This change exposes lower level functions for operating the
(logical) replication protocol, while keeping the high-level
start_replication function that does all the job for you in
case of a synchronous connection.
A number of other changes and fixes are put into this commit.
Introduce ReplicationConnection and ReplicationCursor classes, that
incapsulate initiation of special type of PostgreSQL connection and
handling of special replication commands only available in this special
connection mode.
The handling of stream of replication data from the server is modelled
largely after the existing support for "COPY table TO file" command and
pg_recvlogical tool supplied with PostgreSQL (though, it can also be
used for physical replication.)
It has long been used in wrong ways, with the function receiving a
connection or lobject instead of a cursor. It has always been unnoticed
(nobody has noticed the wrong object attached to the exception in the
wrong cases) but it started crashing the interpreter with Python 3.2 on
Windows.
Thanks to Jason Erickson for finding the problem and helping fixing it.
The value is used to control the number of records to fetch per network
roundtrip in named cursors iteration. Used to avoid the inefficient
arraysize default of 1 without giving this value the magic meaning of
2000.
.c files only need to import psycopg.h: it will in turn import
dependencies from Python and libpq and configure.h. psycopg.h should be
the first to be imported, so the basic imports are not required in
the .h's
As a guideline I'm trying to import from the most specific to the most
generic to detect missing imports in the .h's.
With the current implementation, at best they would silently block. They
actually hang everything.
Implementation posponed after some refactoring of the polling system,
because it will be probably possible to provide an implementation for
'poll()' during COPY which is good for both async and green modes.
Do it by keeping the reference to the last PGresult in the cursor and
calling pq_fetch() before ending the asynchronous execution. This
takes care of handling the possible error state of the PGresult and
also allows the removal of the needsfetch flag, since now after
execution ends the results are already fetched and parsed.
POLL_OK has been changed from 3 to 0 to let the user specify a short loop
just as "if not curs.poll()" instead of having to check for write and read
separately. For an example of this, see examples/notify.py.
It was trying to get all pending results from the connection and if
the client sent many and anyone except the first one would not be
immediately available the loop in curs_get_last_result would call
PQgetResult blockingly.
Avoid that by calling PQisBusy every time and telling the client to
wait for more data if it returns 1.
The methods changed are connection.commit(), rollback(), reset(),
set_isolation_level(), set_client_encoding(), lobject(), cursor(str)
as well as cursor.execute() and cursor.callproc() if another query is
in progress and cursor.executemany(), cursor.copy_{from,to,expert)().
The isread() API was not safe, because the query might have not been
sent fully to the server after calling execute(). To make the async
API complete, a similar mechanism to async connections must be used.
The cursor now has a poll() method that you would use identically to
the poll() method of the connection class.
that should not be exported from the module. This results in a 5%
reduction in code size and shortens the dynamic symbol table.
* psycopg/config.h: If GCC >= 4.0 is installed, define the HIDDEN
symbol to apply the "hidden" visibility attribute.
