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325b357bc2
Commit e7cb7ee145 provided basic
infrastructure for allowing a foreign data wrapper or custom scan
provider to replace a join of one or more tables with a scan.
However, this infrastructure failed to take into account the need
for possible EvalPlanQual rechecks, and ExecScanFetch would fail
an assertion (or just overwrite memory) if such a check was attempted
for a plan containing a pushed-down join. To fix, adjust the EPQ
machinery to skip some processing steps when scanrelid == 0, making
those the responsibility of scan's recheck method, which also has
the responsibility in this case of correctly populating the relevant
slot.
To allow foreign scans to gain control in the right place to make
use of this new facility, add a new, optional RecheckForeignScan
method. Also, allow a foreign scan to have a child plan, which can
be used to correctly populate the slot (or perhaps for something
else, but this is the only use currently envisioned).
KaiGai Kohei, reviewed by Robert Haas, Etsuro Fujita, and Kyotaro
Horiguchi.
192 lines
6.5 KiB
C
192 lines
6.5 KiB
C
/*-------------------------------------------------------------------------
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*
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* fdwapi.h
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* API for foreign-data wrappers
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*
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* Copyright (c) 2010-2015, PostgreSQL Global Development Group
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*
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* src/include/foreign/fdwapi.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef FDWAPI_H
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#define FDWAPI_H
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#include "nodes/execnodes.h"
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#include "nodes/relation.h"
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/* To avoid including explain.h here, reference ExplainState thus: */
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struct ExplainState;
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/*
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* Callback function signatures --- see fdwhandler.sgml for more info.
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*/
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typedef void (*GetForeignRelSize_function) (PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid);
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typedef void (*GetForeignPaths_function) (PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid);
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typedef ForeignScan *(*GetForeignPlan_function) (PlannerInfo *root,
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RelOptInfo *baserel,
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Oid foreigntableid,
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ForeignPath *best_path,
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List *tlist,
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List *scan_clauses,
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Plan *outer_plan);
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typedef void (*BeginForeignScan_function) (ForeignScanState *node,
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int eflags);
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typedef TupleTableSlot *(*IterateForeignScan_function) (ForeignScanState *node);
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typedef bool (*RecheckForeignScan_function) (ForeignScanState *node,
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TupleTableSlot *slot);
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typedef void (*ReScanForeignScan_function) (ForeignScanState *node);
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typedef void (*EndForeignScan_function) (ForeignScanState *node);
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typedef void (*GetForeignJoinPaths_function) (PlannerInfo *root,
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RelOptInfo *joinrel,
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RelOptInfo *outerrel,
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RelOptInfo *innerrel,
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JoinType jointype,
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JoinPathExtraData *extra);
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typedef void (*AddForeignUpdateTargets_function) (Query *parsetree,
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RangeTblEntry *target_rte,
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Relation target_relation);
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typedef List *(*PlanForeignModify_function) (PlannerInfo *root,
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ModifyTable *plan,
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Index resultRelation,
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int subplan_index);
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typedef void (*BeginForeignModify_function) (ModifyTableState *mtstate,
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ResultRelInfo *rinfo,
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List *fdw_private,
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int subplan_index,
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int eflags);
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typedef TupleTableSlot *(*ExecForeignInsert_function) (EState *estate,
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ResultRelInfo *rinfo,
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TupleTableSlot *slot,
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TupleTableSlot *planSlot);
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typedef TupleTableSlot *(*ExecForeignUpdate_function) (EState *estate,
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ResultRelInfo *rinfo,
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TupleTableSlot *slot,
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TupleTableSlot *planSlot);
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typedef TupleTableSlot *(*ExecForeignDelete_function) (EState *estate,
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ResultRelInfo *rinfo,
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TupleTableSlot *slot,
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TupleTableSlot *planSlot);
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typedef void (*EndForeignModify_function) (EState *estate,
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ResultRelInfo *rinfo);
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typedef int (*IsForeignRelUpdatable_function) (Relation rel);
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typedef RowMarkType (*GetForeignRowMarkType_function) (RangeTblEntry *rte,
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LockClauseStrength strength);
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typedef HeapTuple (*RefetchForeignRow_function) (EState *estate,
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ExecRowMark *erm,
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Datum rowid,
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bool *updated);
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typedef void (*ExplainForeignScan_function) (ForeignScanState *node,
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struct ExplainState *es);
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typedef void (*ExplainForeignModify_function) (ModifyTableState *mtstate,
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ResultRelInfo *rinfo,
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List *fdw_private,
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int subplan_index,
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struct ExplainState *es);
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typedef int (*AcquireSampleRowsFunc) (Relation relation, int elevel,
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HeapTuple *rows, int targrows,
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double *totalrows,
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double *totaldeadrows);
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typedef bool (*AnalyzeForeignTable_function) (Relation relation,
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AcquireSampleRowsFunc *func,
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BlockNumber *totalpages);
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typedef List *(*ImportForeignSchema_function) (ImportForeignSchemaStmt *stmt,
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Oid serverOid);
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/*
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* FdwRoutine is the struct returned by a foreign-data wrapper's handler
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* function. It provides pointers to the callback functions needed by the
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* planner and executor.
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*
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* More function pointers are likely to be added in the future. Therefore
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* it's recommended that the handler initialize the struct with
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* makeNode(FdwRoutine) so that all fields are set to NULL. This will
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* ensure that no fields are accidentally left undefined.
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*/
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typedef struct FdwRoutine
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{
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NodeTag type;
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/* Functions for scanning foreign tables */
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GetForeignRelSize_function GetForeignRelSize;
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GetForeignPaths_function GetForeignPaths;
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GetForeignPlan_function GetForeignPlan;
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BeginForeignScan_function BeginForeignScan;
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IterateForeignScan_function IterateForeignScan;
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ReScanForeignScan_function ReScanForeignScan;
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EndForeignScan_function EndForeignScan;
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/*
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* Remaining functions are optional. Set the pointer to NULL for any that
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* are not provided.
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*/
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/* Functions for remote-join planning */
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GetForeignJoinPaths_function GetForeignJoinPaths;
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/* Functions for updating foreign tables */
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AddForeignUpdateTargets_function AddForeignUpdateTargets;
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PlanForeignModify_function PlanForeignModify;
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BeginForeignModify_function BeginForeignModify;
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ExecForeignInsert_function ExecForeignInsert;
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ExecForeignUpdate_function ExecForeignUpdate;
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ExecForeignDelete_function ExecForeignDelete;
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EndForeignModify_function EndForeignModify;
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IsForeignRelUpdatable_function IsForeignRelUpdatable;
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/* Functions for SELECT FOR UPDATE/SHARE row locking */
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GetForeignRowMarkType_function GetForeignRowMarkType;
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RefetchForeignRow_function RefetchForeignRow;
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RecheckForeignScan_function RecheckForeignScan;
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/* Support functions for EXPLAIN */
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ExplainForeignScan_function ExplainForeignScan;
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ExplainForeignModify_function ExplainForeignModify;
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/* Support functions for ANALYZE */
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AnalyzeForeignTable_function AnalyzeForeignTable;
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/* Support functions for IMPORT FOREIGN SCHEMA */
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ImportForeignSchema_function ImportForeignSchema;
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} FdwRoutine;
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/* Functions in foreign/foreign.c */
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extern FdwRoutine *GetFdwRoutine(Oid fdwhandler);
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extern Oid GetForeignServerIdByRelId(Oid relid);
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extern FdwRoutine *GetFdwRoutineByServerId(Oid serverid);
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extern FdwRoutine *GetFdwRoutineByRelId(Oid relid);
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extern FdwRoutine *GetFdwRoutineForRelation(Relation relation, bool makecopy);
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extern bool IsImportableForeignTable(const char *tablename,
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ImportForeignSchemaStmt *stmt);
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#endif /* FDWAPI_H */
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