Subject: Re: using regular expression queries with regular expression indexes
To: pgsql-admin@lists.postgresql.org
References: 
 <CADyzmyykegZ3ZSVm9hYYKirJYGUYYAx_cK1VQYPCz1q+EpQ89g@mail.gmail.com>
From: Thomas Kellerer <shammat@gmx.net>
Message-ID: <fe5ba8cb-4d5a-8ed5-cda2-6cad27a9bf0c@gmx.net>
Date: Thu, 25 Jun 2020 20:17:47 +0200
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.1.21)
 Gecko/20090302 Thunderbird/2.0.0.21 Mnenhy/0.7.5.666
MIME-Version: 1.0
In-Reply-To: 
 <CADyzmyykegZ3ZSVm9hYYKirJYGUYYAx_cK1VQYPCz1q+EpQ89g@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: de-DE
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

Mark Steben schrieb am 25.06.2020 um 18:45:
> I have a query that uses regexp code to confirm if a text field is a dat=
e or not.

Why don't you define it as a date column? (e.g. so that leap years are cor=
retly dealt with)

But if you can't do that, what about a generated column that uses that reg=
ex to populate a boolean flag, e.g. is_valid_date?

Then the expensive regex evaluation would only be done when you change the=
 value, not everytime you query it.

Thomas