UDTF projection

Stores newly-loaded data after it is transformed and/or aggregated by user-defined transformation functions (UDTFs).

Stores newly-loaded data after it is transformed and/or aggregated by user-defined transformation functions (UDTFs). For details and examples, see Pre-aggregating UDTF results.

Syntax

CREATE PROJECTION [ IF NOT EXISTS ] [[database.]schema.]projection
[ (
   { projection-column | grouped-clause
   [ ENCODING encoding-type ]
   [ ACCESSRANK integer ]  }[,...]
) ]
AS { [batch-query](#UDTFBatchQuery) FROM { prepass-query sq-ref | table [[AS] alias] }
     | prepass-query }

batch-query
SELECT { table-column | expr-with-table-columns }[,...], batch-udtf(batch-args)
   OVER (PARTITION BATCH BY partition-column-expr[,...])
   [ AS (batch-output-columns) ]

prepass-query
SELECT { table-column | expr-with-table-columns }[,...], prepass-udtf(prepass-args)
   OVER (PARTITION PREPASS BY partition-column-expr[,...])
   [ AS (prepass-output-columns) ] FROM table

Parameters

IF NOT EXISTS

If an object with the same name exists, return without creating the object. If you do not use this directive and the object already exists, Vertica returns with an error message.

The IF NOT EXISTS clause is useful for SQL scripts where you might not know if the object already exists. The ON ERROR STOP directive can be helpful in scripts.

[database.]schema

Specifies the schema for this projection and its anchor table, where schema must be the same for both. If you specify a database, it must be the current database.

projection

Identifies the projection to create, where projection conforms to conventions described in Identifiers. It must also be unique among all names of sequences, tables, projections, views, and models within the same schema.

projection-column

The name of a projection column. The list of projection columns must match the SELECT list columns and expressions in number, type, and sequence.

If projection column names are omitted, Vertica uses the anchor table column names specified in the SELECT list.

grouped-clause
See GROUPED clause.
ENCODING encoding-type

The column encoding type, by default set to AUTO.

ACCESSRANK integer

Overrides the default access rank for a column. Use this parameter to increase or decrease the speed at which Vertica accesses a column. For more information, see Overriding Default Column Ranking.

AS SELECT

Specifies the table data to query:

{table-column | expr-with-table-columns } [ [AS] alias] }[,...]

You can optionally assign an alias to each column expression and reference that alias elsewhere in the SELECT statement.

batch-udtf(batch-args)
The batch UDTF to invoke each time the following events occur:
  • Tuple mover mergeout

  • Queries on the projection

  • If invoked singly, on data load operations

prepass-udtf(prepass-args)
The pre-pass UDTF to invoke on each load operation such as COPY or INSERT.

If specified in a subquery, the pre-pass UDTF returns transformed data to the batch query for further processing. Otherwise, the pre-pass query results are added to projection data storage.

OVER (PARTITION { BATCH | PREPASS } BY partition-column-expr[,...]
Specifies the UDTF type and how to partition the data it returns:

In both cases, the OVER clause specifies partitioning with one or more column expressions from the SELECT list. The first partition-column-expr is the first column expression in the SELECT list, the second partition-column-expr is the second column expression in the SELECT list, and so on.

AS (batch-output-columns) AS (prepass-output-columns)
Optionally names columns that are returned by the UDTF.

If a pre-pass subquery omits this clause, the outer batch query UDTF arguments (batch-args) must reference the column names as they are defined in the pre-pass UDTF.

table[[AS]alias]
Specifies the projection's anchor table, optionally qualified by an alias.
sq-results
Subquery result set that is returned to the outer batch UDTF.

Privileges

Non-superusers:

  • Anchor table owner

  • CREATE privilege on the schema

  • EXECUTE privileges on all UDTFs that are referenced by the projection

Examples

See Pre-aggregating UDTF results.