Re: [HACKERS] proposal: schema variables

From: Arthur Zakirov <a(dot)zakirov(at)postgrespro(dot)ru>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, Gilles Darold <gilles(dot)darold(at)dalibo(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: [HACKERS] proposal: schema variables
Date: 2018-09-21 19:46:18
Message-ID: 20180921194617.GA8051@artur-book.localdomain
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On Wed, Sep 19, 2018 at 04:36:40PM +0200, Pavel Stehule wrote:
> ON COMMIT DROP is used only for temp variables (transaction or not
> transaction). The purpose is same like for tables. Sometimes you can to
> have object with shorter life than is session.
> ON TRANSACTION END RESET has sense mainly for not transaction variables. I
> see two use cases.
> 1. protect some sensitive data - on transaction end guaranteed reset and
> cleaning on end transaction. So you can be sure, so variable is not
> initialized (has default value), or you are inside transaction.
> 2. automatic initialization - ON TRANSACTION END RESET ensure so variable
> is in init state for any transaction.
> Both cases has sense for transaction or not transaction variables.
> I am thinking so transaction life time for content has sense. Is cheaper to
> reset variable than drop it (what ON COMMIT DROP does)
> What do you think?

Thanks, I understood the cases.

But I think there is more sense to use these options only with transactional
variables. It is more consistent and simple for me.

As a summary, it is 1 voice vs 1 voice :) So it is better to leave the
syntax as is without changes for now.

Arthur Zakirov
Postgres Professional:
Russian Postgres Company

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