performance problem pointed out by phil@vodafone: to wit, we were
spending O(N^2) time to check dropped-ness in an N-deep join tree,
even in the case where the tree was freshly constructed and couldn't
possibly mention any dropped columns. Instead of recursing in
get_rte_attribute_is_dropped(), change the data structure definition:
the joinaliasvars list of a JOIN RTE must have a NULL Const instead
of a Var at any position that references a now-dropped column. This
costs nothing during normal parse-rewrite-plan path, and instead we
have a linear-time update to make when loading a stored rule that
might contain now-dropped columns. While at it, move the responsibility
for acquring locks on relations referenced by rules into this separate
function (which I therefore chose to call AcquireRewriteLocks).
This saves effort --- namely, duplicated lock grabs in parser and rewriter
--- in the normal path at a cost of one extra non-locked heap_open()
in the stored-rule path; seems a good tradeoff. A fringe benefit is
that it is now *much* clearer that we acquire lock on relations referenced
in rules before we make any rewriter decisions based on their properties.
(I don't know of any bug of that ilk, but it wasn't exactly clear before.)
to just around the bare recv() call that gets a command from the client.
The former placement in PostgresMain was unsafe because the intermediate
processing layers (especially SSL) use facilities such as malloc that are
not necessarily re-entrant. Per report from counterstorm.com.
of tuples when passing data up through multiple plan nodes. A slot can now
hold either a normal "physical" HeapTuple, or a "virtual" tuple consisting
of Datum/isnull arrays. Upper plan levels can usually just copy the Datum
arrays, avoiding heap_formtuple() and possible subsequent nocachegetattr()
calls to extract the data again. This work extends Atsushi Ogawa's earlier
patch, which provided the key idea of adding Datum arrays to TupleTableSlots.
(I believe however that something like this was foreseen way back in Berkeley
days --- see the old comment on ExecProject.) A test case involving many
levels of join of fairly wide tables (about 80 columns altogether) showed
about 3x overall speedup, though simple queries will probably not be
helped very much.
I have also duplicated some code in heaptuple.c in order to provide versions
of heap_formtuple and friends that use "bool" arrays to indicate null
attributes, instead of the old convention of "char" arrays containing either
'n' or ' '. This provides a better match to the convention used by
ExecEvalExpr. While I have not made a concerted effort to get rid of uses
of the old routines, I think they should be deprecated and eventually removed.
Also performed an initial run through of upgrading our Copyright date to
extend to 2005 ... first run here was very simple ... change everything
where: grep 1996-2004 && the word 'Copyright' ... scanned through the
generated list with 'less' first, and after, to make sure that I only
picked up the right entries ...
plain SUSET instead. Also delay processing of options received in
client connection request until after we know if the user is a superuser,
so that SUSET values can be set that way by legitimate superusers.
Per recent discussion.
mode see a fresh snapshot for each command in the function, rather than
using the latest interactive command's snapshot. Also, suppress fresh
snapshots as well as CommandCounterIncrement inside STABLE and IMMUTABLE
functions, instead using the snapshot taken for the most closely nested
regular query. (This behavior is only sane for read-only functions, so
the patch also enforces that such functions contain only SELECT commands.)
As per my proposal of 6-Sep-2004; I note that I floated essentially the
same proposal on 19-Jun-2002, but that discussion tailed off without any
action. Since 8.0 seems like the right place to be taking possibly
nontrivial backwards compatibility hits, let's get it done now.
executed. Previously, the DECLARE would succeed but subsequent FETCHes
would fail since the parameter values supplied to DECLARE were not
propagated to the portal created for the cursor.
In support of this, add type Oids to ParamListInfo entries, which seems
like a good idea anyway since code that extracts a value can double-check
that it got the type of value it was expecting.
Oliver Jowett, with minor editorialization by Tom Lane.
possible to trap an error inside a function rather than letting it
propagate out to PostgresMain. You still have to use AbortCurrentTransaction
to clean up, but at least the error handling itself will cooperate.
until Bind is received, so that actual parameter values are visible to the
planner. Make use of the parameter values for estimation purposes (but
don't fold them into the actual plan). This buys back most of the
potential loss of plan quality that ensues from using out-of-line
parameters instead of putting literal values right into the query text.
This patch creates a notion of constant-folding expressions 'for
estimation purposes only', in which case we can be more aggressive than
the normal eval_const_expressions() logic can be. Right now the only
difference in behavior is inserting bound values for Params, but it will
be interesting to look at other possibilities. One that we've seen
come up repeatedly is reducing now() and related functions to current
values, so that queries like ... WHERE timestampcol > now() - '1 day'
have some chance of being planned effectively.
Oliver Jowett, with some kibitzing from Tom Lane.
than being random pieces of other files. Give bgwriter responsibility
for all checkpoint activity (other than a post-recovery checkpoint);
so this child process absorbs the functionality of the former transient
checkpoint and shutdown subprocesses. While at it, create an actual
include file for postmaster.c, which for some reason never had its own
file before.
> >>with allowed values of "all, mod, ddl, none" with default "none".
OK, here is a patch that implements #1. Here is sample output:
test=> set client_min_messages = 'log';
SET
test=> set log_statement = 'mod';
SET
test=> select 1;
?column?
----------
1
(1 row)
test=> update test set x=1;
LOG: statement: update test set x=1;
ERROR: relation "test" does not exist
test=> update test set x=1;
LOG: statement: update test set x=1;
ERROR: relation "test" does not exist
test=> copy test from '/tmp/x';
LOG: statement: copy test from '/tmp/x';
ERROR: relation "test" does not exist
test=> copy test to '/tmp/x';
ERROR: relation "test" does not exist
test=> prepare xx as select 1;
PREPARE
test=> prepare xx as update x set y=1;
LOG: statement: prepare xx as update x set y=1;
ERROR: relation "x" does not exist
test=> explain analyze select 1;;
QUERY PLAN
------------------------------------------------------------------------------------
Result (cost=0.00..0.01 rows=1 width=0) (actual time=0.006..0.007 rows=1 loops=1)
Total runtime: 0.046 ms
(2 rows)
test=> explain analyze update test set x=1;
LOG: statement: explain analyze update test set x=1;
ERROR: relation "test" does not exist
test=> explain update test set x=1;
ERROR: relation "test" does not exist
It checks PREPARE and EXECUTE ANALYZE too. The log_statement values are
'none', 'mod', 'ddl', and 'all'. For 'all', it prints before the query
is parsed, and for ddl/mod, it does it right after parsing using the
node tag (or command tag for CREATE/ALTER/DROP), so any non-parse errors
will print after the log line.
is measured in kilobytes and checked against actual physical execution
stack depth, as per my proposal of 30-Dec. This gives us a fairly
bulletproof defense against crashing due to runaway recursive functions.
handle multiple 'formats' for data I/O. Restructure CommandDest and
DestReceiver stuff one more time (it's finally starting to look a bit
clean though). Code now matches latest 3.0 protocol document as far
as message formats go --- but there is no support for binary I/O yet.
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.
the column by table OID and column number, if it's a simple column
reference. Along the way, get rid of reskey/reskeyop fields in Resdoms.
Turns out that representation was not convenient for either the planner
or the executor; we can make the planner deliver exactly what the
executor wants with no more effort.
initdb forced due to change in stored rule representation.
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.
that the types of untyped string-literal constants are deduced (ie,
when coerce_type is applied to 'em, that's what the type must be).
Remove the ancient hack of storing the input Param-types array as a
global variable, and put the info into ParseState instead. This touches
a lot of files because of adjustment of routine parameter lists, but
it's really not a large patch. Note: PREPARE statement still insists on
exact specification of parameter types, but that could easily be relaxed
now, if we wanted to do so.
I had inadvertently omitted it while rearranging things to support
length-counted incoming messages. Also, change the parser's API back
to accepting a 'char *' query string instead of 'StringInfo', as the
latter wasn't buying us anything except overhead. (I think when I put
it in I had some notion of making the parser API 8-bit-clean, but
seeing that flex depends on null-terminated input, that's not really
ever gonna happen.)
(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
utility statement (DeclareCursorStmt) with a SELECT query dangling from
it, rather than a SELECT query with a few unusual fields in it. Add
code to determine whether a planned query can safely be run backwards.
If DECLARE CURSOR specifies SCROLL, ensure that the plan can be run
backwards by adding a Materialize plan node if it can't. Without SCROLL,
you get an error if you try to fetch backwards from a cursor that can't
handle it. (There is still some discussion about what the exact
behavior should be, but this is necessary infrastructure in any case.)
Along the way, make EXPLAIN DECLARE CURSOR work.
to plan nodes, not vice-versa. All executor state nodes now inherit from
struct PlanState. Copying of plan trees has been simplified by not
storing a list of SubPlans in Plan nodes (eliminating duplicate links).
The executor still needs such a list, but it can build it during
ExecutorStart since it has to scan the plan tree anyway.
No initdb forced since no stored-on-disk structures changed, but you
will need a full recompile because of node-numbering changes.
command status at the interactive level. SPI_processed, etc are set
in the same way as the returned command status would have been set if
the same querystring were issued interactively. Per gripe from
Michael Paesold 25-Sep-02.
Use flex flags -CF. Pass the to-be-scanned string around as StringInfo
type, to avoid querying the length repeatedly. Clean up some code and
remove lex-compatibility cruft. Escape backslash sequences inline. Use
flex-provided yy_scan_buffer() function to set up input, rather than using
myinput().
are now both invoked once per received SQL command (raw parsetree) from
pg_exec_query_string. BeginCommand is actually just an empty routine
at the moment --- all its former operations have been pushed into tuple
receiver setup routines in printtup.c. This makes for a clean distinction
between BeginCommand/EndCommand (once per command) and the tuple receiver
setup/teardown routines (once per ExecutorRun call), whereas the old code
was quite ad hoc. Along the way, clean up the calling conventions for
ExecutorRun a little bit.
report for each received SQL command, regardless of rewriting activity.
Also ensure that this report comes from the 'original' command, not the
last command generated by rewrite; this fixes 7.2 breakage for INSERT
commands that have actions added by rules. Fernando Nasser and Tom Lane.
