Hi
Is it now bug or expected behave. If it is expected, can it mentioned in manual too?
br
Kaido
Is it now bug or expected behave. If it is expected, can it mentioned in manual too?
br
Kaido
On Mon, 22 May 2023 at 20:43, Erik Wienhold <ewie@xxxxxxxxx> wrote:
> On 22/05/2023 15:44 CEST kaido vaikla <kaido.vaikla@xxxxxxxxx> wrote:
>
> I asked from pg jdbc community. Answer was :
> "One thing to note is that the driver uses extended query protocol so the
> queries are not identical.".
> I don't know, is it this now key to understand this issue?
> https://github.com/pgjdbc/pgjdbc/discussions/2902#discussioncomment-5917360
Look's like the extended query protocol is the reason for that. Testing with
psycopg 3.1 (which added pipeline mode to use the extended query protocol)
confirms this:
from psycopg import connect
from psycopg.rows import dict_row
conninfo = 'dbname=postgres'
query = 'SELECT 1'
with connect(conninfo) as con0:
backend_pid = con0.info.backend_pid
server_version = con0.info.server_version
print(f"{backend_pid=} {server_version=}")
con0.execute('SET compute_query_id = on')
print("=> simple query")
con0.execute(query)
with connect(conninfo, row_factory=dict_row) as con1:
with con1.execute('''
SELECT pid, query, query_id
FROM pg_stat_activity
WHERE pid = %s
''', (backend_pid,)) as cur:
for row in cur.fetchall():
print(row)
print("=> extended query")
with con0.pipeline():
con0.execute(query)
with connect(conninfo, row_factory=dict_row) as con1:
with con1.execute('''
SELECT pid, query, query_id
FROM pg_stat_activity
WHERE pid = %s
''', (backend_pid,)) as cur:
for row in cur.fetchall():
print(row)
Gives me:
backend_pid=800121 server_version=150002
=> simple query
{'pid': 800121, 'query': 'SELECT 1', 'query_id': 1147616880456321454}
=> extended query
{'pid': 800121, 'query': 'SELECT 1', 'query_id': None}
I wonder if this is a limitation of the extended query protocol. Computing the
query identifier for a prepared statement with placeholders is not very useful.
But I would think that a useful query identifier can be calculated once the
placeholders are bound to concrete values and the query is executed.
--
Erik
