Overview
The Cassandra Thrift API changed between 0.3, 0.4, 0.5, 0.6, and 0.7; this document explains the 0.7 version.
Cassandra's client API is built entirely on top of Thrift. It should be noted that these documents mention default values, but these are not generated in all of the languages that Thrift supports. Full examples of using Cassandra from Thrift, including setup boilerplate, are found on ThriftExamples. Higher-level clients are linked from ClientOptions.
WARNING: Some SQL/RDBMS terms are used in this documentation for analogy purposes. They should be thought of as just that; analogies. There are few similarities between how data is managed in a traditional RDBMS and Cassandra. Please see DataModel for more information.
Terminology / Abbreviations
Keyspace
CF
SCF
Key
Column
Exceptions
NotFoundException
InvalidRequestException
UnavailableException
TimedOutException
TApplicationException
AuthenticationException
AuthorizationException
Structures
ConsistencyLevel
The ConsistencyLevel is an enum that controls both read and write behavior based on <ReplicationFactor> in your schema definition. The different consistency levels have different meanings, depending on if you're doing a write or read operation. Note that if W + R > ReplicationFactor, where W is the number of nodes to block for on write, and R the number to block for on reads, you will have strongly consistent behavior; that is, readers will always see the most recent write. Of these, the most interesting is to do QUORUM reads and writes, which gives you consistency while still allowing availability in the face of node failures up to half of ReplicationFactor. Of course if latency is more important than consistency then you can use lower values for either or both.
All discussion of "nodes" here refers to nodes responsible for holding data for the given key; "surrogate" nodes involved in HintedHandoff do not count towards achieving the requested ConsistencyLevel.
Write
Level |
Behavior |
|
Ensure that the write has been written to at least 1 node, including HintedHandoff recipients. |
|
Ensure that the write has been written to at least 1 replica's commit log and memory table before responding to the client. |
|
Ensure that the write has been written to |
|
Ensure that the write has been written to |
|
Ensure that the write has been written to |
|
Ensure that the write is written to all |
Read
Level |
Behavior |
|
Not supported. You probably want ONE instead. |
|
Will return the record returned by the first replica to respond. A consistency check is always done in a background thread to fix any consistency issues when |
|
Will query all replicas and return the record with the most recent timestamp once it has at least a majority of replicas ( |
|
Returns the record with the most recent timestamp once a majority of replicas within the local datacenter have replied. |
|
Returns the record with the most recent timestamp once a majority of replicas within each datacenter have replied. |
|
Will query all replicas and return the record with the most recent timestamp once all replicas have replied. Any unresponsive replicas will fail the operation. |
Note: Different language toolkits may have their own Consistency Level defaults as well. To ensure the desired Consistency Level, you should always explicitly set the Consistency Level.
ColumnOrSuperColumn
Due to the lack of inheritance in Thrift, Column and SuperColumn structures are aggregated by the ColumnOrSuperColumn structure. This is used wherever either a Column or SuperColumn would normally be expected.
If the underlying column is a Column, it will be contained within the column attribute. If the underlying column is a SuperColumn, it will be contained within the super_column attribute. The two are mutually exclusive - i.e. only one may be populated.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
N |
The |
|
|
n/a |
N |
The |
Column
The Column is a triplet of a name, value and timestamp. As described above, Column names are unique within a row. Timestamps are arbitrary - they can be any integer you specify, however they must be consistent across your application. It is recommended to use a timestamp value with a fine granularity, such as milliseconds since the UNIX epoch. See DataModel for more information.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The name of the |
|
|
n/a |
Y |
The value of the |
|
|
n/a |
Y |
The timestamp of the |
SuperColumn
A SuperColumn contains no data itself, but instead stores another level of Columns below the key. See DataModel for more details on what SuperColumns are and how they should be used.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The name of the |
|
|
n/a |
Y |
The |
ColumnPath
The ColumnPath is the path to a single column in Cassandra. It might make sense to think of ColumnPath and ColumnParent in terms of a directory structure.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The name of the CF of the column being looked up. |
|
|
n/a |
N |
The super column name. |
|
|
n/a |
N |
The column name. |
ColumnParent
The ColumnParent is the path to the parent of a particular set of Columns. It is used when selecting groups of columns from the same ColumnFamily. In directory structure terms, imagine ColumnParent as ColumnPath + '/../'.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The name of the CF of the column being looked up. |
|
|
n/a |
N |
The super column name. |
SlicePredicate
A SlicePredicate is similar to a mathematic predicate, which is described as "a property that the elements of a set have in common."
SlicePredicate's in Cassandra are described with either a list of column_names or a SliceRange.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
N |
A list of column names to retrieve. This can be used similar to Memcached's "multi-get" feature to fetch N known column names. For instance, if you know you wish to fetch columns 'Joe', 'Jack', and 'Jim' you can pass those column names as a list to fetch all three at once. |
|
|
n/a |
N |
A |
If column_names is specified, slice_range is ignored.
SliceRange
A SliceRange is a structure that stores basic range, ordering and limit information for a query that will return multiple columns. It could be thought of as Cassandra's version of LIMIT and ORDER BY.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The column name to start the slice with. This attribute is not required, though there is no default value, and can be safely set to |
|
|
n/a |
Y |
The column name to stop the slice at. This attribute is not required, though there is no default value, and can be safely set to an empty byte array to not stop until |
|
|
|
Y |
Whether the results should be ordered in reversed order. Similar to |
|
|
|
Y |
How many columns to return. Similar to |
KeyRange
A KeyRange is used by get_range_slices to define the range of keys to get the slices for.
The semantics of start keys and tokens are slightly different. Keys are start-inclusive; tokens are start-exclusive. Token ranges may also wrap – that is, the end token may be less than the start one. Thus, a range from keyX to keyX is a one-element range, but a range from tokenY to tokenY is the full ring.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
N |
The first key in the inclusive |
|
|
n/a |
N |
The last key in the inclusive |
|
|
n/a |
N |
The first token in the exclusive |
|
|
n/a |
N |
The last token in the exclusive |
|
|
100 |
Y |
The total number of keys to permit in the |
KeySlice
A KeySlice encapsulates a mapping of a key to the slice of columns for it as returned by the get_range_slices operation. Normally, when slicing a single key, a list<ColumnOrSuperColumn> of the slice would be returned. When slicing multiple or a range of keys, a list<KeySlice> is instead returned so that each slice can be mapped to their key.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The key for the slice. |
|
|
n/a |
Y |
The columns in the slice. |
IndexOperator
An enum that details the type of operator to use in an IndexExpression. Currently, on EQ is supported for configuring a ColumnFamily, but the other operators may be used in conjunction with and EQ operator on other non-indexed columns.
Operator |
Description |
|
Equality |
|
Greater than or equal to |
|
Greater than |
|
Less than or equal to |
|
Less than |
IndexExpression
A struct that defines the IndexOperator to use against a column for a lookup value. Used only by the IndexClause in the get_indexed_slices method.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The column name to against which the operator and value will be applied |
|
|
n/a |
Y |
The |
|
|
n/a |
Y |
The value to be compared against the column value |
IndexClause
Defines one or more IndexExpression}}s for {{get_indexed_slices. An IndexExpression containing an EQ IndexOperator must be present.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The list of |
|
|
n/a |
Y |
Start the index query at the specified key - can be set to |
|
|
100 |
Y |
The number of results to which the index query will be constrained |
TokenRange
A structure representing structural information about the cluster provided by the describe utility methods detailed below.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The first token in the |
|
|
n/a |
Y |
The last token in the |
|
|
n/a |
Y |
A list of the endpoints (nodes) that replicate data in the |
Mutation
A Mutation encapsulates either a column to insert, or a deletion to execute for a key. Like ColumnOrSuperColumn, the two properties are mutually exclusive - you may only set one on a Mutation.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
N |
The column to insert in to the key. |
|
|
n/a |
N |
The deletion to execute on the key. |
Deletion
A Deletion encapsulates an operation that will delete all columns less than the specified timestamp and matching the predicate. If super_column is specified, the Deletion will operate on columns within the SuperColumn - otherwise it will operate on columns in the top-level of the key.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
The timestamp of the delete operation. |
|
|
n/a |
N |
The super column to delete the column(s) from. |
|
|
n/a |
N |
A predicate to match the column(s) to be deleted from the key/super column. |
AuthenticationRequest
A structure that encapsulates a request for the connection to be authenticated. The authentication credentials are arbitrary - this structure simply provides a mapping of credential name to credential value.
Attribute |
Type |
Default |
Required |
Description |
|
|
n/a |
Y |
A map of named credentials. |
Method calls
login
void login(keyspace, auth_request)
Authenticates with the cluster for operations on the specified keyspace using the specified AuthenticationRequest credentials. Throws AuthenticationException if the credentials are invalid or AuthorizationException if the credentials are valid, but not for the specified keyspace.
get
ColumnOrSuperColumn get(key, column_path, consistency_level)
Get the Column or SuperColumn at the given column_path. If no value is present, NotFoundException is thrown. (This is the only method that can throw an exception under non-failure conditions.)
get_slice
list<ColumnOrSuperColumn> get_slice(key, column_parent, predicate, consistency_level)
Get the group of columns contained by column_parent (either a ColumnFamily name or a ColumnFamily/SuperColumn name pair) specified by the given SlicePredicate struct.
multiget_slice
map<string,list<ColumnOrSuperColumn>> multiget_slice(keys, column_parent, predicate, consistency_level)
Retrieves slices for column_parent and predicate on each of the given keys in parallel. Keys are a `list<string> of the keys to get slices for.
This is similar to get_range_slices, except it operates on a set of non-contiguous keys instead of a range of keys.
get_count
i32 get_count(key, column_parent, predicate, consistency_level)
Counts the columns present in column_parent within the predicate.
The method is not O(1). It takes all the columns from disk to calculate the answer. The only benefit of the method is that you do not need to pull all the columns over Thrift interface to count them.
multiget_count
map<string, i32> multiget_count(keys, column_parent, predicate, consistency_level)
A combination of multiget_slice }}and{{ get_count.
get_range_slices
list<KeySlice> get_range_slices(column_parent, predicate, range, consistency_level)
Replaces get_range_slice. Returns a list of slices for the keys within the specified KeyRange. Unlike get_key_range, this applies the given predicate to all keys in the range, not just those with undeleted matching data. Note that when using RandomPartitioner, keys are stored in the order of their MD5 hash, making it impossible to get a meaningful range of keys between two endpoints.
get_indexed_slices
list<KeySlice> get_indexed_slices(column_parent, index_clause, predicate, consistency_level)
Like get_range_slices, returns a list of slices, but uses IndexClause instead of KeyRange. To use this method, the underlying ColumnFamily of the ColumnParent must have been configured with a column_metadata attribute, specifying at least the name and index_type attributes. See CfDef and ColumnDef above for the list of attributes. Note: the IndexClause must contain one IndexExpression with an EQ operator on a configured index column. Other IndexExpression structs may be added to the IndexClause for non-indexed columns to further refine the results of the EQ expression.
insert
insert(key, column_path, column, consistency_level)
Insert a Column consisting of (name, value, timestamp) at the given column_path.column_family and optional column_path.super_column. Note that a SuperColumn cannot directly contain binary values – it can only contain sub-Columns. Only one sub-Column may be inserted at a time, as well.
batch_mutate
batch_mutate(mutation_map, consistency_level)
Executes the specified mutations on the keyspace. mutation_map is a map<string, map<string, vector<Mutation>>>; the outer map maps the key to the inner map, which maps the column family to the Mutation; can be read as: map<key : string, map<column_family : string, vector<Mutation>>>. To be more specific, the outer map key is a row key, the inner map key is the column family name.
A Mutation specifies either columns to insert or columns to delete. See Mutation and Deletion above for more details.
remove
remove(key, column_path, timestamp, consistency_level)
Remove data from the row specified by key at the granularity specified by column_path, and the given timestamp. Note that all the values in column_path besides column_path.column_family are truly optional: you can remove the entire row by just specifying the ColumnFamily, or you can remove a SuperColumn or a single Column by specifying those levels too. Note that the timestamp is needed, so that if the commands are replayed in a different order on different nodes, the same result is produced.
truncate
truncate(string column_family)
Removes all the rows from the given column family.
describe_cluster_name
string describe_cluster_name()
Gets the name of the cluster.
describe_keyspace
KsDef describe_keyspace(string keyspace)
Gets information about the specified keyspace.
describe_keyspaces
list<KsDef> describe_keyspaces()
Gets a list of all the keyspaces configured for the cluster. (Equivalent to calling describe_keyspace(k) for k in keyspaces.)
describe_partitioner
string describe_partitioner()
Gets the name of the partitioner for the cluster.
describe_ring
list<TokenRange> describe_ring(keyspace)
Gets the token ring; a map of ranges to host addresses. Represented as a set of TokenRange instead of a map from range to list of endpoints, because you can't use Thrift structs as map keys: https://issues.apache.org/jira/browse/THRIFT-162 for the same reason, we can't return a set here, even though order is neither important nor predictable.
describe_snitch
string describe_snitch()
Gets the name of the snitch used for the cluster.
describe_version
string describe_version()
Gets the Thrift API version.
system_add_column_family
string system_add_column_family(CFDef cf_def)
Adds a column family. This method will throw an exception if a column family with the same name is already associated with the keyspace. Returns the new schema version ID.
system_drop_column_family
string system_drop_column_family(ColumnFamily column_family)
Drops a column family. Creates a snapshot and then submits a 'graveyard' compaction during which the abandoned files will be deleted. Returns the new schema version ID.
system_add_keyspace
string system_add_keyspace(KSDef ks_def)
Creates a new keyspace and any column families defined with it. Callers are not required to first create an empty keyspace and then create column families for it. Returns the new schema version ID.
system_drop_keyspace
string system_drop_keyspace(string keyspace)
Drops a keyspace. Creates a snapshot and then submits a 'graveyard' compaction during which the abandoned files will be deleted. Returns the new schema version ID.