Queries such as '!(foo<->bar)' failed to find matching rows when
implemented as a GiST or GIN index search. That's because of
failing to handle phrase searches as tri-valued when considering
a query without any position information for the target tsvector.
We can only say that the phrase operator might match, not that it
does match; and therefore its NOT also might match. The previous
coding incorrectly inverted the approximate phrase result to
decide that there was certainly no match.
To fix, we need to make TS_phrase_execute return a real ternary result,
and then bubble that up accurately in TS_execute. As long as we have
to do that anyway, we can simplify the baroque things TS_phrase_execute
was doing internally to manage tri-valued searching with only a bool
as explicit result.
For now, I left the externally-visible result of TS_execute as a plain
bool. There do not appear to be any outside callers that need to
distinguish a three-way result, given that they passed in a flag
saying what to do in the absence of position data. This might need
to change someday, but we wouldn't want to back-patch such a change.
Although tsginidx.c has its own TS_execute_ternary implementation for
use at upper index levels, that sadly managed to get this case wrong
as well :-(. Fixing it is a lot easier fortunately.
Per bug #16388 from Charles Offenbacher. Back-patch to 9.6 where
phrase search was introduced.
Discussion: https://postgr.es/m/16388-98cffba38d0b7e6e@postgresql.org
Change the key representation so that values that would exceed 127 bytes
are hashed into short strings, and so that the original JSON datatype of
each value is recorded in the index. The hashing rule eliminates the major
objection to having this opclass be the default for jsonb, namely that it
could fail for plausible input data (due to GIN's restrictions on maximum
key length). Preserving datatype information doesn't really buy us much
right now, but it requires no extra space compared to the previous way,
and it might be useful later.
Also, change the consistency-checking functions to request recheck for
exists (jsonb ? text) and related operators. The original analysis that
this is an exactly checkable query was incorrect, since the index does
not preserve information about whether a key appears at top level in
the indexed JSON object. Add a test case demonstrating the problem.
Make some other, mostly cosmetic improvements to the code in jsonb_gin.c
as well.
catversion bump due to on-disk data format change in jsonb_ops indexes.
The new format accepts exactly the same data as the json type. However, it is
stored in a format that does not require reparsing the orgiginal text in order
to process it, making it much more suitable for indexing and other operations.
Insignificant whitespace is discarded, and the order of object keys is not
preserved. Neither are duplicate object keys kept - the later value for a given
key is the only one stored.
The new type has all the functions and operators that the json type has,
with the exception of the json generation functions (to_json, json_agg etc.)
and with identical semantics. In addition, there are operator classes for
hash and btree indexing, and two classes for GIN indexing, that have no
equivalent in the json type.
This feature grew out of previous work by Oleg Bartunov and Teodor Sigaev, which
was intended to provide similar facilities to a nested hstore type, but which
in the end proved to have some significant compatibility issues.
Authors: Oleg Bartunov, Teodor Sigaev, Peter Geoghegan and Andrew Dunstan.
Review: Andres Freund
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.
equally (in glibc: et_EE, sv_SE, tk_TM). It turns out that this was
already taken care of previously by select_1.out, which I had forgotten to
update for an unrelated change. But might as well avoid the issue
altogether.
Oleg Bartunov and Teodor Sigaev, but I did a lot of editorializing,
so anything that's broken is probably my fault.
Documentation is nonexistent as yet, but let's land the patch so we can
get some portability testing done.
basic regression tests for GiST to the standard regression tests.
I took the opportunity to add an rtree-equivalent gist opclass for
circles; the contrib version only covered boxes and polygons, but
indexing circles is very handy for distance searches.
Tom Lane
Andrew Dunstan
Peter Eisentraut
Teodor Sigaev
Bruce Momjian
Vadim B. Mikheev
Thomas G. Lockhart
Marc G. Fournier