src/include/utils/queryenvironment.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * queryenvironment.h
   4  *        Access to functions to mutate the query environment and retrieve the
   5  *        actual data related to entries (if any).
   6  *
   7  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * src/include/utils/queryenvironment.h
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef QUERYENVIRONMENT_H
  15 #define QUERYENVIRONMENT_H
  16
  17 #include "access/tupdesc.h"
  18
  19
  20 typedef enum EphemeralNameRelationType
  21 {
  22         ENR_NAMED_TUPLESTORE            /* named tuplestore relation; e.g., deltas */
  23 } EphemeralNameRelationType;
  24
  25 /*
  26  * Some ephemeral named relations must match some relation (e.g., trigger
  27  * transition tables), so to properly handle cached plans and DDL, we should
  28  * carry the OID of that relation.  In other cases an ENR might be independent
  29  * of any relation which is stored in the system catalogs, so we need to be
  30  * able to directly store the TupleDesc.  We never need both.
  31  */
  32 typedef struct EphemeralNamedRelationMetadataData
  33 {
  34         char       *name;                       /* name used to identify the relation */
  35
  36         /* only one of the next two fields should be used */
  37         Oid                     reliddesc;              /* oid of relation to get tupdesc */
  38         TupleDesc       tupdesc;                /* description of result rows */
  39
  40         EphemeralNameRelationType enrtype;      /* to identify type of relation */
  41         double          enrtuples;              /* estimated number of tuples */
  42 } EphemeralNamedRelationMetadataData;
  43
  44 typedef EphemeralNamedRelationMetadataData *EphemeralNamedRelationMetadata;
  45
  46 /*
  47  * Ephemeral Named Relation data; used for parsing named relations not in the
  48  * catalog, like transition tables in AFTER triggers.
  49  */
  50 typedef struct EphemeralNamedRelationData
  51 {
  52         EphemeralNamedRelationMetadataData md;
  53         void       *reldata;            /* structure for execution-time access to data */
  54 } EphemeralNamedRelationData;
  55
  56 typedef EphemeralNamedRelationData *EphemeralNamedRelation;
  57
  58 /*
  59  * This is an opaque structure outside of queryenvironment.c itself.  The
  60  * intention is to be able to change the implementation or add new context
  61  * features without needing to change existing code for use of existing
  62  * features.
  63  */
  64 typedef struct QueryEnvironment QueryEnvironment;
  65
  66
  67 extern QueryEnvironment *create_queryEnv(void);
  68 extern EphemeralNamedRelationMetadata get_visible_ENR_metadata(QueryEnvironment *queryEnv, const char *refname);
  69 extern void register_ENR(QueryEnvironment *queryEnv, EphemeralNamedRelation enr);
  70 extern void unregister_ENR(QueryEnvironment *queryEnv, const char *name);
  71 extern EphemeralNamedRelation get_ENR(QueryEnvironment *queryEnv, const char *name);
  72 extern TupleDesc ENRMetadataGetTupDesc(EphemeralNamedRelationMetadata enrmd);
  73
  74 #endif                                                  /* QUERYENVIRONMENT_H */