#17266: psycopg2 backend should use get_parameter_status to check if SET TIME
ZONE
is needed
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Reporter: akaariai | Owner: nobody
Type: Uncategorized | Status: new
Component: Database layer (models, ORM) | Version:
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Easy pickings: 0 | UI/UX: 0
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In ticket #17062 Aymeric Augustin suggested the idea for using
get_parameter_status to check if the database default time zone is already
correct. If it is, we can skip the SET TIME ZONE and associated isolation
level handling for every new connection. Ticket #17062 has more details,
but I will copy-paste the most relevant parts here. If this is not done,
for every new connection we need to do these queries:
{{{
26639: LOG: connection authorized: user=akaj database=testdb1
26639: LOG: statement: SHOW default_transaction_isolation
26639: LOG: statement: SET default_transaction_isolation TO DEFAULT
26639: LOG: statement: SET TIME ZONE 'America/Chicago'
26639: LOG: statement: SET default_transaction_isolation TO 'read
uncommitted'
26639: LOG: statement: BEGIN
26639: LOG: statement: first real query...
}}}
If we use get_parameter_status, we can get it down to this:
{{{
27163: LOG: connection authorized: user=akaj database=testdb1
27163: LOG: statement: SHOW default_transaction_isolation
27163: LOG: statement: BEGIN
27163: LOG: statement: first real query
}}}
The get_parameter_status was added in psycopg2 version 2.0.12
[http://initd.org/psycopg/docs/connection.html#connection.get_parameter_status].
I can't find a mention if we need to support versions prior to this. If we
need to support versions prior to 2.0.12, we can just add a check for the
psycopg2 version in use and not use get_parameter_status if the version
doesn't support it.
I will wait until ticket #17062 gets fixed before working on this.
--
Ticket URL: <https://code.djangoproject.com/ticket/17266>
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