org.apache.cassandra.db
Class DefsTable

java.lang.Object
  org.apache.cassandra.db.DefsTable

public class DefsTable
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)

Field Summary

static java.nio.ByteBuffer	DEFINITION_SCHEMA_COLUMN_NAME
static java.lang.String	OLD_MIGRATIONS_CF
static java.lang.String	OLD_SCHEMA_CF

Constructor Summary

DefsTable()

Method Summary

static <T extends org.apache.avro.specific.SpecificRecord> T	deserializeAvro(org.apache.avro.Schema writer, java.nio.ByteBuffer bytes, T ob) Deserialize a single object based on the given Schema.
static void	fixSchemaNanoTimestamps()
static java.util.Collection<KSMetaData>	loadFromStorage(java.util.UUID version) Loads a version of keyspace definitions from storage (using old SCHEMA_CF as a data source) Note: If definitions where found in SCHEMA_CF this method would load them into new schema handling table KEYSPACE_CF
static java.util.Collection<KSMetaData>	loadFromTable() 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 void	save(java.util.Collection<KSMetaData> keyspaces)
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

Field Detail

DEFINITION_SCHEMA_COLUMN_NAME

public static final java.nio.ByteBuffer DEFINITION_SCHEMA_COLUMN_NAME

OLD_MIGRATIONS_CF

public static final java.lang.String OLD_MIGRATIONS_CF

See Also:

Constant Field Values

OLD_SCHEMA_CF

public static final java.lang.String OLD_SCHEMA_CF

See Also:

Constant Field Values

Constructor Detail

DefsTable

public DefsTable()

Method Detail

save

public static void save(java.util.Collection<KSMetaData> keyspaces)

loadFromTable

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

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

Returns:

Collection of found keyspace definitions

fixSchemaNanoTimestamps

public static void fixSchemaNanoTimestamps()

searchComposite

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

loadFromStorage

public static java.util.Collection<KSMetaData> loadFromStorage(java.util.UUID version)
                                                        throws java.io.IOException

Loads a version of keyspace definitions from storage (using old SCHEMA_CF as a data source) Note: If definitions where found in SCHEMA_CF this method would load them into new schema handling table KEYSPACE_CF

Parameters:

version - The version of the latest migration.

Returns:

Collection of found keyspace definitions

Throws:

java.io.IOException - if failed to read SCHEMA_CF or failed to deserialize Avro schema

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

deserializeAvro

public static <T extends org.apache.avro.specific.SpecificRecord> T deserializeAvro(org.apache.avro.Schema writer,
                                                                                    java.nio.ByteBuffer bytes,
                                                                                    T ob)
                                                                         throws java.io.IOException

Deserialize a single object based on the given Schema.

Parameters:

writer - writer's schema

bytes - Array to deserialize from

ob - An empty object to deserialize into (must not be null).

Returns:

serialized Avro object

Throws:

java.io.IOException - if deserialization failed