Horton

Re: [HACKERS] generated columns

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Sergei Kornilov <sk@zsrv.org>, Jaime Casanova <jaime.casanova@2ndquadrant.com>
Date: 2019-01-17T01:12:26Z
Lists: pgsql-hackers 
On Wed, Jan 16, 2019 at 02:14:41PM +0100, Peter Eisentraut wrote:
> On 15/01/2019 08:13, Michael Paquier wrote:
>> When testing a bulk INSERT into a table which has a stored generated
>> column, memory keeps growing in size linearly, which does not seem
>> normal to me.  If inserting more tuples than what I tested (I stopped
>> at 10M because of lack of time), it seems to me that this could result
>> in OOMs.  I would have expected the memory usage to be steady.
> 
> What are you executing exactly?  One INSERT command with many rows?

Yes, something like that grows the memory and CPU usage rather
linearly:
CREATE TABLE tab (a int, b int GENERATED ALWAYS AS (a * 2) STORED);
INSERT INTO tab VALUES (generate_series(1,100000000));
--
Michael

Commits

  1. Generated columns

  2. Add walreceiver API to get remote server version

  3. Add pg_partition_tree to display information about partitions

  4. pg_restore: Augment documentation for -N option

  5. Change delimiter used for display of NextXID