From: PG Bug reporting form <noreply@postgresql.org>
To: pgsql-bugs@lists.postgresql.org
Cc: 798604270@qq.com
Subject: BUG #18976: -0.0 with float8 will be transformed to 0 in prepare statement but not in normal execution
Date: Thu, 03 Jul 2025 03:03:05 +0000
Message-ID: <18976-c1bc92542b90e5e6@postgresql.org> (raw)
The following bug has been logged on the website:
Bug reference: 18976
Logged by: Chi Zhang
Email address: 798604270@qq.com
PostgreSQL version: 18beta1
Operating system: Ubuntu 24.04 and docker
Description:
The value -0.0 with float8 is transformed to 0 in prepared statements but
remains -0 in normal execution. Although 0 and -0 are numerically equal,
this discrepancy can lead to subtle bugs in certain cases—for example, when
the value is cast to a VARCHAR, as illustrated below.
```
PREPARE prepare_query (float8) AS SELECT CAST($1 AS VARCHAR) =
CAST(-0.0::float8 AS VARCHAR);
EXECUTE prepare_query(-0.0); -- f
```
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To: pgsql-bugs@postgresql.org
Cc: noreply@postgresql.org, pgsql-bugs@lists.postgresql.org, 798604270@qq.com
Subject: Re: BUG #18976: -0.0 with float8 will be transformed to 0 in prepare statement but not in normal execution
In-Reply-To: <18976-c1bc92542b90e5e6@postgresql.org>
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