create\_join\_table(join\_table\_name=None, table\_names=None, column\_names=None, expressions=\[], options={"{"}{"}"})\[source]

Creates a table that is the result of a SQL JOIN.

For join details and examples see: Joins. For limitations, see Join Limitations and Cautions.

Parameters

join\_table\_name (str) –

Name of the join table to be created, in \[schema\_name.]table\_name format, using standard name resolution rules and meeting table naming criteria.

table\_names (list of str) –

The list of table names composing the join, each in \[schema\_name.]table\_name format, using standard name resolution rules. Corresponds to a SQL statement FROM clause. The user can provide a single element (which will be automatically promoted to a list internally) or a list.

column\_names (list of str) –

List of member table columns or column expressions to be included in the join. Columns can be prefixed with ‘table\_id.column\_name’, where ‘table\_id’ is the table name or alias. Columns can be aliased via the syntax ‘column\_name as alias’. Wild cards ‘\*’ can be used to include all columns across member tables or ‘table\_id.\*’ for all of a single table’s columns. Columns and column expressions composing the join must be uniquely named or aliased–therefore, the ‘\*’ wild card cannot be used if column names aren’t unique across all tables. The user can provide a single element (which will be automatically promoted to a list internally) or a list.

expressions (list of str) –

An optional list of expressions to combine and filter the joined tables. Corresponds to a SQL statement WHERE clause. For details see: expressions. The default value is an empty list ( \[] ). The user can provide a single element (which will be automatically promoted to a list internally) or a list.

options (dict of str to str) –

Optional parameters. Allowed keys are:

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 join\_table\_name. This is always allowed even if the caller does not have permission to create tables. The generated name is returned in qualified\_join\_table\_name. Allowed values are:
- true
- false
The default value is ‘false’.
collection\_name – \[DEPRECATED–please specify the containing schema for the join as part of input parameter join\_table\_name and use GPUdb.create\_schema() to create the schema if non-existent] Name of a schema for the join. If the schema is non-existent, it will be automatically created. The default value is ‘’.
max\_query\_dimensions – No longer used.
strategy\_definition – The tier strategy for the table and its columns.
ttl – Sets the TTL of the join table specified in input parameter join\_table\_name.
view\_id – View this projection is part of. The default value is ‘’.
no\_count – Return a count of 0 for the join table for logging and for GPUdb.show\_table(); optimization needed for large overlapped equi-join stencils. The default value is ‘false’.
chunk\_size – Maximum number of records per joined-chunk for this table. Defaults to the gpudb.conf file chunk size.
enable\_virtual\_chunking – Collect chunks with accumulated size less than chunk\_size into a single chunk. The default value is ‘false’.
max\_virtual\_chunk\_size – Maximum number of records per virtual-chunk. When set, enables virtual chunking. Defaults to chunk\_size if virtual chunking otherwise enabled.
min\_virtual\_chunk\_size – Minimum number of records per virtual-chunk. When set, enables virtual chunking. Defaults to chunk\_size if virtual chunking otherwise enabled.
enable\_sparse\_virtual\_chunking – Materialize virtual chunks with only non-deleted values. The default value is ‘false’.
enable\_equi\_join\_lazy\_result\_store – Allow using the lazy result store to cache computation of one side of a multichunk equi-join. Reduces computation but also reduces parallelism to the number of chunks on the other side of the equi-join.
enable\_predicate\_equi\_join\_lazy\_result\_store – Allow using the lazy result store to cache computation of one side of a multichunk predicate-equi-join. Reduces computation but also reduces parallelism to the number of chunks on the other side of the equi-join.
enable\_pk\_equi\_join – Use equi-join to do primary key joins rather than using primary key index.

The default value is an empty dict ( {"{"}{"}"} ).

Returns

A dict with the following entries–

join\_table\_name (str) –

Value of input parameter join\_table\_name.

count (long) –

The number of records in the join table filtered by the given select expression.

info (dict of str to str) –

Additional information. Allowed keys are:

qualified\_join\_table\_name – The fully qualified name of the join table (i.e. including the schema).

The default value is an empty dict ( {"{"}{"}"} ).