/create/projection

URL: http://GPUDB_IP_ADDRESS:GPUDB_PORT/create/projection

Creates a new projection of an existing table. A projection represents a subset of the columns (potentially including derived columns) of a table.

For projection details and examples, see Projections. For limitations, see Projection Limitations and Cautions.

Window functions, which can perform operations like moving averages, are available through this endpoint as well as /get/records/bycolumn.

A projection can be created with a different shard key than the source table. By specifying shard_key, the projection will be sharded according to the specified columns, regardless of how the source table is sharded. The source table can even be unsharded or replicated.

If input parameter table_name is empty, selection is performed against a single-row virtual table. This can be useful in executing temporal (NOW()), identity (USER()), or constant-based functions (GEODIST(-77.11, 38.88, -71.06, 42.36)).

Input Parameter Description

Name	Type	Description
table_name	string	Name of the existing table on which the projection is to be applied. An empty table name creates a projection from a single-row virtual table, where columns specified should be constants or constant expressions.
projection_name	string	Name of the projection to be created. Has the same naming restrictions as tables.
column_names	array of strings	List of columns from input parameter table_name to be included in the projection. Can include derived columns. Can be specified as aliased via the syntax 'column_name as alias'.
options	map of string to strings	Optional parameters. The default value is an empty map ( {} ). Supported Parameters (keys) Parameter Description collection_name Name of a collection to which the projection is to be assigned as a child. If the collection provided is non-existent, the collection will be automatically created. If empty, then the projection will be at the top level. The default value is ''. expression An optional filter expression to be applied to the source table prior to the projection. The default value is ''. is_replicated If true then the projection will be replicated even if the source table is not. The default value is false. The supported values are: true false limit The number of records to keep. The default value is ''. order_by Comma-separated list of the columns to be sorted by; e.g. 'timestamp asc, x desc'. The columns specified must be present in input parameter column_names. If any alias is given for any column name, the alias must be used, rather than the original column name. The default value is ''. materialize_on_gpu No longer used. See Resource Management Concepts for information about how resources are managed, Tier Strategy Concepts for how resources are targeted for VRAM, and Tier Strategy Usage for how to specify a table's priority in VRAM. The default value is false. The supported values are: true false chunk_size Indicates the number of records per chunk to be used for this projection. create_indexes Comma-separated list of columns on which to create indexes on the projection. The columns specified must be present in input parameter column_names. If any alias is given for any column name, the alias must be used, rather than the original column name. ttl Sets the TTL of the projection specified in input parameter projection_name. shard_key Comma-separated list of the columns to be sharded on; e.g. 'column1, column2'. The columns specified must be present in input parameter column_names. If any alias is given for any column name, the alias must be used, rather than the original column name. The default value is ''. persist If true, then the projection specified in input parameter projection_name will be persisted and will not expire unless a ttl is specified. If false, then the projection will be an in-memory table and will expire unless a ttl is specified otherwise. The default value is false. The supported values are: true false preserve_dict_encoding If true, then columns that were dict encoded in the source table will be dict encoded in the projection. The default value is true. The supported values are: true false retain_partitions Determines whether the created projection will retain the partitioning scheme from the source table. The default value is false. The supported values are: true false view_id ID of view of which this projection is a member. The default value is ''.

Output Parameter Description

The GPUdb server embeds the endpoint response inside a standard response structure which contains status information and the actual response to the query. Here is a description of the various fields of the wrapper:

Name	Type	Description
status	String	'OK' or 'ERROR'
message	String	Empty if success or an error message
data_type	String	'create_projection_request' or 'none' in case of an error
data	String	Empty string
data_str	JSON or String	This embedded JSON represents the result of the /create/projection endpoint: Name Type Description projection_name string Value of input parameter projection_name. info map of string to strings Additional information. The default value is an empty map ( {} ). Possible Parameters (keys) Parameter Description count Number of records in the final table Empty string in case of an error.