queryenvironment.h

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/*-------------------------------------------------------------------------
 *
 * queryenvironment.h
 *    Access to functions to mutate the query environment and retrieve the
 *    actual data related to entries (if any).
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/utils/queryenvironment.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef QUERYENVIRONMENT_H
#define QUERYENVIRONMENT_H
 
#include "access/tupdesc.h"
 
 
typedef enum EphemeralNameRelationType
{
    ENR_NAMED_TUPLESTORE,       /* named tuplestore relation; e.g., deltas */
} EphemeralNameRelationType;
 
/*
 * Some ephemeral named relations must match some relation (e.g., trigger
 * transition tables), so to properly handle cached plans and DDL, we should
 * carry the OID of that relation.  In other cases an ENR might be independent
 * of any relation which is stored in the system catalogs, so we need to be
 * able to directly store the TupleDesc.  We never need both.
 */
typedef struct EphemeralNamedRelationMetadataData
{
    char       *name;           /* name used to identify the relation */
 
    /* only one of the next two fields should be used */
    Oid         reliddesc;      /* oid of relation to get tupdesc */
    TupleDesc   tupdesc;        /* description of result rows */
 
    EphemeralNameRelationType enrtype;  /* to identify type of relation */
    double      enrtuples;      /* estimated number of tuples */
} EphemeralNamedRelationMetadataData;
 
typedef EphemeralNamedRelationMetadataData *EphemeralNamedRelationMetadata;
 
/*
 * Ephemeral Named Relation data; used for parsing named relations not in the
 * catalog, like transition tables in AFTER triggers.
 */
typedef struct EphemeralNamedRelationData
{
    EphemeralNamedRelationMetadataData md;
    void       *reldata;        /* structure for execution-time access to data */
} EphemeralNamedRelationData;
 
typedef EphemeralNamedRelationData *EphemeralNamedRelation;
 
/*
 * This is an opaque structure outside of queryenvironment.c itself.  The
 * intention is to be able to change the implementation or add new context
 * features without needing to change existing code for use of existing
 * features.
 */
typedef struct QueryEnvironment QueryEnvironment;
 
 
extern QueryEnvironment *create_queryEnv(void);
extern EphemeralNamedRelationMetadata get_visible_ENR_metadata(QueryEnvironment *queryEnv, const char *refname);
extern void register_ENR(QueryEnvironment *queryEnv, EphemeralNamedRelation enr);
extern void unregister_ENR(QueryEnvironment *queryEnv, const char *name);
extern EphemeralNamedRelation get_ENR(QueryEnvironment *queryEnv, const char *name);
extern TupleDesc ENRMetadataGetTupDesc(EphemeralNamedRelationMetadata enrmd);
 
#endif                          /* QUERYENVIRONMENT_H */