codekingpro/portable-devtools

1/*-------------------------------------------------------------------------2 *3 * skey.h4 *	  POSTGRES scan key definitions.5 *6 *7 * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group8 * Portions Copyright (c) 1994, Regents of the University of California9 *10 * src/include/access/skey.h11 *12 *-------------------------------------------------------------------------13 */14#ifndef SKEY_H15#define SKEY_H16 17#include "access/attnum.h"18#include "access/stratnum.h"19#include "fmgr.h"20 21 22/*23 * A ScanKey represents the application of a comparison operator between24 * a table or index column and a constant.  When it's part of an array of25 * ScanKeys, the comparison conditions are implicitly ANDed.  The index26 * column is the left argument of the operator, if it's a binary operator.27 * (The data structure can support unary indexable operators too; in that28 * case sk_argument would go unused.  This is not currently implemented.)29 *30 * For an index scan, sk_strategy and sk_subtype must be set correctly for31 * the operator.  When using a ScanKey in a heap scan, these fields are not32 * used and may be set to InvalidStrategy/InvalidOid.33 *34 * If the operator is collation-sensitive, sk_collation must be set35 * correctly as well.36 *37 * A ScanKey can also represent a ScalarArrayOpExpr, that is a condition38 * "column op ANY(ARRAY[...])".  This is signaled by the SK_SEARCHARRAY39 * flag bit.  The sk_argument is not a value of the operator's right-hand40 * argument type, but rather an array of such values, and the per-element41 * comparisons are to be ORed together.42 *43 * A ScanKey can also represent a condition "column IS NULL" or "column44 * IS NOT NULL"; these cases are signaled by the SK_SEARCHNULL and45 * SK_SEARCHNOTNULL flag bits respectively.  The argument is always NULL,46 * and the sk_strategy, sk_subtype, sk_collation, and sk_func fields are47 * not used (unless set by the index AM).48 *49 * SK_SEARCHARRAY, SK_SEARCHNULL and SK_SEARCHNOTNULL are supported only50 * for index scans, not heap scans; and not all index AMs support them,51 * only those that set amsearcharray or amsearchnulls respectively.52 *53 * A ScanKey can also represent an ordering operator invocation, that is54 * an ordering requirement "ORDER BY indexedcol op constant".  This looks55 * the same as a comparison operator, except that the operator doesn't56 * (usually) yield boolean.  We mark such ScanKeys with SK_ORDER_BY.57 * SK_SEARCHARRAY, SK_SEARCHNULL, SK_SEARCHNOTNULL cannot be used here.58 *59 * Note: in some places, ScanKeys are used as a convenient representation60 * for the invocation of an access method support procedure.  In this case61 * sk_strategy/sk_subtype are not meaningful (but sk_collation can be); and62 * sk_func may refer to a function that returns something other than boolean.63 */64typedef struct ScanKeyData65{66	int			sk_flags;		/* flags, see below */67	AttrNumber	sk_attno;		/* table or index column number */68	StrategyNumber sk_strategy; /* operator strategy number */69	Oid			sk_subtype;		/* strategy subtype */70	Oid			sk_collation;	/* collation to use, if needed */71	FmgrInfo	sk_func;		/* lookup info for function to call */72	Datum		sk_argument;	/* data to compare */73} ScanKeyData;74 75typedef ScanKeyData *ScanKey;76 77/*78 * About row comparisons:79 *80 * The ScanKey data structure also supports row comparisons, that is ordered81 * tuple comparisons like (x, y) > (c1, c2), having the SQL-spec semantics82 * "x > c1 OR (x = c1 AND y > c2)".  Note that this is currently only83 * implemented for btree index searches, not for heapscans or any other index84 * type.  A row comparison is represented by a "header" ScanKey entry plus85 * a separate array of ScanKeys, one for each column of the row comparison.86 * The header entry has these properties:87 *		sk_flags = SK_ROW_HEADER88 *		sk_attno = index column number for leading column of row comparison89 *		sk_strategy = btree strategy code for semantics of row comparison90 *				(ie, < <= > or >=)91 *		sk_subtype, sk_collation, sk_func: not used92 *		sk_argument: pointer to subsidiary ScanKey array93 * If the header is part of a ScanKey array that's sorted by attno, it94 * must be sorted according to the leading column number.95 *96 * The subsidiary ScanKey array appears in logical column order of the row97 * comparison, which may be different from index column order.  The array98 * elements are like a normal ScanKey array except that:99 *		sk_flags must include SK_ROW_MEMBER, plus SK_ROW_END in the last100 *				element (needed since row header does not include a count)101 *		sk_func points to the btree comparison support function for the102 *				opclass, NOT the operator's implementation function.103 * sk_strategy must be the same in all elements of the subsidiary array,104 * that is, the same as in the header entry.105 * SK_SEARCHARRAY, SK_SEARCHNULL, SK_SEARCHNOTNULL cannot be used here.106 */107 108/*109 * ScanKeyData sk_flags110 *111 * sk_flags bits 0-15 are reserved for system-wide use (symbols for those112 * bits should be defined here).  Bits 16-31 are reserved for use within113 * individual index access methods.114 */115#define SK_ISNULL			0x0001	/* sk_argument is NULL */116#define SK_UNARY			0x0002	/* unary operator (not supported!) */117#define SK_ROW_HEADER		0x0004	/* row comparison header (see above) */118#define SK_ROW_MEMBER		0x0008	/* row comparison member (see above) */119#define SK_ROW_END			0x0010	/* last row comparison member */120#define SK_SEARCHARRAY		0x0020	/* scankey represents ScalarArrayOp */121#define SK_SEARCHNULL		0x0040	/* scankey represents "col IS NULL" */122#define SK_SEARCHNOTNULL	0x0080	/* scankey represents "col IS NOT NULL" */123#define SK_ORDER_BY			0x0100	/* scankey is for ORDER BY op */124 125 126/*127 * prototypes for functions in access/common/scankey.c128 */129extern void ScanKeyInit(ScanKey entry,130						AttrNumber attributeNumber,131						StrategyNumber strategy,132						RegProcedure procedure,133						Datum argument);134extern void ScanKeyEntryInitialize(ScanKey entry,135								   int flags,136								   AttrNumber attributeNumber,137								   StrategyNumber strategy,138								   Oid subtype,139								   Oid collation,140								   RegProcedure procedure,141								   Datum argument);142extern void ScanKeyEntryInitializeWithInfo(ScanKey entry,143										   int flags,144										   AttrNumber attributeNumber,145										   StrategyNumber strategy,146										   Oid subtype,147										   Oid collation,148										   FmgrInfo *finfo,149										   Datum argument);150 151#endif							/* SKEY_H */152