'\" t
.\"     Title: REFRESH MATERIALIZED VIEW
.\"    Author: The PostgreSQL Global Development Group
.\" Generator: DocBook XSL Stylesheets v1.75.2 <http://docbook.sf.net/>
.\"      Date: 2016
.\"    Manual: PostgreSQL 9.5.2 Documentation
.\"    Source: PostgreSQL 9.5.2
.\"  Language: English
.\"
.TH "REFRESH MATERIALIZED VIEW" "5sql" "2016" "PostgreSQL 9.5.2" "PostgreSQL 9.5.2 Documentation"
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.SH "NAME"
REFRESH_MATERIALIZED_VIEW \- replace the contents of a materialized view
.SH "SYNOPSIS"
.sp
.nf
REFRESH MATERIALIZED VIEW [ CONCURRENTLY ] \fIname\fR
    [ WITH [ NO ] DATA ]
.fi
.SH "DESCRIPTION"
.PP

\fBREFRESH MATERIALIZED VIEW\fR
completely replaces the contents of a materialized view\&. The old contents are discarded\&. If
WITH DATA
is specified (or defaults) the backing query is executed to provide the new data, and the materialized view is left in a scannable state\&. If
WITH NO DATA
is specified no new data is generated and the materialized view is left in an unscannable state\&.
.PP

CONCURRENTLY
and
WITH NO DATA
may not be specified together\&.
.SH "PARAMETERS"
.PP
CONCURRENTLY
.RS 4
Refresh the materialized view without locking out concurrent selects on the materialized view\&. Without this option a refresh which affects a lot of rows will tend to use fewer resources and complete more quickly, but could block other connections which are trying to read from the materialized view\&. This option may be faster in cases where a small number of rows are affected\&.
.sp
This option is only allowed if there is at least one
UNIQUE
index on the materialized view which uses only column names and includes all rows; that is, it must not index on any expressions nor include a
WHERE
clause\&.
.sp
This option may not be used when the materialized view is not already populated\&.
.sp
Even with this option only one
REFRESH
at a time may run against any one materialized view\&.
.RE
.PP
\fIname\fR
.RS 4
The name (optionally schema\-qualified) of the materialized view to refresh\&.
.RE
.SH "NOTES"
.PP
While the default index for future
\fBCLUSTER\fR(5)
operations is retained,
\fBREFRESH MATERIALIZED VIEW\fR
does not order the generated rows based on this property\&. If you want the data to be ordered upon generation, you must use an
ORDER BY
clause in the backing query\&.
.SH "EXAMPLES"
.PP
This command will replace the contents of the materialized view called
order_summary
using the query from the materialized view\(aqs definition, and leave it in a scannable state:
.sp
.if n \{\
.RS 4
.\}
.nf
REFRESH MATERIALIZED VIEW order_summary;
.fi
.if n \{\
.RE
.\}
.PP
This command will free storage associated with the materialized view
annual_statistics_basis
and leave it in an unscannable state:
.sp
.if n \{\
.RS 4
.\}
.nf
REFRESH MATERIALIZED VIEW annual_statistics_basis WITH NO DATA;
.fi
.if n \{\
.RE
.\}
.SH "COMPATIBILITY"
.PP

\fBREFRESH MATERIALIZED VIEW\fR
is a
PostgreSQL
extension\&.
.SH "SEE ALSO"
CREATE MATERIALIZED VIEW (\fBCREATE_MATERIALIZED_VIEW\fR(5)), ALTER MATERIALIZED VIEW (\fBALTER_MATERIALIZED_VIEW\fR(5)), DROP MATERIALIZED VIEW (\fBDROP_MATERIALIZED_VIEW\fR(5))