DestReceiver pointers instead of just CommandDest values. The DestReceiver
is made at the point where the destination is selected, rather than
deep inside the executor. This cleans up the original kluge implementation
of tstoreReceiver.c, and makes it easy to support retrieving results
from utility statements inside portals. Thus, you can now do fun things
like Bind and Execute a FETCH or EXPLAIN command, and it'll all work
as expected (e.g., you can Describe the portal, or use Execute's count
parameter to suspend the output partway through). Implementation involves
stuffing the utility command's output into a Tuplestore, which would be
kind of annoying for huge output sets, but should be quite acceptable
for typical uses of utility commands.
Per recent discussion on pgsql-general, this is appropriate for spec
compliance, and has the nice side-effect of easing porting from old
pg_dump files that exhibit the 59.999=>60.000 roundoff problem.
Both plannable queries and utility commands are now always executed
within Portals, which have been revamped so that they can handle the
load (they used to be good only for single SELECT queries). Restructure
code to push command-completion-tag selection logic out of postgres.c,
so that it won't have to be duplicated between simple and extended queries.
initdb forced due to addition of a field to Query nodes.
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).
in all cases, leaked TopMemoryContext memory in others. Make the
interaction between SetClientEncoding and InitializeClientEncoding
cleaner and better documented. I suspect these changes should be
back-patched into 7.3, but will wait on Tatsuo's verification.
initial values and runtime changes in selected parameters. This gets
rid of the need for an initial 'select pg_client_encoding()' query in
libpq, bringing us back to one message transmitted in each direction
for a standard connection startup. To allow server version to be sent
using the same GUC mechanism that handles other parameters, invent the
concept of a never-settable GUC parameter: you can 'show server_version'
but it's not settable by any GUC input source. Create 'lc_collate' and
'lc_ctype' never-settable parameters so that people can find out these
settings without need for pg_controldata. (These side ideas were all
discussed some time ago in pgsql-hackers, but not yet implemented.)
rewritten and the protocol is changed, but most elog calls are still
elog calls. Also, we need to contemplate mechanisms for controlling
all this functionality --- eg, how much stuff should appear in the
postmaster log? And what API should libpq expose for it?
have length words. COPY OUT reimplemented per new protocol: it doesn't
need \. anymore, thank goodness. COPY BINARY to/from frontend works,
at least as far as the backend is concerned --- libpq's PQgetline API
is not up to snuff, and will have to be replaced with something that is
null-safe. libpq uses message length words for performance improvement
(no cycles wasted rescanning long messages), but not yet for error
recovery.
account for NULLs; in hindsight this is obvious since the code for
the MCV-lists case would reduce to this when there are zero entries
in both lists. Per example from Alec Mitchell.
expressions, ARRAY(sub-SELECT) expressions, some array functions.
Polymorphic functions using ANYARRAY/ANYELEMENT argument and return
types. Some regression tests in place, documentation is lacking.
Joe Conway, with some kibitzing from Tom Lane.
on UPDATE.
This get's rid of the long standing annoyance that updating a row
that has foreign keys locks all the referenced rows even if the
foreign key values do not change.
The trick is to actually do a check identical to NO ACTION after an
eventually done UPDATE in the SET DEFAULT case. Since a SET DEFAULT
operation should have moved referencing rows to a new "home", a following
NO ACTION check can only fail if the column defaults of the referencing
table resulted in the key we actually deleted. Thanks to Stephan.
Jan
find out about it is to read the documentation that tells you how
dangerous it is. Add default_transaction_read_only to documentation;
seems to have been overlooked in patch that added read-only transactions.
Clean up check_guc comparison script, which has been suffering bit rot.
page when it's read in, per pghackers discussion around 17-Feb. Add a
GUC variable zero_damaged_pages that causes the response to be a WARNING
followed by zeroing the page, rather than the normal ERROR; this is per
Hiroshi's suggestion that there needs to be a way to get at the data
in the rest of the table.
(materialization into a tuple store) discussed on pgsql-hackers earlier.
I've updated the documentation and the regression tests.
Notes on the implementation:
- I needed to change the tuple store API slightly -- it assumes that it
won't be used to hold data across transaction boundaries, so the temp
files that it uses for on-disk storage are automatically reclaimed at
end-of-transaction. I added a flag to tuplestore_begin_heap() to control
this behavior. Is changing the tuple store API in this fashion OK?
- in order to store executor results in a tuple store, I added a new
CommandDest. This works well for the most part, with one exception: the
current DestFunction API doesn't provide enough information to allow the
Executor to store results into an arbitrary tuple store (where the
particular tuple store to use is chosen by the call site of
ExecutorRun). To workaround this, I've temporarily hacked up a solution
that works, but is not ideal: since the receiveTuple DestFunction is
passed the portal name, we can use that to lookup the Portal data
structure for the cursor and then use that to get at the tuple store the
Portal is using. This unnecessarily ties the Portal code with the
tupleReceiver code, but it works...
The proper fix for this is probably to change the DestFunction API --
Tom suggested passing the full QueryDesc to the receiveTuple function.
In that case, callers of ExecutorRun could "subclass" QueryDesc to add
any additional fields that their particular CommandDest needed to get
access to. This approach would work, but I'd like to think about it for
a little bit longer before deciding which route to go. In the mean time,
the code works fine, so I don't think a fix is urgent.
- (semi-related) I added a NO SCROLL keyword to DECLARE CURSOR, and
adjusted the behavior of SCROLL in accordance with the discussion on
-hackers.
- (unrelated) Cleaned up some SGML markup in sql.sgml, copy.sgml
Neil Conway
them as arrays of the internal datatype. This requires treating the
stavalues columns as 'anyarray' rather than 'text[]', which is not 100%
kosher but seems to work fine for the purposes we need for pg_statistic.
Perhaps in the future 'anyarray' will be allowed more generally.
some of the algorithms for higher functions. I see about a factor of ten
speedup on the 'numeric' regression test, but it's unlikely that that test
is representative of real-world applications.
initdb forced due to change of on-disk representation for NUMERIC.
