rel.h

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/*-------------------------------------------------------------------------
 *
 * rel.h
 *    POSTGRES relation descriptor (a/k/a relcache entry) definitions.
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/utils/rel.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef REL_H
#define REL_H
 
#include "access/tupdesc.h"
#include "access/xlog.h"
#include "catalog/catalog.h"
#include "catalog/pg_class.h"
#include "catalog/pg_index.h"
#include "catalog/pg_publication.h"
#include "nodes/bitmapset.h"
#include "partitioning/partdefs.h"
#include "rewrite/prs2lock.h"
#include "storage/block.h"
#include "storage/relfilelocator.h"
#include "storage/smgr.h"
#include "utils/relcache.h"
#include "utils/reltrigger.h"
 
 
/*
 * LockRelId and LockInfo really belong to lmgr.h, but it's more convenient
 * to declare them here so we can have a LockInfoData field in a Relation.
 */
 
typedef struct LockRelId
{
    Oid         relId;          /* a relation identifier */
    Oid         dbId;           /* a database identifier */
} LockRelId;
 
typedef struct LockInfoData
{
    LockRelId   lockRelId;
} LockInfoData;
 
typedef LockInfoData *LockInfo;
 
/*
 * Here are the contents of a relation cache entry.
 */
 
typedef struct RelationData
{
    RelFileLocator rd_locator;  /* relation physical identifier */
    SMgrRelation rd_smgr;       /* cached file handle, or NULL */
    int         rd_refcnt;      /* reference count */
    ProcNumber  rd_backend;     /* owning backend's proc number, if temp rel */
    bool        rd_islocaltemp; /* rel is a temp rel of this session */
    bool        rd_isnailed;    /* rel is nailed in cache */
    bool        rd_isvalid;     /* relcache entry is valid */
    bool        rd_indexvalid;  /* is rd_indexlist valid? (also rd_pkindex and
                                 * rd_replidindex) */
    bool        rd_statvalid;   /* is rd_statlist valid? */
 
    /*----------
     * rd_createSubid is the ID of the highest subtransaction the rel has
     * survived into or zero if the rel or its storage was created before the
     * current top transaction.  (IndexStmt.oldNumber leads to the case of a new
     * rel with an old rd_locator.)  rd_firstRelfilelocatorSubid is the ID of the
     * highest subtransaction an rd_locator change has survived into or zero if
     * rd_locator matches the value it had at the start of the current top
     * transaction.  (Rolling back the subtransaction that
     * rd_firstRelfilelocatorSubid denotes would restore rd_locator to the value it
     * had at the start of the current top transaction.  Rolling back any
     * lower subtransaction would not.)  Their accuracy is critical to
     * RelationNeedsWAL().
     *
     * rd_newRelfilelocatorSubid is the ID of the highest subtransaction the
     * most-recent relfilenumber change has survived into or zero if not changed
     * in the current transaction (or we have forgotten changing it).  This
     * field is accurate when non-zero, but it can be zero when a relation has
     * multiple new relfilenumbers within a single transaction, with one of them
     * occurring in a subsequently aborted subtransaction, e.g.
     *      BEGIN;
     *      TRUNCATE t;
     *      SAVEPOINT save;
     *      TRUNCATE t;
     *      ROLLBACK TO save;
     *      -- rd_newRelfilelocatorSubid is now forgotten
     *
     * If every rd_*Subid field is zero, they are read-only outside
     * relcache.c.  Files that trigger rd_locator changes by updating
     * pg_class.reltablespace and/or pg_class.relfilenode call
     * RelationAssumeNewRelfilelocator() to update rd_*Subid.
     *
     * rd_droppedSubid is the ID of the highest subtransaction that a drop of
     * the rel has survived into.  In entries visible outside relcache.c, this
     * is always zero.
     */
    SubTransactionId rd_createSubid;    /* rel was created in current xact */
    SubTransactionId rd_newRelfilelocatorSubid; /* highest subxact changing
                                                 * rd_locator to current value */
    SubTransactionId rd_firstRelfilelocatorSubid;   /* highest subxact
                                                     * changing rd_locator to
                                                     * any value */
    SubTransactionId rd_droppedSubid;   /* dropped with another Subid set */
 
    Form_pg_class rd_rel;       /* RELATION tuple */
    TupleDesc   rd_att;         /* tuple descriptor */
    Oid         rd_id;          /* relation's object id */
    LockInfoData rd_lockInfo;   /* lock mgr's info for locking relation */
    RuleLock   *rd_rules;       /* rewrite rules */
    MemoryContext rd_rulescxt;  /* private memory cxt for rd_rules, if any */
    TriggerDesc *trigdesc;      /* Trigger info, or NULL if rel has none */
    /* use "struct" here to avoid needing to include rowsecurity.h: */
    struct RowSecurityDesc *rd_rsdesc;  /* row security policies, or NULL */
 
    /* data managed by RelationGetFKeyList: */
    List       *rd_fkeylist;    /* list of ForeignKeyCacheInfo (see below) */
    bool        rd_fkeyvalid;   /* true if list has been computed */
 
    /* data managed by RelationGetPartitionKey: */
    PartitionKey rd_partkey;    /* partition key, or NULL */
    MemoryContext rd_partkeycxt;    /* private context for rd_partkey, if any */
 
    /* data managed by RelationGetPartitionDesc: */
    PartitionDesc rd_partdesc;  /* partition descriptor, or NULL */
    MemoryContext rd_pdcxt;     /* private context for rd_partdesc, if any */
 
    /* Same as above, for partdescs that omit detached partitions */
    PartitionDesc rd_partdesc_nodetached;   /* partdesc w/o detached parts */
    MemoryContext rd_pddcxt;    /* for rd_partdesc_nodetached, if any */
 
    /*
     * pg_inherits.xmin of the partition that was excluded in
     * rd_partdesc_nodetached.  This informs a future user of that partdesc:
     * if this value is not in progress for the active snapshot, then the
     * partdesc can be used, otherwise they have to build a new one.  (This
     * matches what find_inheritance_children_extended would do).
     */
    TransactionId rd_partdesc_nodetached_xmin;
 
    /* data managed by RelationGetPartitionQual: */
    List       *rd_partcheck;   /* partition CHECK quals */
    bool        rd_partcheckvalid;  /* true if list has been computed */
    MemoryContext rd_partcheckcxt;  /* private cxt for rd_partcheck, if any */
 
    /* data managed by RelationGetIndexList: */
    List       *rd_indexlist;   /* list of OIDs of indexes on relation */
    Oid         rd_pkindex;     /* OID of (deferrable?) primary key, if any */
    bool        rd_ispkdeferrable;  /* is rd_pkindex a deferrable PK? */
    Oid         rd_replidindex; /* OID of replica identity index, if any */
 
    /* data managed by RelationGetStatExtList: */
    List       *rd_statlist;    /* list of OIDs of extended stats */
 
    /* data managed by RelationGetIndexAttrBitmap: */
    bool        rd_attrsvalid;  /* are bitmaps of attrs valid? */
    Bitmapset  *rd_keyattr;     /* cols that can be ref'd by foreign keys */
    Bitmapset  *rd_pkattr;      /* cols included in primary key */
    Bitmapset  *rd_idattr;      /* included in replica identity index */
    Bitmapset  *rd_hotblockingattr; /* cols blocking HOT update */
    Bitmapset  *rd_summarizedattr;  /* cols indexed by summarizing indexes */
 
    PublicationDesc *rd_pubdesc;    /* publication descriptor, or NULL */
 
    /*
     * rd_options is set whenever rd_rel is loaded into the relcache entry.
     * Note that you can NOT look into rd_rel for this data.  NULL means "use
     * defaults".
     */
    bytea      *rd_options;     /* parsed pg_class.reloptions */
 
    /*
     * Oid of the handler for this relation. For an index this is a function
     * returning IndexAmRoutine, for table like relations a function returning
     * TableAmRoutine.  This is stored separately from rd_indam, rd_tableam as
     * its lookup requires syscache access, but during relcache bootstrap we
     * need to be able to initialize rd_tableam without syscache lookups.
     */
    Oid         rd_amhandler;   /* OID of index AM's handler function */
 
    /*
     * Table access method.
     */
    const struct TableAmRoutine *rd_tableam;
 
    /* These are non-NULL only for an index relation: */
    Form_pg_index rd_index;     /* pg_index tuple describing this index */
    /* use "struct" here to avoid needing to include htup.h: */
    struct HeapTupleData *rd_indextuple;    /* all of pg_index tuple */
 
    /*
     * index access support info (used only for an index relation)
     *
     * Note: only default support procs for each opclass are cached, namely
     * those with lefttype and righttype equal to the opclass's opcintype. The
     * arrays are indexed by support function number, which is a sufficient
     * identifier given that restriction.
     */
    MemoryContext rd_indexcxt;  /* private memory cxt for this stuff */
    /* use "struct" here to avoid needing to include amapi.h: */
    struct IndexAmRoutine *rd_indam;    /* index AM's API struct */
    Oid        *rd_opfamily;    /* OIDs of op families for each index col */
    Oid        *rd_opcintype;   /* OIDs of opclass declared input data types */
    RegProcedure *rd_support;   /* OIDs of support procedures */
    struct FmgrInfo *rd_supportinfo;    /* lookup info for support procedures */
    int16      *rd_indoption;   /* per-column AM-specific flags */
    List       *rd_indexprs;    /* index expression trees, if any */
    List       *rd_indpred;     /* index predicate tree, if any */
    Oid        *rd_exclops;     /* OIDs of exclusion operators, if any */
    Oid        *rd_exclprocs;   /* OIDs of exclusion ops' procs, if any */
    uint16     *rd_exclstrats;  /* exclusion ops' strategy numbers, if any */
    Oid        *rd_indcollation;    /* OIDs of index collations */
    bytea     **rd_opcoptions;  /* parsed opclass-specific options */
 
    /*
     * rd_amcache is available for index and table AMs to cache private data
     * about the relation.  This must be just a cache since it may get reset
     * at any time (in particular, it will get reset by a relcache inval
     * message for the relation).  If used, it must point to a single memory
     * chunk palloc'd in CacheMemoryContext, or in rd_indexcxt for an index
     * relation.  A relcache reset will include freeing that chunk and setting
     * rd_amcache = NULL.
     */
    void       *rd_amcache;     /* available for use by index/table AM */
 
    /*
     * foreign-table support
     *
     * rd_fdwroutine must point to a single memory chunk palloc'd in
     * CacheMemoryContext.  It will be freed and reset to NULL on a relcache
     * reset.
     */
 
    /* use "struct" here to avoid needing to include fdwapi.h: */
    struct FdwRoutine *rd_fdwroutine;   /* cached function pointers, or NULL */
 
    /*
     * Hack for CLUSTER, rewriting ALTER TABLE, etc: when writing a new
     * version of a table, we need to make any toast pointers inserted into it
     * have the existing toast table's OID, not the OID of the transient toast
     * table.  If rd_toastoid isn't InvalidOid, it is the OID to place in
     * toast pointers inserted into this rel.  (Note it's set on the new
     * version of the main heap, not the toast table itself.)  This also
     * causes toast_save_datum() to try to preserve toast value OIDs.
     */
    Oid         rd_toastoid;    /* Real TOAST table's OID, or InvalidOid */
 
    bool        pgstat_enabled; /* should relation stats be counted */
    /* use "struct" here to avoid needing to include pgstat.h: */
    struct PgStat_TableStatus *pgstat_info; /* statistics collection area */
} RelationData;
 
 
/*
 * ForeignKeyCacheInfo
 *      Information the relcache can cache about foreign key constraints
 *
 * This is basically just an image of relevant columns from pg_constraint.
 * We make it a subclass of Node so that copyObject() can be used on a list
 * of these, but we also ensure it is a "flat" object without substructure,
 * so that list_free_deep() is sufficient to free such a list.
 * The per-FK-column arrays can be fixed-size because we allow at most
 * INDEX_MAX_KEYS columns in a foreign key constraint.
 *
 * Currently, we mostly cache fields of interest to the planner, but the set
 * of fields has already grown the constraint OID for other uses.
 */
typedef struct ForeignKeyCacheInfo
{
    pg_node_attr(no_equal, no_read, no_query_jumble)
 
    NodeTag     type;
    /* oid of the constraint itself */
    Oid         conoid;
    /* relation constrained by the foreign key */
    Oid         conrelid;
    /* relation referenced by the foreign key */
    Oid         confrelid;
    /* number of columns in the foreign key */
    int         nkeys;
 
    /* Is enforced ? */
    bool        conenforced;
 
    /*
     * these arrays each have nkeys valid entries:
     */
    /* cols in referencing table */
    AttrNumber  conkey[INDEX_MAX_KEYS] pg_node_attr(array_size(nkeys));
    /* cols in referenced table */
    AttrNumber  confkey[INDEX_MAX_KEYS] pg_node_attr(array_size(nkeys));
    /* PK = FK operator OIDs */
    Oid         conpfeqop[INDEX_MAX_KEYS] pg_node_attr(array_size(nkeys));
} ForeignKeyCacheInfo;
 
 
/*
 * StdRdOptions
 *      Standard contents of rd_options for heaps.
 *
 * RelationGetFillFactor() and RelationGetTargetPageFreeSpace() can only
 * be applied to relations that use this format or a superset for
 * private options data.
 */
 /* autovacuum-related reloptions. */
typedef struct AutoVacOpts
{
    bool        enabled;
    int         vacuum_threshold;
    int         vacuum_max_threshold;
    int         vacuum_ins_threshold;
    int         analyze_threshold;
    int         vacuum_cost_limit;
    int         freeze_min_age;
    int         freeze_max_age;
    int         freeze_table_age;
    int         multixact_freeze_min_age;
    int         multixact_freeze_max_age;
    int         multixact_freeze_table_age;
    int         log_min_duration;
    float8      vacuum_cost_delay;
    float8      vacuum_scale_factor;
    float8      vacuum_ins_scale_factor;
    float8      analyze_scale_factor;
} AutoVacOpts;
 
/* StdRdOptions->vacuum_index_cleanup values */
typedef enum StdRdOptIndexCleanup
{
    STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO = 0,
    STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF,
    STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON,
} StdRdOptIndexCleanup;
 
typedef struct StdRdOptions
{
    int32       vl_len_;        /* varlena header (do not touch directly!) */
    int         fillfactor;     /* page fill factor in percent (0..100) */
    int         toast_tuple_target; /* target for tuple toasting */
    AutoVacOpts autovacuum;     /* autovacuum-related options */
    bool        user_catalog_table; /* use as an additional catalog relation */
    int         parallel_workers;   /* max number of parallel workers */
    StdRdOptIndexCleanup vacuum_index_cleanup;  /* controls index vacuuming */
    bool        vacuum_truncate;    /* enables vacuum to truncate a relation */
    bool        vacuum_truncate_set;    /* whether vacuum_truncate is set */
 
    /*
     * Fraction of pages in a relation that vacuum can eagerly scan and fail
     * to freeze. 0 if disabled, -1 if unspecified.
     */
    double      vacuum_max_eager_freeze_failure_rate;
} StdRdOptions;
 
#define HEAP_MIN_FILLFACTOR         10
#define HEAP_DEFAULT_FILLFACTOR     100
 
/*
 * RelationGetToastTupleTarget
 *      Returns the relation's toast_tuple_target.  Note multiple eval of argument!
 */
#define RelationGetToastTupleTarget(relation, defaulttarg) \
    ((relation)->rd_options ? \
     ((StdRdOptions *) (relation)->rd_options)->toast_tuple_target : (defaulttarg))
 
/*
 * RelationGetFillFactor
 *      Returns the relation's fillfactor.  Note multiple eval of argument!
 */
#define RelationGetFillFactor(relation, defaultff) \
    ((relation)->rd_options ? \
     ((StdRdOptions *) (relation)->rd_options)->fillfactor : (defaultff))
 
/*
 * RelationGetTargetPageUsage
 *      Returns the relation's desired space usage per page in bytes.
 */
#define RelationGetTargetPageUsage(relation, defaultff) \
    (BLCKSZ * RelationGetFillFactor(relation, defaultff) / 100)
 
/*
 * RelationGetTargetPageFreeSpace
 *      Returns the relation's desired freespace per page in bytes.
 */
#define RelationGetTargetPageFreeSpace(relation, defaultff) \
    (BLCKSZ * (100 - RelationGetFillFactor(relation, defaultff)) / 100)
 
/*
 * RelationIsUsedAsCatalogTable
 *      Returns whether the relation should be treated as a catalog table
 *      from the pov of logical decoding.  Note multiple eval of argument!
 */
#define RelationIsUsedAsCatalogTable(relation)  \
    ((relation)->rd_options && \
     ((relation)->rd_rel->relkind == RELKIND_RELATION || \
      (relation)->rd_rel->relkind == RELKIND_MATVIEW) ? \
     ((StdRdOptions *) (relation)->rd_options)->user_catalog_table : false)
 
/*
 * RelationGetParallelWorkers
 *      Returns the relation's parallel_workers reloption setting.
 *      Note multiple eval of argument!
 */
#define RelationGetParallelWorkers(relation, defaultpw) \
    ((relation)->rd_options ? \
     ((StdRdOptions *) (relation)->rd_options)->parallel_workers : (defaultpw))
 
/* ViewOptions->check_option values */
typedef enum ViewOptCheckOption
{
    VIEW_OPTION_CHECK_OPTION_NOT_SET,
    VIEW_OPTION_CHECK_OPTION_LOCAL,
    VIEW_OPTION_CHECK_OPTION_CASCADED,
} ViewOptCheckOption;
 
/*
 * ViewOptions
 *      Contents of rd_options for views
 */
typedef struct ViewOptions
{
    int32       vl_len_;        /* varlena header (do not touch directly!) */
    bool        security_barrier;
    bool        security_invoker;
    ViewOptCheckOption check_option;
} ViewOptions;
 
/*
 * RelationIsSecurityView
 *      Returns whether the relation is security view, or not.  Note multiple
 *      eval of argument!
 */
#define RelationIsSecurityView(relation)                                    \
    (AssertMacro(relation->rd_rel->relkind == RELKIND_VIEW),                \
     (relation)->rd_options ?                                               \
      ((ViewOptions *) (relation)->rd_options)->security_barrier : false)
 
/*
 * RelationHasSecurityInvoker
 *      Returns true if the relation has the security_invoker property set.
 *      Note multiple eval of argument!
 */
#define RelationHasSecurityInvoker(relation)                                \
    (AssertMacro(relation->rd_rel->relkind == RELKIND_VIEW),                \
     (relation)->rd_options ?                                               \
      ((ViewOptions *) (relation)->rd_options)->security_invoker : false)
 
/*
 * RelationHasCheckOption
 *      Returns true if the relation is a view defined with either the local
 *      or the cascaded check option.  Note multiple eval of argument!
 */
#define RelationHasCheckOption(relation)                                    \
    (AssertMacro(relation->rd_rel->relkind == RELKIND_VIEW),                \
     (relation)->rd_options &&                                              \
     ((ViewOptions *) (relation)->rd_options)->check_option !=              \
     VIEW_OPTION_CHECK_OPTION_NOT_SET)
 
/*
 * RelationHasLocalCheckOption
 *      Returns true if the relation is a view defined with the local check
 *      option.  Note multiple eval of argument!
 */
#define RelationHasLocalCheckOption(relation)                               \
    (AssertMacro(relation->rd_rel->relkind == RELKIND_VIEW),                \
     (relation)->rd_options &&                                              \
     ((ViewOptions *) (relation)->rd_options)->check_option ==              \
     VIEW_OPTION_CHECK_OPTION_LOCAL)
 
/*
 * RelationHasCascadedCheckOption
 *      Returns true if the relation is a view defined with the cascaded check
 *      option.  Note multiple eval of argument!
 */
#define RelationHasCascadedCheckOption(relation)                            \
    (AssertMacro(relation->rd_rel->relkind == RELKIND_VIEW),                \
     (relation)->rd_options &&                                              \
     ((ViewOptions *) (relation)->rd_options)->check_option ==              \
      VIEW_OPTION_CHECK_OPTION_CASCADED)
 
/*
 * RelationIsValid
 *      True iff relation descriptor is valid.
 */
#define RelationIsValid(relation) ((relation) != NULL)
 
/*
 * RelationHasReferenceCountZero
 *      True iff relation reference count is zero.
 *
 * Note:
 *      Assumes relation descriptor is valid.
 */
#define RelationHasReferenceCountZero(relation) \
        ((bool)((relation)->rd_refcnt == 0))
 
/*
 * RelationGetForm
 *      Returns pg_class tuple for a relation.
 *
 * Note:
 *      Assumes relation descriptor is valid.
 */
#define RelationGetForm(relation) ((relation)->rd_rel)
 
/*
 * RelationGetRelid
 *      Returns the OID of the relation
 */
#define RelationGetRelid(relation) ((relation)->rd_id)
 
/*
 * RelationGetNumberOfAttributes
 *      Returns the total number of attributes in a relation.
 */
#define RelationGetNumberOfAttributes(relation) ((relation)->rd_rel->relnatts)
 
/*
 * IndexRelationGetNumberOfAttributes
 *      Returns the number of attributes in an index.
 */
#define IndexRelationGetNumberOfAttributes(relation) \
        ((relation)->rd_index->indnatts)
 
/*
 * IndexRelationGetNumberOfKeyAttributes
 *      Returns the number of key attributes in an index.
 */
#define IndexRelationGetNumberOfKeyAttributes(relation) \
        ((relation)->rd_index->indnkeyatts)
 
/*
 * RelationGetDescr
 *      Returns tuple descriptor for a relation.
 */
#define RelationGetDescr(relation) ((relation)->rd_att)
 
/*
 * RelationGetRelationName
 *      Returns the rel's name.
 *
 * Note that the name is only unique within the containing namespace.
 */
#define RelationGetRelationName(relation) \
    (NameStr((relation)->rd_rel->relname))
 
/*
 * RelationGetNamespace
 *      Returns the rel's namespace OID.
 */
#define RelationGetNamespace(relation) \
    ((relation)->rd_rel->relnamespace)
 
/*
 * RelationIsMapped
 *      True if the relation uses the relfilenumber map.  Note multiple eval
 *      of argument!
 */
#define RelationIsMapped(relation) \
    (RELKIND_HAS_STORAGE((relation)->rd_rel->relkind) && \
     ((relation)->rd_rel->relfilenode == InvalidRelFileNumber))
 
#ifndef FRONTEND
/*
 * RelationGetSmgr
 *      Returns smgr file handle for a relation, opening it if needed.
 *
 * Very little code is authorized to touch rel->rd_smgr directly.  Instead
 * use this function to fetch its value.
 */
static inline SMgrRelation
RelationGetSmgr(Relation rel)
{
    if (unlikely(rel->rd_smgr == NULL))
    {
        rel->rd_smgr = smgropen(rel->rd_locator, rel->rd_backend);
        smgrpin(rel->rd_smgr);
    }
    return rel->rd_smgr;
}
 
/*
 * RelationCloseSmgr
 *      Close the relation at the smgr level, if not already done.
 */
static inline void
RelationCloseSmgr(Relation relation)
{
    if (relation->rd_smgr != NULL)
    {
        smgrunpin(relation->rd_smgr);
        smgrclose(relation->rd_smgr);
        relation->rd_smgr = NULL;
    }
}
#endif                          /* !FRONTEND */
 
/*
 * RelationGetTargetBlock
 *      Fetch relation's current insertion target block.
 *
 * Returns InvalidBlockNumber if there is no current target block.  Note
 * that the target block status is discarded on any smgr-level invalidation,
 * so there's no need to re-open the smgr handle if it's not currently open.
 */
#define RelationGetTargetBlock(relation) \
    ( (relation)->rd_smgr != NULL ? (relation)->rd_smgr->smgr_targblock : InvalidBlockNumber )
 
/*
 * RelationSetTargetBlock
 *      Set relation's current insertion target block.
 */
#define RelationSetTargetBlock(relation, targblock) \
    do { \
        RelationGetSmgr(relation)->smgr_targblock = (targblock); \
    } while (0)
 
/*
 * RelationIsPermanent
 *      True if relation is permanent.
 */
#define RelationIsPermanent(relation) \
    ((relation)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT)
 
/*
 * RelationNeedsWAL
 *      True if relation needs WAL.
 *
 * Returns false if wal_level = minimal and this relation is created or
 * truncated in the current transaction.  See "Skipping WAL for New
 * RelFileLocator" in src/backend/access/transam/README.
 */
#define RelationNeedsWAL(relation)                                      \
    (RelationIsPermanent(relation) && (XLogIsNeeded() ||                \
      (relation->rd_createSubid == InvalidSubTransactionId &&           \
       relation->rd_firstRelfilelocatorSubid == InvalidSubTransactionId)))
 
/*
 * RelationUsesLocalBuffers
 *      True if relation's pages are stored in local buffers.
 */
#define RelationUsesLocalBuffers(relation) \
    ((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP)
 
/*
 * RELATION_IS_LOCAL
 *      If a rel is either temp or newly created in the current transaction,
 *      it can be assumed to be accessible only to the current backend.
 *      This is typically used to decide that we can skip acquiring locks.
 *
 * Beware of multiple eval of argument
 */
#define RELATION_IS_LOCAL(relation) \
    ((relation)->rd_islocaltemp || \
     (relation)->rd_createSubid != InvalidSubTransactionId)
 
/*
 * RELATION_IS_OTHER_TEMP
 *      Test for a temporary relation that belongs to some other session.
 *
 * Beware of multiple eval of argument
 */
#define RELATION_IS_OTHER_TEMP(relation) \
    ((relation)->rd_rel->relpersistence == RELPERSISTENCE_TEMP && \
     !(relation)->rd_islocaltemp)
 
 
/*
 * RelationIsScannable
 *      Currently can only be false for a materialized view which has not been
 *      populated by its query.  This is likely to get more complicated later,
 *      so use a macro which looks like a function.
 */
#define RelationIsScannable(relation) ((relation)->rd_rel->relispopulated)
 
/*
 * RelationIsPopulated
 *      Currently, we don't physically distinguish the "populated" and
 *      "scannable" properties of matviews, but that may change later.
 *      Hence, use the appropriate one of these macros in code tests.
 */
#define RelationIsPopulated(relation) ((relation)->rd_rel->relispopulated)
 
/*
 * RelationIsAccessibleInLogicalDecoding
 *      True if we need to log enough information to have access via
 *      decoding snapshot.
 */
#define RelationIsAccessibleInLogicalDecoding(relation) \
    (XLogLogicalInfoActive() && \
     RelationNeedsWAL(relation) && \
     (IsCatalogRelation(relation) || RelationIsUsedAsCatalogTable(relation)))
 
/*
 * RelationIsLogicallyLogged
 *      True if we need to log enough information to extract the data from the
 *      WAL stream.
 *
 * We don't log information for unlogged tables (since they don't WAL log
 * anyway), for foreign tables (since they don't WAL log, either),
 * and for system tables (their content is hard to make sense of, and
 * it would complicate decoding slightly for little gain). Note that we *do*
 * log information for user defined catalog tables since they presumably are
 * interesting to the user...
 */
#define RelationIsLogicallyLogged(relation) \
    (XLogLogicalInfoActive() && \
     RelationNeedsWAL(relation) && \
     (relation)->rd_rel->relkind != RELKIND_FOREIGN_TABLE &&    \
     !IsCatalogRelation(relation))
 
/* routines in utils/cache/relcache.c */
extern void RelationIncrementReferenceCount(Relation rel);
extern void RelationDecrementReferenceCount(Relation rel);
 
#endif                          /* REL_H */