Skip site navigation (1) Skip section navigation (2)

WAL Question

From: Harry Yau <harry(at)regaltronic(dot)com>
To: PGH <pgsql-hackers(at)postgresql(dot)org>, PGG <pgsql-general(at)postgresql(dot)org>
Subject: WAL Question
Date: 2001-07-04 01:43:22
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-generalpgsql-hackers
Hi Dear:

    I am using Postgres 7.0 on RedHat Linux 6.3 right now. I wanna know
is there transaction log in PostGres 7.0? I know there is WAL in 7.1. I
am also thinking to upgrade to 7.1.2 too. I have read a lot of message
in the PostgreSQL mailing list archive which is about the WAL.
    The following is some conclusion of what I learn from there:

   * checkpoint is made according to the config setting of
     checkpoint_segment and checkpoint_timeout.
   * after a checkpoint has been made, the log flush to the disk drive.
   * after a checkpoint has been made, any log segments writtend before
     the redo record ( the record in the log whick the REDO operation
     begin) are REMOVE to free disk space in WAL directory.
   * seems to me, everything is automatic.

Please, point me out if there anything wrong.
    However, there is still something really confusing me. In PostgreSQL

7.1 Documentation Chapter 9 WAL , 9.2.1 Database Recovery with WAL, it
tell me about the flow of the process to recover from WAL: 1. reads
pg_control, 2. reads checkpoint record, 3. reads redo record, and then
finally 4. REDO operation. I wonder do we need to run all the above
procedures manually, after a crash?? or They will REALLY be
automatically run when re-start the postgres after a crash?? It sounds
like a miracle for me!!

Thank You very Much
Harry Yau

pgsql-hackers by date

Next:From: Christopher Kings-LynneDate: 2001-07-04 01:52:08
Subject: RE: [OT] Any major users of postgresql?
Previous:From: Bruce MomjianDate: 2001-07-04 01:04:24
Subject: Re: stuck spin lock with many concurrent users

pgsql-general by date

Next:From: Tatsuo IshiiDate: 2001-07-04 02:22:32
Subject: Re: Error: "Conversion between UNICODE..."
Previous:From: Martijn van OosterhoutDate: 2001-07-04 00:33:44
Subject: Re: [PATCH] Partial indicies almost working (I think)

Privacy Policy | About PostgreSQL
Copyright © 1996-2018 The PostgreSQL Global Development Group