static uint32
build_hash_key(const void *key, Size keysize __attribute__((unused)))
{
    Assert(key);

    BMBuildHashKey *keyData = (BMBuildHashKey*)key;
	Datum *k = keyData->attributeValueArr;
	bool *isNull = keyData->isNullArr;

	int i;
	uint32 hashkey = 0;

	for(i = 0; i < cur_bmbuild->natts; i++)
	{
		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

        if ( isNull[i] && cur_bmbuild->hash_func_is_strict[i])
        {
            /* leave hashkey unmodified, equivalent to hashcode 0 */
        }
        else
        {
            hashkey ^= DatumGetUInt32(FunctionCall1(&cur_bmbuild->hash_funcs[i], k[i]));
        }

	}
	return hashkey;
}

/*
 * Add bits of given value to the signature.
 */
void
signValue(BloomState *state, SignType *sign, Datum value, int attno)
{
	uint32		hashVal;
	int			nBit,
				j;

	/*
	 * init generator with "column's" number to get "hashed" seed for new
	 * value. We don't want to map the same numbers from different columns
	 * into the same bits!
	 */
	mySrand(attno);

	/*
	 * Init hash sequence to map our value into bits. the same values in
	 * different columns will be mapped into different bits because of step
	 * above
	 */
	hashVal = DatumGetInt32(FunctionCall1(&state->hashFn[attno], value));
	mySrand(hashVal ^ myRand());

	for (j = 0; j < state->opts.bitSize[attno]; j++)
	{
		/* prevent mutiple evaluation */
		nBit = myRand() % (state->opts.bloomLength * BITSIGNTYPE);
		SETBIT(sign, nBit);
	}
}

/*
 * worker_hash returns the hashed value of the given value.
 */
Datum
worker_hash(PG_FUNCTION_ARGS)
{
	Datum valueDatum = PG_GETARG_DATUM(0);
	Datum hashedValueDatum = 0;
	TypeCacheEntry *typeEntry = NULL;
	FmgrInfo *hashFunction = NULL;
	Oid valueDataType = InvalidOid;

	/* figure out hash function from the data type */
	valueDataType = get_fn_expr_argtype(fcinfo->flinfo, 0);
	typeEntry = lookup_type_cache(valueDataType, TYPECACHE_HASH_PROC_FINFO);

	if (typeEntry->hash_proc_finfo.fn_oid == InvalidOid)
	{
		ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						errmsg("cannot find a hash function for the input type"),
						errhint("Cast input to a data type with a hash function.")));
	}

	hashFunction = palloc0(sizeof(FmgrInfo));
	fmgr_info_copy(hashFunction, &(typeEntry->hash_proc_finfo), CurrentMemoryContext);

	/* calculate hash value */
	hashedValueDatum = FunctionCall1(hashFunction, valueDatum);

	PG_RETURN_INT32(hashedValueDatum);
}

void
hlparsetext(TSCfgInfo * cfg, HLPRSTEXT * prs, QUERYTYPE * query, char *buf, int4 buflen)
{
    int			type,
                lenlemm;
    char	   *lemm = NULL;
    WParserInfo *prsobj = findprs(cfg->prs_id);
    LexizeData	ldata;
    TSLexeme   *norms;
    ParsedLex  *lexs;

    prsobj->prs = (void *) DatumGetPointer(
                      FunctionCall2(
                          &(prsobj->start_info),
                          PointerGetDatum(buf),
                          Int32GetDatum(buflen)
                      )
                  );

    LexizeInit(&ldata, cfg);

    do
    {
        type = DatumGetInt32(FunctionCall3(
                                 &(prsobj->getlexeme_info),
                                 PointerGetDatum(prsobj->prs),
                                 PointerGetDatum(&lemm),
                                 PointerGetDatum(&lenlemm)));

        if (type > 0 && lenlemm >= MAXSTRLEN)
        {
#ifdef IGNORE_LONGLEXEME
            ereport(NOTICE,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("A word you are indexing is too long. It will be ignored.")));
            continue;
#else
            ereport(ERROR,
                    (errcode(ERRCODE_SYNTAX_ERROR),
                     errmsg("A word you are indexing is too long")));
#endif
        }

        LexizeAddLemm(&ldata, type, lemm, lenlemm);

        do
        {
            if ((norms = LexizeExec(&ldata, &lexs)) != NULL)
                addHLParsedLex(prs, query, lexs, norms);
            else
                addHLParsedLex(prs, query, lexs, NULL);
        } while (norms);

    } while (type > 0);

    FunctionCall1(
        &(prsobj->end_info),
        PointerGetDatum(prsobj->prs)
    );
}

/*
 * Compute the hash value for a tuple
 *
 * The passed-in key is a pointer to TupleHashEntryData.  In an actual hash
 * table entry, the firstTuple field points to a tuple (in MinimalTuple
 * format).  LookupTupleHashEntry sets up a dummy TupleHashEntryData with a
 * NULL firstTuple field --- that cues us to look at the inputslot instead.
 * This convention avoids the need to materialize virtual input tuples unless
 * they actually need to get copied into the table.
 *
 * Also, the caller must select an appropriate memory context for running
 * the hash functions. (dynahash.c doesn't change CurrentMemoryContext.)
 */
static uint32
TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
{
	TupleHashTable hashtable = (TupleHashTable) tb->private_data;
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	uint32		hashkey = hashtable->hash_iv;
	TupleTableSlot *slot;
	FmgrInfo   *hashfunctions;
	int			i;

	if (tuple == NULL)
	{
		/* Process the current input tuple for the table */
		slot = hashtable->inputslot;
		hashfunctions = hashtable->in_hash_funcs;
	}
	else
	{
		/*
		 * Process a tuple already stored in the table.
		 *
		 * (this case never actually occurs due to the way simplehash.h is
		 * used, as the hash-value is stored in the entries)
		 */
		slot = hashtable->tableslot;
		ExecStoreMinimalTuple(tuple, slot, false);
		hashfunctions = hashtable->tab_hash_funcs;
	}

	for (i = 0; i < numCols; i++)
	{
		AttrNumber	att = keyColIdx[i];
		Datum		attr;
		bool		isNull;

		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

		attr = slot_getattr(slot, att, &isNull);

		if (!isNull)			/* treat nulls as having hash key 0 */
		{
			uint32		hkey;

			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
												attr));
			hashkey ^= hkey;
		}
	}

	/*
	 * The way hashes are combined above, among each other and with the IV,
	 * doesn't lead to good bit perturbation. As the IV's goal is to lead to
	 * achieve that, perform a round of hashing of the combined hash -
	 * resulting in near perfect perturbation.
	 */
	return murmurhash32(hashkey);
}

/*
 * Convert using a from-SQL transform function.
 */
static PyObject *
PLyObject_FromTransform(PLyDatumToOb *arg, Datum d)
{
	Datum		t;

	t = FunctionCall1(&arg->u.transform.typtransform, d);
	return (PyObject *) DatumGetPointer(t);
}

/*
 * Build a BrinDesc used to create or scan a BRIN index
 */
BrinDesc *
brin_build_desc(Relation rel)
{
	BrinOpcInfo **opcinfo;
	BrinDesc   *bdesc;
	TupleDesc	tupdesc;
	int			totalstored = 0;
	int			keyno;
	long		totalsize;
	MemoryContext cxt;
	MemoryContext oldcxt;

	cxt = AllocSetContextCreate(CurrentMemoryContext,
								"brin desc cxt",
								ALLOCSET_SMALL_INITSIZE,
								ALLOCSET_SMALL_MINSIZE,
								ALLOCSET_SMALL_MAXSIZE);
	oldcxt = MemoryContextSwitchTo(cxt);
	tupdesc = RelationGetDescr(rel);

	/*
	 * Obtain BrinOpcInfo for each indexed column.  While at it, accumulate
	 * the number of columns stored, since the number is opclass-defined.
	 */
	opcinfo = (BrinOpcInfo **) palloc(sizeof(BrinOpcInfo *) * tupdesc->natts);
	for (keyno = 0; keyno < tupdesc->natts; keyno++)
	{
		FmgrInfo   *opcInfoFn;

		opcInfoFn = index_getprocinfo(rel, keyno + 1, BRIN_PROCNUM_OPCINFO);

		opcinfo[keyno] = (BrinOpcInfo *)
			DatumGetPointer(FunctionCall1(opcInfoFn,
										  tupdesc->attrs[keyno]->atttypid));
		totalstored += opcinfo[keyno]->oi_nstored;
	}

	/* Allocate our result struct and fill it in */
	totalsize = offsetof(BrinDesc, bd_info) +
		sizeof(BrinOpcInfo *) * tupdesc->natts;

	bdesc = palloc(totalsize);
	bdesc->bd_context = cxt;
	bdesc->bd_index = rel;
	bdesc->bd_tupdesc = tupdesc;
	bdesc->bd_disktdesc = NULL; /* generated lazily */
	bdesc->bd_totalstored = totalstored;

	for (keyno = 0; keyno < tupdesc->natts; keyno++)
		bdesc->bd_info[keyno] = opcinfo[keyno];
	pfree(opcinfo);

	MemoryContextSwitchTo(oldcxt);

	return bdesc;
}

/* ----------------
 *		index_markpos  - mark a scan position
 * ----------------
 */
void
index_markpos(IndexScanDesc scan)
{
	FmgrInfo   *procedure;

	SCAN_CHECKS;
	GET_SCAN_PROCEDURE(ammarkpos);

	FunctionCall1(procedure, PointerGetDatum(scan));
}

/*
 * _hash_datum2hashkey -- given a Datum, call the index's hash procedure
 *
 * The Datum is assumed to be of the index's column type, so we can use the
 * "primary" hash procedure that's tracked for us by the generic index code.
 */
uint32
_hash_datum2hashkey(Relation rel, Datum key)
{
	FmgrInfo   *procinfo;

	/* XXX assumes index has only one attribute */
	procinfo = index_getprocinfo(rel, 1, HASHPROC);

	return DatumGetUInt32(FunctionCall1(procinfo, key));
}

static void
prs_setup_firstcall(FuncCallContext *funcctx, Oid prsid, text *txt)
{
	TupleDesc	tupdesc;
	MemoryContext oldcontext;
	PrsStorage *st;
	TSParserCacheEntry *prs = lookup_ts_parser_cache(prsid);
	char	   *lex = NULL;
	int			llen = 0,
				type = 0;
	void	   *prsdata;

	oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

	st = (PrsStorage *) palloc(sizeof(PrsStorage));
	st->cur = 0;
	st->len = 16;
	st->list = (LexemeEntry *) palloc(sizeof(LexemeEntry) * st->len);

	prsdata = (void *) DatumGetPointer(FunctionCall2(&prs->prsstart,
											   PointerGetDatum(VARDATA(txt)),
									Int32GetDatum(VARSIZE(txt) - VARHDRSZ)));

	while ((type = DatumGetInt32(FunctionCall3(&prs->prstoken,
											   PointerGetDatum(prsdata),
											   PointerGetDatum(&lex),
											   PointerGetDatum(&llen)))) != 0)
	{
		if (st->cur >= st->len)
		{
			st->len = 2 * st->len;
			st->list = (LexemeEntry *) repalloc(st->list, sizeof(LexemeEntry) * st->len);
		}
		st->list[st->cur].lexeme = palloc(llen + 1);
		memcpy(st->list[st->cur].lexeme, lex, llen);
		st->list[st->cur].lexeme[llen] = '\0';
		st->list[st->cur].type = type;
		st->cur++;
	}

	FunctionCall1(&prs->prsend, PointerGetDatum(prsdata));

	st->len = st->cur;
	st->cur = 0;

	funcctx->user_fctx = (void *) st;
	tupdesc = CreateTemplateTupleDesc(2, false);
	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "tokid",
					   INT4OID, -1, 0);
	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "token",
					   TEXTOID, -1, 0);

	funcctx->attinmeta = TupleDescGetAttInMetadata(tupdesc);
	MemoryContextSwitchTo(oldcontext);
}

/* ----------------
 *		index_restrpos	- restore a scan position
 *
 * NOTE: this only restores the internal scan state of the index AM.
 * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 * for ExecRestrPos().
 * ----------------
 */
void
index_restrpos(IndexScanDesc scan)
{
	FmgrInfo   *procedure;

	SCAN_CHECKS;
	GET_SCAN_PROCEDURE(amrestrpos);

	scan->kill_prior_tuple = false;		/* for safety */

	FunctionCall1(procedure, PointerGetDatum(scan));
}

/*
 * Compute the hash value for a tuple
 *
 * The passed-in key is a pointer to TupleHashEntryData.  In an actual hash
 * table entry, the firstTuple field points to a tuple (in MinimalTuple
 * format).  LookupTupleHashEntry sets up a dummy TupleHashEntryData with a
 * NULL firstTuple field --- that cues us to look at the inputslot instead.
 * This convention avoids the need to materialize virtual input tuples unless
 * they actually need to get copied into the table.
 *
 * Also, the caller must select an appropriate memory context for running
 * the hash functions. (dynahash.c doesn't change CurrentMemoryContext.)
 */
static uint32
TupleHashTableHash(struct tuplehash_hash *tb, const MinimalTuple tuple)
{
	TupleHashTable hashtable = (TupleHashTable) tb->private_data;
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	uint32		hashkey = hashtable->hash_iv;
	TupleTableSlot *slot;
	FmgrInfo   *hashfunctions;
	int			i;

	if (tuple == NULL)
	{
		/* Process the current input tuple for the table */
		slot = hashtable->inputslot;
		hashfunctions = hashtable->in_hash_funcs;
	}
	else
	{
		/*
		 * Process a tuple already stored in the table.
		 *
		 * (this case never actually occurs due to the way simplehash.h is
		 * used, as the hash-value is stored in the entries)
		 */
		slot = hashtable->tableslot;
		ExecStoreMinimalTuple(tuple, slot, false);
		hashfunctions = hashtable->tab_hash_funcs;
	}

	for (i = 0; i < numCols; i++)
	{
		AttrNumber	att = keyColIdx[i];
		Datum		attr;
		bool		isNull;

		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

		attr = slot_getattr(slot, att, &isNull);

		if (!isNull)			/* treat nulls as having hash key 0 */
		{
			uint32		hkey;

			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
												attr));
			hashkey ^= hkey;
		}
	}

	return hashkey;
}

/*
 * Convert using a to-SQL transform function.
 */
static Datum
PLyObject_ToTransform(PLyObToDatum *arg, PyObject *plrv,
					  bool *isnull, bool inarray)
{
	if (plrv == Py_None)
	{
		*isnull = true;
		return (Datum) 0;
	}
	*isnull = false;
	return FunctionCall1(&arg->u.transform.typtransform, PointerGetDatum(plrv));
}

/*
 * Compute the hash value for a tuple
 *
 * The passed-in key is a pointer to TupleHashEntryData.  In an actual hash
 * table entry, the firstTuple field points to a tuple (in MinimalTuple
 * format).  LookupTupleHashEntry sets up a dummy TupleHashEntryData with a
 * NULL firstTuple field --- that cues us to look at the inputslot instead.
 * This convention avoids the need to materialize virtual input tuples unless
 * they actually need to get copied into the table.
 *
 * CurTupleHashTable must be set before calling this, since dynahash.c
 * doesn't provide any API that would let us get at the hashtable otherwise.
 *
 * Also, the caller must select an appropriate memory context for running
 * the hash functions. (dynahash.c doesn't change CurrentMemoryContext.)
 */
static uint32
TupleHashTableHash(const void *key, Size keysize)
{
	MinimalTuple tuple = ((const TupleHashEntryData *) key)->firstTuple;
	TupleTableSlot *slot;
	TupleHashTable hashtable = CurTupleHashTable;
	int			numCols = hashtable->numCols;
	AttrNumber *keyColIdx = hashtable->keyColIdx;
	FmgrInfo   *hashfunctions;
	uint32		hashkey = 0;
	int			i;

	if (tuple == NULL)
	{
		/* Process the current input tuple for the table */
		slot = hashtable->inputslot;
		hashfunctions = hashtable->in_hash_funcs;
	}
	else
	{
		/* Process a tuple already stored in the table */
		/* (this case never actually occurs in current dynahash.c code) */
		slot = hashtable->tableslot;
		ExecStoreMinimalTuple(tuple, slot, false);
		hashfunctions = hashtable->tab_hash_funcs;
	}

	for (i = 0; i < numCols; i++)
	{
		AttrNumber	att = keyColIdx[i];
		Datum		attr;
		bool		isNull;

		/* rotate hashkey left 1 bit at each step */
		hashkey = (hashkey << 1) | ((hashkey & 0x80000000) ? 1 : 0);

		attr = slot_getattr(slot, att, &isNull);

		if (!isNull)			/* treat nulls as having hash key 0 */
		{
			uint32		hkey;

			hkey = DatumGetUInt32(FunctionCall1(&hashfunctions[i],
												attr));
			hashkey ^= hkey;
		}
	}

	return hashkey;
}

/*
 * FindShardInterval finds a single shard interval in the cache for the
 * given partition column value.
 */
ShardInterval *
FindShardInterval(Datum partitionColumnValue, ShardInterval **shardIntervalCache,
				  int shardCount, char partitionMethod, FmgrInfo *compareFunction,
				  FmgrInfo *hashFunction, bool useBinarySearch)
{
	ShardInterval *shardInterval = NULL;

	if (partitionMethod == DISTRIBUTE_BY_HASH)
	{
		int hashedValue = DatumGetInt32(FunctionCall1(hashFunction,
													  partitionColumnValue));
		if (useBinarySearch)
		{
			Assert(compareFunction != NULL);

			shardInterval = SearchCachedShardInterval(Int32GetDatum(hashedValue),
													  shardIntervalCache, shardCount,
													  compareFunction);
		}
		else
		{
			uint64 hashTokenIncrement = HASH_TOKEN_COUNT / shardCount;
			int shardIndex = (uint32) (hashedValue - INT32_MIN) / hashTokenIncrement;

			Assert(shardIndex <= shardCount);

			/*
			 * If the shard count is not power of 2, the range of the last
			 * shard becomes larger than others. For that extra piece of range,
			 * we still need to use the last shard.
			 */
			if (shardIndex == shardCount)
			{
				shardIndex = shardCount - 1;
			}

			shardInterval = shardIntervalCache[shardIndex];
		}
	}
	else
	{
		Assert(compareFunction != NULL);

		shardInterval = SearchCachedShardInterval(partitionColumnValue,
												  shardIntervalCache, shardCount,
												  compareFunction);
	}

	return shardInterval;
}

/* ----------------
 *		index_can_return - does index support index-only scans?
 * ----------------
 */
bool
index_can_return(Relation indexRelation)
{
	FmgrInfo   *procedure;

	RELATION_CHECKS;

	/* amcanreturn is optional; assume FALSE if not provided by AM */
	if (!RegProcedureIsValid(indexRelation->rd_am->amcanreturn))
		return false;

	GET_REL_PROCEDURE(amcanreturn);

	return DatumGetBool(FunctionCall1(procedure,
									  PointerGetDatum(indexRelation)));
}

/* ----------------
 *		index_restrpos	- restore a scan position
 *
 * NOTE: this only restores the internal scan state of the index AM.
 * The current result tuple (scan->xs_ctup) doesn't change.  See comments
 * for ExecRestrPos().
 *
 * NOTE: in the presence of HOT chains, mark/restore only works correctly
 * if the scan's snapshot is MVCC-safe; that ensures that there's at most one
 * returnable tuple in each HOT chain, and so restoring the prior state at the
 * granularity of the index AM is sufficient.  Since the only current user
 * of mark/restore functionality is nodeMergejoin.c, this effectively means
 * that merge-join plans only work for MVCC snapshots.  This could be fixed
 * if necessary, but for now it seems unimportant.
 * ----------------
 */
void
index_restrpos(IndexScanDesc scan)
{
	FmgrInfo   *procedure;

	Assert(IsMVCCSnapshot(scan->xs_snapshot));

	SCAN_CHECKS;
	GET_SCAN_PROCEDURE(amrestrpos);

	scan->xs_continue_hot = false;

	scan->kill_prior_tuple = false;		/* for safety */

	FunctionCall1(procedure, PointerGetDatum(scan));
}

void 
initForecastModel(ModelInfo *modelInfo, MemoryContext memoryContext)
{
	MemoryContext oldContext = NULL;
		
	if (memoryContext != CurrentMemoryContext)
		oldContext = MemoryContextSwitchTo(memoryContext);
		
	FunctionCall1(&(modelInfo->algInfo->algInitModel), PointerGetDatum(modelInfo));
	
	modelInfo->disAggKeyDenominator=0.0;
	modelInfo->disaggkey=1;

	if (oldContext != NULL)
		MemoryContextSwitchTo(oldContext);
}

Datum json_agg_common_transfn( PG_FUNCTION_ARGS, bool top_object )
{
	StringInfo state;
	char *serialized_value;
	FmgrInfo	flinfo;

	state = PG_ARGISNULL(0) ? NULL : (StringInfo) PG_GETARG_POINTER(0);

	/* Append the value unless null. */
	if (!PG_ARGISNULL(1))
	{
		/* On the first time through, we ignore the delimiter. */
		if (state == NULL)
		{
			state = makeJsonAggState(fcinfo);

			if( top_object )
				appendStringInfoChar(state, '{');  /* begin top-level json object */

			if(!PG_ARGISNULL(2)) /* output array json-name */
			{
				appendStringInfoQuotedString(state, PG_TEXT_DATUM_GET_CSTR( PG_GETARG_DATUM(2) ));
				appendStringInfoChar(state, ':');  /* array name delimiter */
			}
			appendStringInfoChar(state, '[');  /* array begin */
		}
		else
			appendStringInfoChar(state, ',');  /* delimiter */

		//call to serialize_record( ... )
		MemSet( &flinfo, 0, sizeof( flinfo ) );
		flinfo.fn_addr = serialize_record;
		flinfo.fn_nargs = 1;
		flinfo.fn_mcxt = fcinfo->flinfo->fn_mcxt;

		serialized_value = PG_TEXT_DATUM_GET_CSTR( FunctionCall1( &flinfo, PG_GETARG_DATUM(1) ) );

		appendStringInfoString(state, serialized_value);	  /* append value */
	}

	/*
	 * The transition type for json_agg() is declared to be "internal",
	 * which is a pass-by-value type the same size as a pointer.
	 */

	PG_RETURN_POINTER(state);
}

/*
 * initialize a GiST entry with a compressed version of key
 */
void
gistcentryinit(GISTSTATE *giststate, int nkey,
			   GISTENTRY *e, Datum k, Relation r,
			   Page pg, OffsetNumber o, bool l, bool isNull)
{
	if (!isNull)
	{
		GISTENTRY  *cep;

		gistentryinit(*e, k, r, pg, o, l);
		cep = (GISTENTRY *)
			DatumGetPointer(FunctionCall1(&giststate->compressFn[nkey],
										  PointerGetDatum(e)));
		/* compressFn may just return the given pointer */
		if (cep != e)
			gistentryinit(*e, cep->key, cep->rel, cep->page, cep->offset,
						  cep->leafkey);
	}
	else
		gistentryinit(*e, (Datum) 0, r, pg, o, l);
}