/*-------------------------------------------------------------------------
 *
 * execAmi.c--
 *    miscellanious executor access method routines
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    $Header: /cvsroot/pgsql/src/backend/executor/execAmi.c,v 1.4 1996/11/08 00:45:54 scrappy Exp $
 *
 *-------------------------------------------------------------------------
 */
/*
 *   INTERFACE ROUTINES
 *
 *   	ExecOpenScanR	\			      /	amopen
 *   	ExecBeginScan	 \			     /	ambeginscan
 *   	ExecCloseR	  \			    /	amclose
 *    	ExecInsert	   \  executor interface   /	aminsert
 *   	ExecReScanNode	   /  to access methods    \	amrescan
 *   	ExecReScanR	  /			    \	amrescan
 *   	ExecMarkPos	 /			     \	ammarkpos
 *   	ExecRestrPos    /			      \	amrestpos
 *
 *	ExecCreatR	function to create temporary relations
 *
 */
#include <stdio.h>	/* for sprintf() */

#include "postgres.h"

#include "executor/executor.h"
#include "storage/smgr.h"
#include "utils/mcxt.h"
#include "executor/nodeSeqscan.h"
#include "executor/nodeIndexscan.h"
#include "executor/nodeSort.h"
#include "executor/nodeTee.h"
#include "executor/execdebug.h"
#include "optimizer/internal.h" /* for _TEMP_RELATION_ID_ */
#include "access/genam.h"
#include "access/heapam.h"
#include "catalog/heap.h"

/* ----------------------------------------------------------------
 *   	ExecOpenScanR
 *
 * old comments:
 *   	Parameters:
 *   	  relation -- relation to be opened and scanned.
 *   	  nkeys	   -- number of keys
 *   	  skeys    -- keys to restrict scanning
 *           isindex  -- if this is true, the relation is the relid of
 *                       an index relation, else it is an index into the
 *                       range table.
 *   	Returns the relation as(relDesc scanDesc)
 *         If this structure is changed, need to modify the access macros
 *   	defined in execInt.h.
 * ----------------------------------------------------------------
 */
void
ExecOpenScanR(Oid relOid,
	      int nkeys,
	      ScanKey skeys,
	      bool isindex,
	      ScanDirection dir,
	      TimeQual timeRange,
	      Relation *returnRelation,		/* return */
	      Pointer *returnScanDesc) 		/* return */
{
    Relation relation;
    Pointer  scanDesc;
    
    /* ----------------
     *	note: scanDesc returned by ExecBeginScan can be either
     *	      a HeapScanDesc or an IndexScanDesc so for now we
     *	      make it a Pointer.  There should be a better scan
     *	      abstraction someday -cim 9/9/89
     * ----------------
     */
    relation = ExecOpenR(relOid, isindex);
    scanDesc = ExecBeginScan(relation,
			     nkeys,
			     skeys,
			     isindex,
			     dir,
			     timeRange);
    
    if (returnRelation != NULL)
	*returnRelation = relation;
    if (scanDesc != NULL)
	*returnScanDesc = scanDesc;
}
 
/* ----------------------------------------------------------------
 *	ExecOpenR
 *
 *	returns a relation descriptor given an object id.
 * ----------------------------------------------------------------
 */
Relation
ExecOpenR(Oid relationOid, bool isindex)
{
    Relation relation;
    relation = (Relation) NULL;

    /* ----------------
     *	open the relation with the correct call depending
     *  on whether this is a heap relation or an index relation.
     * ----------------
     */
    if (isindex) {
	relation = index_open(relationOid);
    } else
	relation = heap_open(relationOid);
	
    if (relation == NULL)
	elog(DEBUG, "ExecOpenR: relation == NULL, heap_open failed.");

    return relation;
}
 
/* ----------------------------------------------------------------
 *   	ExecBeginScan
 *
 *   	beginscans a relation in current direction.
 *
 *	XXX fix parameters to AMbeginscan (and btbeginscan)
 *		currently we need to pass a flag stating whether
 *		or not the scan should begin at an endpoint of
 *		the relation.. Right now we always pass false
 *		-cim 9/14/89
 * ----------------------------------------------------------------
 */
Pointer
ExecBeginScan(Relation relation,
	      int nkeys,
	      ScanKey skeys,
	      bool isindex,
	      ScanDirection dir,
	      TimeQual time_range)
{
    Pointer  scanDesc;
    
    scanDesc =   NULL;

    /* ----------------
     *	open the appropriate type of scan.
     *	
     *  Note: ambeginscan()'s second arg is a boolean indicating
     *	      that the scan should be done in reverse..  That is,
     *	      if you pass it true, then the scan is backward.
     * ----------------
     */
    if (isindex) {
	scanDesc = (Pointer) index_beginscan(relation,
					     false,	/* see above comment */
					     nkeys,
					     skeys);
    } else {
	scanDesc = (Pointer) heap_beginscan(relation,
					    ScanDirectionIsBackward(dir),
					    time_range,
					    nkeys,
					    skeys);
    }
   
    if (scanDesc == NULL)
	elog(DEBUG, "ExecBeginScan: scanDesc = NULL, heap_beginscan failed.");
    
    
    return scanDesc;
}
 
/* ----------------------------------------------------------------
 *   	ExecCloseR
 *
 *	closes the relation and scan descriptor for a scan or sort
 *	node.  Also closes index relations and scans for index scans.
 *
 * old comments
 *   	closes the relation indicated in 'relID'
 * ----------------------------------------------------------------
 */
void
ExecCloseR(Plan *node)
{
    CommonScanState *state;
    Relation	 relation;
    HeapScanDesc scanDesc;
    
    /* ----------------
     *  shut down the heap scan and close the heap relation
     * ----------------
     */
    switch (nodeTag(node)) {
	
    case T_SeqScan:
	state =  ((SeqScan *)node)->scanstate;
	break;

    case T_IndexScan:
	state = ((IndexScan *)node)->scan.scanstate;
	break;
	
    case T_Material:
	state = &(((Material *)node)->matstate->csstate);
	break;
	
    case T_Sort:
	state =  &(((Sort *)node)->sortstate->csstate);
	break;

    case T_Agg:
	state = &(((Agg *)node)->aggstate->csstate);
	break;

    default:
	elog(DEBUG, "ExecCloseR: not a scan, material, or sort node!");
	return;
    }
    
    relation = state->css_currentRelation;
    scanDesc = state->css_currentScanDesc;
    
    if (scanDesc != NULL)
	heap_endscan(scanDesc);
    
    if (relation != NULL)
	heap_close(relation);
    
    /* ----------------
     *	if this is an index scan then we have to take care
     *  of the index relations as well..
     * ----------------
     */
    if (nodeTag(node) == T_IndexScan) {
	IndexScan	 *iscan= (IndexScan *)node;
	IndexScanState	 *indexstate;
	int		 numIndices;
	RelationPtr	 indexRelationDescs;
	IndexScanDescPtr indexScanDescs;
	int		 i;
	
	indexstate = 	     iscan->indxstate;
	numIndices =         indexstate->iss_NumIndices;
	indexRelationDescs = indexstate->iss_RelationDescs;
	indexScanDescs =     indexstate->iss_ScanDescs;
	
	for (i = 0; i<numIndices; i++) {
	    /* ----------------
	     *	shut down each of the scans and
	     *  close each of the index relations
	     * ----------------
	     */
	    if (indexScanDescs[i] != NULL)
		index_endscan(indexScanDescs[i]);
	    
	    if (indexRelationDescs[i] != NULL)
		index_close(indexRelationDescs[i]);
	}
    }
}
 
/* ----------------------------------------------------------------
 *   	ExecReScan
 *
 *	XXX this should be extended to cope with all the node types..
 *
 *	takes the new expression context as an argument, so that 
 *	index scans needn't have their scan keys updated separately
 *	- marcel 09/20/94
 * ----------------------------------------------------------------
 */
void
ExecReScan(Plan *node, ExprContext *exprCtxt, Plan *parent)
{
    switch(nodeTag(node)) {
    case T_SeqScan:
	ExecSeqReScan((SeqScan *) node, exprCtxt, parent);
	return;
    
    case T_IndexScan:
	ExecIndexReScan((IndexScan *) node, exprCtxt, parent);
	return;

    case T_Material:
	/* the first call to ExecReScan should have no effect because
	 * everything is initialized properly already.  the following
	 * calls will be handled by ExecSeqReScan() because the nodes
	 * below the Material node have already been materialized into
	 * a temp relation.
	 */
	return;

    case T_Tee:
	ExecTeeReScan((Tee*) node, exprCtxt, parent);
	break;

    default:
	elog(WARN, "ExecReScan: not a seqscan or indexscan node.");
	return;
    }
}
 
/* ----------------------------------------------------------------
 *   	ExecReScanR
 *
 *	XXX this does not do the right thing with indices yet.
 * ----------------------------------------------------------------
 */
HeapScanDesc
ExecReScanR(Relation relDesc,	/* LLL relDesc unused  */
	    HeapScanDesc scanDesc,
	    ScanDirection direction,
	    int nkeys,		/* LLL nkeys unused  */
	    ScanKey skeys)
{
    if (scanDesc != NULL)
	heap_rescan(scanDesc,			/* scan desc */
		    ScanDirectionIsBackward(direction), /* backward flag */
		    skeys);			/* scan keys */
    
    return scanDesc;
}
 
/* ----------------------------------------------------------------
 *   	ExecMarkPos
 *
 *	Marks the current scan position.  
 *
 *	XXX Needs to be extended to include all the node types.
 * ----------------------------------------------------------------
 */
void
ExecMarkPos(Plan *node)
{
    switch(nodeTag(node)) {
    case T_SeqScan:
	ExecSeqMarkPos((SeqScan *) node);
	break;

    case T_IndexScan:
	ExecIndexMarkPos((IndexScan *) node);
	break;

    case T_Sort:
	ExecSortMarkPos((Sort *) node);
	break;

    default:
	/* elog(DEBUG, "ExecMarkPos: unsupported node type"); */
	break;
    }
    return;
}
 
/* ----------------------------------------------------------------
 *   	ExecRestrPos
 *
 *   	restores the scan position previously saved with ExecMarkPos()
 * ----------------------------------------------------------------
 */
void
ExecRestrPos(Plan *node)
{
    switch(nodeTag(node)) {
    case T_SeqScan:
	ExecSeqRestrPos((SeqScan *) node);
	return;
    
    case T_IndexScan:
	ExecIndexRestrPos((IndexScan *) node);
	return;
    
    case T_Sort:
	ExecSortRestrPos((Sort *) node);
	return;

    default:
	/* elog(DEBUG, "ExecRestrPos: node type not supported"); */
	return;
    }
}
 
/* ----------------------------------------------------------------
 *   	ExecCreatR
 *
 * old comments
 *   	Creates a relation.
 *
 *   	Parameters:
 *   	  attrType  -- type information on the attributes.
 *   	  accessMtd -- access methods used to access the created relation.
 *   	  relation  -- optional. Either an index to the range table or
 *   		       negative number indicating a temporary relation.
 *   		       A temporary relation is assume is this field is absent.
 * ----------------------------------------------------------------
 */

Relation
ExecCreatR(TupleDesc tupType,
	   Oid relationOid)
{
    Relation 	relDesc;

    EU3_printf("ExecCreatR: %s type=%d oid=%d\n",
	       "entering: ", tupType, relationOid);
    CXT1_printf("ExecCreatR: context is %d\n", CurrentMemoryContext);
    
    relDesc = NULL;
    
    if (relationOid == _TEMP_RELATION_ID_ ) {
	/* ----------------
	 *   create a temporary relation
	 *   (currently the planner always puts a _TEMP_RELATION_ID
	 *   in the relation argument so we expect this to be the case although
	 *   it's possible that someday we'll get the name from
	 *   from the range table.. -cim 10/12/89)
	 * ----------------
	 */
/*
	sprintf(tempname, "temp_%d.%d", getpid(), tmpcnt++);
	EU1_printf("ExecCreatR: attempting to create %s\n", tempname);
*/
      /* heap_creatr creates a name if the argument to heap_creatr is '\0 ' */
	relDesc = heap_creatr("",
			      DEFAULT_SMGR,
			      tupType);
    } else {
	/* ----------------
	 *	use a relation from the range table
	 * ----------------
	 */
	elog(DEBUG, "ExecCreatR: %s",
	     "stuff using range table id's is not functional");
    }
    
    if (relDesc == NULL)
	elog(DEBUG, "ExecCreatR: failed to create relation.");
    
    EU1_printf("ExecCreatR: returning relDesc=%d\n", relDesc);
    
    return relDesc;
}
 
