Adding upstream version 16.2.upstream/16.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2100 insertions, 0 deletions

diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
new file mode 100644
index 0000000..ac7b279
--- /dev/null
+++ b/src/include/access/tableam.h
@@ -0,0 +1,2100 @@
+/*-------------------------------------------------------------------------
+ *
+ * tableam.h
+ *	  POSTGRES table access method definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/access/tableam.h
+ *
+ * NOTES
+ *		See tableam.sgml for higher level documentation.
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TABLEAM_H
+#define TABLEAM_H
+
+#include "access/relscan.h"
+#include "access/sdir.h"
+#include "access/xact.h"
+#include "executor/tuptable.h"
+#include "utils/rel.h"
+#include "utils/snapshot.h"
+
+
+#define DEFAULT_TABLE_ACCESS_METHOD	"heap"
+
+/* GUCs */
+extern PGDLLIMPORT char *default_table_access_method;
+extern PGDLLIMPORT bool synchronize_seqscans;
+
+
+struct BulkInsertStateData;
+struct IndexInfo;
+struct SampleScanState;
+struct TBMIterateResult;
+struct VacuumParams;
+struct ValidateIndexState;
+
+/*
+ * Bitmask values for the flags argument to the scan_begin callback.
+ */
+typedef enum ScanOptions
+{
+	/* one of SO_TYPE_* may be specified */
+	SO_TYPE_SEQSCAN = 1 << 0,
+	SO_TYPE_BITMAPSCAN = 1 << 1,
+	SO_TYPE_SAMPLESCAN = 1 << 2,
+	SO_TYPE_TIDSCAN = 1 << 3,
+	SO_TYPE_TIDRANGESCAN = 1 << 4,
+	SO_TYPE_ANALYZE = 1 << 5,
+
+	/* several of SO_ALLOW_* may be specified */
+	/* allow or disallow use of access strategy */
+	SO_ALLOW_STRAT = 1 << 6,
+	/* report location to syncscan logic? */
+	SO_ALLOW_SYNC = 1 << 7,
+	/* verify visibility page-at-a-time? */
+	SO_ALLOW_PAGEMODE = 1 << 8,
+
+	/* unregister snapshot at scan end? */
+	SO_TEMP_SNAPSHOT = 1 << 9
+} ScanOptions;
+
+/*
+ * Result codes for table_{update,delete,lock_tuple}, and for visibility
+ * routines inside table AMs.
+ */
+typedef enum TM_Result
+{
+	/*
+	 * Signals that the action succeeded (i.e. update/delete performed, lock
+	 * was acquired)
+	 */
+	TM_Ok,
+
+	/* The affected tuple wasn't visible to the relevant snapshot */
+	TM_Invisible,
+
+	/* The affected tuple was already modified by the calling backend */
+	TM_SelfModified,
+
+	/*
+	 * The affected tuple was updated by another transaction. This includes
+	 * the case where tuple was moved to another partition.
+	 */
+	TM_Updated,
+
+	/* The affected tuple was deleted by another transaction */
+	TM_Deleted,
+
+	/*
+	 * The affected tuple is currently being modified by another session. This
+	 * will only be returned if table_(update/delete/lock_tuple) are
+	 * instructed not to wait.
+	 */
+	TM_BeingModified,
+
+	/* lock couldn't be acquired, action skipped. Only used by lock_tuple */
+	TM_WouldBlock
+} TM_Result;
+
+/*
+ * Result codes for table_update(..., update_indexes*..).
+ * Used to determine which indexes to update.
+ */
+typedef enum TU_UpdateIndexes
+{
+	/* No indexed columns were updated (incl. TID addressing of tuple) */
+	TU_None,
+
+	/* A non-summarizing indexed column was updated, or the TID has changed */
+	TU_All,
+
+	/* Only summarized columns were updated, TID is unchanged */
+	TU_Summarizing
+} TU_UpdateIndexes;
+
+/*
+ * When table_tuple_update, table_tuple_delete, or table_tuple_lock fail
+ * because the target tuple is already outdated, they fill in this struct to
+ * provide information to the caller about what happened.
+ *
+ * ctid is the target's ctid link: it is the same as the target's TID if the
+ * target was deleted, or the location of the replacement tuple if the target
+ * was updated.
+ *
+ * xmax is the outdating transaction's XID.  If the caller wants to visit the
+ * replacement tuple, it must check that this matches before believing the
+ * replacement is really a match.
+ *
+ * cmax is the outdating command's CID, but only when the failure code is
+ * TM_SelfModified (i.e., something in the current transaction outdated the
+ * tuple); otherwise cmax is zero.  (We make this restriction because
+ * HeapTupleHeaderGetCmax doesn't work for tuples outdated in other
+ * transactions.)
+ */
+typedef struct TM_FailureData
+{
+	ItemPointerData ctid;
+	TransactionId xmax;
+	CommandId	cmax;
+	bool		traversed;
+} TM_FailureData;
+
+/*
+ * State used when calling table_index_delete_tuples().
+ *
+ * Represents the status of table tuples, referenced by table TID and taken by
+ * index AM from index tuples.  State consists of high level parameters of the
+ * deletion operation, plus two mutable palloc()'d arrays for information
+ * about the status of individual table tuples.  These are conceptually one
+ * single array.  Using two arrays keeps the TM_IndexDelete struct small,
+ * which makes sorting the first array (the deltids array) fast.
+ *
+ * Some index AM callers perform simple index tuple deletion (by specifying
+ * bottomup = false), and include only known-dead deltids.  These known-dead
+ * entries are all marked knowndeletable = true directly (typically these are
+ * TIDs from LP_DEAD-marked index tuples), but that isn't strictly required.
+ *
+ * Callers that specify bottomup = true are "bottom-up index deletion"
+ * callers.  The considerations for the tableam are more subtle with these
+ * callers because they ask the tableam to perform highly speculative work,
+ * and might only expect the tableam to check a small fraction of all entries.
+ * Caller is not allowed to specify knowndeletable = true for any entry
+ * because everything is highly speculative.  Bottom-up caller provides
+ * context and hints to tableam -- see comments below for details on how index
+ * AMs and tableams should coordinate during bottom-up index deletion.
+ *
+ * Simple index deletion callers may ask the tableam to perform speculative
+ * work, too.  This is a little like bottom-up deletion, but not too much.
+ * The tableam will only perform speculative work when it's practically free
+ * to do so in passing for simple deletion caller (while always performing
+ * whatever work is needed to enable knowndeletable/LP_DEAD index tuples to
+ * be deleted within index AM).  This is the real reason why it's possible for
+ * simple index deletion caller to specify knowndeletable = false up front
+ * (this means "check if it's possible for me to delete corresponding index
+ * tuple when it's cheap to do so in passing").  The index AM should only
+ * include "extra" entries for index tuples whose TIDs point to a table block
+ * that tableam is expected to have to visit anyway (in the event of a block
+ * orientated tableam).  The tableam isn't strictly obligated to check these
+ * "extra" TIDs, but a block-based AM should always manage to do so in
+ * practice.
+ *
+ * The final contents of the deltids/status arrays are interesting to callers
+ * that ask tableam to perform speculative work (i.e. when _any_ items have
+ * knowndeletable set to false up front).  These index AM callers will
+ * naturally need to consult final state to determine which index tuples are
+ * in fact deletable.
+ *
+ * The index AM can keep track of which index tuple relates to which deltid by
+ * setting idxoffnum (and/or relying on each entry being uniquely identifiable
+ * using tid), which is important when the final contents of the array will
+ * need to be interpreted -- the array can shrink from initial size after
+ * tableam processing and/or have entries in a new order (tableam may sort
+ * deltids array for its own reasons).  Bottom-up callers may find that final
+ * ndeltids is 0 on return from call to tableam, in which case no index tuple
+ * deletions are possible.  Simple deletion callers can rely on any entries
+ * they know to be deletable appearing in the final array as deletable.
+ */
+typedef struct TM_IndexDelete
+{
+	ItemPointerData tid;		/* table TID from index tuple */
+	int16		id;				/* Offset into TM_IndexStatus array */
+} TM_IndexDelete;
+
+typedef struct TM_IndexStatus
+{
+	OffsetNumber idxoffnum;		/* Index am page offset number */
+	bool		knowndeletable; /* Currently known to be deletable? */
+
+	/* Bottom-up index deletion specific fields follow */
+	bool		promising;		/* Promising (duplicate) index tuple? */
+	int16		freespace;		/* Space freed in index if deleted */
+} TM_IndexStatus;
+
+/*
+ * Index AM/tableam coordination is central to the design of bottom-up index
+ * deletion.  The index AM provides hints about where to look to the tableam
+ * by marking some entries as "promising".  Index AM does this with duplicate
+ * index tuples that are strongly suspected to be old versions left behind by
+ * UPDATEs that did not logically modify indexed values.  Index AM may find it
+ * helpful to only mark entries as promising when they're thought to have been
+ * affected by such an UPDATE in the recent past.
+ *
+ * Bottom-up index deletion casts a wide net at first, usually by including
+ * all TIDs on a target index page.  It is up to the tableam to worry about
+ * the cost of checking transaction status information.  The tableam is in
+ * control, but needs careful guidance from the index AM.  Index AM requests
+ * that bottomupfreespace target be met, while tableam measures progress
+ * towards that goal by tallying the per-entry freespace value for known
+ * deletable entries. (All !bottomup callers can just set these space related
+ * fields to zero.)
+ */
+typedef struct TM_IndexDeleteOp
+{
+	Relation	irel;			/* Target index relation */
+	BlockNumber iblknum;		/* Index block number (for error reports) */
+	bool		bottomup;		/* Bottom-up (not simple) deletion? */
+	int			bottomupfreespace;	/* Bottom-up space target */
+
+	/* Mutable per-TID information follows (index AM initializes entries) */
+	int			ndeltids;		/* Current # of deltids/status elements */
+	TM_IndexDelete *deltids;
+	TM_IndexStatus *status;
+} TM_IndexDeleteOp;
+
+/* "options" flag bits for table_tuple_insert */
+/* TABLE_INSERT_SKIP_WAL was 0x0001; RelationNeedsWAL() now governs */
+#define TABLE_INSERT_SKIP_FSM		0x0002
+#define TABLE_INSERT_FROZEN			0x0004
+#define TABLE_INSERT_NO_LOGICAL		0x0008
+
+/* flag bits for table_tuple_lock */
+/* Follow tuples whose update is in progress if lock modes don't conflict  */
+#define TUPLE_LOCK_FLAG_LOCK_UPDATE_IN_PROGRESS	(1 << 0)
+/* Follow update chain and lock latest version of tuple */
+#define TUPLE_LOCK_FLAG_FIND_LAST_VERSION		(1 << 1)
+
+
+/* Typedef for callback function for table_index_build_scan */
+typedef void (*IndexBuildCallback) (Relation index,
+									ItemPointer tid,
+									Datum *values,
+									bool *isnull,
+									bool tupleIsAlive,
+									void *state);
+
+/*
+ * API struct for a table AM.  Note this must be allocated in a
+ * server-lifetime manner, typically as a static const struct, which then gets
+ * returned by FormData_pg_am.amhandler.
+ *
+ * In most cases it's not appropriate to call the callbacks directly, use the
+ * table_* wrapper functions instead.
+ *
+ * GetTableAmRoutine() asserts that required callbacks are filled in, remember
+ * to update when adding a callback.
+ */
+typedef struct TableAmRoutine
+{
+	/* this must be set to T_TableAmRoutine */
+	NodeTag		type;
+
+
+	/* ------------------------------------------------------------------------
+	 * Slot related callbacks.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * Return slot implementation suitable for storing a tuple of this AM.
+	 */
+	const TupleTableSlotOps *(*slot_callbacks) (Relation rel);
+
+
+	/* ------------------------------------------------------------------------
+	 * Table scan callbacks.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * Start a scan of `rel`.  The callback has to return a TableScanDesc,
+	 * which will typically be embedded in a larger, AM specific, struct.
+	 *
+	 * If nkeys != 0, the results need to be filtered by those scan keys.
+	 *
+	 * pscan, if not NULL, will have already been initialized with
+	 * parallelscan_initialize(), and has to be for the same relation. Will
+	 * only be set coming from table_beginscan_parallel().
+	 *
+	 * `flags` is a bitmask indicating the type of scan (ScanOptions's
+	 * SO_TYPE_*, currently only one may be specified), options controlling
+	 * the scan's behaviour (ScanOptions's SO_ALLOW_*, several may be
+	 * specified, an AM may ignore unsupported ones) and whether the snapshot
+	 * needs to be deallocated at scan_end (ScanOptions's SO_TEMP_SNAPSHOT).
+	 */
+	TableScanDesc (*scan_begin) (Relation rel,
+								 Snapshot snapshot,
+								 int nkeys, struct ScanKeyData *key,
+								 ParallelTableScanDesc pscan,
+								 uint32 flags);
+
+	/*
+	 * Release resources and deallocate scan. If TableScanDesc.temp_snap,
+	 * TableScanDesc.rs_snapshot needs to be unregistered.
+	 */
+	void		(*scan_end) (TableScanDesc scan);
+
+	/*
+	 * Restart relation scan.  If set_params is set to true, allow_{strat,
+	 * sync, pagemode} (see scan_begin) changes should be taken into account.
+	 */
+	void		(*scan_rescan) (TableScanDesc scan, struct ScanKeyData *key,
+								bool set_params, bool allow_strat,
+								bool allow_sync, bool allow_pagemode);
+
+	/*
+	 * Return next tuple from `scan`, store in slot.
+	 */
+	bool		(*scan_getnextslot) (TableScanDesc scan,
+									 ScanDirection direction,
+									 TupleTableSlot *slot);
+
+	/*-----------
+	 * Optional functions to provide scanning for ranges of ItemPointers.
+	 * Implementations must either provide both of these functions, or neither
+	 * of them.
+	 *
+	 * Implementations of scan_set_tidrange must themselves handle
+	 * ItemPointers of any value. i.e, they must handle each of the following:
+	 *
+	 * 1) mintid or maxtid is beyond the end of the table; and
+	 * 2) mintid is above maxtid; and
+	 * 3) item offset for mintid or maxtid is beyond the maximum offset
+	 * allowed by the AM.
+	 *
+	 * Implementations can assume that scan_set_tidrange is always called
+	 * before scan_getnextslot_tidrange or after scan_rescan and before any
+	 * further calls to scan_getnextslot_tidrange.
+	 */
+	void		(*scan_set_tidrange) (TableScanDesc scan,
+									  ItemPointer mintid,
+									  ItemPointer maxtid);
+
+	/*
+	 * Return next tuple from `scan` that's in the range of TIDs defined by
+	 * scan_set_tidrange.
+	 */
+	bool		(*scan_getnextslot_tidrange) (TableScanDesc scan,
+											  ScanDirection direction,
+											  TupleTableSlot *slot);
+
+	/* ------------------------------------------------------------------------
+	 * Parallel table scan related functions.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * Estimate the size of shared memory needed for a parallel scan of this
+	 * relation. The snapshot does not need to be accounted for.
+	 */
+	Size		(*parallelscan_estimate) (Relation rel);
+
+	/*
+	 * Initialize ParallelTableScanDesc for a parallel scan of this relation.
+	 * `pscan` will be sized according to parallelscan_estimate() for the same
+	 * relation.
+	 */
+	Size		(*parallelscan_initialize) (Relation rel,
+											ParallelTableScanDesc pscan);
+
+	/*
+	 * Reinitialize `pscan` for a new scan. `rel` will be the same relation as
+	 * when `pscan` was initialized by parallelscan_initialize.
+	 */
+	void		(*parallelscan_reinitialize) (Relation rel,
+											  ParallelTableScanDesc pscan);
+
+
+	/* ------------------------------------------------------------------------
+	 * Index Scan Callbacks
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * Prepare to fetch tuples from the relation, as needed when fetching
+	 * tuples for an index scan.  The callback has to return an
+	 * IndexFetchTableData, which the AM will typically embed in a larger
+	 * structure with additional information.
+	 *
+	 * Tuples for an index scan can then be fetched via index_fetch_tuple.
+	 */
+	struct IndexFetchTableData *(*index_fetch_begin) (Relation rel);
+
+	/*
+	 * Reset index fetch. Typically this will release cross index fetch
+	 * resources held in IndexFetchTableData.
+	 */
+	void		(*index_fetch_reset) (struct IndexFetchTableData *data);
+
+	/*
+	 * Release resources and deallocate index fetch.
+	 */
+	void		(*index_fetch_end) (struct IndexFetchTableData *data);
+
+	/*
+	 * Fetch tuple at `tid` into `slot`, after doing a visibility test
+	 * according to `snapshot`. If a tuple was found and passed the visibility
+	 * test, return true, false otherwise.
+	 *
+	 * Note that AMs that do not necessarily update indexes when indexed
+	 * columns do not change, need to return the current/correct version of
+	 * the tuple that is visible to the snapshot, even if the tid points to an
+	 * older version of the tuple.
+	 *
+	 * *call_again is false on the first call to index_fetch_tuple for a tid.
+	 * If there potentially is another tuple matching the tid, *call_again
+	 * needs to be set to true by index_fetch_tuple, signaling to the caller
+	 * that index_fetch_tuple should be called again for the same tid.
+	 *
+	 * *all_dead, if all_dead is not NULL, should be set to true by
+	 * index_fetch_tuple iff it is guaranteed that no backend needs to see
+	 * that tuple. Index AMs can use that to avoid returning that tid in
+	 * future searches.
+	 */
+	bool		(*index_fetch_tuple) (struct IndexFetchTableData *scan,
+									  ItemPointer tid,
+									  Snapshot snapshot,
+									  TupleTableSlot *slot,
+									  bool *call_again, bool *all_dead);
+
+
+	/* ------------------------------------------------------------------------
+	 * Callbacks for non-modifying operations on individual tuples
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * Fetch tuple at `tid` into `slot`, after doing a visibility test
+	 * according to `snapshot`. If a tuple was found and passed the visibility
+	 * test, returns true, false otherwise.
+	 */
+	bool		(*tuple_fetch_row_version) (Relation rel,
+											ItemPointer tid,
+											Snapshot snapshot,
+											TupleTableSlot *slot);
+
+	/*
+	 * Is tid valid for a scan of this relation.
+	 */
+	bool		(*tuple_tid_valid) (TableScanDesc scan,
+									ItemPointer tid);
+
+	/*
+	 * Return the latest version of the tuple at `tid`, by updating `tid` to
+	 * point at the newest version.
+	 */
+	void		(*tuple_get_latest_tid) (TableScanDesc scan,
+										 ItemPointer tid);
+
+	/*
+	 * Does the tuple in `slot` satisfy `snapshot`?  The slot needs to be of
+	 * the appropriate type for the AM.
+	 */
+	bool		(*tuple_satisfies_snapshot) (Relation rel,
+											 TupleTableSlot *slot,
+											 Snapshot snapshot);
+
+	/* see table_index_delete_tuples() */
+	TransactionId (*index_delete_tuples) (Relation rel,
+										  TM_IndexDeleteOp *delstate);
+
+
+	/* ------------------------------------------------------------------------
+	 * Manipulations of physical tuples.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/* see table_tuple_insert() for reference about parameters */
+	void		(*tuple_insert) (Relation rel, TupleTableSlot *slot,
+								 CommandId cid, int options,
+								 struct BulkInsertStateData *bistate);
+
+	/* see table_tuple_insert_speculative() for reference about parameters */
+	void		(*tuple_insert_speculative) (Relation rel,
+											 TupleTableSlot *slot,
+											 CommandId cid,
+											 int options,
+											 struct BulkInsertStateData *bistate,
+											 uint32 specToken);
+
+	/* see table_tuple_complete_speculative() for reference about parameters */
+	void		(*tuple_complete_speculative) (Relation rel,
+											   TupleTableSlot *slot,
+											   uint32 specToken,
+											   bool succeeded);
+
+	/* see table_multi_insert() for reference about parameters */
+	void		(*multi_insert) (Relation rel, TupleTableSlot **slots, int nslots,
+								 CommandId cid, int options, struct BulkInsertStateData *bistate);
+
+	/* see table_tuple_delete() for reference about parameters */
+	TM_Result	(*tuple_delete) (Relation rel,
+								 ItemPointer tid,
+								 CommandId cid,
+								 Snapshot snapshot,
+								 Snapshot crosscheck,
+								 bool wait,
+								 TM_FailureData *tmfd,
+								 bool changingPart);
+
+	/* see table_tuple_update() for reference about parameters */
+	TM_Result	(*tuple_update) (Relation rel,
+								 ItemPointer otid,
+								 TupleTableSlot *slot,
+								 CommandId cid,
+								 Snapshot snapshot,
+								 Snapshot crosscheck,
+								 bool wait,
+								 TM_FailureData *tmfd,
+								 LockTupleMode *lockmode,
+								 TU_UpdateIndexes *update_indexes);
+
+	/* see table_tuple_lock() for reference about parameters */
+	TM_Result	(*tuple_lock) (Relation rel,
+							   ItemPointer tid,
+							   Snapshot snapshot,
+							   TupleTableSlot *slot,
+							   CommandId cid,
+							   LockTupleMode mode,
+							   LockWaitPolicy wait_policy,
+							   uint8 flags,
+							   TM_FailureData *tmfd);
+
+	/*
+	 * Perform operations necessary to complete insertions made via
+	 * tuple_insert and multi_insert with a BulkInsertState specified. In-tree
+	 * access methods ceased to use this.
+	 *
+	 * Typically callers of tuple_insert and multi_insert will just pass all
+	 * the flags that apply to them, and each AM has to decide which of them
+	 * make sense for it, and then only take actions in finish_bulk_insert for
+	 * those flags, and ignore others.
+	 *
+	 * Optional callback.
+	 */
+	void		(*finish_bulk_insert) (Relation rel, int options);
+
+
+	/* ------------------------------------------------------------------------
+	 * DDL related functionality.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * This callback needs to create new relation storage for `rel`, with
+	 * appropriate durability behaviour for `persistence`.
+	 *
+	 * Note that only the subset of the relcache filled by
+	 * RelationBuildLocalRelation() can be relied upon and that the relation's
+	 * catalog entries will either not yet exist (new relation), or will still
+	 * reference the old relfilelocator.
+	 *
+	 * As output *freezeXid, *minmulti must be set to the values appropriate
+	 * for pg_class.{relfrozenxid, relminmxid}. For AMs that don't need those
+	 * fields to be filled they can be set to InvalidTransactionId and
+	 * InvalidMultiXactId, respectively.
+	 *
+	 * See also table_relation_set_new_filelocator().
+	 */
+	void		(*relation_set_new_filelocator) (Relation rel,
+												 const RelFileLocator *newrlocator,
+												 char persistence,
+												 TransactionId *freezeXid,
+												 MultiXactId *minmulti);
+
+	/*
+	 * This callback needs to remove all contents from `rel`'s current
+	 * relfilelocator. No provisions for transactional behaviour need to be
+	 * made.  Often this can be implemented by truncating the underlying
+	 * storage to its minimal size.
+	 *
+	 * See also table_relation_nontransactional_truncate().
+	 */
+	void		(*relation_nontransactional_truncate) (Relation rel);
+
+	/*
+	 * See table_relation_copy_data().
+	 *
+	 * This can typically be implemented by directly copying the underlying
+	 * storage, unless it contains references to the tablespace internally.
+	 */
+	void		(*relation_copy_data) (Relation rel,
+									   const RelFileLocator *newrlocator);
+
+	/* See table_relation_copy_for_cluster() */
+	void		(*relation_copy_for_cluster) (Relation NewTable,
+											  Relation OldTable,
+											  Relation OldIndex,
+											  bool use_sort,
+											  TransactionId OldestXmin,
+											  TransactionId *xid_cutoff,
+											  MultiXactId *multi_cutoff,
+											  double *num_tuples,
+											  double *tups_vacuumed,
+											  double *tups_recently_dead);
+
+	/*
+	 * React to VACUUM command on the relation. The VACUUM can be triggered by
+	 * a user or by autovacuum. The specific actions performed by the AM will
+	 * depend heavily on the individual AM.
+	 *
+	 * On entry a transaction is already established, and the relation is
+	 * locked with a ShareUpdateExclusive lock.
+	 *
+	 * Note that neither VACUUM FULL (and CLUSTER), nor ANALYZE go through
+	 * this routine, even if (for ANALYZE) it is part of the same VACUUM
+	 * command.
+	 *
+	 * There probably, in the future, needs to be a separate callback to
+	 * integrate with autovacuum's scheduling.
+	 */
+	void		(*relation_vacuum) (Relation rel,
+									struct VacuumParams *params,
+									BufferAccessStrategy bstrategy);
+
+	/*
+	 * Prepare to analyze block `blockno` of `scan`. The scan has been started
+	 * with table_beginscan_analyze().  See also
+	 * table_scan_analyze_next_block().
+	 *
+	 * The callback may acquire resources like locks that are held until
+	 * table_scan_analyze_next_tuple() returns false. It e.g. can make sense
+	 * to hold a lock until all tuples on a block have been analyzed by
+	 * scan_analyze_next_tuple.
+	 *
+	 * The callback can return false if the block is not suitable for
+	 * sampling, e.g. because it's a metapage that could never contain tuples.
+	 *
+	 * XXX: This obviously is primarily suited for block-based AMs. It's not
+	 * clear what a good interface for non block based AMs would be, so there
+	 * isn't one yet.
+	 */
+	bool		(*scan_analyze_next_block) (TableScanDesc scan,
+											BlockNumber blockno,
+											BufferAccessStrategy bstrategy);
+
+	/*
+	 * See table_scan_analyze_next_tuple().
+	 *
+	 * Not every AM might have a meaningful concept of dead rows, in which
+	 * case it's OK to not increment *deadrows - but note that that may
+	 * influence autovacuum scheduling (see comment for relation_vacuum
+	 * callback).
+	 */
+	bool		(*scan_analyze_next_tuple) (TableScanDesc scan,
+											TransactionId OldestXmin,
+											double *liverows,
+											double *deadrows,
+											TupleTableSlot *slot);
+
+	/* see table_index_build_range_scan for reference about parameters */
+	double		(*index_build_range_scan) (Relation table_rel,
+										   Relation index_rel,
+										   struct IndexInfo *index_info,
+										   bool allow_sync,
+										   bool anyvisible,
+										   bool progress,
+										   BlockNumber start_blockno,
+										   BlockNumber numblocks,
+										   IndexBuildCallback callback,
+										   void *callback_state,
+										   TableScanDesc scan);
+
+	/* see table_index_validate_scan for reference about parameters */
+	void		(*index_validate_scan) (Relation table_rel,
+										Relation index_rel,
+										struct IndexInfo *index_info,
+										Snapshot snapshot,
+										struct ValidateIndexState *state);
+
+
+	/* ------------------------------------------------------------------------
+	 * Miscellaneous functions.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * See table_relation_size().
+	 *
+	 * Note that currently a few callers use the MAIN_FORKNUM size to figure
+	 * out the range of potentially interesting blocks (brin, analyze). It's
+	 * probable that we'll need to revise the interface for those at some
+	 * point.
+	 */
+	uint64		(*relation_size) (Relation rel, ForkNumber forkNumber);
+
+
+	/*
+	 * This callback should return true if the relation requires a TOAST table
+	 * and false if it does not.  It may wish to examine the relation's tuple
+	 * descriptor before making a decision, but if it uses some other method
+	 * of storing large values (or if it does not support them) it can simply
+	 * return false.
+	 */
+	bool		(*relation_needs_toast_table) (Relation rel);
+
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid			(*relation_toast_am) (Relation rel);
+
+	/*
+	 * This callback is invoked when detoasting a value stored in a toast
+	 * table implemented by this AM.  See table_relation_fetch_toast_slice()
+	 * for more details.
+	 */
+	void		(*relation_fetch_toast_slice) (Relation toastrel, Oid valueid,
+											   int32 attrsize,
+											   int32 sliceoffset,
+											   int32 slicelength,
+											   struct varlena *result);
+
+
+	/* ------------------------------------------------------------------------
+	 * Planner related functions.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * See table_relation_estimate_size().
+	 *
+	 * While block oriented, it shouldn't be too hard for an AM that doesn't
+	 * internally use blocks to convert into a usable representation.
+	 *
+	 * This differs from the relation_size callback by returning size
+	 * estimates (both relation size and tuple count) for planning purposes,
+	 * rather than returning a currently correct estimate.
+	 */
+	void		(*relation_estimate_size) (Relation rel, int32 *attr_widths,
+										   BlockNumber *pages, double *tuples,
+										   double *allvisfrac);
+
+
+	/* ------------------------------------------------------------------------
+	 * Executor related functions.
+	 * ------------------------------------------------------------------------
+	 */
+
+	/*
+	 * Prepare to fetch / check / return tuples from `tbmres->blockno` as part
+	 * of a bitmap table scan. `scan` was started via table_beginscan_bm().
+	 * Return false if there are no tuples to be found on the page, true
+	 * otherwise.
+	 *
+	 * This will typically read and pin the target block, and do the necessary
+	 * work to allow scan_bitmap_next_tuple() to return tuples (e.g. it might
+	 * make sense to perform tuple visibility checks at this time). For some
+	 * AMs it will make more sense to do all the work referencing `tbmres`
+	 * contents here, for others it might be better to defer more work to
+	 * scan_bitmap_next_tuple.
+	 *
+	 * If `tbmres->blockno` is -1, this is a lossy scan and all visible tuples
+	 * on the page have to be returned, otherwise the tuples at offsets in
+	 * `tbmres->offsets` need to be returned.
+	 *
+	 * XXX: Currently this may only be implemented if the AM uses md.c as its
+	 * storage manager, and uses ItemPointer->ip_blkid in a manner that maps
+	 * blockids directly to the underlying storage. nodeBitmapHeapscan.c
+	 * performs prefetching directly using that interface.  This probably
+	 * needs to be rectified at a later point.
+	 *
+	 * XXX: Currently this may only be implemented if the AM uses the
+	 * visibilitymap, as nodeBitmapHeapscan.c unconditionally accesses it to
+	 * perform prefetching.  This probably needs to be rectified at a later
+	 * point.
+	 *
+	 * Optional callback, but either both scan_bitmap_next_block and
+	 * scan_bitmap_next_tuple need to exist, or neither.
+	 */
+	bool		(*scan_bitmap_next_block) (TableScanDesc scan,
+										   struct TBMIterateResult *tbmres);
+
+	/*
+	 * Fetch the next tuple of a bitmap table scan into `slot` and return true
+	 * if a visible tuple was found, false otherwise.
+	 *
+	 * For some AMs it will make more sense to do all the work referencing
+	 * `tbmres` contents in scan_bitmap_next_block, for others it might be
+	 * better to defer more work to this callback.
+	 *
+	 * Optional callback, but either both scan_bitmap_next_block and
+	 * scan_bitmap_next_tuple need to exist, or neither.
+	 */
+	bool		(*scan_bitmap_next_tuple) (TableScanDesc scan,
+										   struct TBMIterateResult *tbmres,
+										   TupleTableSlot *slot);
+
+	/*
+	 * Prepare to fetch tuples from the next block in a sample scan. Return
+	 * false if the sample scan is finished, true otherwise. `scan` was
+	 * started via table_beginscan_sampling().
+	 *
+	 * Typically this will first determine the target block by calling the
+	 * TsmRoutine's NextSampleBlock() callback if not NULL, or alternatively
+	 * perform a sequential scan over all blocks.  The determined block is
+	 * then typically read and pinned.
+	 *
+	 * As the TsmRoutine interface is block based, a block needs to be passed
+	 * to NextSampleBlock(). If that's not appropriate for an AM, it
+	 * internally needs to perform mapping between the internal and a block
+	 * based representation.
+	 *
+	 * Note that it's not acceptable to hold deadlock prone resources such as
+	 * lwlocks until scan_sample_next_tuple() has exhausted the tuples on the
+	 * block - the tuple is likely to be returned to an upper query node, and
+	 * the next call could be off a long while. Holding buffer pins and such
+	 * is obviously OK.
+	 *
+	 * Currently it is required to implement this interface, as there's no
+	 * alternative way (contrary e.g. to bitmap scans) to implement sample
+	 * scans. If infeasible to implement, the AM may raise an error.
+	 */
+	bool		(*scan_sample_next_block) (TableScanDesc scan,
+										   struct SampleScanState *scanstate);
+
+	/*
+	 * This callback, only called after scan_sample_next_block has returned
+	 * true, should determine the next tuple to be returned from the selected
+	 * block using the TsmRoutine's NextSampleTuple() callback.
+	 *
+	 * The callback needs to perform visibility checks, and only return
+	 * visible tuples. That obviously can mean calling NextSampleTuple()
+	 * multiple times.
+	 *
+	 * The TsmRoutine interface assumes that there's a maximum offset on a
+	 * given page, so if that doesn't apply to an AM, it needs to emulate that
+	 * assumption somehow.
+	 */
+	bool		(*scan_sample_next_tuple) (TableScanDesc scan,
+										   struct SampleScanState *scanstate,
+										   TupleTableSlot *slot);
+
+} TableAmRoutine;
+
+
+/* ----------------------------------------------------------------------------
+ * Slot functions.
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Returns slot callbacks suitable for holding tuples of the appropriate type
+ * for the relation.  Works for tables, views, foreign tables and partitioned
+ * tables.
+ */
+extern const TupleTableSlotOps *table_slot_callbacks(Relation relation);
+
+/*
+ * Returns slot using the callbacks returned by table_slot_callbacks(), and
+ * registers it on *reglist.
+ */
+extern TupleTableSlot *table_slot_create(Relation relation, List **reglist);
+
+
+/* ----------------------------------------------------------------------------
+ * Table scan functions.
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Start a scan of `rel`. Returned tuples pass a visibility test of
+ * `snapshot`, and if nkeys != 0, the results are filtered by those scan keys.
+ */
+static inline TableScanDesc
+table_beginscan(Relation rel, Snapshot snapshot,
+				int nkeys, struct ScanKeyData *key)
+{
+	uint32		flags = SO_TYPE_SEQSCAN |
+		SO_ALLOW_STRAT | SO_ALLOW_SYNC | SO_ALLOW_PAGEMODE;
+
+	return rel->rd_tableam->scan_begin(rel, snapshot, nkeys, key, NULL, flags);
+}
+
+/*
+ * Like table_beginscan(), but for scanning catalog. It'll automatically use a
+ * snapshot appropriate for scanning catalog relations.
+ */
+extern TableScanDesc table_beginscan_catalog(Relation relation, int nkeys,
+											 struct ScanKeyData *key);
+
+/*
+ * Like table_beginscan(), but table_beginscan_strat() offers an extended API
+ * that lets the caller control whether a nondefault buffer access strategy
+ * can be used, and whether syncscan can be chosen (possibly resulting in the
+ * scan not starting from block zero).  Both of these default to true with
+ * plain table_beginscan.
+ */
+static inline TableScanDesc
+table_beginscan_strat(Relation rel, Snapshot snapshot,
+					  int nkeys, struct ScanKeyData *key,
+					  bool allow_strat, bool allow_sync)
+{
+	uint32		flags = SO_TYPE_SEQSCAN | SO_ALLOW_PAGEMODE;
+
+	if (allow_strat)
+		flags |= SO_ALLOW_STRAT;
+	if (allow_sync)
+		flags |= SO_ALLOW_SYNC;
+
+	return rel->rd_tableam->scan_begin(rel, snapshot, nkeys, key, NULL, flags);
+}
+
+/*
+ * table_beginscan_bm is an alternative entry point for setting up a
+ * TableScanDesc for a bitmap heap scan.  Although that scan technology is
+ * really quite unlike a standard seqscan, there is just enough commonality to
+ * make it worth using the same data structure.
+ */
+static inline TableScanDesc
+table_beginscan_bm(Relation rel, Snapshot snapshot,
+				   int nkeys, struct ScanKeyData *key)
+{
+	uint32		flags = SO_TYPE_BITMAPSCAN | SO_ALLOW_PAGEMODE;
+
+	return rel->rd_tableam->scan_begin(rel, snapshot, nkeys, key, NULL, flags);
+}
+
+/*
+ * table_beginscan_sampling is an alternative entry point for setting up a
+ * TableScanDesc for a TABLESAMPLE scan.  As with bitmap scans, it's worth
+ * using the same data structure although the behavior is rather different.
+ * In addition to the options offered by table_beginscan_strat, this call
+ * also allows control of whether page-mode visibility checking is used.
+ */
+static inline TableScanDesc
+table_beginscan_sampling(Relation rel, Snapshot snapshot,
+						 int nkeys, struct ScanKeyData *key,
+						 bool allow_strat, bool allow_sync,
+						 bool allow_pagemode)
+{
+	uint32		flags = SO_TYPE_SAMPLESCAN;
+
+	if (allow_strat)
+		flags |= SO_ALLOW_STRAT;
+	if (allow_sync)
+		flags |= SO_ALLOW_SYNC;
+	if (allow_pagemode)
+		flags |= SO_ALLOW_PAGEMODE;
+
+	return rel->rd_tableam->scan_begin(rel, snapshot, nkeys, key, NULL, flags);
+}
+
+/*
+ * table_beginscan_tid is an alternative entry point for setting up a
+ * TableScanDesc for a Tid scan. As with bitmap scans, it's worth using
+ * the same data structure although the behavior is rather different.
+ */
+static inline TableScanDesc
+table_beginscan_tid(Relation rel, Snapshot snapshot)
+{
+	uint32		flags = SO_TYPE_TIDSCAN;
+
+	return rel->rd_tableam->scan_begin(rel, snapshot, 0, NULL, NULL, flags);
+}
+
+/*
+ * table_beginscan_analyze is an alternative entry point for setting up a
+ * TableScanDesc for an ANALYZE scan.  As with bitmap scans, it's worth using
+ * the same data structure although the behavior is rather different.
+ */
+static inline TableScanDesc
+table_beginscan_analyze(Relation rel)
+{
+	uint32		flags = SO_TYPE_ANALYZE;
+
+	return rel->rd_tableam->scan_begin(rel, NULL, 0, NULL, NULL, flags);
+}
+
+/*
+ * End relation scan.
+ */
+static inline void
+table_endscan(TableScanDesc scan)
+{
+	scan->rs_rd->rd_tableam->scan_end(scan);
+}
+
+/*
+ * Restart a relation scan.
+ */
+static inline void
+table_rescan(TableScanDesc scan,
+			 struct ScanKeyData *key)
+{
+	scan->rs_rd->rd_tableam->scan_rescan(scan, key, false, false, false, false);
+}
+
+/*
+ * Restart a relation scan after changing params.
+ *
+ * This call allows changing the buffer strategy, syncscan, and pagemode
+ * options before starting a fresh scan.  Note that although the actual use of
+ * syncscan might change (effectively, enabling or disabling reporting), the
+ * previously selected startblock will be kept.
+ */
+static inline void
+table_rescan_set_params(TableScanDesc scan, struct ScanKeyData *key,
+						bool allow_strat, bool allow_sync, bool allow_pagemode)
+{
+	scan->rs_rd->rd_tableam->scan_rescan(scan, key, true,
+										 allow_strat, allow_sync,
+										 allow_pagemode);
+}
+
+/*
+ * Update snapshot used by the scan.
+ */
+extern void table_scan_update_snapshot(TableScanDesc scan, Snapshot snapshot);
+
+/*
+ * Return next tuple from `scan`, store in slot.
+ */
+static inline bool
+table_scan_getnextslot(TableScanDesc sscan, ScanDirection direction, TupleTableSlot *slot)
+{
+	slot->tts_tableOid = RelationGetRelid(sscan->rs_rd);
+
+	/* We don't expect actual scans using NoMovementScanDirection */
+	Assert(direction == ForwardScanDirection ||
+		   direction == BackwardScanDirection);
+
+	/*
+	 * We don't expect direct calls to table_scan_getnextslot with valid
+	 * CheckXidAlive for catalog or regular tables.  See detailed comments in
+	 * xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_scan_getnextslot call during logical decoding");
+
+	return sscan->rs_rd->rd_tableam->scan_getnextslot(sscan, direction, slot);
+}
+
+/* ----------------------------------------------------------------------------
+ * TID Range scanning related functions.
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * table_beginscan_tidrange is the entry point for setting up a TableScanDesc
+ * for a TID range scan.
+ */
+static inline TableScanDesc
+table_beginscan_tidrange(Relation rel, Snapshot snapshot,
+						 ItemPointer mintid,
+						 ItemPointer maxtid)
+{
+	TableScanDesc sscan;
+	uint32		flags = SO_TYPE_TIDRANGESCAN | SO_ALLOW_PAGEMODE;
+
+	sscan = rel->rd_tableam->scan_begin(rel, snapshot, 0, NULL, NULL, flags);
+
+	/* Set the range of TIDs to scan */
+	sscan->rs_rd->rd_tableam->scan_set_tidrange(sscan, mintid, maxtid);
+
+	return sscan;
+}
+
+/*
+ * table_rescan_tidrange resets the scan position and sets the minimum and
+ * maximum TID range to scan for a TableScanDesc created by
+ * table_beginscan_tidrange.
+ */
+static inline void
+table_rescan_tidrange(TableScanDesc sscan, ItemPointer mintid,
+					  ItemPointer maxtid)
+{
+	/* Ensure table_beginscan_tidrange() was used. */
+	Assert((sscan->rs_flags & SO_TYPE_TIDRANGESCAN) != 0);
+
+	sscan->rs_rd->rd_tableam->scan_rescan(sscan, NULL, false, false, false, false);
+	sscan->rs_rd->rd_tableam->scan_set_tidrange(sscan, mintid, maxtid);
+}
+
+/*
+ * Fetch the next tuple from `sscan` for a TID range scan created by
+ * table_beginscan_tidrange().  Stores the tuple in `slot` and returns true,
+ * or returns false if no more tuples exist in the range.
+ */
+static inline bool
+table_scan_getnextslot_tidrange(TableScanDesc sscan, ScanDirection direction,
+								TupleTableSlot *slot)
+{
+	/* Ensure table_beginscan_tidrange() was used. */
+	Assert((sscan->rs_flags & SO_TYPE_TIDRANGESCAN) != 0);
+
+	/* We don't expect actual scans using NoMovementScanDirection */
+	Assert(direction == ForwardScanDirection ||
+		   direction == BackwardScanDirection);
+
+	return sscan->rs_rd->rd_tableam->scan_getnextslot_tidrange(sscan,
+															   direction,
+															   slot);
+}
+
+
+/* ----------------------------------------------------------------------------
+ * Parallel table scan related functions.
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Estimate the size of shared memory needed for a parallel scan of this
+ * relation.
+ */
+extern Size table_parallelscan_estimate(Relation rel, Snapshot snapshot);
+
+/*
+ * Initialize ParallelTableScanDesc for a parallel scan of this
+ * relation. `pscan` needs to be sized according to parallelscan_estimate()
+ * for the same relation.  Call this just once in the leader process; then,
+ * individual workers attach via table_beginscan_parallel.
+ */
+extern void table_parallelscan_initialize(Relation rel,
+										  ParallelTableScanDesc pscan,
+										  Snapshot snapshot);
+
+/*
+ * Begin a parallel scan. `pscan` needs to have been initialized with
+ * table_parallelscan_initialize(), for the same relation. The initialization
+ * does not need to have happened in this backend.
+ *
+ * Caller must hold a suitable lock on the relation.
+ */
+extern TableScanDesc table_beginscan_parallel(Relation relation,
+											  ParallelTableScanDesc pscan);
+
+/*
+ * Restart a parallel scan.  Call this in the leader process.  Caller is
+ * responsible for making sure that all workers have finished the scan
+ * beforehand.
+ */
+static inline void
+table_parallelscan_reinitialize(Relation rel, ParallelTableScanDesc pscan)
+{
+	rel->rd_tableam->parallelscan_reinitialize(rel, pscan);
+}
+
+
+/* ----------------------------------------------------------------------------
+ *  Index scan related functions.
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Prepare to fetch tuples from the relation, as needed when fetching tuples
+ * for an index scan.
+ *
+ * Tuples for an index scan can then be fetched via table_index_fetch_tuple().
+ */
+static inline IndexFetchTableData *
+table_index_fetch_begin(Relation rel)
+{
+	return rel->rd_tableam->index_fetch_begin(rel);
+}
+
+/*
+ * Reset index fetch. Typically this will release cross index fetch resources
+ * held in IndexFetchTableData.
+ */
+static inline void
+table_index_fetch_reset(struct IndexFetchTableData *scan)
+{
+	scan->rel->rd_tableam->index_fetch_reset(scan);
+}
+
+/*
+ * Release resources and deallocate index fetch.
+ */
+static inline void
+table_index_fetch_end(struct IndexFetchTableData *scan)
+{
+	scan->rel->rd_tableam->index_fetch_end(scan);
+}
+
+/*
+ * Fetches, as part of an index scan, tuple at `tid` into `slot`, after doing
+ * a visibility test according to `snapshot`. If a tuple was found and passed
+ * the visibility test, returns true, false otherwise. Note that *tid may be
+ * modified when we return true (see later remarks on multiple row versions
+ * reachable via a single index entry).
+ *
+ * *call_again needs to be false on the first call to table_index_fetch_tuple() for
+ * a tid. If there potentially is another tuple matching the tid, *call_again
+ * will be set to true, signaling that table_index_fetch_tuple() should be called
+ * again for the same tid.
+ *
+ * *all_dead, if all_dead is not NULL, will be set to true by
+ * table_index_fetch_tuple() iff it is guaranteed that no backend needs to see
+ * that tuple. Index AMs can use that to avoid returning that tid in future
+ * searches.
+ *
+ * The difference between this function and table_tuple_fetch_row_version()
+ * is that this function returns the currently visible version of a row if
+ * the AM supports storing multiple row versions reachable via a single index
+ * entry (like heap's HOT). Whereas table_tuple_fetch_row_version() only
+ * evaluates the tuple exactly at `tid`. Outside of index entry ->table tuple
+ * lookups, table_tuple_fetch_row_version() is what's usually needed.
+ */
+static inline bool
+table_index_fetch_tuple(struct IndexFetchTableData *scan,
+						ItemPointer tid,
+						Snapshot snapshot,
+						TupleTableSlot *slot,
+						bool *call_again, bool *all_dead)
+{
+	/*
+	 * We don't expect direct calls to table_index_fetch_tuple with valid
+	 * CheckXidAlive for catalog or regular tables.  See detailed comments in
+	 * xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_index_fetch_tuple call during logical decoding");
+
+	return scan->rel->rd_tableam->index_fetch_tuple(scan, tid, snapshot,
+													slot, call_again,
+													all_dead);
+}
+
+/*
+ * This is a convenience wrapper around table_index_fetch_tuple() which
+ * returns whether there are table tuple items corresponding to an index
+ * entry.  This likely is only useful to verify if there's a conflict in a
+ * unique index.
+ */
+extern bool table_index_fetch_tuple_check(Relation rel,
+										  ItemPointer tid,
+										  Snapshot snapshot,
+										  bool *all_dead);
+
+
+/* ------------------------------------------------------------------------
+ * Functions for non-modifying operations on individual tuples
+ * ------------------------------------------------------------------------
+ */
+
+
+/*
+ * Fetch tuple at `tid` into `slot`, after doing a visibility test according to
+ * `snapshot`. If a tuple was found and passed the visibility test, returns
+ * true, false otherwise.
+ *
+ * See table_index_fetch_tuple's comment about what the difference between
+ * these functions is. It is correct to use this function outside of index
+ * entry->table tuple lookups.
+ */
+static inline bool
+table_tuple_fetch_row_version(Relation rel,
+							  ItemPointer tid,
+							  Snapshot snapshot,
+							  TupleTableSlot *slot)
+{
+	/*
+	 * We don't expect direct calls to table_tuple_fetch_row_version with
+	 * valid CheckXidAlive for catalog or regular tables.  See detailed
+	 * comments in xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_tuple_fetch_row_version call during logical decoding");
+
+	return rel->rd_tableam->tuple_fetch_row_version(rel, tid, snapshot, slot);
+}
+
+/*
+ * Verify that `tid` is a potentially valid tuple identifier. That doesn't
+ * mean that the pointed to row needs to exist or be visible, but that
+ * attempting to fetch the row (e.g. with table_tuple_get_latest_tid() or
+ * table_tuple_fetch_row_version()) should not error out if called with that
+ * tid.
+ *
+ * `scan` needs to have been started via table_beginscan().
+ */
+static inline bool
+table_tuple_tid_valid(TableScanDesc scan, ItemPointer tid)
+{
+	return scan->rs_rd->rd_tableam->tuple_tid_valid(scan, tid);
+}
+
+/*
+ * Return the latest version of the tuple at `tid`, by updating `tid` to
+ * point at the newest version.
+ */
+extern void table_tuple_get_latest_tid(TableScanDesc scan, ItemPointer tid);
+
+/*
+ * Return true iff tuple in slot satisfies the snapshot.
+ *
+ * This assumes the slot's tuple is valid, and of the appropriate type for the
+ * AM.
+ *
+ * Some AMs might modify the data underlying the tuple as a side-effect. If so
+ * they ought to mark the relevant buffer dirty.
+ */
+static inline bool
+table_tuple_satisfies_snapshot(Relation rel, TupleTableSlot *slot,
+							   Snapshot snapshot)
+{
+	return rel->rd_tableam->tuple_satisfies_snapshot(rel, slot, snapshot);
+}
+
+/*
+ * Determine which index tuples are safe to delete based on their table TID.
+ *
+ * Determines which entries from index AM caller's TM_IndexDeleteOp state
+ * point to vacuumable table tuples.  Entries that are found by tableam to be
+ * vacuumable are naturally safe for index AM to delete, and so get directly
+ * marked as deletable.  See comments above TM_IndexDelete and comments above
+ * TM_IndexDeleteOp for full details.
+ *
+ * Returns a snapshotConflictHorizon transaction ID that caller places in
+ * its index deletion WAL record.  This might be used during subsequent REDO
+ * of the WAL record when in Hot Standby mode -- a recovery conflict for the
+ * index deletion operation might be required on the standby.
+ */
+static inline TransactionId
+table_index_delete_tuples(Relation rel, TM_IndexDeleteOp *delstate)
+{
+	return rel->rd_tableam->index_delete_tuples(rel, delstate);
+}
+
+
+/* ----------------------------------------------------------------------------
+ *  Functions for manipulations of physical tuples.
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Insert a tuple from a slot into table AM routine.
+ *
+ * The options bitmask allows the caller to specify options that may change the
+ * behaviour of the AM. The AM will ignore options that it does not support.
+ *
+ * If the TABLE_INSERT_SKIP_FSM option is specified, AMs are free to not reuse
+ * free space in the relation. This can save some cycles when we know the
+ * relation is new and doesn't contain useful amounts of free space.
+ * TABLE_INSERT_SKIP_FSM is commonly passed directly to
+ * RelationGetBufferForTuple. See that method for more information.
+ *
+ * TABLE_INSERT_FROZEN should only be specified for inserts into
+ * relation storage created during the current subtransaction and when
+ * there are no prior snapshots or pre-existing portals open.
+ * This causes rows to be frozen, which is an MVCC violation and
+ * requires explicit options chosen by user.
+ *
+ * TABLE_INSERT_NO_LOGICAL force-disables the emitting of logical decoding
+ * information for the tuple. This should solely be used during table rewrites
+ * where RelationIsLogicallyLogged(relation) is not yet accurate for the new
+ * relation.
+ *
+ * Note that most of these options will be applied when inserting into the
+ * heap's TOAST table, too, if the tuple requires any out-of-line data.
+ *
+ * The BulkInsertState object (if any; bistate can be NULL for default
+ * behavior) is also just passed through to RelationGetBufferForTuple. If
+ * `bistate` is provided, table_finish_bulk_insert() needs to be called.
+ *
+ * On return the slot's tts_tid and tts_tableOid are updated to reflect the
+ * insertion. But note that any toasting of fields within the slot is NOT
+ * reflected in the slots contents.
+ */
+static inline void
+table_tuple_insert(Relation rel, TupleTableSlot *slot, CommandId cid,
+				   int options, struct BulkInsertStateData *bistate)
+{
+	rel->rd_tableam->tuple_insert(rel, slot, cid, options,
+								  bistate);
+}
+
+/*
+ * Perform a "speculative insertion". These can be backed out afterwards
+ * without aborting the whole transaction.  Other sessions can wait for the
+ * speculative insertion to be confirmed, turning it into a regular tuple, or
+ * aborted, as if it never existed.  Speculatively inserted tuples behave as
+ * "value locks" of short duration, used to implement INSERT .. ON CONFLICT.
+ *
+ * A transaction having performed a speculative insertion has to either abort,
+ * or finish the speculative insertion with
+ * table_tuple_complete_speculative(succeeded = ...).
+ */
+static inline void
+table_tuple_insert_speculative(Relation rel, TupleTableSlot *slot,
+							   CommandId cid, int options,
+							   struct BulkInsertStateData *bistate,
+							   uint32 specToken)
+{
+	rel->rd_tableam->tuple_insert_speculative(rel, slot, cid, options,
+											  bistate, specToken);
+}
+
+/*
+ * Complete "speculative insertion" started in the same transaction. If
+ * succeeded is true, the tuple is fully inserted, if false, it's removed.
+ */
+static inline void
+table_tuple_complete_speculative(Relation rel, TupleTableSlot *slot,
+								 uint32 specToken, bool succeeded)
+{
+	rel->rd_tableam->tuple_complete_speculative(rel, slot, specToken,
+												succeeded);
+}
+
+/*
+ * Insert multiple tuples into a table.
+ *
+ * This is like table_tuple_insert(), but inserts multiple tuples in one
+ * operation. That's often faster than calling table_tuple_insert() in a loop,
+ * because e.g. the AM can reduce WAL logging and page locking overhead.
+ *
+ * Except for taking `nslots` tuples as input, and an array of TupleTableSlots
+ * in `slots`, the parameters for table_multi_insert() are the same as for
+ * table_tuple_insert().
+ *
+ * Note: this leaks memory into the current memory context. You can create a
+ * temporary context before calling this, if that's a problem.
+ */
+static inline void
+table_multi_insert(Relation rel, TupleTableSlot **slots, int nslots,
+				   CommandId cid, int options, struct BulkInsertStateData *bistate)
+{
+	rel->rd_tableam->multi_insert(rel, slots, nslots,
+								  cid, options, bistate);
+}
+
+/*
+ * Delete a tuple.
+ *
+ * NB: do not call this directly unless prepared to deal with
+ * concurrent-update conditions.  Use simple_table_tuple_delete instead.
+ *
+ * Input parameters:
+ *	relation - table to be modified (caller must hold suitable lock)
+ *	tid - TID of tuple to be deleted
+ *	cid - delete command ID (used for visibility test, and stored into
+ *		cmax if successful)
+ *	crosscheck - if not InvalidSnapshot, also check tuple against this
+ *	wait - true if should wait for any conflicting update to commit/abort
+ * Output parameters:
+ *	tmfd - filled in failure cases (see below)
+ *	changingPart - true iff the tuple is being moved to another partition
+ *		table due to an update of the partition key. Otherwise, false.
+ *
+ * Normal, successful return value is TM_Ok, which means we did actually
+ * delete it.  Failure return codes are TM_SelfModified, TM_Updated, and
+ * TM_BeingModified (the last only possible if wait == false).
+ *
+ * In the failure cases, the routine fills *tmfd with the tuple's t_ctid,
+ * t_xmax, and, if possible, t_cmax.  See comments for struct
+ * TM_FailureData for additional info.
+ */
+static inline TM_Result
+table_tuple_delete(Relation rel, ItemPointer tid, CommandId cid,
+				   Snapshot snapshot, Snapshot crosscheck, bool wait,
+				   TM_FailureData *tmfd, bool changingPart)
+{
+	return rel->rd_tableam->tuple_delete(rel, tid, cid,
+										 snapshot, crosscheck,
+										 wait, tmfd, changingPart);
+}
+
+/*
+ * Update a tuple.
+ *
+ * NB: do not call this directly unless you are prepared to deal with
+ * concurrent-update conditions.  Use simple_table_tuple_update instead.
+ *
+ * Input parameters:
+ *	relation - table to be modified (caller must hold suitable lock)
+ *	otid - TID of old tuple to be replaced
+ *	slot - newly constructed tuple data to store
+ *	cid - update command ID (used for visibility test, and stored into
+ *		cmax/cmin if successful)
+ *	crosscheck - if not InvalidSnapshot, also check old tuple against this
+ *	wait - true if should wait for any conflicting update to commit/abort
+ * Output parameters:
+ *	tmfd - filled in failure cases (see below)
+ *	lockmode - filled with lock mode acquired on tuple
+ *  update_indexes - in success cases this is set to true if new index entries
+ *		are required for this tuple
+ *
+ * Normal, successful return value is TM_Ok, which means we did actually
+ * update it.  Failure return codes are TM_SelfModified, TM_Updated, and
+ * TM_BeingModified (the last only possible if wait == false).
+ *
+ * On success, the slot's tts_tid and tts_tableOid are updated to match the new
+ * stored tuple; in particular, slot->tts_tid is set to the TID where the
+ * new tuple was inserted, and its HEAP_ONLY_TUPLE flag is set iff a HOT
+ * update was done.  However, any TOAST changes in the new tuple's
+ * data are not reflected into *newtup.
+ *
+ * In the failure cases, the routine fills *tmfd with the tuple's t_ctid,
+ * t_xmax, and, if possible, t_cmax.  See comments for struct TM_FailureData
+ * for additional info.
+ */
+static inline TM_Result
+table_tuple_update(Relation rel, ItemPointer otid, TupleTableSlot *slot,
+				   CommandId cid, Snapshot snapshot, Snapshot crosscheck,
+				   bool wait, TM_FailureData *tmfd, LockTupleMode *lockmode,
+				   TU_UpdateIndexes *update_indexes)
+{
+	return rel->rd_tableam->tuple_update(rel, otid, slot,
+										 cid, snapshot, crosscheck,
+										 wait, tmfd,
+										 lockmode, update_indexes);
+}
+
+/*
+ * Lock a tuple in the specified mode.
+ *
+ * Input parameters:
+ *	relation: relation containing tuple (caller must hold suitable lock)
+ *	tid: TID of tuple to lock
+ *	snapshot: snapshot to use for visibility determinations
+ *	cid: current command ID (used for visibility test, and stored into
+ *		tuple's cmax if lock is successful)
+ *	mode: lock mode desired
+ *	wait_policy: what to do if tuple lock is not available
+ *	flags:
+ *		If TUPLE_LOCK_FLAG_LOCK_UPDATE_IN_PROGRESS, follow the update chain to
+ *		also lock descendant tuples if lock modes don't conflict.
+ *		If TUPLE_LOCK_FLAG_FIND_LAST_VERSION, follow the update chain and lock
+ *		latest version.
+ *
+ * Output parameters:
+ *	*slot: contains the target tuple
+ *	*tmfd: filled in failure cases (see below)
+ *
+ * Function result may be:
+ *	TM_Ok: lock was successfully acquired
+ *	TM_Invisible: lock failed because tuple was never visible to us
+ *	TM_SelfModified: lock failed because tuple updated by self
+ *	TM_Updated: lock failed because tuple updated by other xact
+ *	TM_Deleted: lock failed because tuple deleted by other xact
+ *	TM_WouldBlock: lock couldn't be acquired and wait_policy is skip
+ *
+ * In the failure cases other than TM_Invisible and TM_Deleted, the routine
+ * fills *tmfd with the tuple's t_ctid, t_xmax, and, if possible, t_cmax.  See
+ * comments for struct TM_FailureData for additional info.
+ */
+static inline TM_Result
+table_tuple_lock(Relation rel, ItemPointer tid, Snapshot snapshot,
+				 TupleTableSlot *slot, CommandId cid, LockTupleMode mode,
+				 LockWaitPolicy wait_policy, uint8 flags,
+				 TM_FailureData *tmfd)
+{
+	return rel->rd_tableam->tuple_lock(rel, tid, snapshot, slot,
+									   cid, mode, wait_policy,
+									   flags, tmfd);
+}
+
+/*
+ * Perform operations necessary to complete insertions made via
+ * tuple_insert and multi_insert with a BulkInsertState specified.
+ */
+static inline void
+table_finish_bulk_insert(Relation rel, int options)
+{
+	/* optional callback */
+	if (rel->rd_tableam && rel->rd_tableam->finish_bulk_insert)
+		rel->rd_tableam->finish_bulk_insert(rel, options);
+}
+
+
+/* ------------------------------------------------------------------------
+ * DDL related functionality.
+ * ------------------------------------------------------------------------
+ */
+
+/*
+ * Create storage for `rel` in `newrlocator`, with persistence set to
+ * `persistence`.
+ *
+ * This is used both during relation creation and various DDL operations to
+ * create new rel storage that can be filled from scratch.  When creating
+ * new storage for an existing relfilelocator, this should be called before the
+ * relcache entry has been updated.
+ *
+ * *freezeXid, *minmulti are set to the xid / multixact horizon for the table
+ * that pg_class.{relfrozenxid, relminmxid} have to be set to.
+ */
+static inline void
+table_relation_set_new_filelocator(Relation rel,
+								   const RelFileLocator *newrlocator,
+								   char persistence,
+								   TransactionId *freezeXid,
+								   MultiXactId *minmulti)
+{
+	rel->rd_tableam->relation_set_new_filelocator(rel, newrlocator,
+												  persistence, freezeXid,
+												  minmulti);
+}
+
+/*
+ * Remove all table contents from `rel`, in a non-transactional manner.
+ * Non-transactional meaning that there's no need to support rollbacks. This
+ * commonly only is used to perform truncations for relation storage created in
+ * the current transaction.
+ */
+static inline void
+table_relation_nontransactional_truncate(Relation rel)
+{
+	rel->rd_tableam->relation_nontransactional_truncate(rel);
+}
+
+/*
+ * Copy data from `rel` into the new relfilelocator `newrlocator`. The new
+ * relfilelocator may not have storage associated before this function is
+ * called. This is only supposed to be used for low level operations like
+ * changing a relation's tablespace.
+ */
+static inline void
+table_relation_copy_data(Relation rel, const RelFileLocator *newrlocator)
+{
+	rel->rd_tableam->relation_copy_data(rel, newrlocator);
+}
+
+/*
+ * Copy data from `OldTable` into `NewTable`, as part of a CLUSTER or VACUUM
+ * FULL.
+ *
+ * Additional Input parameters:
+ * - use_sort - if true, the table contents are sorted appropriate for
+ *   `OldIndex`; if false and OldIndex is not InvalidOid, the data is copied
+ *   in that index's order; if false and OldIndex is InvalidOid, no sorting is
+ *   performed
+ * - OldIndex - see use_sort
+ * - OldestXmin - computed by vacuum_get_cutoffs(), even when
+ *   not needed for the relation's AM
+ * - *xid_cutoff - ditto
+ * - *multi_cutoff - ditto
+ *
+ * Output parameters:
+ * - *xid_cutoff - rel's new relfrozenxid value, may be invalid
+ * - *multi_cutoff - rel's new relminmxid value, may be invalid
+ * - *tups_vacuumed - stats, for logging, if appropriate for AM
+ * - *tups_recently_dead - stats, for logging, if appropriate for AM
+ */
+static inline void
+table_relation_copy_for_cluster(Relation OldTable, Relation NewTable,
+								Relation OldIndex,
+								bool use_sort,
+								TransactionId OldestXmin,
+								TransactionId *xid_cutoff,
+								MultiXactId *multi_cutoff,
+								double *num_tuples,
+								double *tups_vacuumed,
+								double *tups_recently_dead)
+{
+	OldTable->rd_tableam->relation_copy_for_cluster(OldTable, NewTable, OldIndex,
+													use_sort, OldestXmin,
+													xid_cutoff, multi_cutoff,
+													num_tuples, tups_vacuumed,
+													tups_recently_dead);
+}
+
+/*
+ * Perform VACUUM on the relation. The VACUUM can be triggered by a user or by
+ * autovacuum. The specific actions performed by the AM will depend heavily on
+ * the individual AM.
+ *
+ * On entry a transaction needs to already been established, and the
+ * table is locked with a ShareUpdateExclusive lock.
+ *
+ * Note that neither VACUUM FULL (and CLUSTER), nor ANALYZE go through this
+ * routine, even if (for ANALYZE) it is part of the same VACUUM command.
+ */
+static inline void
+table_relation_vacuum(Relation rel, struct VacuumParams *params,
+					  BufferAccessStrategy bstrategy)
+{
+	rel->rd_tableam->relation_vacuum(rel, params, bstrategy);
+}
+
+/*
+ * Prepare to analyze block `blockno` of `scan`. The scan needs to have been
+ * started with table_beginscan_analyze().  Note that this routine might
+ * acquire resources like locks that are held until
+ * table_scan_analyze_next_tuple() returns false.
+ *
+ * Returns false if block is unsuitable for sampling, true otherwise.
+ */
+static inline bool
+table_scan_analyze_next_block(TableScanDesc scan, BlockNumber blockno,
+							  BufferAccessStrategy bstrategy)
+{
+	return scan->rs_rd->rd_tableam->scan_analyze_next_block(scan, blockno,
+															bstrategy);
+}
+
+/*
+ * Iterate over tuples in the block selected with
+ * table_scan_analyze_next_block() (which needs to have returned true, and
+ * this routine may not have returned false for the same block before). If a
+ * tuple that's suitable for sampling is found, true is returned and a tuple
+ * is stored in `slot`.
+ *
+ * *liverows and *deadrows are incremented according to the encountered
+ * tuples.
+ */
+static inline bool
+table_scan_analyze_next_tuple(TableScanDesc scan, TransactionId OldestXmin,
+							  double *liverows, double *deadrows,
+							  TupleTableSlot *slot)
+{
+	return scan->rs_rd->rd_tableam->scan_analyze_next_tuple(scan, OldestXmin,
+															liverows, deadrows,
+															slot);
+}
+
+/*
+ * table_index_build_scan - scan the table to find tuples to be indexed
+ *
+ * This is called back from an access-method-specific index build procedure
+ * after the AM has done whatever setup it needs.  The parent table relation
+ * is scanned to find tuples that should be entered into the index.  Each
+ * such tuple is passed to the AM's callback routine, which does the right
+ * things to add it to the new index.  After we return, the AM's index
+ * build procedure does whatever cleanup it needs.
+ *
+ * The total count of live tuples is returned.  This is for updating pg_class
+ * statistics.  (It's annoying not to be able to do that here, but we want to
+ * merge that update with others; see index_update_stats.)  Note that the
+ * index AM itself must keep track of the number of index tuples; we don't do
+ * so here because the AM might reject some of the tuples for its own reasons,
+ * such as being unable to store NULLs.
+ *
+ * If 'progress', the PROGRESS_SCAN_BLOCKS_TOTAL counter is updated when
+ * starting the scan, and PROGRESS_SCAN_BLOCKS_DONE is updated as we go along.
+ *
+ * A side effect is to set indexInfo->ii_BrokenHotChain to true if we detect
+ * any potentially broken HOT chains.  Currently, we set this if there are any
+ * RECENTLY_DEAD or DELETE_IN_PROGRESS entries in a HOT chain, without trying
+ * very hard to detect whether they're really incompatible with the chain tip.
+ * This only really makes sense for heap AM, it might need to be generalized
+ * for other AMs later.
+ */
+static inline double
+table_index_build_scan(Relation table_rel,
+					   Relation index_rel,
+					   struct IndexInfo *index_info,
+					   bool allow_sync,
+					   bool progress,
+					   IndexBuildCallback callback,
+					   void *callback_state,
+					   TableScanDesc scan)
+{
+	return table_rel->rd_tableam->index_build_range_scan(table_rel,
+														 index_rel,
+														 index_info,
+														 allow_sync,
+														 false,
+														 progress,
+														 0,
+														 InvalidBlockNumber,
+														 callback,
+														 callback_state,
+														 scan);
+}
+
+/*
+ * As table_index_build_scan(), except that instead of scanning the complete
+ * table, only the given number of blocks are scanned.  Scan to end-of-rel can
+ * be signaled by passing InvalidBlockNumber as numblocks.  Note that
+ * restricting the range to scan cannot be done when requesting syncscan.
+ *
+ * When "anyvisible" mode is requested, all tuples visible to any transaction
+ * are indexed and counted as live, including those inserted or deleted by
+ * transactions that are still in progress.
+ */
+static inline double
+table_index_build_range_scan(Relation table_rel,
+							 Relation index_rel,
+							 struct IndexInfo *index_info,
+							 bool allow_sync,
+							 bool anyvisible,
+							 bool progress,
+							 BlockNumber start_blockno,
+							 BlockNumber numblocks,
+							 IndexBuildCallback callback,
+							 void *callback_state,
+							 TableScanDesc scan)
+{
+	return table_rel->rd_tableam->index_build_range_scan(table_rel,
+														 index_rel,
+														 index_info,
+														 allow_sync,
+														 anyvisible,
+														 progress,
+														 start_blockno,
+														 numblocks,
+														 callback,
+														 callback_state,
+														 scan);
+}
+
+/*
+ * table_index_validate_scan - second table scan for concurrent index build
+ *
+ * See validate_index() for an explanation.
+ */
+static inline void
+table_index_validate_scan(Relation table_rel,
+						  Relation index_rel,
+						  struct IndexInfo *index_info,
+						  Snapshot snapshot,
+						  struct ValidateIndexState *state)
+{
+	table_rel->rd_tableam->index_validate_scan(table_rel,
+											   index_rel,
+											   index_info,
+											   snapshot,
+											   state);
+}
+
+
+/* ----------------------------------------------------------------------------
+ * Miscellaneous functionality
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Return the current size of `rel` in bytes. If `forkNumber` is
+ * InvalidForkNumber, return the relation's overall size, otherwise the size
+ * for the indicated fork.
+ *
+ * Note that the overall size might not be the equivalent of the sum of sizes
+ * for the individual forks for some AMs, e.g. because the AMs storage does
+ * not neatly map onto the builtin types of forks.
+ */
+static inline uint64
+table_relation_size(Relation rel, ForkNumber forkNumber)
+{
+	return rel->rd_tableam->relation_size(rel, forkNumber);
+}
+
+/*
+ * table_relation_needs_toast_table - does this relation need a toast table?
+ */
+static inline bool
+table_relation_needs_toast_table(Relation rel)
+{
+	return rel->rd_tableam->relation_needs_toast_table(rel);
+}
+
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
+/*
+ * Fetch all or part of a TOAST value from a TOAST table.
+ *
+ * If this AM is never used to implement a TOAST table, then this callback
+ * is not needed. But, if toasted values are ever stored in a table of this
+ * type, then you will need this callback.
+ *
+ * toastrel is the relation in which the toasted value is stored.
+ *
+ * valueid identifies which toast value is to be fetched. For the heap,
+ * this corresponds to the values stored in the chunk_id column.
+ *
+ * attrsize is the total size of the toast value to be fetched.
+ *
+ * sliceoffset is the offset within the toast value of the first byte that
+ * should be fetched.
+ *
+ * slicelength is the number of bytes from the toast value that should be
+ * fetched.
+ *
+ * result is caller-allocated space into which the fetched bytes should be
+ * stored.
+ */
+static inline void
+table_relation_fetch_toast_slice(Relation toastrel, Oid valueid,
+								 int32 attrsize, int32 sliceoffset,
+								 int32 slicelength, struct varlena *result)
+{
+	toastrel->rd_tableam->relation_fetch_toast_slice(toastrel, valueid,
+													 attrsize,
+													 sliceoffset, slicelength,
+													 result);
+}
+
+
+/* ----------------------------------------------------------------------------
+ * Planner related functionality
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Estimate the current size of the relation, as an AM specific workhorse for
+ * estimate_rel_size(). Look there for an explanation of the parameters.
+ */
+static inline void
+table_relation_estimate_size(Relation rel, int32 *attr_widths,
+							 BlockNumber *pages, double *tuples,
+							 double *allvisfrac)
+{
+	rel->rd_tableam->relation_estimate_size(rel, attr_widths, pages, tuples,
+											allvisfrac);
+}
+
+
+/* ----------------------------------------------------------------------------
+ * Executor related functionality
+ * ----------------------------------------------------------------------------
+ */
+
+/*
+ * Prepare to fetch / check / return tuples from `tbmres->blockno` as part of
+ * a bitmap table scan. `scan` needs to have been started via
+ * table_beginscan_bm(). Returns false if there are no tuples to be found on
+ * the page, true otherwise.
+ *
+ * Note, this is an optionally implemented function, therefore should only be
+ * used after verifying the presence (at plan time or such).
+ */
+static inline bool
+table_scan_bitmap_next_block(TableScanDesc scan,
+							 struct TBMIterateResult *tbmres)
+{
+	/*
+	 * We don't expect direct calls to table_scan_bitmap_next_block with valid
+	 * CheckXidAlive for catalog or regular tables.  See detailed comments in
+	 * xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_scan_bitmap_next_block call during logical decoding");
+
+	return scan->rs_rd->rd_tableam->scan_bitmap_next_block(scan,
+														   tbmres);
+}
+
+/*
+ * Fetch the next tuple of a bitmap table scan into `slot` and return true if
+ * a visible tuple was found, false otherwise.
+ * table_scan_bitmap_next_block() needs to previously have selected a
+ * block (i.e. returned true), and no previous
+ * table_scan_bitmap_next_tuple() for the same block may have
+ * returned false.
+ */
+static inline bool
+table_scan_bitmap_next_tuple(TableScanDesc scan,
+							 struct TBMIterateResult *tbmres,
+							 TupleTableSlot *slot)
+{
+	/*
+	 * We don't expect direct calls to table_scan_bitmap_next_tuple with valid
+	 * CheckXidAlive for catalog or regular tables.  See detailed comments in
+	 * xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_scan_bitmap_next_tuple call during logical decoding");
+
+	return scan->rs_rd->rd_tableam->scan_bitmap_next_tuple(scan,
+														   tbmres,
+														   slot);
+}
+
+/*
+ * Prepare to fetch tuples from the next block in a sample scan. Returns false
+ * if the sample scan is finished, true otherwise. `scan` needs to have been
+ * started via table_beginscan_sampling().
+ *
+ * This will call the TsmRoutine's NextSampleBlock() callback if necessary
+ * (i.e. NextSampleBlock is not NULL), or perform a sequential scan over the
+ * underlying relation.
+ */
+static inline bool
+table_scan_sample_next_block(TableScanDesc scan,
+							 struct SampleScanState *scanstate)
+{
+	/*
+	 * We don't expect direct calls to table_scan_sample_next_block with valid
+	 * CheckXidAlive for catalog or regular tables.  See detailed comments in
+	 * xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_scan_sample_next_block call during logical decoding");
+	return scan->rs_rd->rd_tableam->scan_sample_next_block(scan, scanstate);
+}
+
+/*
+ * Fetch the next sample tuple into `slot` and return true if a visible tuple
+ * was found, false otherwise. table_scan_sample_next_block() needs to
+ * previously have selected a block (i.e. returned true), and no previous
+ * table_scan_sample_next_tuple() for the same block may have returned false.
+ *
+ * This will call the TsmRoutine's NextSampleTuple() callback.
+ */
+static inline bool
+table_scan_sample_next_tuple(TableScanDesc scan,
+							 struct SampleScanState *scanstate,
+							 TupleTableSlot *slot)
+{
+	/*
+	 * We don't expect direct calls to table_scan_sample_next_tuple with valid
+	 * CheckXidAlive for catalog or regular tables.  See detailed comments in
+	 * xact.c where these variables are declared.
+	 */
+	if (unlikely(TransactionIdIsValid(CheckXidAlive) && !bsysscan))
+		elog(ERROR, "unexpected table_scan_sample_next_tuple call during logical decoding");
+	return scan->rs_rd->rd_tableam->scan_sample_next_tuple(scan, scanstate,
+														   slot);
+}
+
+
+/* ----------------------------------------------------------------------------
+ * Functions to make modifications a bit simpler.
+ * ----------------------------------------------------------------------------
+ */
+
+extern void simple_table_tuple_insert(Relation rel, TupleTableSlot *slot);
+extern void simple_table_tuple_delete(Relation rel, ItemPointer tid,
+									  Snapshot snapshot);
+extern void simple_table_tuple_update(Relation rel, ItemPointer otid,
+									  TupleTableSlot *slot, Snapshot snapshot,
+									  TU_UpdateIndexes *update_indexes);
+
+
+/* ----------------------------------------------------------------------------
+ * Helper functions to implement parallel scans for block oriented AMs.
+ * ----------------------------------------------------------------------------
+ */
+
+extern Size table_block_parallelscan_estimate(Relation rel);
+extern Size table_block_parallelscan_initialize(Relation rel,
+												ParallelTableScanDesc pscan);
+extern void table_block_parallelscan_reinitialize(Relation rel,
+												  ParallelTableScanDesc pscan);
+extern BlockNumber table_block_parallelscan_nextpage(Relation rel,
+													 ParallelBlockTableScanWorker pbscanwork,
+													 ParallelBlockTableScanDesc pbscan);
+extern void table_block_parallelscan_startblock_init(Relation rel,
+													 ParallelBlockTableScanWorker pbscanwork,
+													 ParallelBlockTableScanDesc pbscan);
+
+
+/* ----------------------------------------------------------------------------
+ * Helper functions to implement relation sizing for block oriented AMs.
+ * ----------------------------------------------------------------------------
+ */
+
+extern uint64 table_block_relation_size(Relation rel, ForkNumber forkNumber);
+extern void table_block_relation_estimate_size(Relation rel,
+											   int32 *attr_widths,
+											   BlockNumber *pages,
+											   double *tuples,
+											   double *allvisfrac,
+											   Size overhead_bytes_per_tuple,
+											   Size usable_bytes_per_page);
+
+/* ----------------------------------------------------------------------------
+ * Functions in tableamapi.c
+ * ----------------------------------------------------------------------------
+ */
+
+extern const TableAmRoutine *GetTableAmRoutine(Oid amhandler);
+extern const TableAmRoutine *GetHeapamTableAmRoutine(void);
+
+#endif							/* TABLEAM_H */