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help / color / mirror / Atom feedFrom: Ron Johnson <[email protected]>
To: Tom Lane <[email protected]>
Cc: Pgsql-admin <[email protected]>
Subject: Re: Request For Feature: pg_dump
Date: Fri, 22 May 2026 13:20:58 -0400
Message-ID: <CANzqJaCJGS9S=ibJ_rOmP=acA7n0XCA5R4FbMH+AH3WURhey8Q@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CANzqJaCNaqhQ9duPP+eKU2OR1wjGYW-FBQ2FZXqnBRb6XAnKQA@mail.gmail.com>
<[email protected]>
On Fri, May 22, 2026 at 12:53 PM Tom Lane <[email protected]> wrote:
> Ron Johnson <[email protected]> writes:
> > In --format=directory mode, remove .dat files with zero data records, and
> > mark that table's toc.dat entry that it's an empty table.
>
> > Justification: *lots* of empty tables means *lots* of teeny-tiny files in
> > the DB's dump directory. That unnecessarily bloats the fs, and makes "du
> > -c" really really slow.
>
> Evidence please? Most file systems that I've looked at optimize
> zero-size files pretty well.
>
They aren't zero bytes.
It's those pesky 5 (or 14 or whatever size that gzip and lz4 produces) byte
files. 66 thousand tiny files plus 8 thousand files with data in them
makes for a 2.4MB directory. That's big and slow.
$ find . -size 14c | wc
66180 66180 1191240
$ zstd -dk 2115841.dat.zst
2115841.dat.zst : 5 bytes
$ cat 2115841.dat
\.
$ dir | grep " 14 " | head -n20
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115841.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115842.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115843.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115844.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115845.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115851.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115899.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115901.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115902.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115903.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115905.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115907.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115909.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115913.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115915.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115917.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115919.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115923.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115926.dat.zst
-rw-r--r-- 1 postgres postgres 14 2026-05-22 00:50:30
2115931.dat.zst
--
Death to <Redacted>, and butter sauce.
Don't boil me, I'm still alive.
<Redacted> lobster!
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To: [email protected]
Cc: [email protected], [email protected], [email protected]
Subject: Re: Request For Feature: pg_dump
In-Reply-To: <CANzqJaCJGS9S=ibJ_rOmP=acA7n0XCA5R4FbMH+AH3WURhey8Q@mail.gmail.com>
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