module and teach PREPARE and protocol-level prepared statements to use it.
In service of this, rearrange utility-statement processing so that parse
analysis does not assume table schemas can't change before execution for
utility statements (necessary because we don't attempt to re-acquire locks
for utility statements when reusing a stored plan).  This requires some
refactoring of the ProcessUtility API, but it ends up cleaner anyway,
for instance we can get rid of the QueryContext global.

Still to do: fix up SPI and related code to use the plan cache; I'm tempted to
try to make SQL functions use it too.  Also, there are at least some aspects
of system state that we want to ensure remain the same during a replan as in
the original processing; search_path certainly ought to behave that way for
instance, and perhaps there are others.

proposal.  Parameter logging works even for binary-format parameters, and
logging overhead is avoided when disabled.

log_statement = all output for the src/test/examples/testlibpq3.c example
now looks like

LOG:  statement: execute <unnamed>: SELECT * FROM test1 WHERE t = $1
DETAIL:  parameters: $1 = 'joe''s place'
LOG:  statement: execute <unnamed>: SELECT * FROM test1 WHERE i = $1::int4
DETAIL:  parameters: $1 = '2'

and log_min_duration_statement = 0 results in

LOG:  duration: 2.431 ms  parse <unnamed>: SELECT * FROM test1 WHERE t = $1
LOG:  duration: 2.335 ms  bind <unnamed> to <unnamed>: SELECT * FROM test1 WHERE t = $1
DETAIL:  parameters: $1 = 'joe''s place'
LOG:  duration: 0.394 ms  execute <unnamed>: SELECT * FROM test1 WHERE t = $1
DETAIL:  parameters: $1 = 'joe''s place'
LOG:  duration: 1.251 ms  parse <unnamed>: SELECT * FROM test1 WHERE i = $1::int4
LOG:  duration: 0.566 ms  bind <unnamed> to <unnamed>: SELECT * FROM test1 WHERE i = $1::int4
DETAIL:  parameters: $1 = '2'
LOG:  duration: 0.173 ms  execute <unnamed>: SELECT * FROM test1 WHERE i = $1::int4
DETAIL:  parameters: $1 = '2'

(This example demonstrates the folly of ignoring parse/bind steps for duration
logging purposes, BTW.)

Along the way, create a less ad-hoc mechanism for determining which commands
are logged by log_statement = mod and log_statement = ddl.  The former coding
was actually missing quite a few things that look like ddl to me, and it
did not handle EXECUTE or extended query protocol correctly at all.

This commit does not do anything about the question of whether log_duration
should be removed or made less redundant with log_min_duration_statement.

and documentation to reference 8.0 instead of 7.5.

performance front, but with feature freeze upon us I think it's time to
drive a stake in the ground and say that this will be in 7.5.

Alvaro Herrera, with some help from Tom Lane.

proposal.  Eliminate several dozen now-unnecessary hacks to avoid palloc(0).
(It's likely there are more that I didn't find.)

$Header: -> $PostgreSQL Changes ...

of extended query features in new FE/BE protocol.  TransactionCommandContext
is gone (PortalContext replaces it for some purposes), and QueryContext
has taken on a new meaning (MessageContext plays its old role).

for details).  It doesn't really do that much yet, since there are no
short-term memory contexts in the executor, but the infrastructure is
in place and long-term contexts are handled reasonably.  A few long-
standing bugs have been fixed, such as 'VACUUM; anything' in a single
query string crashing.  Also, out-of-memory is now considered a
recoverable ERROR, not FATAL.
Eliminate a large amount of crufty, now-dead code in and around
memory management.
Fix problem with holding off SIGTRAP, SIGSEGV, etc in postmaster and
backend startup.