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Remove server and libpq support for old FE/BE protocol version 2.

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Protocol version 3 was introduced in PostgreSQL 7.4. There shouldn't be
many clients or servers left out there without version 3 support. But as
a courtesy, I kept just enough of the old protocol support that we can
still send the "unsupported protocol version" error in v2 format, so that
old clients can display the message properly. Likewise, libpq still
understands v2 ErrorResponse messages when establishing a connection.

The impetus to do this now is that I'm working on a patch to COPY
FROM, to always prefetch some data. We cannot do that safely with the
old protocol, because it requires parsing the input one byte at a time
to detect the end-of-copy marker.

Reviewed-by: Tom Lane, Alvaro Herrera, John Naylor
Discussion: https://www.postgresql.org/message-id/9ec25819-0a8a-d51a-17dc-4150bb3cca3b%40iki.fi
This commit is contained in:
Heikki Linnakangas
2021-03-04 10:45:55 +02:00
parent 0a687c8f10
commit 3174d69fb9
33 changed files with 301 additions and 3112 deletions
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22
src/backend/tcop/dest.c
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@@ -226,13 +226,8 @@ EndReplicationCommand(const char *commandTag)
/* ----------------
* NullCommand - tell dest that an empty query string was recognized
*
* In FE/BE protocol version 1.0, this hack is necessary to support
* libpq's crufty way of determining whether a multiple-command
* query string is done. In protocol 2.0 it's probably not really
* necessary to distinguish empty queries anymore, but we still do it
* for backwards compatibility with 1.0. In protocol 3.0 it has some
* use again, since it ensures that there will be a recognizable end
* to the response to an Execute message.
* This ensures that there will be a recognizable end to the response
* to an Execute message in the extended query protocol.
* ----------------
*/
void
@@ -244,14 +239,8 @@ NullCommand(CommandDest dest)
case DestRemoteExecute:
case DestRemoteSimple:
/*
* tell the fe that we saw an empty query string. In protocols
* before 3.0 this has a useless empty-string message body.
*/
if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
pq_putemptymessage('I');
else
pq_putmessage('I', "", 1);
/* Tell the FE that we saw an empty query string */
pq_putemptymessage('I');
break;
case DestNone:
@@ -286,7 +275,6 @@ ReadyForQuery(CommandDest dest)
case DestRemote:
case DestRemoteExecute:
case DestRemoteSimple:
if (PG_PROTOCOL_MAJOR(FrontendProtocol) >= 3)
{
StringInfoData buf;
@@ -294,8 +282,6 @@ ReadyForQuery(CommandDest dest)
pq_sendbyte(&buf, TransactionBlockStatusCode());
pq_endmessage(&buf);
}
else
pq_putemptymessage('Z');
/* Flush output at end of cycle in any case. */
pq_flush();
break;