commit执行失败求助：demoimage表无变更问题排查

Hey there, let's break down why your COMMIT; isn't working as expected and why your demoimage table stays unchanged when you comment that line out. Here are the most likely causes and actionable steps to fix them:

1. Your Changes Are Stuck in an Uncommitted Transaction #

First, let's clarify how PostgreSQL handles transactions:

• When you run SQL directly in psql, it uses autocommit mode by default. Every statement gets committed immediately after running—so you see changes right away.
• If your code explicitly starts a transaction (with BEGIN; or a driver-specific method like conn.beginTransaction()), all your edits live in that transaction until you run COMMIT;. Commenting out COMMIT; means the transaction never gets finalized, so none of those changes are saved to the database. That's why your demoimage table looks untouched.

Quick Test: #

Add a query for the updated rows inside the same transaction (right after your mapping SQL, before the commented-out COMMIT;). If you can see the changes here but not in a separate psql session, this is definitely the root cause.

2. An Uncaught Error Is Rolling Back Your Transaction #

Even if you keep COMMIT; in your code, if an error pops up before that line runs, PostgreSQL will automatically roll back the transaction. Your code might seem like it "runs successfully" because the error is being silently caught or ignored.

How to Check: #

• Add detailed logging to your code: log the result of every SQL statement (success/failure, number of rows affected).
• Look for error-handling logic that triggers ROLLBACK; without alerting you. Many frameworks roll back transactions automatically if an exception is thrown.

3. Mismatched Database Connections or Schemas #

It's a long shot, but double-check that your code connects to the exact same database and schema as your psql session. Sometimes code uses a different schema (e.g., public.demoimage vs. my_schema.demoimage) or a staging database instead of production—so your changes are happening elsewhere, not in the table you're checking.

4. Driver/Framework Transaction Settings #

If you're using a database driver or ORM (like SQLAlchemy, Django ORM, etc.), check its autocommit settings. Some tools disable autocommit by default, requiring explicit COMMIT; calls. If you accidentally set autocommit to false and then skip COMMIT;, your changes won't persist.

Next Steps to Fix: #

• Restore the COMMIT; statement and add a log line right after it to confirm it's actually being executed.
• Wrap your code in a try-catch block to catch any exceptions that might be blocking the commit.
• Compare the exact SQL your code runs with what you execute in psql—even small differences (like missing schema qualifiers or parameter values) can cause issues.

Hope this helps you track down the problem!

内容的提问来源于stack exchange，提问作者wafflepie