our own command (or more generally, xmin = our xact and cmin >= current
command ID) should not be seen as good. Else we may try to update rows
we already updated. This error was inserted last August while fixing the
even bigger problem that the old coding wouldn't see *any* tuples inserted
by our own transaction as good. Per report from Euler Taveira de Oliveira.
generate their output tuple descriptors from their target lists (ie, using
ExecAssignResultTypeFromTL()). We long ago fixed things so that all node
types have minimally valid tlists, so there's no longer any good reason to
have two different ways of doing it. This change is needed to fix bug
reported by Hayden James: the fix of 2005-11-03 to emit the correct column
names after optimizing away a SubqueryScan node didn't work if the new
top-level plan node used ExecAssignResultTypeFromOuterPlan to generate its
tupdesc, since the next plan node down won't have the correct column labels.
the ProcessUtility case, resulting in an intratransaction memory leak
if a utility command actually did return any tuples, as reported by
Dmitry Karasik. Fix this and also make the behavior more consistent
for cases involving nested SPI operations and multiple query trees,
by ensuring that we store the state locally until it is ready to be
returned to the caller.
insufficient paranoia in code that follows t_ctid links. (We must do both
because even with VACUUM doing it properly, the intermediate state with
a dangling t_ctid link is visible concurrently during lazy VACUUM, and
could be seen afterwards if either type of VACUUM crashes partway through.)
Also try to improve documentation about what's going on. Patch is a bit
bulky because passing the XMAX information around required changing the
APIs of some low-level heapam.c routines, but it's not conceptually very
complicated. Per trouble report from Teodor and subsequent analysis.
This needs to be back-patched, but I'll do that after 8.1 beta is out.
When one side of the join has a NULL, we don't want to uselessly try
to match it against every remaining tuple of the other side. While
at it, rewrite the comparison machinery to avoid multiple evaluations
of the left and right input expressions and to use a btree comparator
where available, instead of double operator calls. Also revise the
state machine to eliminate redundant comparisons and hopefully make it
more readable too.
to produce when running the executor. This is consistent with the internal
executor APIs (such as ExecutorRun), which also use a long for this purpose.
It also allows FETCH_ALL to be passed -- since FETCH_ALL is defined as
LONG_MAX, this wouldn't have worked on platforms where int and long are of
different sizes. Per report from Tzahi Fadida.
node, as this behavior is now better done as a bitmap OR indexscan.
This allows considerable simplification in nodeIndexscan.c itself as
well as several planner modules concerned with indexscan plan generation.
Also we can improve the sharing of code between regular and bitmap
indexscans, since they are now working with nigh-identical Plan nodes.
scans, using in-memory tuple ID bitmaps as the intermediary. The planner
frontend (path creation and cost estimation) is not there yet, so none
of this code can be executed. I have tested it using some hacked planner
code that is far too ugly to see the light of day, however. Committing
now so that the bulk of the infrastructure changes go in before the tree
drifts under me.
return just a single tuple at a time. Currently the only such node
type is Hash, but I expect we will soon have indexscans that can return
tuple bitmaps. A side benefit is that EXPLAIN ANALYZE now shows the
correct tuple count for a Hash node.
executing a statement that fires triggers. Formerly this time was
included in "Total runtime" but not otherwise accounted for.
As a side benefit, we avoid re-opening relations when firing non-deferred
AFTER triggers, because the trigger code can re-use the main executor's
ResultRelInfo data structure.
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.
a tuple are being accessed via ExecEvalVar and the attcacheoff shortcut
isn't usable (due to nulls and/or varlena columns). To do this, cache
Datums extracted from a tuple in the associated TupleTableSlot.
Also some code cleanup in and around the TupleTable handling.
Atsushi Ogawa with some kibitzing by Tom Lane.
on-the-fly, and thereby avoid blowing out memory when the planner has
underestimated the hash table size. Hash join will now obey the
work_mem limit with some faithfulness. Per my recent proposal
(hash aggregate part isn't done yet though).
look at the actual aggregate transition datatypes and the actual overhead
needed by nodeAgg.c, instead of using pessimistic round numbers.
Per a discussion with Michael Tiemann.
We don't really want to start a new SPI connection, just keep using the old
one; otherwise we have memory management problems as illustrated by
John Kennedy's bug report of today. This requires a bit of a hack to
ensure the SPI stack state is properly restored, but then again what we
were doing before was a hack too, strictly speaking. Add a regression
test to cover this case.
columns. The returned tuple needs to have appropriate NULL columns
inserted so that it actually matches the declared rowtype. It seemed
convenient to use a JunkFilter for this, so I made some cleanups and
simplifications in the JunkFilter code to allow it to support this
additional functionality. (That in turn exposed a latent bug in
nodeAppend.c, which is that it was returning a tuple slot whose
descriptor didn't match its data.) Also, move check_sql_fn_retval
out of pg_proc.c and into functions.c, where it seems to more naturally
belong.
as per recent discussions. Invent SubTransactionIds that are managed like
CommandIds (ie, counter is reset at start of each top transaction), and
use these instead of TransactionIds to keep track of subtransaction status
in those modules that need it. This means that a subtransaction does not
need an XID unless it actually inserts/modifies rows in the database.
Accordingly, don't assign it an XID nor take a lock on the XID until it
tries to do that. This saves a lot of overhead for subtransactions that
are only used for error recovery (eg plpgsql exceptions). Also, arrange
to release a subtransaction's XID lock as soon as the subtransaction
exits, in both the commit and abort cases. This avoids holding many
unique locks after a long series of subtransactions. The price is some
additional overhead in XactLockTableWait, but that seems acceptable.
Finally, restructure the state machine in xact.c to have a more orthogonal
set of states for subtransactions.
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.
Create a shared function to convert a SPI error code into a string
(replacing near-duplicate code in several PLs), and use it anywhere
that a SPI function call error is reported.
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.
rather than allowing them only in a few special cases as before. In
particular you can now pass a ROW() construct to a function that accepts
a rowtype parameter. Internal generation of RowExprs fixes a number of
corner cases that used to not work very well, such as referencing the
whole-row result of a JOIN or subquery. This represents a further step in
the work I started a month or so back to make rowtype values into
first-class citizens.
results with tuples as ordinary varlena Datums. This commit does not
in itself do much for us, except eliminate the horrid memory leak
associated with evaluation of whole-row variables. However, it lays the
groundwork for allowing composite types as table columns, and perhaps
some other useful features as well. Per my proposal of a few days ago.
directly to the appropriate per-node execution function, using a function
pointer stored by ExecInitExpr. This speeds things up by eliminating one
level of function call. The function-pointer technique also enables further
small improvements such as only making one-time tests once (and then
changing the function pointer). Overall this seems to gain about 10%
on evaluation of simple expressions, which isn't earthshaking but seems
a worthwhile gain for a relatively small hack. Per recent discussion
on pghackers.
+extern Oid SPI_getargtypeid(void *plan, int argIndex);
+extern int SPI_getargcount(void *plan);
+extern bool SPI_is_cursor_plan(void *plan);
Thomas Hallgren
when scanning a table that we need all the columns from. In case of
SELECT INTO, we have to check that the hasoids flag matches the desired
output type, too. Per report from Mike Mascari.
for sure...). Rather than relying on the query context of a rangetable
entry to identify what permissions it wants checked, store a full AclMode
mask in each RTE, and check exactly those bits. This allows an RTE
specifying, say, INSERT privilege on a view to be copied into a derived
UPDATE query without changing meaning. Per recent discussion thread.
initdb forced due to change of stored rule representation.
shut down cleanly if the plan node is ReScanned before the SRFs are run
to completion. This fixes the problem for SQL-language functions, but
still need work on functions using the SRF_XXX() macros.
discussion on pgsql-hackers: in READ COMMITTED mode we just have to force
a QuerySnapshot update in the trigger, but in SERIALIZABLE mode we have
to run the scan under a current snapshot and then complain if any rows
would be updated/deleted that are not visible in the transaction snapshot.
to allow es_snapshot to be set to SnapshotNow rather than a query snapshot.
This solves a bug reported by Wade Klaver, wherein triggers fired as a
result of RI cascade updates could misbehave.
as well as the hash function (formerly the comparison function was hardwired
as memcmp()). This makes it possible to eliminate the special-purpose
hashtable management code in execGrouping.c in favor of using dynahash to
manage tuple hashtables; which is a win because dynahash knows how to expand
a hashtable when the original size estimate was too small, whereas the
special-purpose code was too stupid to do that. (See recent gripe from
Stephan Szabo about poor performance when hash table size estimate is way
off.) Free side benefit: when using string_hash, the default comparison
function is now strncmp() instead of memcmp(). This should eliminate some
part of the overhead associated with larger NAMEDATALEN values.
Tom Lane