Sequence/constraint bug

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Milo Hyson
Your email address : milo(at)cyberlifeservices(dot)com

System Configuration
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Architecture (example: Intel Pentium) : Intel Pentium Pro

Operating System (example: Linux 2.0.26 ELF) : Linux 2.2.14 ELF

PostgreSQL version (example: PostgreSQL-6.5.3): PostgreSQL-6.5.3

Compiler used (example: gcc 2.8.0) : egcs 1.1.2

Please enter a FULL description of your problem:
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When inserting new rows into a table with a serial field, if a constraint
check fails, the sequence for the serial field is still incremented. As a
result you lose a number.

Please describe a way to repeat the problem. Please try to provide a
concise reproducible example, if at all possible:
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1) CREATE TABLE dummy (id serial, other int4 NOT NULL CHECK(other <> 0));

2) INSERT INTO dummy (other) VALUES(1);

3) INSERT INTO dummy (other) VALUES(2);

4) INSERT INTO dummy (other) VALUES(0);

5) INSERT INTO dummy (other) VALUES(3);

6) SELECT * FROM dummy;

You'll see the following:

id other
-- -----
1 1
2 2
4 3