Date: Wed, 3 Apr 2019 22:41:07 -0700
From: Shawn Debnath <sdn@amazon.com>
To: Thomas Munro <thomas.munro@gmail.com>
CC: Andres Freund <andres@anarazel.de>, Robert Haas <robertmhaas@gmail.com>,
        Tom Lane <tgl@sss.pgh.pa.us>, Dmitry Dolgov <9erthalion6@gmail.com>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Refactoring the checkpointer's fsync request queue
Message-ID: <20190404054107.GA22298@f01898859afd.ant.amazon.com>
References: 
 <CA+Tgmob19umNQogKHknsG+smLUZeHihNAk-h+KxPd82SDi10WQ@mail.gmail.com>
 <20190326164758.GA78630@f01898859afd.ant.amazon.com>
 <CA+hUKG+=vJEEFYG_OyGScdPVy2Lw+MEk9aNHPCSiaa58QoxjJA@mail.gmail.com>
 <CA+hUKG+1k+sWCPVgBe0M9BR9e4hBva5ODWCydY7R8v02C6KOAQ@mail.gmail.com>
 <20190403214423.GA45392@f01898859afd.ant.amazon.com>
 <CA+hUKG+=-p4oiNC=U6yjtDigAvTXxGbe2__c=cVSxdxZYBxTPQ@mail.gmail.com>
 <CA+hUKG+2Uri6dzddX3_K2mpWT3dRz-3Dzoja3-a3=3EYrvGEYg@mail.gmail.com>
 <20190404041945.GA16205@f01898859afd.ant.amazon.com>
 <20190404043559.syfy3v57ygma2bs4@alap3.anarazel.de>
 <CA+hUKGKwjTgaBF020sJ+MuEcWcOubmuoaS36xpJfWxuPY6AMpA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: 
 <CA+hUKGKwjTgaBF020sJ+MuEcWcOubmuoaS36xpJfWxuPY6AMpA@mail.gmail.com>
User-Agent: Mutt/1.11.4 (2019-03-13)
Precedence: Bulk
Precedence: bulk

On Thu, Apr 04, 2019 at 05:39:14PM +1300, Thomas Munro wrote:
> On Thu, Apr 4, 2019 at 5:36 PM Andres Freund <andres@anarazel.de> wrote:
> > On 2019-04-03 21:19:45 -0700, Shawn Debnath wrote:
> > > +typedef struct FileTag
> > > +{
> > > +     int16           handler;                /* SyncRequstHandler value, saving space */
> > > +     int16           forknum;                /* ForkNumber, saving space */
> > > +     RelFileNode rnode;
> > > +     BlockNumber segno;
> > > +} FileTag;
> >
> > Seems odd to me to use BlockNumber for segno.
> 
> That is a tradition in md.c code.  I had a new typedef SegmentNumber
> in all sync.{c,h} stuff in an earlier version, but had trouble
> figuring out where to define it...

Thomas, this is why I had defined segment.h with the contents below :-)

+++ b/src/include/storage/segment.h
[...]
+/*
+ * Segment Number:
+ *
+ * Each relation and its forks are divided into segments. This
+ * definition formalizes the definition of the segment number.
+ */
+typedef uint32 SegmentNumber;
+
+#define InvalidSegmentNumber ((SegmentNumber) 0xFFFFFFFF)

My last iteration, v12, patch had it. See [1] for comments on removal of 
segment.h.


[1] 
https://www.postgresql.org/message-id/20190403214423.GA45392%40f01898859afd.ant.amazon.com

-- 
Shawn Debnath
Amazon Web Services (AWS)