I can see that there are two issues in the design of Dead Space Map
in the recent discussions:
1. information accuracy of dead spaces
2. memory management
I'll write up the discussion about the 1st for now.
We need to increase page-tracking status for effective vacuum. 1 bit per
block is
On Jan 3, 2007, at 11:42 PM, ITAGAKI Takahiro wrote:
BTW, if we want to achieve the index-only scan, we might have to do
more
aggressive VACUUM FREEZE. There were many comments that we should
avoid
vacuuming pages that contain only unfrozen tuples or a few dead
tuples.
I think it it true for
"Jochem van Dieten" <[EMAIL PROTECTED]> wrote:
> On 12/28/06, ITAGAKI Takahiro wrote:
> >
> > | [TODO item] Allow data to be pulled directly from indexes
> > | Another idea is to maintain a bitmap of heap pages where all rows are
> > | visible to all backends, and allow index lookups to reference
On Sat, 2006-12-30 at 09:22 +1100, Russell Smith wrote:
> Simon Riggs wrote:
> > FSM code ignores any block with less space than 1 average tuple, which
> > is a pretty reasonable rule.
> >
> FSM serves a different purpose than DSM and therefore has an entirely
> different set of rules governing
Simon Riggs wrote:
On Fri, 2006-12-29 at 10:49 -0500, Tom Lane wrote:
"Simon Riggs" <[EMAIL PROTECTED]> writes:
I would suggest that we tracked whether a block has had 0, 1 or 1+
updates/deletes against it. When a block has 1+ it can then be
worthwhile to VACUUM it and to place it onto
On Fri, 2006-12-29 at 16:41 -0500, Tom Lane wrote:
> "Simon Riggs" <[EMAIL PROTECTED]> writes:
> > On Fri, 2006-12-29 at 10:49 -0500, Tom Lane wrote:
> >> Counterexample: table in which all tuples exceed half a page.
>
> > Current FSM code will ignore those too, if they are less than the
> > avera
"Simon Riggs" <[EMAIL PROTECTED]> writes:
> On Fri, 2006-12-29 at 10:49 -0500, Tom Lane wrote:
>> Counterexample: table in which all tuples exceed half a page.
> Current FSM code will ignore those too, if they are less than the
> average size of the tuple so far requested. Thats a pretty wierd
> c
On Fri, 2006-12-29 at 10:49 -0500, Tom Lane wrote:
> "Simon Riggs" <[EMAIL PROTECTED]> writes:
> > I would suggest that we tracked whether a block has had 0, 1 or 1+
> > updates/deletes against it. When a block has 1+ it can then be
> > worthwhile to VACUUM it and to place it onto the FSM. Two dead
"Simon Riggs" <[EMAIL PROTECTED]> writes:
> I would suggest that we tracked whether a block has had 0, 1 or 1+
> updates/deletes against it. When a block has 1+ it can then be
> worthwhile to VACUUM it and to place it onto the FSM. Two dead tuples is
> really the minimum space worth reclaiming on a
On Thu, 2006-12-28 at 21:35 +, Heikki Linnakangas wrote:
> I only used 1 bit, just like in Itagaki's approach.
1 bit may not be enough.
In many cases, a block will receive only 1 UPDATE or DELETE. If we then
mark this in the DSM, when we VACUUM that block it will not have
sufficient space f
Gavin Sherry wrote:
On Thu, 28 Dec 2006, Heikki Linnakangas wrote:
ITAGAKI Takahiro wrote:
I experimented with a different DSM design last winter. I got busy with
other things and never posted it AFAIR, but the idea was to store a
bitmap in the special area on every 32k heap page. That had some
Heikki Linnakangas <[EMAIL PROTECTED]> writes:
> I experimented with a different DSM design last winter. I got busy with
> other things and never posted it AFAIR, but the idea was to store a
> bitmap in the special area on every 32k heap page. That had some advantages:
> * doesn't require a new
Heikki Linnakangas <[EMAIL PROTECTED]> wrote:
> > We use 1 bit per block, so we cannot separate pages that need either
> > vacuum or freeze only. The reason is that we cannot determine where to
> > record before/after updated tuples. If the transaction is commited,
> > before-version should be re
On 12/28/06, ITAGAKI Takahiro wrote:
| [TODO item] Allow data to be pulled directly from indexes
| Another idea is to maintain a bitmap of heap pages where all rows are
| visible to all backends, and allow index lookups to reference that bitmap
| to avoid heap lookups
It is not done yet, but we
On Thu, 28 Dec 2006, Heikki Linnakangas wrote:
> ITAGAKI Takahiro wrote:
> > Hello,
> >
> > NTT staffs are working on TODO item:
> > | Create a bitmap of pages that need vacuuming
> >
> > We call the bitmap "Dead Space Map" (DSM), that allows VACUUM to scan
> > only pages that need vacuuming or fr
ITAGAKI Takahiro wrote:
Hello,
NTT staffs are working on TODO item:
| Create a bitmap of pages that need vacuuming
We call the bitmap "Dead Space Map" (DSM), that allows VACUUM to scan
only pages that need vacuuming or freezing. We'd like to discuss the
design on hackers and make agreements wit
Hello,
NTT staffs are working on TODO item:
| Create a bitmap of pages that need vacuuming
We call the bitmap "Dead Space Map" (DSM), that allows VACUUM to scan
only pages that need vacuuming or freezing. We'd like to discuss the
design on hackers and make agreements with community.
We implement
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