[HACKERS] NULL's support in SP-GiST

[Oleg Bartunov]

Hi there,

attached patch introduces NULLs indexing for SP-GiST. With this patch
Sp-GiST supports IS NULL, IS NOT NULL clauses, as well as full index scan.


needed because they know how to reconstruct an original value.

Unlike BTree we can't introduce a rule like "NULL is greater than
anything else", because Sp-GiST  doesn't know  semantics of indexed data.
Also, Sp-GiST is essentially single-column index, so we can





        Regards,
                Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: o...@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83

We added boolean satisfyAll field in spgInnerConsistentIn and spgLeafConsistentIn structures, which informs the user-defined methods, that all search results satisfy a query and should be returned. Calls of consistent methods are store null values outside the main structure of index and use separate code path to work with NULLs. Actually, storing just ItemPointer (instead of the whole index tuple) is enough for NULLs, so we can reuse data tree storage from GIN, which used for storing ItemPointers for each indexed values. For that purpose, GinPageOpaqueData and SpGistPageOpaqueData should be compatible, at least at flag's positions and values. In fact, it's needed only for vacuum code, which produces full index scan.

spgist_null-0.8.gz
Description: Binary data

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