Στις 15/9/23 18:23, ο/η Tom Lane έγραψε:
Achilleas Mantzios - cloud<a.mantz...@cloud.gatewaynet.com> writes:
*FreeBSD*
-> Index Only Scan using mail_vessel_addressbook_address_regex_idx
on mail_vessel_addressbook (cost=0.42..2912.06 rows=620 width=32)
(actual time=96.704..96.705 rows=1 loops=1)
Filter: ('f...@bar.com'::text ~* address_regex)
Rows Removed by Filter: 14738
Heap Fetches: 0
Buffers: shared hit=71
*Linux*
-> Index Only Scan using mail_vessel_addressbook_address_regex_idx
on mail_vessel_addressbook (cost=0.42..2913.04 rows=620 width=32)
(actual time=1768.724..1768.725 rows=1 loops=1)
Filter: ('f...@bar.com'::text ~* address_regex)
Rows Removed by Filter: 97781
Heap Fetches: 0
Buffers: shared hit=530
The file in FreeBSD came by pg_dump from the linux system, I am puzzled
why this huge difference in Buffers: shared hit.
The "rows removed" value is also quite a bit different, so it's not
just a matter of buffer touches --- there's evidently some real difference
in how much of the index is being scanned. I speculate that you are
using different collations on the two systems, and FreeBSD's collation
happens to place the first matching row earlier in the index.
Thank you, I see that both systems use en_US.UTF-8 as lc_collate and
lc_ctype, and that in both systems :
dynacom=# \dOS+
List of collations
Schema | Name | Collate | Ctype | Provider | Description
------------+---------+---------+-------+----------+------------------------------
pg_catalog | C | C | C | libc | standard C collation
pg_catalog | POSIX | POSIX | POSIX | libc | standard POSIX
collation
pg_catalog | default | | | default | database's default
collation
(3 rows)
dynacom=# \l
List of databases
Name | Owner | Encoding | Collate | Ctype | Access
privileges
-----------+----------+-----------+-------------+-------------+------------------------
dynacom | postgres | SQL_ASCII | en_US.UTF-8 | en_US.UTF-8 |
the below seems ok
FreeBSD :
postgres@[local]/dynacom=# select * from (values
('a'),('Z'),('_'),('.'),('0')) as qry order by column1::text;
column1
---------
_
.
0
a
Z
(5 rows)
Linux:
dynacom=# select * from (values ('a'),('Z'),('_'),('.'),('0')) as qry
order by column1::text;
column1
---------
_
.
0
a
Z
(5 rows)
dynacom=#
but :
Freebsd :
postgres@[local]/dynacom=# select distinct address_regex from
mail_vessel_addressbook order by address_regex::text ASC limit 5;
address_regex
----------------------------------------------------------
_cmo.ship.inf@<hide>.<hid>
_EMD_REEFER@hide>.<hid>
_OfficeHayPoint@hide>.<hid>
_Sabtank_PCQ1_All_SSVSSouth_area@hide>.<hid>
_Sabtank_PCQ1_Lead_OperatorsSouth_area@hide>.<hid>
(5 rows)
While in Linux :
dynacom=# select distinct address_regex from mail_vessel_addressbook
order by address_regex::text ASC limit 5;
address_regex
-----------------------------------
0033240902573@<hidden>.<hid>
0033442057364@<hidden>.<hid>
0072usl@<hidden>.<hid>
0081354426912@<hidden>.<hid>
00862163602861@<hidden>.<hid>
(5 rows)
somethings does not seem right.
regards, tom lane
--
Achilleas Mantzios
IT DEV - HEAD
IT DEPT
Dynacom Tankers Mgmt
