Re: App very unresponsive while performing simple update

From: Greg Stark <gsstark(at)mit(dot)edu>
To: "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>
Cc: Greg Stark <gsstark(at)mit(dot)edu>, Brendan Duddridge <brendan(at)clickspace(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: App very unresponsive while performing simple update
Date: 2006-06-01 04:30:46
Message-ID: 87hd35ijk9.fsf@stark.xeocode.com
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"Jim C. Nasby" <jnasby(at)pervasive(dot)com> writes:

> I tried duplicating this but couldn't. What's the data in the tables?

Sorry, I had intended to include the definition and data:

stark=> create table t1 (a integer primary key, b integer);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "t1_pkey" for table "t1"
CREATE TABLE

stark=> create table t2 (a integer, b integer primary key);
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "t2_pkey" for table "t2"
CREATE TABLE

stark=> insert into t1 values (1,2);
INSERT 0 1

stark=> insert into t2 values (1,2);
INSERT 0 1

stark=> alter table t1 add constraint fk foreign key (b) references t2 deferrable initially deferred ;
ALTER TABLE

stark=> alter table t2 add constraint fk foreign key (a) references t1 deferrable initially deferred ;
ALTER TABLE

stark=> \d t1
Table "public.t1"
Column | Type | Modifiers
--------+---------+-----------
a | integer | not null
b | integer |
Indexes:
"t1_pkey" PRIMARY KEY, btree (a)
Foreign-key constraints:
"fk" FOREIGN KEY (b) REFERENCES t2(b) DEFERRABLE INITIALLY DEFERRED

stark=> \d t2
Table "public.t2"
Column | Type | Modifiers
--------+---------+-----------
a | integer |
b | integer | not null
Indexes:
"t2_pkey" PRIMARY KEY, btree (b)
Foreign-key constraints:
"fk" FOREIGN KEY (a) REFERENCES t1(a) DEFERRABLE INITIALLY DEFERRED

stark=> select * from t1;
a | b
---+---
1 | 2
(1 row)

stark=> select * from t2;
a | b
---+---
1 | 2
(1 row)

--
greg

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