Subject: Java : Postgres double precession issue with different data format text and binary

From: Rahul Uniyal <[email-masked]>
Date: Sat, 16 Mar 2024 20:40:29 +0530

Hello Team,

Hope everyone is doing well here.

I am writing this email to understand an issue I'm facing when fetching data in our Java application. We are using PostgreSQL JDBC Driver version 42.6.0.

Issue:

We are encountering an issue where the double precision data type in PostgreSQL is giving some intermittent results when fetching data. For example, in the database the value is 40, but sometimes this value is fetched as 40.0. Similarly, for a value of 0.0005, it is being fetched as 0.00050, resulting in extra trailing zeros.

While debugging, it seems like this issue is caused by the different data formats, such as Text and Binary. There is some logic in the PgResultSet class that converts values based on this data format.

Example:

Below is an example where we are getting different data formats for the same table:

Text Format: [Field(id,FLOAT8,8,T), Field(client_id,FLOAT8,8,T), Field(create_ts,TIMESTAMP,8,T), ...]

Binary Format: [Field(id,FLOAT8,8,B), Field(client_id,FLOAT8,8,B), ...] (notice some format changes)

We are not sure why different formats are coming for the same table.

Schema:

Below is the schema for the table used:

SQL

 CREATE TABLE IF NOT EXISTS SUBMISSION_QUEUE(
  ID               DOUBLE PRECISION,
  CLIENT_ID           DOUBLE PRECISION,
  OCODE VARCHAR(20) NOT NULL,
  PAYLOAD_TYPE        VARCHAR(20),
  REPOSITORY VARCHAR(16),
  SUB_REPOSITORY          VARCHAR(20),
  FORCE_GENERATION_FLAG   BOOLEAN,
IS_JMX_CALL BOOLEAN,
INSTANCE_ID           DOUBLE PRECISION,
CREATE_TS         TIMESTAMP(6) NOT NULL,
);

Request:

Team, would it be possible to give some insight on this issue? Any help would be greatly appreciated.

Thanks,