Re: [GENERAL] Incremental refresh - Materialized view - Mailing list pgsql-general

From Melvin Davidson
Subject Re: [GENERAL] Incremental refresh - Materialized view
Date
Msg-id CANu8FiyFvJ9wqRwTJMPXeAujtJpuGaxdELBUiZa3GC3GLC4thw@mail.gmail.com
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In response to Re: [GENERAL] Incremental refresh - Materialized view  (Rakesh Kumar <rakeshkumar464@outlook.com>)
List pgsql-general


On Tue, Nov 7, 2017 at 7:08 AM, Rakesh Kumar <rakeshkumar464@outlook.com> wrote:
You have already been informed. PG, as yet, does not allow incremental refresh of a MV.  It allows online refresh of a MV, but that it does by doing a full table scan of the base table and rebuilding the MV.



From: Krithika Venkatesh <krithikavenkatesh31@gmail.com>
To: John R Pierce <pierce@hogranch.com>
Cc: pgsql-general@postgresql.org
Sent: Tuesday, November 7, 2017 2:35 AM
Subject: Re: [GENERAL] Incremental refresh - Materialized view

Materialized view log is one of the feature in oracle. It creates a log in which the changes made to the table are recorded. This log is required for an asynchronous materialized view that is refreshed incrementally.

I read in the below link about incrementally refreshing the materialized view in postgresql:


Can someone let me how to do incremental refresh using Write Ahead Log

Thanks,
Krithika





On 07-Nov-2017 12:37 PM, "John R Pierce" <pierce@hogranch.com> wrote:
On 11/6/2017 10:38 PM, Krithika Venkatesh wrote:
I need to implement incremental refresh of materialized view.

Please let me know how to do the incremental refresh of materialized view in postgresql 9.5.9 version.

Is there anything similar to materialized view log in postgresql.


you refresh a materialized view with REFRESH MATERIALIZED VIEW name;    There's no 'incremental' methods, as views can be quite complex.

I do not know what you mean by 'materialized view log', is this a feature of some other database server ?



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john r pierce, recycling bits in santa cruz



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>Please let me know how to do the incremental refresh of materialized view in postgresql 9.5.9 version. 

As previously stated, there is currently no such thing as an incremental refresh of a materialized view.
I believe what you are looking for is:
REFRESH MATERIALIZED VIEW CONCURRENTLY mat_view_name;

Specifying CONCURRENTLY with prevent locking of the underlying table(s), but will extend the
time it takes to complete the refresh.

--
Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.

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