The original idea was that we could use an isNull-style bool array
directly as a GinNullCategory array. However, the existing code already
acknowledges that that doesn't really work, because of the possibility
that bool as currently defined can have arbitrary bit patterns for true
values. So it has to loop through the nullFlags array to set each bool
value to an acceptable value. But if we are looping through the whole
array anyway, we might as well build a proper GinNullCategory array
instead and abandon the type casting. That makes the code much safer in
case bool is ever changed to something else.
Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
Don't move parenthesized lines to the left, even if that means they
flow past the right margin.
By default, BSD indent lines up statement continuation lines that are
within parentheses so that they start just to the right of the preceding
left parenthesis. However, traditionally, if that resulted in the
continuation line extending to the right of the desired right margin,
then indent would push it left just far enough to not overrun the margin,
if it could do so without making the continuation line start to the left of
the current statement indent. That makes for a weird mix of indentations
unless one has been completely rigid about never violating the 80-column
limit.
This behavior has been pretty universally panned by Postgres developers.
Hence, disable it with indent's new -lpl switch, so that parenthesized
lines are always lined up with the preceding left paren.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4d wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls
had typos in the context-sizing parameters. While none of these led to
especially significant problems, they did create minor inefficiencies,
and it's now clear that expecting people to copy-and-paste those calls
accurately is not a great idea. Let's reduce the risk of future errors
by introducing single macros that encapsulate the common use-cases.
Three such macros are enough to cover all but two special-purpose contexts;
those two calls can be left as-is, I think.
While this patch doesn't in itself improve matters for third-party
extensions, it doesn't break anything for them either, and they can
gradually adopt the simplified notation over time.
In passing, change TopMemoryContext to use the default allocation
parameters. Formerly it could only be extended 8K at a time. That was
probably reasonable when this code was written; but nowadays we create
many more contexts than we did then, so that it's not unusual to have a
couple hundred K in TopMemoryContext, even without considering various
dubious code that sticks other things there. There seems no good reason
not to let it use growing blocks like most other contexts.
Back-patch to 9.6, mostly because that's still close enough to HEAD that
it's easy to do so, and keeping the branches in sync can be expected to
avoid some future back-patching pain. The bugs fixed by these changes
don't seem to be significant enough to justify fixing them further back.
Discussion: <21072.1472321324@sss.pgh.pa.us>
Commit d88976cfa1 removed this code from ginFreeScanKeys():
- if (entry->list)
- pfree(entry->list);
evidently in the belief that that ItemPointer array is allocated in the
keyCtx and so would be reclaimed by the following MemoryContextReset.
Unfortunately, it isn't and it won't. It'd likely be a good idea for
that to become so, but as a simple and back-patchable fix in the
meantime, restore this code to ginFreeScanKeys().
Also, add a similar pfree to where startScanEntry() is about to zero out
entry->list. I am not sure if there are any code paths where this
change prevents a leak today, but it seems like cheap future-proofing.
In passing, make the initial allocation of so->entries[] use palloc
not palloc0. The code doesn't depend on unused entries being zero;
if it did, the array-enlargement code in ginFillScanEntry() would be
wrong. So using palloc0 initially can only serve to confuse readers
about what the invariant is.
Per report from Felipe de Jesús Molina Bravo, via Jaime Casanova in
<CAJGNTeMR1ndMU2Thpr8GPDUfiHTV7idELJRFusA5UXUGY1y-eA@mail.gmail.com>
This patch reduces pg_am to just two columns, a name and a handler
function. All the data formerly obtained from pg_am is now provided
in a C struct returned by the handler function. This is similar to
the designs we've adopted for FDWs and tablesample methods. There
are multiple advantages. For one, the index AM's support functions
are now simple C functions, making them faster to call and much less
error-prone, since the C compiler can now check function signatures.
For another, this will make it far more practical to define index access
methods in installable extensions.
A disadvantage is that SQL-level code can no longer see attributes
of index AMs; in particular, some of the crosschecks in the opr_sanity
regression test are no longer possible from SQL. We've addressed that
by adding a facility for the index AM to perform such checks instead.
(Much more could be done in that line, but for now we're content if the
amvalidate functions more or less replace what opr_sanity used to do.)
We might also want to expose some sort of reporting functionality, but
this patch doesn't do that.
Alexander Korotkov, reviewed by Petr Jelínek, and rather heavily
editorialized on by me.
It was getting tedious to track and release all the different things that
form a scan key. We were leaking at least the queryCategories array, and
possibly more, on a rescan. That was visible if a GIN index was used in a
nested loop join. This also protects from leaks in extractQuery method.
No backpatching, given the lack of complaints from the field. Maybe later,
after this has received more field testing.
The requiredEntries / additionalEntries arrays were not freed in
freeScanKeys() like other per-key stuff.
It's not obvious, but startScanKey() was only ever called after the keys
have been initialized with ginNewScanKey(). That's why it doesn't need to
worry about freeing existing arrays. The ginIsNewKey() test in gingetbitmap
was never true, because ginrescan free's the existing keys, and it's not OK
to call gingetbitmap twice in a row without calling ginrescan in between.
To make that clear, remove the unnecessary ginIsNewKey(). And just to be
extra sure that nothing funny happens if there is an existing key after all,
call freeScanKeys() to free it if it exists. This makes the code more
straightforward.
(I'm seeing other similar leaks in testing a query that rescans an GIN index
scan, but that's a different issue. This just fixes the obvious leak with
those two arrays.)
Backpatch to 9.4, where GIN fast scan was added.
If you have a GIN query like "rare & frequent", we currently fetch all the
items that match either rare or frequent, call the consistent function for
each item, and let the consistent function filter out items that only match
one of the terms. However, if we can deduce that "rare" must be present for
the overall qual to be true, we can scan all the rare items, and for each
rare item, skip over to the next frequent item with the same or greater TID.
That greatly speeds up "rare & frequent" type queries.
To implement that, introduce the concept of a tri-state consistent function,
where the 3rd value is MAYBE, indicating that we don't know if that term is
present. Operator classes only provide a boolean consistent function, so we
simulate the tri-state consistent function by calling the boolean function
several times, with the MAYBE arguments set to all combinations of TRUE and
FALSE. Testing all combinations is only feasible for a small number of MAYBE
arguments, but it is envisioned that we'll provide a way for operator
classes to provide a native tri-state consistent function, which can be much
more efficient. But that is not included in this patch.
We were already using that trick to for lossy pages, calling the consistent
function with the lossy entry set to TRUE and FALSE. Now that we have the
tri-state consistent function, use it for lossy pages too.
Alexander Korotkov, with fair amount of refactoring by me.
Experimentation with contrib/btree_gist shows that the majority of the GIST
support functions potentially need collation information. Safest policy
seems to be to pass it to all of them, instead of making assumptions about
which ones could possibly need it.
The original coding could combine duplicate entries only when they
originated from the same qual condition. In particular it could not
combine cases where multiple qual conditions all give rise to full-index
scan requests, which is an expensive case well worth optimizing. Refactor
so that duplicates are recognized across all the quals.
Per my recent proposal(s). Null key datums can now be returned by
extractValue and extractQuery functions, and will be stored in the index.
Also, placeholder entries are made for indexable items that are NULL or
contain no keys according to extractValue. This means that the index is
now always complete, having at least one entry for every indexed heap TID,
and so we can get rid of the prohibition on full-index scans. A full-index
scan is implemented much the same way as partial-match scans were already:
we build a bitmap representing all the TIDs found in the index, and then
drive the results off that.
Also, introduce a concept of a "search mode" that can be requested by
extractQuery when the operator requires matching to empty items (this is
just as cheap as matching to a single key) or requires a full index scan
(which is not so cheap, but it sure beats failing or giving wrong answers).
The behavior remains backward compatible for opclasses that don't return
any null keys or request a non-default search mode.
Using these features, we can now make the GIN index opclass for anyarray
behave in a way that matches the actual anyarray operators for &&, <@, @>,
and = ... which it failed to do before in assorted corner cases.
This commit fixes the core GIN code and ginarrayprocs.c, updates the
documentation, and adds some simple regression test cases for the new
behaviors using the array operators. The tsearch and contrib GIN opclass
support functions still need to be looked over and probably fixed.
Another thing I intend to fix separately is that this is pretty inefficient
for cases where more than one scan condition needs a full-index search:
we'll run duplicate GinScanEntrys, each one of which builds a large bitmap.
There is some existing logic to merge duplicate GinScanEntrys but it needs
refactoring to make it work for entries belonging to different scan keys.
Note that most of gin.h has been split out into a new file gin_private.h,
so that gin.h doesn't export anything that's not supposed to be used by GIN
opclasses or the rest of the backend. I did quite a bit of other code
beautification work as well, mostly fixing comments and choosing more
appropriate names for things.
This is a heavily revised version of builtin_knngist_core-0.9. The
ordering operators are no longer mixed in with actual quals, which would
have confused not only humans but significant parts of the planner.
Instead, ordering operators are carried separately throughout planning and
execution.
Since the API for ambeginscan and amrescan functions had to be changed
anyway, this commit takes the opportunity to rationalize that a bit.
RelationGetIndexScan no longer forces a premature index_rescan call;
instead, callers of index_beginscan must call index_rescan too. Aside from
making the AM-side initialization logic a bit less peculiar, this has the
advantage that we do not make a useless extra am_rescan call when there are
runtime key values. AMs formerly could not assume that the key values
passed to amrescan were actually valid; now they can.
Teodor Sigaev and Tom Lane
The GIN code has absolutely no business exporting GIN-specific functions
with names as generic as compareItemPointers() or newScanKey(); that's
just trouble waiting to happen. I got annoyed about this again just now
and decided to fix it. This commit ensures that all global symbols
defined in access/gin/ have names including "gin" or "Gin". There were a
couple of cases, like names involving "PostingItem", where arguably the
names were already sufficiently nongeneric; but I figured as long as I was
risking creating merge problems for unapplied GIN patches I might as well
impose a uniform policy.
I didn't touch any static symbol names. There might be some places
where it'd be appropriate to rename some static functions to match
siblings that are exported, but I'll leave that for another time.
routines to make them behave better in the presence of "lossy" index pointers.
The previous coding was outright incorrect for some cases, as recently
reported by Artur Dabrowski: scanGetItem would fail to return index entries in
cases where one index key had multiple exact pointers on the same page as
another key had a lossy pointer. Also, keyGetItem was extremely inefficient
for cases where a single index key generates multiple "entry" streams, such as
an @@ operator with a multiple-clause tsquery. The presence of a lossy page
pointer in any one stream defeated its ability to use the opclass
consistentFn, resulting in probing many heap pages that didn't really need to
be visited. In Artur's example case, a query like
WHERE tsvector @@ to_tsquery('a & b')
was about 50X slower than the theoretically equivalent
WHERE tsvector @@ to_tsquery('a') AND tsvector @@ to_tsquery('b')
The way that I chose to fix this was to have GIN call the consistentFn
twice with both TRUE and FALSE values for the in-doubt entry stream,
returning a hit if either call produces TRUE, but not if they both return
FALSE. The code handles this for the case of a single in-doubt entry stream,
but punts (falling back to the stupid behavior) if there's more than one lossy
reference to the same page. The idea could be scaled up to deal with multiple
lossy references, but I think that would probably be wasted complexity. At
least to judge by Artur's example, such cases don't occur often enough to be
worth trying to optimize.
Back-patch to 8.4. 8.3 did not have lossy GIN index pointers, so not
subject to these problems.
method to pass extra data to the consistent() and comparePartial() methods.
This is the core infrastructure needed to support the soon-to-appear
contrib/btree_gin module. The APIs are still upward compatible with the
definitions used in 8.3 and before, although *not* with the previous 8.4devel
function definitions.
catversion bump for changes in pg_proc entries (although these are just
cosmetic, since GIN doesn't actually look at the function signature before
calling it...)
Teodor Sigaev and Oleg Bartunov
bitmap. This is extracted from Greg Stark's posix_fadvise patch; it seems
worth committing separately, since it's potentially useful independently of
posix_fadvise.
corresponding struct definitions. This allows other headers to avoid including
certain highly-loaded headers such as rel.h and relscan.h, instead using just
relcache.h, heapam.h or genam.h, which are more lightweight and thus cause less
unnecessary dependencies.
unnecessary #include lines in it. Also, move some tuple routine prototypes and
macros to htup.h, which allows removal of heapam.h inclusion from some .c
files.
For this to work, a new header file access/sysattr.h needed to be created,
initially containing attribute numbers of system columns, for pg_dump usage.
While at it, make contrib ltree, intarray and hstore header files more
consistent with our header style.
and aborted transactions have different effects; also teach it not to assume
that prepared transactions are always committed.
Along the way, simplify the pgstats API by tying counting directly to
Relations; I cannot detect any redeeming social value in having stats
pointers in HeapScanDesc and IndexScanDesc structures. And fix a few
corner cases in which counts might be missed because the relation's
pgstat_info pointer hadn't been set.
In this case extractQuery should returns -1 as nentries. This changes
prototype of extractQuery method to use int32* instead of uint32* for
nentries argument.
Based on that gincostestimate may see two corner cases: nothing will be found
or seqscan should be used.
Per proposal at http://archives.postgresql.org/pgsql-hackers/2007-01/msg01581.php
PS tsearch_core patch should be sightly modified to support changes, but I'm
waiting a verdict about reviewing of tsearch_core patch.
Bruce Momjian