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Allow row comparisons to be used as indexscan qualifications.

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This completes the project to upgrade our handling of row comparisons.
This commit is contained in:
Tom Lane
2006-01-25 20:29:24 +00:00
parent 06d45e485d
commit 3a0a16cb7e
11 changed files with 996 additions and 142 deletions
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35
src/include/access/skey.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/skey.h,v 1.30 2006/01/14 22:03:35 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/skey.h,v 1.31 2006/01/25 20:29:24 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -69,6 +69,36 @@ typedef struct ScanKeyData
typedef ScanKeyData *ScanKey;
/*
* About row comparisons:
*
* The ScanKey data structure also supports row comparisons, that is ordered
* tuple comparisons like (x, y) > (c1, c2), having the SQL-spec semantics
* "x > c1 OR (x = c1 AND y > c2)". Note that this is currently only
* implemented for btree index searches, not for heapscans or any other index
* type. A row comparison is represented by a "header" ScanKey entry plus
* a separate array of ScanKeys, one for each column of the row comparison.
* The header entry has these properties:
* sk_flags = SK_ROW_HEADER
* sk_attno = index column number for leading column of row comparison
* sk_strategy = btree strategy code for semantics of row comparison
* (ie, < <= > or >=)
* sk_subtype, sk_func: not used
* sk_argument: pointer to subsidiary ScanKey array
* If the header is part of a ScanKey array that's sorted by attno, it
* must be sorted according to the leading column number.
*
* The subsidiary ScanKey array appears in logical column order of the row
* comparison, which may be different from index column order. The array
* elements are like a normal ScanKey array except that:
* sk_flags must include SK_ROW_MEMBER, plus SK_ROW_END in the last
* element (needed since row header does not include a count)
* sk_func points to the btree comparison support function for the
* opclass, NOT the operator's implementation function.
* sk_strategy must be the same in all elements of the subsidiary array,
* that is, the same as in the header entry.
*/
/*
* ScanKeyData sk_flags
*
@ -78,6 +108,9 @@ typedef ScanKeyData *ScanKey;
*/
#define SK_ISNULL 0x0001 /* sk_argument is NULL */
#define SK_UNARY 0x0002 /* unary operator (currently unsupported) */
#define SK_ROW_HEADER 0x0004 /* row comparison header (see above) */
#define SK_ROW_MEMBER 0x0008 /* row comparison member (see above) */
#define SK_ROW_END 0x0010 /* last row comparison member (see above) */
/*