Re: WIP: Avoid creation of the free space map for small tables - Mailing list pgsql-hackers

From John Naylor
Subject Re: WIP: Avoid creation of the free space map for small tables
Date
Msg-id CACPNZCs1RfmzuSUYpCF+GvC3MQs=qM9qUaJ1HLcrM4y=Sq6WZQ@mail.gmail.com
Whole thread Raw
In response to Re: WIP: Avoid creation of the free space map for small tables  (Amit Kapila <amit.kapila16@gmail.com>)
Responses Re: WIP: Avoid creation of the free space map for small tables  (Amit Kapila <amit.kapila16@gmail.com>)
Re: WIP: Avoid creation of the free space map for small tables  (Amit Kapila <amit.kapila16@gmail.com>)
List pgsql-hackers
On Mon, Jan 28, 2019 at 4:53 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> There are a few buildfarm failures due to this commit, see my email on
> pgsql-committers.  If you have time, you can also once look into
> those.

I didn't see anything in common with the configs of the failed
members. None have a non-default BLCKSZ that I can see.

Looking at this typical example from woodlouse:

================== pgsql.build/src/test/regress/regression.diffs
==================
--- C:/buildfarm/buildenv/HEAD/pgsql.build/src/test/regress/expected/fsm.out
2019-01-28 04:43:09.031456700 +0100
+++ C:/buildfarm/buildenv/HEAD/pgsql.build/src/test/regress/results/fsm.out
2019-01-28 05:06:20.351100400 +0100
@@ -26,7 +26,7 @@
 pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
  heap_size | fsm_size
 -----------+----------
-     24576 |        0
+     32768 |        0
 (1 row)

***It seems like the relation extended when the new records should
have gone into block 0.

 -- Extend table with enough blocks to exceed the FSM threshold
@@ -56,7 +56,7 @@
 SELECT pg_relation_size('fsm_check_size', 'fsm') AS fsm_size;
  fsm_size
 ----------
-    16384
+    24576
 (1 row)

***And here it seems vacuum didn't truncate the FSM. I wonder if the
heap didn't get truncated either.

-- 
John Naylor                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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