listed in the column's most-common-values statistics entry. This gives
us an exact selectivity result for the portion of the column population
represented by the MCV list, which can be a big leg up in accuracy if
that's a large fraction of the population. The heuristics involving
pattern contents and prefix are applied only to the part of the population
not included in the MCV list.
one argument at a time and then inserting the argument into a Python
list via PyList_SetItem(). This "steals" the reference to the argument:
that is, the reference to the new list member is now held by the Python
list itself. This works fine, except if an elog occurs. This causes the
function's PG_CATCH() block to be invoked, which decrements the
reference counts on both the current argument and the list of arguments.
If the elog happens to occur during the second or subsequent iteration
of the loop, the reference count on the current argument will be
decremented twice.
The fix is simple: set the local pointer to the current argument to NULL
immediately after adding it to the argument list. This ensures that the
Py_XDECREF() in the PG_CATCH() block doesn't double-decrement.
operator names. This is needed when dumping operator definitions that have
COMMUTATOR (or similar) links to operators in other schemas.
Apparently Daniel Whitter is the first person ever to try this :-(
and nail a couple more system indexes into cache. This doesn't make
any difference in normal system operation, but when forcing constant
cache resets it's difficult to get through the rules regression test
without these changes.
access information about the prepared statements that are available
in the current session. Original patch from Joachim Wieland, various
improvements by Neil Conway.
The "statement" column of the view contains the literal query string
sent by the client, without any rewriting or pretty printing. This
means that prepared statements created via SQL will be prefixed with
"PREPARE ... AS ", whereas those prepared via the FE/BE protocol will
not. That is unfortunate, but discussion on -patches did not yield an
efficient way to improve this, and there is some merit in returning
exactly what the client sent to the backend.
Catalog version bumped, regression tests updated.
use it. While it normally has been opened earlier during btree index
build, testing shows that it's possible for the link to be closed again
if an sinval reset occurs while the index is being built.
dead and have become unreferenced. Before 8.1, such members were left
for AtEOXact_CatCache() to clean up, but now AtEOXact_CatCache isn't
supposed to have anything to do. In an assert-enabled build this bug
leads to an assertion failure at transaction end, but in a non-assert
build the dead member is effectively just a small memory leak.
Per report from Jeremy Drake.
rather than elog(FATAL), when there is no more room in ShmemBackendArray.
This is a security issue since too many connection requests arriving close
together could cause the postmaster to shut down, resulting in denial of
service. Reported by Yoshiyuki Asaba, fixed by Magnus Hagander.
the relation but it finds a pre-existing valid buffer. The buffer does not
correspond to any page known to the kernel, so we *must* do smgrextend to
ensure that the space becomes allocated. The 7.x branches all do this
correctly, but the corner case got lost somewhere during 8.0 bufmgr rewrites.
(My fault no doubt :-( ... I think I assumed that such a buffer must be
not-BM_VALID, which is not so.)
< STABLE | DEFAULT ]. [wallog]
> STABLE | DEFAULT ]. Tables using non-default logging should not use
> referential integrity with default-logging tables, and tables using
> stable logging probably can not have indexes. [wallog]
< the table. Another option is to avoid transaction logging entirely
< and truncate or drop the table on crash recovery. These should be
< implemented using ALTER TABLE, e.g. ALTER TABLE PERSISTENCE [ DROP |
< TRUNCATE | STABLE | DEFAULT ]. [wallog]
> the table. This would affect COPY, and perhaps INSERT/UPDATE too.
> Another option is to avoid transaction logging entirely and truncate
> or drop the table on crash recovery. These should be implemented
> using ALTER TABLE, e.g. ALTER TABLE PERSISTENCE [ DROP | TRUNCATE |
> STABLE | DEFAULT ]. [wallog]
>
> * Allow control over which tables are WAL-logged
>
> Allow tables to bypass WAL writes and just fsync() dirty pages on
> commit. To do this, only a single writer can modify the table, and
> writes must happen only on new pages. Readers can continue accessing
> the table. Another option is to avoid transaction logging entirely
> and truncate or drop the table on crash recovery. These should be
> implemented using ALTER TABLE, e.g. ALTER TABLE PERSISTENCE [ DROP |
> TRUNCATE | STABLE | DEFAULT ]. [wallog]
an LWLock instead of a spinlock. This hardly matters on Unix machines
but should improve startup performance on Windows (or any port using
EXEC_BACKEND). Per previous discussion.
