src/backend/access/appendonly/appendonly_visimap_udf.c - cloudberry - Git at Google

 /*------------------------------------------------------------------------------
  *
  * AppendOnlyVisimap UDFs
  *   User-defined functions (UDF) for support of append-only visimap
  *
  * Copyright (c) 2013-Present VMware, Inc. or its affiliates.
  *
  *
  * IDENTIFICATION
  *	    src/backend/access/appendonly/appendonly_visimap_udf.c
  *
  *------------------------------------------------------------------------------
 */
 #include "postgres.h"

 #include "access/appendonly_visimap.h"
 #include "access/appendonly_visimap_entry.h"
 #include "access/appendonly_visimap_store.h"
 #include "access/table.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_am.h"
 #include "catalog/pg_appendonly.h"
 #include "cdb/cdbappendonlyblockdirectory.h"
 #include "utils/guc.h"
 #include "utils/memutils.h"
 #include "funcapi.h"
 #include "utils/builtins.h"
 #include "utils/snapmgr.h"

 Datum gp_aovisimap(PG_FUNCTION_ARGS);

 Datum
 gp_aovisimap(PG_FUNCTION_ARGS)
 {
 	Oid			aoRelOid = PG_GETARG_OID(0);
 	Datum		values[3];
 	bool		nulls[3];
 	HeapTuple	tuple;
 	Datum		result;

     Oid visimaprelid;
     Oid visimapidxid;
 	typedef struct Context
 	{
 		Relation	aorel;
 		AppendOnlyVisimapScan visiMapScan;
 		AOTupleId	aoTupleId;

 	} Context;

 	FuncCallContext *funcctx;
 	Context    *context;

 	if (SRF_IS_FIRSTCALL())
 	{
 		TupleDesc	tupdesc;
 		MemoryContext oldcontext;

 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();

 		/*
 		 * switch to memory context appropriate for multiple function calls
 		 */
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

 		/* build tupdesc for result tuples */
 		tupdesc = CreateTemplateTupleDesc(3);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "tid",
 						   TIDOID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "segno",
 						   INT4OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "row_num",
 						   INT8OID, -1, 0);

 		funcctx->tuple_desc = BlessTupleDesc(tupdesc);

 		/*
 		 * Collect all the locking information that we will format and send
 		 * out as a result set.
 		 */
 		context = (Context *) palloc0(sizeof(Context));

 		context->aorel = table_open(aoRelOid, AccessShareLock);
 		if (!RelationStorageIsAO(context->aorel))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("function not supported on relation")));

 		Snapshot sst = GetLatestSnapshot();

         GetAppendOnlyEntryAuxOids(context->aorel,
                                   NULL, NULL, NULL,
                                   &visimaprelid, &visimapidxid);

 		AppendOnlyVisimapScan_Init(&context->visiMapScan,
 								   visimaprelid,
 								   visimapidxid,
 								   AccessShareLock,
 								   sst);

 		AOTupleIdSetInvalid(&context->aoTupleId);

 		funcctx->user_fctx = (void *) context;

 		MemoryContextSwitchTo(oldcontext);
 	}

 	funcctx = SRF_PERCALL_SETUP();
 	context = (Context *) funcctx->user_fctx;

 	while (true)
 	{
 		if (!AppendOnlyVisimapScan_GetNextInvisible(
 													&context->visiMapScan,
 													&context->aoTupleId))
 		{
 			break;
 		}
 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, false, sizeof(nulls));
 		values[0] = ItemPointerGetDatum((ItemPointer) &context->aoTupleId);
 		values[1] = Int32GetDatum(AOTupleIdGet_segmentFileNum(&context->aoTupleId));
 		values[2] = Int64GetDatum(AOTupleIdGet_rowNum(&context->aoTupleId));

 		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 		result = HeapTupleGetDatum(tuple);

 		SRF_RETURN_NEXT(funcctx, result);
 	}

 	AppendOnlyVisimapScan_Finish(&context->visiMapScan, AccessShareLock);
 	table_close(context->aorel, AccessShareLock);
 	pfree(context);
 	funcctx->user_fctx = NULL;
 	SRF_RETURN_DONE(funcctx);
 }

 Datum gp_aovisimap_hidden_info(PG_FUNCTION_ARGS);

 Datum
 gp_aovisimap_hidden_info(PG_FUNCTION_ARGS)
 {
 	Oid			aoRelOid = PG_GETARG_OID(0);
 	Datum		values[3];
 	bool		nulls[3];
 	HeapTuple	tuple;
 	Datum		result;
     Oid         visimaprelid;
     Oid         visimapidxid;

 	typedef struct Context
 	{
 		AppendOnlyVisimap visiMap;

 		Relation	parentRelation;

 		FileSegInfo **appendonlySegfileInfo;
 		AOCSFileSegInfo **aocsSegfileInfo;
 		int			segfile_info_total;

 		int			i;
 	} Context;

 	FuncCallContext *funcctx;
 	Context    *context;

 	if (SRF_IS_FIRSTCALL())
 	{
 		TupleDesc	tupdesc;
 		MemoryContext oldcontext;
 		Snapshot	snapshot;

 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();

 		/*
 		 * switch to memory context appropriate for multiple function calls
 		 */
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

 		/* build tupdesc for result tuples */
 		tupdesc = CreateTemplateTupleDesc(3);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "segno",
 						   INT4OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "hidden_tupcount",
 						   INT8OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "total_tupcount",
 						   INT8OID, -1, 0);

 		funcctx->tuple_desc = BlessTupleDesc(tupdesc);

 		/*
 		 * Collect all the locking information that we will format and send
 		 * out as a result set.
 		 */
 		context = (Context *) palloc0(sizeof(Context));

 		context->parentRelation = table_open(aoRelOid, AccessShareLock);
 		if (!RelationStorageIsAO(context->parentRelation))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("function not supported on relation")));

         Oid segrelid;
 		snapshot = GetLatestSnapshot();
         GetAppendOnlyEntryAuxOids(context->parentRelation,
                                   &segrelid, NULL, NULL,
                                   &visimaprelid, &visimapidxid);

 		AppendOnlyVisimap_Init(&context->visiMap,
 							   visimaprelid,
 							   visimapidxid,
 							   AccessShareLock,
 							   snapshot);

 		if (RelationIsAoRows(context->parentRelation))
 		{
 			context->appendonlySegfileInfo = GetAllFileSegInfo(context->parentRelation,
 															   snapshot,
 															   &context->segfile_info_total,
 															   NULL);
 		}
 		else
 		{
 			Assert(RelationIsAoCols(context->parentRelation));
 			context->aocsSegfileInfo = GetAllAOCSFileSegInfo(context->parentRelation,
 															 snapshot, &context->segfile_info_total, NULL);
 		}
 		context->i = 0;

 		funcctx->user_fctx = (void *) context;

 		MemoryContextSwitchTo(oldcontext);
 	}

 	funcctx = SRF_PERCALL_SETUP();
 	context = (Context *) funcctx->user_fctx;

 	while (context->i < context->segfile_info_total)
 	{
 		int64		tupcount;
 		int			segno;

 		if (context->appendonlySegfileInfo)
 		{
 			FileSegInfo *fsinfo = context->appendonlySegfileInfo[context->i];

 			tupcount = fsinfo->total_tupcount;
 			segno = fsinfo->segno;
 		}
 		else if (context->aocsSegfileInfo)
 		{
 			AOCSFileSegInfo *fsinfo = context->aocsSegfileInfo[context->i];

 			tupcount = fsinfo->total_tupcount;
 			segno = fsinfo->segno;
 		}
 		else
 			ereport(ERROR,
 					(errmsg("invalid function context"),
 					 errdetail("Storage must be either row or column oriented.")));

 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, false, sizeof(nulls));
 		values[0] = Int32GetDatum(segno);
 		values[1] = Int64GetDatum(AppendOnlyVisimap_GetSegmentFileHiddenTupleCount(
 																				   &context->visiMap, segno));
 		values[2] = Int64GetDatum(tupcount);

 		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 		result = HeapTupleGetDatum(tuple);

 		context->i++;
 		SRF_RETURN_NEXT(funcctx, result);
 	}

 	AppendOnlyVisimap_Finish(&context->visiMap, AccessShareLock);
 	if (context->appendonlySegfileInfo)
 	{
 		FreeAllSegFileInfo(context->appendonlySegfileInfo, context->segfile_info_total);
 		pfree(context->appendonlySegfileInfo);
 		context->appendonlySegfileInfo = NULL;
 	}
 	if (context->aocsSegfileInfo)
 	{
 		FreeAllAOCSSegFileInfo(context->aocsSegfileInfo, context->segfile_info_total);
 		pfree(context->aocsSegfileInfo);
 		context->aocsSegfileInfo = NULL;

 	}
 	table_close(context->parentRelation, AccessShareLock);
 	pfree(context);
 	funcctx->user_fctx = NULL;

 	SRF_RETURN_DONE(funcctx);
 }

 Datum gp_aovisimap_entry(PG_FUNCTION_ARGS);

 static void
 gp_aovisimap_encode_bitmap(char *bitmapBuffer, Bitmapset *bms)
 {
 	int			i;
 	int			last = -1;

 	Assert(bitmapBuffer);

 	memset(bitmapBuffer, '0', APPENDONLY_VISIMAP_MAX_RANGE + 1);
 	bitmapBuffer[APPENDONLY_VISIMAP_MAX_RANGE] = 0;

 	i = -1;
 	while ((i = bms_next_member(bms, i)) >= 0)
 	{
 		last = i;
 		Assert(i < APPENDONLY_VISIMAP_MAX_RANGE);
 		bitmapBuffer[i] = '1';
 	}
 	bitmapBuffer[last + 1] = 0;
 }

 Datum
 gp_aovisimap_entry(PG_FUNCTION_ARGS)
 {
 	Oid			aoRelOid = PG_GETARG_OID(0);
 	Datum		values[4];
 	bool		nulls[4];
 	HeapTuple	tuple;
 	Datum		result;
     Oid         visimaprelid;
     Oid         visimapidxid;

 	typedef struct Context
 	{
 		AppendOnlyVisimap visiMap;

 		Relation	parentRelation;

 		SysScanDesc indexScan;

 		text	   *bitmapBuffer;
 	} Context;

 	FuncCallContext *funcctx;
 	Context    *context;

 	if (SRF_IS_FIRSTCALL())
 	{
 		TupleDesc	tupdesc;
 		MemoryContext oldcontext;

 		/* create a function context for cross-call persistence */
 		funcctx = SRF_FIRSTCALL_INIT();

 		/*
 		 * switch to memory context appropriate for multiple function calls
 		 */
 		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

 		/* build tupdesc for result tuples */
 		tupdesc = CreateTemplateTupleDesc(4);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "segno",
 						   INT4OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "first_row_num",
 						   INT8OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "hidden_tupcount",
 						   INT4OID, -1, 0);
 		TupleDescInitEntry(tupdesc, (AttrNumber) 4, "bitmap",
 						   TEXTOID, -1, 0);

 		funcctx->tuple_desc = BlessTupleDesc(tupdesc);

 		/*
 		 * Collect all the locking information that we will format and send
 		 * out as a result set.
 		 */
 		context = (Context *) palloc0(sizeof(Context));

 		context->parentRelation = table_open(aoRelOid, AccessShareLock);
 		if (!RelationStorageIsAO(context->parentRelation))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("function not supported on relation")));

         Snapshot sst = GetLatestSnapshot();

         GetAppendOnlyEntryAuxOids(context->parentRelation,
                                   NULL, NULL, NULL,
                                   &visimaprelid, &visimapidxid);

 		AppendOnlyVisimap_Init(&context->visiMap,
 							   visimaprelid,
 							   visimapidxid,
 							   AccessShareLock,
 							   sst);

 		context->indexScan = AppendOnlyVisimapStore_BeginScan(&
 															  context->visiMap.visimapStore, 0, NULL);

 		context->bitmapBuffer = palloc0(VARHDRSZ + APPENDONLY_VISIMAP_MAX_RANGE + 1);

 		funcctx->user_fctx = (void *) context;

 		MemoryContextSwitchTo(oldcontext);
 	}

 	funcctx = SRF_PERCALL_SETUP();
 	context = (Context *) funcctx->user_fctx;

 	if (AppendOnlyVisimapStore_GetNext(&context->visiMap.visimapStore,
 									   context->indexScan,
 									   ForwardScanDirection,
 									   &context->visiMap.visimapEntry,
 									   NULL))
 	{
 		AppendOnlyVisimapEntry *visimapEntry = &context->visiMap.visimapEntry;

 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, false, sizeof(nulls));
 		values[0] = Int32GetDatum(visimapEntry->segmentFileNum);
 		values[1] = Int64GetDatum(visimapEntry->firstRowNum);
 		values[2] = Int32GetDatum(
 								  (int32) AppendOnlyVisimapEntry_GetHiddenTupleCount(visimapEntry));

 		gp_aovisimap_encode_bitmap(VARDATA(context->bitmapBuffer),
 								   visimapEntry->bitmap);
 		SET_VARSIZE(context->bitmapBuffer, APPENDONLY_VISIMAP_MAX_RANGE);
 		values[3] = PointerGetDatum(context->bitmapBuffer);

 		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
 		result = HeapTupleGetDatum(tuple);

 		SRF_RETURN_NEXT(funcctx, result);
 	}

 	AppendOnlyVisimapStore_EndScan(&context->visiMap.visimapStore,
 								   context->indexScan);
 	AppendOnlyVisimap_Finish(&context->visiMap, AccessShareLock);
 	table_close(context->parentRelation, AccessShareLock);

 	pfree(context->bitmapBuffer);
 	pfree(context);
 	funcctx->user_fctx = NULL;

 	SRF_RETURN_DONE(funcctx);
 }
	/*------------------------------------------------------------------------------
	*
	* AppendOnlyVisimap UDFs
	* User-defined functions (UDF) for support of append-only visimap
	*
	* Copyright (c) 2013-Present VMware, Inc. or its affiliates.
	*
	*
	* IDENTIFICATION
	* src/backend/access/appendonly/appendonly_visimap_udf.c
	*
	*------------------------------------------------------------------------------
	*/
	#include "postgres.h"

	#include "access/appendonly_visimap.h"
	#include "access/appendonly_visimap_entry.h"
	#include "access/appendonly_visimap_store.h"
	#include "access/table.h"
	#include "catalog/namespace.h"
	#include "catalog/pg_am.h"
	#include "catalog/pg_appendonly.h"
	#include "cdb/cdbappendonlyblockdirectory.h"
	#include "utils/guc.h"
	#include "utils/memutils.h"
	#include "funcapi.h"
	#include "utils/builtins.h"
	#include "utils/snapmgr.h"

	Datum gp_aovisimap(PG_FUNCTION_ARGS);

	Datum
	gp_aovisimap(PG_FUNCTION_ARGS)
	{
	Oid aoRelOid = PG_GETARG_OID(0);
	Datum values[3];
	bool nulls[3];
	HeapTuple tuple;
	Datum result;

	Oid visimaprelid;
	Oid visimapidxid;
	typedef struct Context
	{
	Relation aorel;
	AppendOnlyVisimapScan visiMapScan;
	AOTupleId aoTupleId;

	} Context;

	FuncCallContext *funcctx;
	Context *context;

	if (SRF_IS_FIRSTCALL())
	{
	TupleDesc tupdesc;
	MemoryContext oldcontext;

	/* create a function context for cross-call persistence */
	funcctx = SRF_FIRSTCALL_INIT();

	/*
	* switch to memory context appropriate for multiple function calls
	*/
	oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

	/* build tupdesc for result tuples */
	tupdesc = CreateTemplateTupleDesc(3);
	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "tid",
	TIDOID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "segno",
	INT4OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "row_num",
	INT8OID, -1, 0);

	funcctx->tuple_desc = BlessTupleDesc(tupdesc);

	/*
	* Collect all the locking information that we will format and send
	* out as a result set.
	*/
	context = (Context *) palloc0(sizeof(Context));

	context->aorel = table_open(aoRelOid, AccessShareLock);
	if (!RelationStorageIsAO(context->aorel))
	ereport(ERROR,
	(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
	errmsg("function not supported on relation")));

	Snapshot sst = GetLatestSnapshot();

	GetAppendOnlyEntryAuxOids(context->aorel,
	NULL, NULL, NULL,
	&visimaprelid, &visimapidxid);

	AppendOnlyVisimapScan_Init(&context->visiMapScan,
	visimaprelid,
	visimapidxid,
	AccessShareLock,
	sst);

	AOTupleIdSetInvalid(&context->aoTupleId);

	funcctx->user_fctx = (void *) context;

	MemoryContextSwitchTo(oldcontext);
	}

	funcctx = SRF_PERCALL_SETUP();
	context = (Context *) funcctx->user_fctx;

	while (true)
	{
	if (!AppendOnlyVisimapScan_GetNextInvisible(
	&context->visiMapScan,
	&context->aoTupleId))
	{
	break;
	}
	MemSet(values, 0, sizeof(values));
	MemSet(nulls, false, sizeof(nulls));
	values[0] = ItemPointerGetDatum((ItemPointer) &context->aoTupleId);
	values[1] = Int32GetDatum(AOTupleIdGet_segmentFileNum(&context->aoTupleId));
	values[2] = Int64GetDatum(AOTupleIdGet_rowNum(&context->aoTupleId));

	tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
	result = HeapTupleGetDatum(tuple);

	SRF_RETURN_NEXT(funcctx, result);
	}

	AppendOnlyVisimapScan_Finish(&context->visiMapScan, AccessShareLock);
	table_close(context->aorel, AccessShareLock);
	pfree(context);
	funcctx->user_fctx = NULL;
	SRF_RETURN_DONE(funcctx);
	}

	Datum gp_aovisimap_hidden_info(PG_FUNCTION_ARGS);

	Datum
	gp_aovisimap_hidden_info(PG_FUNCTION_ARGS)
	{
	Oid aoRelOid = PG_GETARG_OID(0);
	Datum values[3];
	bool nulls[3];
	HeapTuple tuple;
	Datum result;
	Oid visimaprelid;
	Oid visimapidxid;

	typedef struct Context
	{
	AppendOnlyVisimap visiMap;

	Relation parentRelation;

	FileSegInfo **appendonlySegfileInfo;
	AOCSFileSegInfo **aocsSegfileInfo;
	int segfile_info_total;

	int i;
	} Context;

	FuncCallContext *funcctx;
	Context *context;

	if (SRF_IS_FIRSTCALL())
	{
	TupleDesc tupdesc;
	MemoryContext oldcontext;
	Snapshot snapshot;

	/* create a function context for cross-call persistence */
	funcctx = SRF_FIRSTCALL_INIT();

	/*
	* switch to memory context appropriate for multiple function calls
	*/
	oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

	/* build tupdesc for result tuples */
	tupdesc = CreateTemplateTupleDesc(3);
	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "segno",
	INT4OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "hidden_tupcount",
	INT8OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "total_tupcount",
	INT8OID, -1, 0);

	funcctx->tuple_desc = BlessTupleDesc(tupdesc);

	/*
	* Collect all the locking information that we will format and send
	* out as a result set.
	*/
	context = (Context *) palloc0(sizeof(Context));

	context->parentRelation = table_open(aoRelOid, AccessShareLock);
	if (!RelationStorageIsAO(context->parentRelation))
	ereport(ERROR,
	(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
	errmsg("function not supported on relation")));

	Oid segrelid;
	snapshot = GetLatestSnapshot();
	GetAppendOnlyEntryAuxOids(context->parentRelation,
	&segrelid, NULL, NULL,
	&visimaprelid, &visimapidxid);

	AppendOnlyVisimap_Init(&context->visiMap,
	visimaprelid,
	visimapidxid,
	AccessShareLock,
	snapshot);

	if (RelationIsAoRows(context->parentRelation))
	{
	context->appendonlySegfileInfo = GetAllFileSegInfo(context->parentRelation,
	snapshot,
	&context->segfile_info_total,
	NULL);
	}
	else
	{
	Assert(RelationIsAoCols(context->parentRelation));
	context->aocsSegfileInfo = GetAllAOCSFileSegInfo(context->parentRelation,
	snapshot, &context->segfile_info_total, NULL);
	}
	context->i = 0;

	funcctx->user_fctx = (void *) context;

	MemoryContextSwitchTo(oldcontext);
	}

	funcctx = SRF_PERCALL_SETUP();
	context = (Context *) funcctx->user_fctx;

	while (context->i < context->segfile_info_total)
	{
	int64 tupcount;
	int segno;

	if (context->appendonlySegfileInfo)
	{
	FileSegInfo *fsinfo = context->appendonlySegfileInfo[context->i];

	tupcount = fsinfo->total_tupcount;
	segno = fsinfo->segno;
	}
	else if (context->aocsSegfileInfo)
	{
	AOCSFileSegInfo *fsinfo = context->aocsSegfileInfo[context->i];

	tupcount = fsinfo->total_tupcount;
	segno = fsinfo->segno;
	}
	else
	ereport(ERROR,
	(errmsg("invalid function context"),
	errdetail("Storage must be either row or column oriented.")));

	MemSet(values, 0, sizeof(values));
	MemSet(nulls, false, sizeof(nulls));
	values[0] = Int32GetDatum(segno);
	values[1] = Int64GetDatum(AppendOnlyVisimap_GetSegmentFileHiddenTupleCount(
	&context->visiMap, segno));
	values[2] = Int64GetDatum(tupcount);

	tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
	result = HeapTupleGetDatum(tuple);

	context->i++;
	SRF_RETURN_NEXT(funcctx, result);
	}

	AppendOnlyVisimap_Finish(&context->visiMap, AccessShareLock);
	if (context->appendonlySegfileInfo)
	{
	FreeAllSegFileInfo(context->appendonlySegfileInfo, context->segfile_info_total);
	pfree(context->appendonlySegfileInfo);
	context->appendonlySegfileInfo = NULL;
	}
	if (context->aocsSegfileInfo)
	{
	FreeAllAOCSSegFileInfo(context->aocsSegfileInfo, context->segfile_info_total);
	pfree(context->aocsSegfileInfo);
	context->aocsSegfileInfo = NULL;

	}
	table_close(context->parentRelation, AccessShareLock);
	pfree(context);
	funcctx->user_fctx = NULL;

	SRF_RETURN_DONE(funcctx);
	}

	Datum gp_aovisimap_entry(PG_FUNCTION_ARGS);

	static void
	gp_aovisimap_encode_bitmap(char bitmapBuffer, Bitmapset bms)
	{
	int i;
	int last = -1;

	Assert(bitmapBuffer);

	memset(bitmapBuffer, '0', APPENDONLY_VISIMAP_MAX_RANGE + 1);
	bitmapBuffer[APPENDONLY_VISIMAP_MAX_RANGE] = 0;

	i = -1;
	while ((i = bms_next_member(bms, i)) >= 0)
	{
	last = i;
	Assert(i < APPENDONLY_VISIMAP_MAX_RANGE);
	bitmapBuffer[i] = '1';
	}
	bitmapBuffer[last + 1] = 0;
	}

	Datum
	gp_aovisimap_entry(PG_FUNCTION_ARGS)
	{
	Oid aoRelOid = PG_GETARG_OID(0);
	Datum values[4];
	bool nulls[4];
	HeapTuple tuple;
	Datum result;
	Oid visimaprelid;
	Oid visimapidxid;

	typedef struct Context
	{
	AppendOnlyVisimap visiMap;

	Relation parentRelation;

	SysScanDesc indexScan;

	text *bitmapBuffer;
	} Context;

	FuncCallContext *funcctx;
	Context *context;

	if (SRF_IS_FIRSTCALL())
	{
	TupleDesc tupdesc;
	MemoryContext oldcontext;

	/* create a function context for cross-call persistence */
	funcctx = SRF_FIRSTCALL_INIT();

	/*
	* switch to memory context appropriate for multiple function calls
	*/
	oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

	/* build tupdesc for result tuples */
	tupdesc = CreateTemplateTupleDesc(4);
	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "segno",
	INT4OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "first_row_num",
	INT8OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 3, "hidden_tupcount",
	INT4OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 4, "bitmap",
	TEXTOID, -1, 0);

	funcctx->tuple_desc = BlessTupleDesc(tupdesc);

	/*
	* Collect all the locking information that we will format and send
	* out as a result set.
	*/
	context = (Context *) palloc0(sizeof(Context));

	context->parentRelation = table_open(aoRelOid, AccessShareLock);
	if (!RelationStorageIsAO(context->parentRelation))
	ereport(ERROR,
	(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
	errmsg("function not supported on relation")));

	Snapshot sst = GetLatestSnapshot();

	GetAppendOnlyEntryAuxOids(context->parentRelation,
	NULL, NULL, NULL,
	&visimaprelid, &visimapidxid);

	AppendOnlyVisimap_Init(&context->visiMap,
	visimaprelid,
	visimapidxid,
	AccessShareLock,
	sst);

	context->indexScan = AppendOnlyVisimapStore_BeginScan(&
	context->visiMap.visimapStore, 0, NULL);

	context->bitmapBuffer = palloc0(VARHDRSZ + APPENDONLY_VISIMAP_MAX_RANGE + 1);

	funcctx->user_fctx = (void *) context;

	MemoryContextSwitchTo(oldcontext);
	}

	funcctx = SRF_PERCALL_SETUP();
	context = (Context *) funcctx->user_fctx;

	if (AppendOnlyVisimapStore_GetNext(&context->visiMap.visimapStore,
	context->indexScan,
	ForwardScanDirection,
	&context->visiMap.visimapEntry,
	NULL))
	{
	AppendOnlyVisimapEntry *visimapEntry = &context->visiMap.visimapEntry;

	MemSet(values, 0, sizeof(values));
	MemSet(nulls, false, sizeof(nulls));
	values[0] = Int32GetDatum(visimapEntry->segmentFileNum);
	values[1] = Int64GetDatum(visimapEntry->firstRowNum);
	values[2] = Int32GetDatum(
	(int32) AppendOnlyVisimapEntry_GetHiddenTupleCount(visimapEntry));

	gp_aovisimap_encode_bitmap(VARDATA(context->bitmapBuffer),
	visimapEntry->bitmap);
	SET_VARSIZE(context->bitmapBuffer, APPENDONLY_VISIMAP_MAX_RANGE);
	values[3] = PointerGetDatum(context->bitmapBuffer);

	tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
	result = HeapTupleGetDatum(tuple);

	SRF_RETURN_NEXT(funcctx, result);
	}

	AppendOnlyVisimapStore_EndScan(&context->visiMap.visimapStore,
	context->indexScan);
	AppendOnlyVisimap_Finish(&context->visiMap, AccessShareLock);
	table_close(context->parentRelation, AccessShareLock);

	pfree(context->bitmapBuffer);
	pfree(context);
	funcctx->user_fctx = NULL;

	SRF_RETURN_DONE(funcctx);
	}