Date: Sun, 28 Jan 2018 17:58:24 -0500
From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, ian@thepathcentral.com,
	pgsql-docs@postgresql.org,
	Andrew Gierth <andrew@tao11.riddles.org.uk>
Subject: Re: Trigger behaviour not as stated
Message-ID: <20180128225824.GA5022@momjian.us>
References: <20171129193934.27108.30796@wrigleys.postgresql.org>
 <20180124181008.GK17109@momjian.us>
 <20180124220701.GP17109@momjian.us>
 <CAEepm=1cAO8y4dFv_xd=43iP7f4T3A2hYAzjgjQagHtt7H87Fw@mail.gmail.com>
 <28238.1517167118@sss.pgh.pa.us>
 <20180128203402.GB4380@momjian.us>
 <15634.1517173027@sss.pgh.pa.us>
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On Sun, Jan 28, 2018 at 03:57:07PM -0500, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > Uh, I don't think we want to highlight the statement vs row difference
> > here but the fact that statement triggers fire on the referenced object
> > and not on the effected rows.  I have attached an updated patch which I
> > think is an improvement
> 
>      statement-level triggers for its partitions or child tables.  In contrast,
> !    row-level triggers are fired on the rows in effected partitions or
> !    child tables, even if they are not referenced in the query.
> 
> I still think that that's not well written.  A large part of the confusion
> here is over what "referenced" means.  To my mind, child tables/partitions
> are referenced by an inherited query, just not explicitly.  So that's why
> I'd prefer wording like "directly named in the query" (or "explicitly
> named").  If you insist on using "referenced" you could write "explicitly
> referenced", but IMO that's longer and no clearer.
> 
> A lesser complaint is that this reads like the antecedent of "they" is the
> rows, not the tables containing them, making the meaning of "referenced"
> even less clear.
> 
> Maybe something like
> 
>     In contrast, row-level triggers are fired for individual row change
>     events, and the triggers that are fired for an event are those
>     attached to the specific table containing the changed row, even if
>     it is a partition or child table not directly named in the query.

Oh, I am sorry.  I was focused on the first part of the sentence and
didn't notice your change to the second part.  How is this attachment?

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +

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diff --git a/doc/src/sgml/ref/create_trigger.sgml b/doc/src/sgml/ref/create_trigger.sgml
new file mode 100644
index a8c0b57..6519757
*** a/doc/src/sgml/ref/create_trigger.sgml
--- b/doc/src/sgml/ref/create_trigger.sgml
*************** UPDATE OF <replaceable>column_name1</rep
*** 501,509 ****
  
    <para>
     Modifying a partitioned table or a table with inheritance children fires
!    statement-level triggers directly attached to that table, but not
     statement-level triggers for its partitions or child tables.  In contrast,
!    row-level triggers are fired for all affected partitions or child tables.
     If a statement-level trigger has been defined with transition relations
     named by a <literal>REFERENCING</literal> clause, then before and after
     images of rows are visible from all affected partitions or child tables.
--- 501,510 ----
  
    <para>
     Modifying a partitioned table or a table with inheritance children fires
!    statement-level triggers directly attached to the referenced table, but not
     statement-level triggers for its partitions or child tables.  In contrast,
!    row-level triggers are fired on the rows in effected partitions or
!    child tables, even if they are not explicitly named in the query.
     If a statement-level trigger has been defined with transition relations
     named by a <literal>REFERENCING</literal> clause, then before and after
     images of rows are visible from all affected partitions or child tables.

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