From: Rui DeSousa <rui.desousa@icloud.com>
Message-Id: <2A5A54F1-9954-40B5-8E87-5F8BA6C8D6C6@icloud.com>
Content-Type: multipart/alternative;
	boundary="Apple-Mail=_41CB3D64-BB83-4CF2-9EBF-24C485662260"
Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.10\))
Subject: Re: Pg_repack
Date: Mon, 12 Aug 2024 13:54:50 -0400
In-Reply-To: 
 <CANzqJaByQvYhDELeO3n63VPPWenFdOm03qt2g_Ev4qsXCb7dYw@mail.gmail.com>
Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
To: Ron Johnson <ronljohnsonjr@gmail.com>
References: 
 <CA+M9Y+B03KvHX2qUfvepv6_u72V7b-_zR_=SnMueBrG5xQ34Jw@mail.gmail.com>
 <202408121548.x5qz5npcikiw@alvherre.pgsql>
 <CANzqJaByQvYhDELeO3n63VPPWenFdOm03qt2g_Ev4qsXCb7dYw@mail.gmail.com>
Archived-At: 
 <https://www.postgresql.org/message-id/2A5A54F1-9954-40B5-8E87-5F8BA6C8D6C6%40icloud.com>
Precedence: bulk


--Apple-Mail=_41CB3D64-BB83-4CF2-9EBF-24C485662260
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=utf-8


> On Aug 12, 2024, at 12:06 PM, Ron Johnson <ronljohnsonjr@gmail.com> =
wrote:
>=20
> But pg_repack is just a better VACUUM FULL, and VACUUM FULL has to be =
better than autovacuum because it fully vacuums a table.
>=20

No.

Vacuum =E2=80=94 actually vacuums by removing dead tuples that are no =
longer needed, freezing tuples, etc. The removal of dead tuples frees =
space on the given page and it also truncates the fully empty pages that =
are located at the end of the file if it can.

Vacuum FULL =E2=80=94 is something completely different.  It rebuilds =
the entire table thus it coalesces all free space and by proxy does the =
same as vacuum (removing dead tuples that are no longer needed).
	=E2=80=94 It does this by creating a new table and then swapping =
in the new table when; regardless of the number of dead tuples.

Vacuum FULL should not be run on a regular basis.


--Apple-Mail=_41CB3D64-BB83-4CF2-9EBF-24C485662260
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
	charset=utf-8

<html><head><meta http-equiv=3D"Content-Type" content=3D"text/html; =
charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; line-break: after-white-space;" class=3D""><br =
class=3D""><div><br class=3D""><blockquote type=3D"cite" class=3D""><div =
class=3D"">On Aug 12, 2024, at 12:06 PM, Ron Johnson &lt;<a =
href=3D"mailto:ronljohnsonjr@gmail.com" =
class=3D"">ronljohnsonjr@gmail.com</a>&gt; wrote:</div><br =
class=3D"Apple-interchange-newline"><div class=3D""><meta =
charset=3D"UTF-8" class=3D""><div style=3D"caret-color: rgb(0, 0, 0); =
font-family: Helvetica; font-size: 12px; font-style: normal; =
font-variant-caps: normal; font-weight: 400; letter-spacing: normal; =
text-align: start; text-indent: 0px; text-transform: none; white-space: =
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; =
text-decoration: none;" class=3D"">But pg_repack is just a better VACUUM =
FULL, and VACUUM FULL has to be better than autovacuum because it<span =
class=3D"Apple-converted-space">&nbsp;</span><b =
class=3D"">fully</b>&nbsp;vacuums a table.</div><br =
class=3D"Apple-interchange-newline"></div></blockquote></div><br =
class=3D""><div class=3D"">No.</div><div class=3D""><br =
class=3D""></div><div class=3D"">Vacuum =E2=80=94 actually vacuums by =
removing dead tuples that are no longer needed, freezing tuples, etc. =
The removal of dead tuples frees space on the given page and it also =
truncates the fully empty pages that are located at the end of the file =
if it can.</div><div class=3D""><br class=3D""></div><div =
class=3D"">Vacuum FULL =E2=80=94 is something completely different. =
&nbsp;It rebuilds the entire table thus it coalesces all free space and =
by proxy does the same as vacuum (removing dead tuples that are no =
longer needed).</div><div class=3D""><span class=3D"Apple-tab-span" =
style=3D"white-space:pre">	</span>=E2=80=94 It does this by =
creating a new table and then swapping in the new table when; regardless =
of the number of dead tuples.</div><div class=3D""><br =
class=3D""></div><div class=3D"">Vacuum FULL should not be run on a =
regular basis.</div><div class=3D""><br class=3D""></div><div =
class=3D""><br class=3D""></div></body></html>=

--Apple-Mail=_41CB3D64-BB83-4CF2-9EBF-24C485662260--