Fix autocommit footguns in performance tests

[tristan957]

psycopg2 has the following warning related to autocommit:

By default, any query execution, including a simple SELECT will start
a transaction: for long-running programs, if no further action is
taken, the session will remain “idle in transaction”, an undesirable
condition for several reasons (locks are held by the session, tables
bloat…). For long lived scripts, either ensure to terminate a
transaction as soon as possible or use an autocommit connection.

In the 2.9 release notes, psycopg2 also made the following change:

with connection starts a transaction on autocommit transactions too

Some of these connections are indeed long-lived, so we were retaining tons of WAL on the endpoints because we had a transaction pinned in the past.

Link: https://www.psycopg.org/docs/news.html#what-s-new-in-psycopg-2-9
Link: psycopg/psycopg2#941

[bayandin]

Good find!

[github-actions]

5382 tests run: 5162 passed, 0 failed, 220 skipped (full report)

---

Flaky tests (2)

Postgres 17

• test_readonly_node_gc: debug-x86-64
• test_create_churn_during_restart: debug-x86-64

Code coverage* (full report)

• functions: 31.8% (7891 of 24834 functions)
• lines: 49.5% (62458 of 126257 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
2bedbbd at 2024-11-12T21:10:30.694Z :recycle:}