[OT] Very strange postgresql behaviour

Hi all,

I have postgresql 7.4.2 running on debian and I have the oddest
postgresql behaviour I've ever seen.

I do the following queries:

espsm_asme=# select customer_app_config_id, customer_app_config_name
from customer_app_config where customer_app_config_id = 5929 or
customer_app_config_id = 11527 order by customer_app_config_id;

customer_app_config_id | customer_app_config_name
------------------------+--------------------------
5929 | INFO
(1 row)

I do the same query but changing the order of the or conditions:

espsm_asme=# select customer_app_config_id, customer_app_config_name
from customer_app_config where customer_app_config_id = 11527 or
customer_app_config_id = 5929 order by customer_app_config_id;

customer_app_config_id | customer_app_config_name
------------------------+--------------------------
11527 | MOVIDOSERENA TONI 5523
(1 row)

As you can see, the configuration 5929 and 11527 both exists, but
when I do the queries they don't appear.

Here below you have the execution plans. Those queries use an index,
I have done reindex table customer_app_config but nothing has changed.

espsm_asme=# explain analyze select customer_app_config_id,
customer_app_config_name from customer_app_config where
customer_app_config_id = 11527 or customer_app_config_id = 5929 order by
customer_app_config_id;

QUERY PLAN

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort (cost=10.28..10.29 rows=2 width=28) (actual time=0.252..0.253
rows=1 loops=1)
Sort Key: customer_app_config_id
-> Index Scan using pk_cag_customer_application_id,
pk_cag_customer_application_id on customer_app_config (cost=0.00..10.27
rows=2 width=28) (actual time=0.168..0.232 rows=1 loops=1)
Index Cond: ((customer_app_config_id = 11527::numeric) OR
(customer_app_config_id = 5929::numeric))
Total runtime: 0.305 ms
(5 rows)

espsm_asme=# explain analyze select customer_app_config_id,
customer_app_config_name from customer_app_config where
customer_app_config_id = 5929 or customer_app_config_id = 11527 order by
customer_app_config_id;

QUERY PLAN

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort (cost=10.28..10.29 rows=2 width=28) (actual time=0.063..0.064
rows=1 loops=1)
Sort Key: customer_app_config_id
-> Index Scan using pk_cag_customer_application_id,
pk_cag_customer_application_id on customer_app_config (cost=0.00..10.27
rows=2 width=28) (actual time=0.034..0.053 rows=1 loops=1)
Index Cond: ((customer_app_config_id = 5929::numeric) OR
(customer_app_config_id = 11527::numeric))
Total runtime: 0.114 ms
(5 rows)

The table definition is the following:

espsm_asme=# \d customer_app_config
Table "public.customer_app_config"
Column | Type | Modifiers
--------------------------+-----------------------+--------------------
customer_app_config_id | numeric(10,0) | not null
customer_app_config_name | character varying(32) | not null
keyword | character varying(43) |
application_id | numeric(10,0) | not null
customer_id | numeric(10,0) | not null
customer_app_contents_id | numeric(10,0) |
number_access_id | numeric(10,0) |
prefix | character varying(10) |
separator | numeric(1,0) | default 0
on_hold | numeric(1,0) | not null default 0
with_toss | numeric(1,0) | not null default 0
number_id | numeric(10,0) |
param_separator_id | numeric(4,0) | default 1
memory_timeout | integer |
with_memory | numeric(1,0) | default 0
session_enabled | numeric(1,0) | default 0
session_timeout | integer |
number | character varying(15) |
Indexes:
"pk_cag_customer_application_id" primary key, btree
(customer_app_config_id)
"un_cag_kwordnumber" unique, btree (keyword, number_id)
"idx_cappconfig_ccontentsid" btree (customer_app_contents_id)
"idx_cappconfig_cusidappid" btree (customer_id, application_id)
"idx_cappconfig_customerid" btree (customer_id)
"idx_cappconfig_onhold" btree (on_hold)
"idx_cappconfig_onholdkeyw" btree (on_hold, keyword)
Rules:

A lot of rules that I don't paste as matter of length.

Do you have any idea about how I can fix this?

--
Arnau