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* BUG #19739: Parameterized first autocommit statement can have different `transaction_timestamp()` and `statement
@ 2026-10-02 22:37 PG Bug reporting form <noreply@postgresql.org>
2026-10-03 21:58 ` Re: BUG #19739: Parameterized first autocommit statement can have different `transaction_timestamp()` and `statement Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 2+ messages in thread
From: PG Bug reporting form @ 2026-10-02 22:37 UTC (permalink / raw)
To: pgsql-bugs@lists.postgresql.org; +Cc: theshallow27@gmail.com
The following bug has been logged on the website:
Bug reference: 19739
Logged by: Shallow
Email address: theshallow27@gmail.com
PostgreSQL version: 18.6
Operating system: Linux
Description:
The documentation says `transaction_timestamp()` and
`statement_timestamp()` return the same value during the first statement of
a
transaction. With a parameterized query executed as the first command on a
fresh autocommit connection, they differ. The same query without parameters
returns equality. Parameterized execution uses the extended query protocol,
so
this may expose a distinction between Parse/Bind/Execute message timing and
the documented “first statement” guarantee.
**Reproduction:** Using Psycopg with autocommit enabled on a fresh
connection:
```python
cur.execute(
"SELECT transaction_timestamp() = statement_timestamp() WHERE %s::int =
0",
(0,),
)
print(cur.fetchone()) # (False,)
```
Control query on a fresh autocommit connection:
```sql
SELECT transaction_timestamp() = statement_timestamp(); -- true
```
**Expected result:** The parameterized query, as the first SQL statement in
an
implicit transaction, should return `true`; alternatively, the documentation
should clarify how extended-protocol messages affect the guarantee.
^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: BUG #19739: Parameterized first autocommit statement can have different `transaction_timestamp()` and `statement
2026-10-02 22:37 BUG #19739: Parameterized first autocommit statement can have different `transaction_timestamp()` and `statement PG Bug reporting form <noreply@postgresql.org>
@ 2026-10-03 21:58 ` Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 0 replies; 2+ messages in thread
From: Tom Lane @ 2026-10-03 21:58 UTC (permalink / raw)
To: theshallow27@gmail.com; +Cc: pgsql-bugs@lists.postgresql.org
PG Bug reporting form <noreply@postgresql.org> writes:
> The documentation says `transaction_timestamp()` and
> `statement_timestamp()` return the same value during the first statement of
> a
> transaction. With a parameterized query executed as the first command on a
> fresh autocommit connection, they differ.
Strictly speaking, that depends on which steps of an extended-protocol
query count as separate statements. But I don't think we're going to
modify this documentation to dive into details as abstruse as that;
it would merely confuse the same people the comment is meant to help.
regards, tom lane
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2026-10-02 22:37 BUG #19739: Parameterized first autocommit statement can have different `transaction_timestamp()` and `statement PG Bug reporting form <noreply@postgresql.org>
2026-10-03 21:58 ` Tom Lane <tgl@sss.pgh.pa.us>
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