CREATE TABLE

Creates a new table in the selected keyspace. Use IF NOT EXISTS to suppress the error message if the table already exists; no table is created.

Syntax

CREATE TABLE [ IF NOT EXISTS ] [<keyspace_name>.]<table_name>
  ( <column_definition> [ , ... ] | [ PRIMARY KEY (partition_key_column_name, clustering_column_name) ] )
  [ WITH COMPACT STORAGE ] (1)
  [ AND <table_options> ]
  [ CLUSTERING ORDER BY [ <clustering_column_name> [ ASC | DESC ] ][ , ... ] ] (2)
  ifdef::dse68[]
  [ AND ( VERTEX LABEL <vl_name> | EDGE LABEL ) <el_name> FROM <vl_name> TO <vl_name>]
  endif::dse68[]
  [ [ AND ] ID = '<table_hash_tag>' ] ] ; (3)
1 ONLY SUPPORTED FOR DSE 5.1 OR EARLER. Use only to migrate to a later DSE version.
2 The CLUSTERING ORDER BY clause is optional. If not specified, the default is ASC.
3 The ID clause is optional. If specified, the table is created with a hash tag that is used to identify the table in the schema. If a table is accidentally dropped, use this option to recreate the table and run a commit log replay to retrieve the data.
Syntax legend
Legend
Syntax conventions Description

UPPERCASE

Literal keyword.

Lowercase

Not literal.

< >

Variable value. Replace with a user-defined value.

[]

Optional. Square brackets ([]) surround optional command arguments. Do not type the square brackets.

( )

Group. Parentheses ( ( ) ) identify a group to choose from. Do not type the parentheses.

|

Or. A vertical bar (|) separates alternative elements. Type any one of the elements. Do not type the vertical bar.

...

Repeatable. An ellipsis ( ... ) indicates that you can repeat the syntax element as often as required.

'<Literal string>'

Single quotation (') marks must surround literal strings in CQL statements. Use single quotation marks to preserve upper case.

{ <key> : <value> }

Map collection. Braces ({ }) enclose map collections or key value pairs. A colon separates the key and the value.

<datatype2

Set, list, map, or tuple. Angle brackets ( < > ) enclose data types in a set, list, map, or tuple. Separate the data types with a comma.

<cql_statement>;

End CQL statement. A semicolon (;) terminates all CQL statements.

[--]

Separate the command line options from the command arguments with two hyphens ( -- ). This syntax is useful when arguments might be mistaken for command line options.

' <<schema\> ... </schema\>> '

Search CQL only: Single quotation marks (') surround an entire XML schema declaration.

@<xml_entity>='<xml_entity_type>'

Search CQL only: Identify the entity and literal value to overwrite the XML element in the schema and solrConfig files.

Parameters

Parameter Description Default

keyspace_name

Optional. Name of the keyspace that contains the table.

Keyspace and table name conventions:

The name of a keyspace or a table is a string of alphanumeric characters and underscores, but it must begin with a letter. If case must be maintained, the name must be encased in double quotes, such as "MyTable".

Since tables are defined within a keyspace, you can either use the keyspace as part of the table creation command, or create a table in the current keyspace. To specify the keyspace as part of a table name, use the keyspace name, a period (.), and table name, such as cycling.cyclist-stats.

If no name is specified, the current keyspace is used.

table_name

Name of the table.

column_definition

List of column_names and their CQL data types. The optional PRIMARY KEY clause specifies the primary key column if the table has only a single partition key. The optional STATIC keyword is used to define a static column, which has a single value shared by all rows in a partition.

column_name

Name of the column.

cql_type

CQL data type. See CQL data types.

column_list

List of columns that make up the primary key. The first column is the partition key. If there is more than one column in the partition key, enclose the columns in parentheses. Additional columns are clustering columns.

partition_key_column_name

Name of the partition key column. One or more partition key columns are required.

cluster_column_name

Name of the clustering column. Optional. One or more clustering columns can be defined. Also define ASC or DESC for the clustering order.

ASC

Options

Table options are specified using the WITH keyword. Tunes data handling, including I/O operations, compression, and compaction. A single value can be specified for each options. Some options have sub-properties that are specified using a simple JSON format, with key-value pairs in a comma-separated list enclosed by curly braces.

Option Description Default

ADDITIONAL_WRITE_POLICY

Same as speculative_retry but for writes.

99p

BLOOM_FILTER_FP_CHANCE

False-positive probability for SSTable bloom filter. When a client requests data, the bloom filter checks if the row exists before executing disk I/O. Values range from 0 to 1.0, where: 0 is the minimum value use to enable the largest possible bloom filter (uses the most memory) and 1.0 is the maximum value disabling the bloom filter.

Recommended setting: 0.1. A higher value yields diminishing returns.

0.01

CACHING

Optimizes the use of cache memory without manual tuning. Weighs the cached data by size and access frequency. Coordinate this setting with the global caching properties in the cassandra.yaml file. Valid values:

  • ALL-- all primary keys or rows

  • NONE-- no primary keys or rows

  • <N>: (rows per partition only) — specify a whole number Default: { 'keys': 'ALL', 'rows_per_partition': 'NONE' }

{'keys': 'ALL', 'rows_per_partition': 'NONE'}

CDC

Creates a Change Data Capture (CDC) log on the table.

Valid values:

  • TRUE- create CDC log

  • FALSE- do not create CDC log

false

COMMENT

Provide comments that pertain to the table.

''

COMPACTION

Configures the compaction strategy. See Compaction sub-properties for more information.

COMPRESSION

Configures the compression algorithm. See Compression sub-properties for more information.

{'chunk_length_in_kb': '16', 'class': 'org.apache.cassandra.io.compress.LZ4Compressor'}

CRC_CHECK_CHANCE

Probability that a read request will check the CRC of a row.

1.0

DCLOCAL_READ_REPAIR_CHANCE

Probability that a successful read operation triggers a read repair, limited to the same datacenter as the coordinator node.

This option is deprecated and should be set to 0.0.

DEFAULT_TTL

TTL (Time To Live) in seconds, where zero is disabled. The maximum configurable value is 630720000 (20 years). Beginning in 2018, the expiration timestamp can exceed the maximum value supported by the storage engine.

The database storage engine can only encode TTL timestamps through January 19 2038 03:14:07 UTC due to the Year 2038 problem. The TTL date overflow policy determines whether requests with expiration timestamps later than the maximum date are rejected or inserted. See -Dcassandra.expiration_date_overflow_policy.

If the value is greater than zero, TTL is enabled for the entire table and an expiration timestamp is added to each column. A new TTL timestamp is calculated each time the data is updated and the row is removed after all the data expires.

0

EXTENSIONS

Specifies the table extensions.

{}

GC_GRACE_SECONDS

Seconds after data is marked with a tombstone (deletion marker) before it is eligible for garbage-collection. In a single-node cluster, this property can safely be set to zero. You can also reduce this value for tables whose data is not explicitly deleted; for example, tables containing only data with TTL set, or tables with default_time_to_live set. Tombstone records within the grace period are excluded from hint or batched mutations. There are consideration to consider if you lower the value, such as the potential for data loss. See the usage notes for more information.

864000 (10 days) The default value allows time for the database to maximize consistency prior to deletion.

MAX_INDEX_INTERVAL

If the total memory usage of all index summaries reaches this value, CQL decreases the index summaries for the coldest SSTables to the maximum set by max_index_interval. The max_index_interval is the sparsest possible sampling in relation to memory pressure.

2048

MAX_TTL

Maximum TTL (Time To Live) in seconds.

20 years in seconds

MEMTABLE_FLUSH_PERIOD_IN_MS

Milliseconds before memtables associated with the table are flushed. When memtable_flush_period_in_ms = 0, the memtable will flush when:

  • the flush threshold is met

  • on shutdown

  • on nodetool flush

  • when commitlogs get full

0

MIN_INDEX_INTERVAL

Minimum gap between index entries in the index summary. A lower min_index_interval means the index summary contains more entries from the index, which allows the database to search fewer index entries to execute a read. A larger index summary may also use more memory. The value for min_index_interval is the densest possible sampling of the index.

128

READ_REPAIR

Sets read repair behavior. Choices are BLOCKING or NONE.

BLOCKING

SPECULATIVE_RETRY

Configures rapid read protection. Normal read requests are sent to just enough replica nodes to satisfy the consistency level. In rapid read protection, extra read requests are sent to other replicas, even after the consistency level has been met. The speculative retry property specifies the trigger for these extra read requests.

  • ALWAYS: The coordinator node sends extra read requests to all other replicas after every read of that table.

  • <X>percentile: Track each table’s typical read latency (in milliseconds). Coordinator node retrieves the typical latency time of the table being read and calculates X percent of that figure. The coordinator sends redundant read requests if the number of milliseconds it waits without responses exceeds that calculated figure.

For example, if the speculative_retry property for Table_A is set to 80percentile, and that table’s typical latency is 60 milliseconds, the coordinator node handling a read of Table_A would send a normal read request first, and send out redundant read requests if it received no responses within 48ms, which is 80% of 60ms.

  • <N>ms: The coordinator node sends extra read requests to all other replicas if the coordinator node has not received any responses within N milliseconds.

  • NONE: The coordinator node does not send extra read requests after any read of that table.

99p

Compression sub-properties

Configure by specifying the compression algorithm class followed by the sub-properties in simple JSON format. Custom compression classes can be implemented using the org.apache.cassandra.io.compress.ICompressor interface. Use only compression class implementations bundled with DSE.

compression = {
   ['class' : '<compression_algorithm_name>',
     'chunk_length_in_kb' : '<value>',
     'crc_check_chance' : '<value>',]
   | 'sstable_compression' : '']
}

Property

Description

Default

class

Sets the compressor name. CQL provides the following built-in classes:

  • LZ4Compressor

  • SnappyCompressor

  • DeflateCompressor

Choosing the right compressor depends on your requirements for space savings over read performance. LZ4 is fastest to decompress, followed by Snappy, then by Deflate. Compression effectiveness is inversely correlated with decompression speed. The extra compression from Deflate or Snappy is not enough to make up for the decreased performance for general-purpose workloads, but for archival data they may be worth considering.

LZ4Compressor

chunk_length_in_kb

Size (in KB) of the block. On disk, SSTables are compressed by block to allow random reads. Values larger than the default value might improve the compression rate, but increases the minimum size of data to be read from disk when a read occurs. The default value is a good middle ground for compressing tables. Adjust compression size to account for read/write access patterns (how much data is typically requested at once) and the average size of rows in the table.

64

crc_check_chance

When compression is enabled, each compressed block includes a checksum of that block for the purpose of detecting disk bit rot and avoiding the propagation of corruption to other replica. This option defines the probability with which those checksums are checked during read. By default they are always checked. Set to 0 to disable checksum checking and to 0.5, for instance, to check them on every other read.

1.0

sstable_compression

Disables compression.

Specify a null value.

Compaction sub-properties

Configure by specifying the compaction algorithm class followed by the sub-properties in simple JSON format. Use only compaction implementations bundled with CQL. See How is data maintained? for more details.

compaction = {
     'class' : '<compaction_strategy_name>',
     '<property_name>' : <value> [, ...] }

where the <compaction_strategy_name> is SizeTieredCompactionStrategy, TimeWindowCompactionStrategy, or LeveledCompactionStrategy.

Common properties

The following properties apply to all compaction strategies.

compaction = {
     'class' : 'compaction_strategy_name',
     'enabled' : (true | false),
     'log_all' : (true | false),
     'only_purge_repaired_tombstone' : (true | false),
     'tombstone_threshold' : <ratio>,
     'tombstone_compaction_interval' : <sec>,
     'unchecked_tombstone_compaction' : (true | false),
     'min_threshold' : <num_sstables>,
     'max_threshold' : <num_sstables> }
Property Description Default

enabled

Enable background compaction.

  • true runs minor compactions.

  • false disables minor compactions.

Use nodetool enableautocompaction to start running compactions.

true

log_all

Activates advanced logging for the entire cluster.

false

only_purge_repaired_tombstone

Enabling this property prevents data from resurrecting when repair is not run within the gc_grace_seconds. When its been a long time between repairs, the database keeps all tombstones.

  • true - Only allow tombstone purges on repaired SSTables.

  • false - Purge tombstones on SSTables during compaction even if the table has not been repaired.

false

tombstone_threshold

The ratio of garbage-collectable tombstones to all contained columns. If the ratio exceeds this limit, compactions starts only on that table to purge the tombstones.

0.2

tombstone_compaction_interval

Number of seconds before compaction can run on an SSTable after it is created. An SSTable is eligible for compaction when it exceeds the tombstone_threshold. Because it might not be possible to drop tombstones when doing a single SSTable compaction, and since the compaction is triggered base on an estimated tombstone ratio, this setting makes the minimum interval between two single SSTable compactions tunable to prevent an SSTable from being constantly re-compacted.

86400 (1 day)

unchecked_tombstone_compaction

Setting to true allows tombstone compaction to run without pre-checking which tables are eligible for the operation. Even without this pre-check, DSE checks an SSTable to make sure it is safe to drop tombstones.

false

min_threshold

The minimum number of SSTables to trigger a minor compaction. Restriction: Not used in LeveledCompactionStrategy.

4

max_threshold

The maximum number of SSTables before a minor compaction is triggered. Restriction: Not used in LeveledCompactionStrategy.

32

SizeTieredCompactionStrategy

The compaction class SizeTieredCompactionStrategy (STCS) is the default compaction strategy. The compaction class SizeTieredCompactionStrategy (STCS) triggers a minor compaction when table meets the min_threshold. Minor compactions do not involve all the tables in a keyspace. See SizeTieredCompactionStrategy (STCS).

The following properties only apply to SizeTieredCompactionStrategy:

compaction = {
     'class' : 'SizeTieredCompactionStrategy',
     'bucket_high' : <factor>,
     'bucket_low' : <factor>,
     'min_sstable_size' : <int> }
Property Description Default

bucket_high

Size-tiered compaction merges sets of SSTables that are approximately the same size. The database compares each SSTable size to the average of all SSTable sizes for this table on the node. It merges SSTables whose size in KB are within [average-size * bucket_low] and [average-size * bucket_high].

1.5

bucket_low

Size-tiered compaction merges sets of SSTables that are approximately the same size. The database compares each SSTable size to the average of all SSTable sizes for this table on the node. It merges SSTables whose size in KB are within [average-size * bucket_low] and [average-size * bucket_high].

0.5

min_sstable_size

STCS groups SSTables into buckets. The bucketing process groups SSTables that differ in size by less than 50%. This bucketing process is too fine-grained for small SSTables. If your SSTables are small, use this option to define a size threshold in MB below which all SSTables belong to one unique bucket.

50 (MB)

The cold_reads_to_omit property for SizeTieredCompactionStrategy (STCS) is no longer supported.

TimeWindowCompactionStrategy

The compaction class TimeWindowCompactionStrategy (TWCS) compacts SSTables using a series of time windows or buckets. TWCS creates a new time window within each successive time period. During the active time window, TWCS compacts all SSTables flushed from memory into larger SSTables using STCS. At the end of the time period, all of these SSTables are compacted into a single SSTable. Then the next time window starts and the process repeats. See TimeWindowCompactionStrategy (TWCS).

All of the properties for STCS are also valid for TWCS.

The following properties apply only to TimeWindowCompactionStrategy:

compaction = {
     'class' : 'TimeWindowCompactionStrategy,
     'compaction_window_unit' : <days>,
     'compaction_window_size' : <int>,
     'split_during_flush' : (true | false) }
Property Description Default

compaction_window_unit

Time unit used to define the bucket size. The value is based on the Java TimeUnit. For the list of valid values, see the Java API TimeUnit page located at https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/TimeUnit.html.

days

compaction_window_size

Units per bucket.

1

split_during_flush

Prevents mixing older data from repairs and hints with newer data from the current time window. During a flush operation, determines whether data partitions are split based on the configured time window.

  • false - the data partitions are not split based on the configured time window.

  • true - ensure that data repaired by NodeSync is placed in the correct TWCS window. Enable split_during_flush when using NodeSync with TWCS or when running node repairs.

false

During the flush operation, the data is split into a maximum of 12 windows. Each window holds the data in a separate SSTable. If the current time is <t0> and each window has a time duration of <w>, the data is split in the SSTables as follows:

  • SSTable 0 contains data for the time period < <t0> - 10 * <w>

  • SSTables 1 to 10 contain data for the 10 equal time periods from (<t0> - 10 * <w>) through to (<t0> - 1 * <w>)

  • SSTable 11, the 12th table, contains data for the time period > <t0>

LeveledCompactionStrategy

The compaction class LeveledCompactionStrategy (LCS) creates SSTables of a fixed, relatively small size (160 MB by default) that are grouped into levels. Within each level, SSTables are guaranteed to be non-overlapping. Each level (L0, L1, L2 and so on) is 10 times as large as the previous. Disk I/O is more uniform and predictable on higher than on lower levels as SSTables are continuously being compacted into progressively larger levels. At each level, row keys are merged into non-overlapping SSTables in the next level. See LeveledCompactionStrategy (LCS).

For more guidance, see When to Use Leveled Compaction and Leveled Compaction blog.

The following properties only apply to LeveledCompactionStrategy:

compaction = {
     'class' : 'LeveledCompactionStrategy,
     'sstable_size_in_mb' : <int> }
Property Description Default

sstable_size_in_mb

The target size for SSTables that use the LeveledCompactionStrategy. Although SSTable sizes should be less or equal to sstable_size_in_mb, it is possible that compaction could produce a larger SSTable during compaction. This occurs when data for a given partition key is exceptionally large. The DSE database does not split the data into two SSTables.

160

The default value, 160 MB, may be inefficient and negatively impact database indexing and the queries that rely on indexes. For example, consider the benefit of using higher values for sstable_size_in_mb in tables that use (SAI) indexes. For related information, see Compaction strategies.

DateTieredCompactionStrategy (deprecated)

Use TimeWindowCompactionStrategy instead.

Stores data written within a certain period of time in the same SSTable.

Property Description Default

base_time_seconds

The size of the first time window.

3600

max_sstable_age_days (deprecated)

DSE does not compact SSTables if its most recent data is older than this property. Fractional days can be set.

1000

max_window_size_seconds

The maximum window size in seconds.

86400

timestamp_resolution

Units, <MICROSECONDS> or <MILLISECONDS>, to match the timestamp of inserted data.

MICROSECONDS

Usage Notes

All tables must have at least one column that is part of the primary key. A primary key is made up of a partition key and zero or more clustering columns. Partition keys can be composite, i.e., made up of multiple columns. A static column is a column that is shared by all rows in a partition, and is stored only once per partition. A static column cannot be part of the primary key. Primary keys can include frozen collections and UDTs.

GC Grace Period Considerations

If you lower the gc_grace_seconds value, consider its interaction with these operations:

  • hint replays: When a node goes down and then comes back up, other nodes replay the write operations (called hints) that are queued for that node while it was unresponsive. The database does not replay hints older than gc_grace_seconds after creation. The max_hint_window_in_ms setting in the cassandra.yaml file sets the time limit (3 hours by default) for collecting hints for the unresponsive node.

  • batch replays: Like hint queues, batch operations store database mutations that are replayed in sequence. As with hints, the database does not replay a batched mutation older than gc_grace_seconds after creation. If your application uses batch operations, consider the possibility that decreasing gc_grace_seconds increases the chance that a batched write operation may restore deleted data. The batchlog_replay_throttle_in_kb property in the cassandra.yaml file give some control of the batch replay process. The most important factors, however, are the size and scope of the batches you use.

Examples

Detailed examples can be found for each type of indexing:

Type Example links

Single partition key in current keyspace

Link

Single partition key in another keyspace

Link

Primary key specified separately

Link

Mixed-case table name

Link

Multi-column (composite) partition key

Link

Clustering columns

Link

Frozen UDTs

Link

Geo-spatial data

Link

With CDC log

Link

Sort in descending order

Link

Restore table using ID

Link

COMPACT STORAGE

Link

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