55 lines
1.7 KiB
C
55 lines
1.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* attmap.h
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* Definitions for PostgreSQL attribute mappings
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*
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*
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* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/attmap.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef ATTMAP_H
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#define ATTMAP_H
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#include "access/attnum.h"
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#include "access/tupdesc.h"
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/*
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* Attribute mapping structure
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*
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* This maps attribute numbers between a pair of relations, designated
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* 'input' and 'output' (most typically inheritance parent and child
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* relations), whose common columns may have different attribute numbers.
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* Such difference may arise due to the columns being ordered differently
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* in the two relations or the two relations having dropped columns at
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* different positions.
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*
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* 'maplen' is set to the number of attributes of the 'output' relation,
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* taking into account any of its dropped attributes, with the corresponding
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* elements of the 'attnums' array set to 0.
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*/
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typedef struct AttrMap
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{
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AttrNumber *attnums;
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int maplen;
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} AttrMap;
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extern AttrMap *make_attrmap(int maplen);
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extern void free_attrmap(AttrMap *map);
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/* Conversion routines to build mappings */
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extern AttrMap *build_attrmap_by_name(TupleDesc indesc,
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TupleDesc outdesc,
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bool missing_ok);
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extern AttrMap *build_attrmap_by_name_if_req(TupleDesc indesc,
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TupleDesc outdesc,
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bool missing_ok);
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extern AttrMap *build_attrmap_by_position(TupleDesc indesc,
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TupleDesc outdesc,
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const char *msg);
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#endif /* ATTMAP_H */
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