Re: Vaccuum allows read access? - Mailing list pgsql-hackers

From JanWieck@t-online.de (Jan Wieck)
Subject Re: Vaccuum allows read access?
Date
Msg-id 200007221120.NAA08555@hot.jw.home
Whole thread Raw
In response to Re: Vaccuum allows read access?  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Vaccuum allows read access?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > In the current sources, analyze allows read-access.  I don't think
> > vacuum allows any other access because the rows are moving in the file.
>
> VACUUM *must* have exclusive lock.
>
> ANALYZE actually is only a reader (AccessShareLock) and does not lock
> out either reading or writing in current sources.
   Some related issue though.
   On  the phone we discussed about the btree splitpage problems   and  you  said  that  the  current  btree
implementation is   optimized  for  concurrent read and insert access, not so for   concurrent deletes.
 
   This might get to be a problem with the  overwriting  storage   manager.   If  it  wants to reuse space of outdated
tuplesin   the main heap, it needs to delete index tuples as well. Isn't   that in conflict with the btree design?
 


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#================================================== JanWieck@Yahoo.com #




pgsql-hackers by date:

Previous
From: JanWieck@t-online.de (Jan Wieck)
Date:
Subject: Re: TOAST & vacuum
Next
From: The Hermit Hacker
Date:
Subject: Re: Hello PL/Python