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Fix an additional set of problems in GIN's handling of lossy page pointers.

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Although the key-combining code claimed to work correctly if its input
contained both lossy and exact pointers for a single page in a single TID
stream, in fact this did not work, and could not work without pretty
fundamental redesign.  Modify keyGetItem so that it will not return such a
stream, by handling lossy-pointer cases a bit more explicitly than we did
before.

Per followup investigation of a gripe from Artur Dabrowski.
An example of a query that failed given his data set is
select count(*) from search_tab where
(to_tsvector('german', keywords ) @@ to_tsquery('german', 'ee:* | dd:*')) and
(to_tsvector('german', keywords ) @@ to_tsquery('german', 'aa:*'));

Back-patch to 8.4 where the lossy pointer code was introduced.
This commit is contained in:
Tom Lane
2010-08-01 19:16:39 +00:00
parent 0454f13161
commit d4fe61b083
2 changed files with 139 additions and 68 deletions
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13
src/include/access/gin.h
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@@ -4,7 +4,7 @@
*
* Copyright (c) 2006-2010, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/include/access/gin.h,v 1.40 2010/08/01 02:12:42 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/gin.h,v 1.41 2010/08/01 19:16:39 tgl Exp $
*--------------------------------------------------------------------------
*/
#ifndef GIN_H
@@ -107,13 +107,22 @@ typedef struct GinMetaPageData
* We use our own ItemPointerGet(BlockNumber|GetOffsetNumber)
* to avoid Asserts, since sometimes the ip_posid isn't "valid"
*/
#define GinItemPointerGetBlockNumber(pointer) \
BlockIdGetBlockNumber(&(pointer)->ip_blkid)
#define GinItemPointerGetOffsetNumber(pointer) \
((pointer)->ip_posid)
/*
* Special-case item pointer values needed by the GIN search logic.
* MIN: sorts less than any valid item pointer
* MAX: sorts greater than any valid item pointer
* LOSSY PAGE: indicates a whole heap page, sorts after normal item
* pointers for that page
* Note that these are all distinguishable from an "invalid" item pointer
* (which is InvalidBlockNumber/0) as well as from all normal item
* pointers (which have item numbers in the range 1..MaxHeapTuplesPerPage).
*/
#define ItemPointerSetMin(p) \
ItemPointerSet((p), (BlockNumber)0, (OffsetNumber)0)
#define ItemPointerIsMin(p) \