data was corrupted during transportation or failed to apply fs operations