/create/union

URL: http://<db.host>:<db.port>/create/union

Merges data from one or more tables with comparable data types into a new table.

The following merges are supported:

UNION (DISTINCT/ALL) - For data set union details and examples, see Union. For limitations, see Union Limitations and Cautions.

INTERSECT (DISTINCT/ALL) - For data set intersection details and examples, see Intersect. For limitations, see Intersect Limitations.

EXCEPT (DISTINCT/ALL) - For data set subtraction details and examples, see Except. For limitations, see Except Limitations.

MERGE VIEWS - For a given set of filtered views on a single table, creates a single filtered view containing all of the unique records across all of the given filtered data sets.

Non-charN 'string' and 'bytes' column types cannot be merged, nor can columns marked as store-only.

Input Parameter Description

Name

Type

Description

table_name

string

Name of the table to be created, in [schema_name.]table_name format, using standard name resolution rules and meeting table naming criteria.

table_names

array of strings

The list of table names to merge, in [schema_name.]table_name format, using standard name resolution rules. Must contain the names of one or more existing tables.

input_column_names

array of arrays of strings

The list of columns from each of the corresponding input tables.

output_column_names

array of strings

The list of names of the columns to be stored in the output table.

options

map of string to strings

Optional parameters. The default value is an empty map ( {} ).

Supported Parameters (keys)

Parameter Description

create_temp_table

If true, a unique temporary table name will be generated in the sys_temp schema and used in place of input parameter table_name. If persist is false (or unspecified), then this is always allowed even if the caller does not have permission to create tables. The generated name is returned in qualified_table_name. The default value is false. The supported values are:

true
false

collection_name

[DEPRECATED--please specify the containing schema for the projection as part of input parameter table_name and use /create/schema to create the schema if non-existent] Name of the schema for the output table. If the schema provided is non-existent, it will be automatically created. The default value is ''.

mode

The mode describes what rows of the tables being unioned will be retained. The default value is union_all.

Supported Values	Description
union_all	Retains all rows from the specified tables.
union	Retains all unique rows from the specified tables (synonym for union_distinct).
union_distinct	Retains all unique rows from the specified tables.
except	Retains all unique rows from the first table that do not appear in the second table (only works on 2 tables).
except_all	Retains all rows(including duplicates) from the first table that do not appear in the second table (only works on 2 tables).
intersect	Retains all unique rows that appear in both of the specified tables (only works on 2 tables).
intersect_all	Retains all rows(including duplicates) that appear in both of the specified tables (only works on 2 tables).

long_hash

When true use 128 bit hash for union-distinct, except, except_all, intersect and intersect_all modes. Otherwise use 64 bit hash.

chunk_size

Indicates the number of records per chunk to be used for this output table.

chunk_column_max_memory

Indicates the target maximum data size for each column in a chunk to be used for this output table.

chunk_max_memory

Indicates the target maximum data size for all columns in a chunk to be used for this output table.

create_indexes

Comma-separated list of columns on which to create indexes on the output table. The columns specified must be present in input parameter output_column_names.

ttl

Sets the TTL of the output table specified in input parameter table_name.

persist

If true, then the output table specified in input parameter table_name will be persisted and will not expire unless a ttl is specified. If false, then the output table 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

view_id

ID of view of which this output table is a member. The default value is ''.

force_replicated

If true, then the output table specified in input parameter table_name will be replicated even if the source tables are not. The default value is false. The supported values are:

true
false

strategy_definition

The tier strategy for the table and its columns.

compression_codec

The default compression codec for this table's columns.

no_count

Return a count of 0 for the union table response to avoid the cost of counting; optimization needed for many chunk virtual_union's. The default value is 'false'.

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_union_response' 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/union endpoint:

Name

Type

Description

table_name

string

Value of input parameter table_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
qualified_table_name	The fully qualified name of the result table (i.e. including the schema)

Empty string in case of an error.