src/backend/utils/misc/queryjumble.c

/*-------------------------------------------------------------------------
 *
 * queryjumble.c
 *	 Query normalization and fingerprinting.
 *
 * Normalization is a process whereby similar queries, typically differing only
 * in their constants (though the exact rules are somewhat more subtle than
 * that) are recognized as equivalent, and are tracked as a single entry.  This
 * is particularly useful for non-prepared queries.
 *
 * Normalization is implemented by fingerprinting queries, selectively
 * serializing those fields of each query tree's nodes that are judged to be
 * essential to the query.  This is referred to as a query jumble.  This is
 * distinct from a regular serialization in that various extraneous
 * information is ignored as irrelevant or not essential to the query, such
 * as the collations of Vars and, most notably, the values of constants.
 *
 * This jumble is acquired at the end of parse analysis of each query, and
 * a 64-bit hash of it is stored into the query's Query.queryId field.
 * The server then copies this value around, making it available in plan
 * tree(s) generated from the query.  The executor can then use this value
 * to blame query costs on the proper queryId.
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  src/backend/utils/misc/queryjumble.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "common/hashfn.h"
#include "miscadmin.h"
#include "parser/scansup.h"
#include "utils/queryjumble.h"

#define JUMBLE_SIZE				1024	/* query serialization buffer size */

/* GUC parameters */
int			compute_query_id = COMPUTE_QUERY_ID_AUTO;

/* True when compute_query_id is ON, or AUTO and a module requests them */
bool		query_id_enabled = false;

static uint64 compute_utility_query_id(const char *str, int query_location, int query_len);
static void AppendJumble(JumbleState *jstate,
						 const unsigned char *item, Size size);
static void JumbleQueryInternal(JumbleState *jstate, Query *query);
static void JumbleRangeTable(JumbleState *jstate, List *rtable);
static void JumbleRowMarks(JumbleState *jstate, List *rowMarks);
static void JumbleExpr(JumbleState *jstate, Node *node);
static void RecordConstLocation(JumbleState *jstate, int location);

/*
 * Given a possibly multi-statement source string, confine our attention to the
 * relevant part of the string.
 */
const char *
CleanQuerytext(const char *query, int *location, int *len)
{
	int			query_location = *location;
	int			query_len = *len;

	/* First apply starting offset, unless it's -1 (unknown). */
	if (query_location >= 0)
	{
		Assert(query_location <= strlen(query));
		query += query_location;
		/* Length of 0 (or -1) means "rest of string" */
		if (query_len <= 0)
			query_len = strlen(query);
		else
			Assert(query_len <= strlen(query));
	}
	else
	{
		/* If query location is unknown, distrust query_len as well */
		query_location = 0;
		query_len = strlen(query);
	}

	/*
	 * Discard leading and trailing whitespace, too.  Use scanner_isspace()
	 * not libc's isspace(), because we want to match the lexer's behavior.
	 */
	while (query_len > 0 && scanner_isspace(query[0]))
		query++, query_location++, query_len--;
	while (query_len > 0 && scanner_isspace(query[query_len - 1]))
		query_len--;

	*location = query_location;
	*len = query_len;

	return query;
}

JumbleState *
JumbleQueryDirect(Query *query, const char *querytext) 
{
	JumbleState *jstate = NULL;

	Assert(IsA(query, Query));
	Assert(query->utilityStmt == NULL);

	jstate = (JumbleState *) palloc(sizeof(JumbleState));

	/* Set up workspace for query jumbling */
	jstate->jumble = (unsigned char *) palloc(JUMBLE_SIZE);
	jstate->jumble_len = 0;
	jstate->clocations_buf_size = 32;
	jstate->clocations = (LocationLen *)
		palloc(jstate->clocations_buf_size * sizeof(LocationLen));
	jstate->clocations_count = 0;
	jstate->highest_extern_param_id = 0;

	/* Compute query ID and mark the Query node with it */
	JumbleQueryInternal(jstate, query);
	query->queryId = DatumGetUInt64(hash_any_extended(jstate->jumble,
													  jstate->jumble_len,
													  0));

	/*
	 * If we are unlucky enough to get a hash of zero, use 1 instead, to
	 * prevent confusion with the utility-statement case.
	 */
	if (query->queryId == UINT64CONST(0))
		query->queryId = UINT64CONST(1);

	return jstate;
}

JumbleState *
JumbleQuery(Query *query, const char *querytext)
{
	Assert(IsQueryIdEnabled());

	if (query->utilityStmt)
	{
		query->queryId = compute_utility_query_id(querytext,
												  query->stmt_location,
												  query->stmt_len);
		return NULL;
	}
	else
	{
		return JumbleQueryDirect(query, querytext);
	}
}

/*
 * Enables query identifier computation.
 *
 * Third-party plugins can use this function to inform core that they require
 * a query identifier to be computed.
 */
void
EnableQueryId(void)
{
	if (compute_query_id != COMPUTE_QUERY_ID_OFF)
		query_id_enabled = true;
}

/*
 * Compute a query identifier for the given utility query string.
 */
static uint64
compute_utility_query_id(const char *query_text, int query_location, int query_len)
{
	uint64		queryId;
	const char *sql;

	/*
	 * Confine our attention to the relevant part of the string, if the query
	 * is a portion of a multi-statement source string.
	 */
	sql = CleanQuerytext(query_text, &query_location, &query_len);

	queryId = DatumGetUInt64(hash_any_extended((const unsigned char *) sql,
											   query_len, 0));

	/*
	 * If we are unlucky enough to get a hash of zero(invalid), use queryID as
	 * 2 instead, queryID 1 is already in use for normal statements.
	 */
	if (queryId == UINT64CONST(0))
		queryId = UINT64CONST(2);

	return queryId;
}

/*
 * AppendJumble: Append a value that is substantive in a given query to
 * the current jumble.
 */
static void
AppendJumble(JumbleState *jstate, const unsigned char *item, Size size)
{
	unsigned char *jumble = jstate->jumble;
	Size		jumble_len = jstate->jumble_len;

	/*
	 * Whenever the jumble buffer is full, we hash the current contents and
	 * reset the buffer to contain just that hash value, thus relying on the
	 * hash to summarize everything so far.
	 */
	while (size > 0)
	{
		Size		part_size;

		if (jumble_len >= JUMBLE_SIZE)
		{
			uint64		start_hash;

			start_hash = DatumGetUInt64(hash_any_extended(jumble,
														  JUMBLE_SIZE, 0));
			memcpy(jumble, &start_hash, sizeof(start_hash));
			jumble_len = sizeof(start_hash);
		}
		part_size = Min(size, JUMBLE_SIZE - jumble_len);
		memcpy(jumble + jumble_len, item, part_size);
		jumble_len += part_size;
		item += part_size;
		size -= part_size;
	}
	jstate->jumble_len = jumble_len;
}

/*
 * Wrappers around AppendJumble to encapsulate details of serialization
 * of individual local variable elements.
 */
#define APP_JUMB(item) \
	AppendJumble(jstate, (const unsigned char *) &(item), sizeof(item))
#define APP_JUMB_STRING(str) \
	AppendJumble(jstate, (const unsigned char *) (str), strlen(str) + 1)

/*
 * JumbleQueryInternal: Selectively serialize the query tree, appending
 * significant data to the "query jumble" while ignoring nonsignificant data.
 *
 * Rule of thumb for what to include is that we should ignore anything not
 * semantically significant (such as alias names) as well as anything that can
 * be deduced from child nodes (else we'd just be double-hashing that piece
 * of information).
 */
static void
JumbleQueryInternal(JumbleState *jstate, Query *query)
{
	APP_JUMB(query->commandType);
	/* resultRelation is usually predictable from commandType */
	JumbleExpr(jstate, (Node *) query->cteList);
	JumbleRangeTable(jstate, query->rtable);
	JumbleExpr(jstate, (Node *) query->jointree);
	JumbleExpr(jstate, (Node *) query->targetList);
	JumbleExpr(jstate, (Node *) query->onConflict);
	JumbleExpr(jstate, (Node *) query->returningList);
	JumbleExpr(jstate, (Node *) query->groupClause);
	APP_JUMB(query->groupDistinct);
	JumbleExpr(jstate, (Node *) query->groupingSets);
	JumbleExpr(jstate, query->havingQual);
	JumbleExpr(jstate, (Node *) query->windowClause);
	JumbleExpr(jstate, (Node *) query->distinctClause);
	JumbleExpr(jstate, (Node *) query->sortClause);
	JumbleExpr(jstate, query->limitOffset);
	JumbleExpr(jstate, query->limitCount);
	APP_JUMB(query->limitOption);
	JumbleRowMarks(jstate, query->rowMarks);
	JumbleExpr(jstate, query->setOperations);
}

/*
 * Jumble a range table
 */
static void
JumbleRangeTable(JumbleState *jstate, List *rtable)
{
	ListCell   *lc;

	foreach(lc, rtable)
	{
		RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc);

		APP_JUMB(rte->rtekind);
		switch (rte->rtekind)
		{
			case RTE_RELATION:
				APP_JUMB(rte->relid);
				JumbleExpr(jstate, (Node *) rte->tablesample);
				APP_JUMB(rte->inh);
				break;
			case RTE_SUBQUERY:
				JumbleQueryInternal(jstate, rte->subquery);
				break;
			case RTE_JOIN:
				APP_JUMB(rte->jointype);
				break;
			case RTE_FUNCTION:
				JumbleExpr(jstate, (Node *) rte->functions);
				break;
			case RTE_TABLEFUNC:
				JumbleExpr(jstate, (Node *) rte->tablefunc);
				break;
			case RTE_VALUES:
				JumbleExpr(jstate, (Node *) rte->values_lists);
				break;
			case RTE_CTE:

				/*
				 * Depending on the CTE name here isn't ideal, but it's the
				 * only info we have to identify the referenced WITH item.
				 */
				APP_JUMB_STRING(rte->ctename);
				APP_JUMB(rte->ctelevelsup);
				break;
			case RTE_NAMEDTUPLESTORE:
				APP_JUMB_STRING(rte->enrname);
				break;
			case RTE_RESULT:
				break;
			default:
				elog(ERROR, "unrecognized RTE kind: %d", (int) rte->rtekind);
				break;
		}
	}
}

/*
 * Jumble a rowMarks list
 */
static void
JumbleRowMarks(JumbleState *jstate, List *rowMarks)
{
	ListCell   *lc;

	foreach(lc, rowMarks)
	{
		RowMarkClause *rowmark = lfirst_node(RowMarkClause, lc);

		if (!rowmark->pushedDown)
		{
			APP_JUMB(rowmark->rti);
			APP_JUMB(rowmark->strength);
			APP_JUMB(rowmark->waitPolicy);
		}
	}
}

/*
 * Jumble an expression tree
 *
 * In general this function should handle all the same node types that
 * expression_tree_walker() does, and therefore it's coded to be as parallel
 * to that function as possible.  However, since we are only invoked on
 * queries immediately post-parse-analysis, we need not handle node types
 * that only appear in planning.
 *
 * Note: the reason we don't simply use expression_tree_walker() is that the
 * point of that function is to support tree walkers that don't care about
 * most tree node types, but here we care about all types.  We should complain
 * about any unrecognized node type.
 */
static void
JumbleExpr(JumbleState *jstate, Node *node)
{
	ListCell   *temp;

	if (node == NULL)
		return;

	/* Guard against stack overflow due to overly complex expressions */
	check_stack_depth();

	/*
	 * We always emit the node's NodeTag, then any additional fields that are
	 * considered significant, and then we recurse to any child nodes.
	 */
	APP_JUMB(node->type);

	switch (nodeTag(node))
	{
		case T_Var:
			{
				Var		   *var = (Var *) node;

				APP_JUMB(var->varno);
				APP_JUMB(var->varattno);
				APP_JUMB(var->varlevelsup);
			}
			break;
		case T_Const:
			{
				Const	   *c = (Const *) node;

				/* We jumble only the constant's type, not its value */
				APP_JUMB(c->consttype);
				/* Also, record its parse location for query normalization */
				RecordConstLocation(jstate, c->location);
			}
			break;
		case T_Param:
			{
				Param	   *p = (Param *) node;

				APP_JUMB(p->paramkind);
				APP_JUMB(p->paramid);
				APP_JUMB(p->paramtype);
				/* Also, track the highest external Param id */
				if (p->paramkind == PARAM_EXTERN &&
					p->paramid > jstate->highest_extern_param_id)
					jstate->highest_extern_param_id = p->paramid;
			}
			break;
		case T_Aggref:
			{
				Aggref	   *expr = (Aggref *) node;

				APP_JUMB(expr->aggfnoid);
				JumbleExpr(jstate, (Node *) expr->aggdirectargs);
				JumbleExpr(jstate, (Node *) expr->args);
				JumbleExpr(jstate, (Node *) expr->aggorder);
				JumbleExpr(jstate, (Node *) expr->aggdistinct);
				JumbleExpr(jstate, (Node *) expr->aggfilter);
			}
			break;
		case T_GroupingFunc:
			{
				GroupingFunc *grpnode = (GroupingFunc *) node;

				JumbleExpr(jstate, (Node *) grpnode->refs);
				APP_JUMB(grpnode->agglevelsup);
			}
			break;
		case T_WindowFunc:
			{
				WindowFunc *expr = (WindowFunc *) node;

				APP_JUMB(expr->winfnoid);
				APP_JUMB(expr->winref);
				JumbleExpr(jstate, (Node *) expr->args);
				JumbleExpr(jstate, (Node *) expr->aggfilter);
			}
			break;
		case T_SubscriptingRef:
			{
				SubscriptingRef *sbsref = (SubscriptingRef *) node;

				JumbleExpr(jstate, (Node *) sbsref->refupperindexpr);
				JumbleExpr(jstate, (Node *) sbsref->reflowerindexpr);
				JumbleExpr(jstate, (Node *) sbsref->refexpr);
				JumbleExpr(jstate, (Node *) sbsref->refassgnexpr);
			}
			break;
		case T_FuncExpr:
			{
				FuncExpr   *expr = (FuncExpr *) node;

				APP_JUMB(expr->funcid);
				JumbleExpr(jstate, (Node *) expr->args);
			}
			break;
		case T_NamedArgExpr:
			{
				NamedArgExpr *nae = (NamedArgExpr *) node;

				APP_JUMB(nae->argnumber);
				JumbleExpr(jstate, (Node *) nae->arg);
			}
			break;
		case T_OpExpr:
		case T_DistinctExpr:	/* struct-equivalent to OpExpr */
		case T_NullIfExpr:		/* struct-equivalent to OpExpr */
			{
				OpExpr	   *expr = (OpExpr *) node;

				APP_JUMB(expr->opno);
				JumbleExpr(jstate, (Node *) expr->args);
			}
			break;
		case T_ScalarArrayOpExpr:
			{
				ScalarArrayOpExpr *expr = (ScalarArrayOpExpr *) node;

				APP_JUMB(expr->opno);
				APP_JUMB(expr->useOr);
				JumbleExpr(jstate, (Node *) expr->args);
			}
			break;
		case T_BoolExpr:
			{
				BoolExpr   *expr = (BoolExpr *) node;

				APP_JUMB(expr->boolop);
				JumbleExpr(jstate, (Node *) expr->args);
			}
			break;
		case T_SubLink:
			{
				SubLink    *sublink = (SubLink *) node;

				APP_JUMB(sublink->subLinkType);
				APP_JUMB(sublink->subLinkId);
				JumbleExpr(jstate, (Node *) sublink->testexpr);
				JumbleQueryInternal(jstate, castNode(Query, sublink->subselect));
			}
			break;
		case T_FieldSelect:
			{
				FieldSelect *fs = (FieldSelect *) node;

				APP_JUMB(fs->fieldnum);
				JumbleExpr(jstate, (Node *) fs->arg);
			}
			break;
		case T_FieldStore:
			{
				FieldStore *fstore = (FieldStore *) node;

				JumbleExpr(jstate, (Node *) fstore->arg);
				JumbleExpr(jstate, (Node *) fstore->newvals);
			}
			break;
		case T_RelabelType:
			{
				RelabelType *rt = (RelabelType *) node;

				APP_JUMB(rt->resulttype);
				JumbleExpr(jstate, (Node *) rt->arg);
			}
			break;
		case T_CoerceViaIO:
			{
				CoerceViaIO *cio = (CoerceViaIO *) node;

				APP_JUMB(cio->resulttype);
				JumbleExpr(jstate, (Node *) cio->arg);
			}
			break;
		case T_ArrayCoerceExpr:
			{
				ArrayCoerceExpr *acexpr = (ArrayCoerceExpr *) node;

				APP_JUMB(acexpr->resulttype);
				JumbleExpr(jstate, (Node *) acexpr->arg);
				JumbleExpr(jstate, (Node *) acexpr->elemexpr);
			}
			break;
		case T_ConvertRowtypeExpr:
			{
				ConvertRowtypeExpr *crexpr = (ConvertRowtypeExpr *) node;

				APP_JUMB(crexpr->resulttype);
				JumbleExpr(jstate, (Node *) crexpr->arg);
			}
			break;
		case T_CollateExpr:
			{
				CollateExpr *ce = (CollateExpr *) node;

				APP_JUMB(ce->collOid);
				JumbleExpr(jstate, (Node *) ce->arg);
			}
			break;
		case T_CaseExpr:
			{
				CaseExpr   *caseexpr = (CaseExpr *) node;

				JumbleExpr(jstate, (Node *) caseexpr->arg);
				foreach(temp, caseexpr->args)
				{
					CaseWhen   *when = lfirst_node(CaseWhen, temp);

					JumbleExpr(jstate, (Node *) when->expr);
					JumbleExpr(jstate, (Node *) when->result);
				}
				JumbleExpr(jstate, (Node *) caseexpr->defresult);
			}
			break;
		case T_CaseTestExpr:
			{
				CaseTestExpr *ct = (CaseTestExpr *) node;

				APP_JUMB(ct->typeId);
			}
			break;
		case T_ArrayExpr:
			JumbleExpr(jstate, (Node *) ((ArrayExpr *) node)->elements);
			break;
		case T_RowExpr:
			JumbleExpr(jstate, (Node *) ((RowExpr *) node)->args);
			break;
		case T_RowCompareExpr:
			{
				RowCompareExpr *rcexpr = (RowCompareExpr *) node;

				APP_JUMB(rcexpr->rctype);
				JumbleExpr(jstate, (Node *) rcexpr->largs);
				JumbleExpr(jstate, (Node *) rcexpr->rargs);
			}
			break;
		case T_CoalesceExpr:
			JumbleExpr(jstate, (Node *) ((CoalesceExpr *) node)->args);
			break;
		case T_MinMaxExpr:
			{
				MinMaxExpr *mmexpr = (MinMaxExpr *) node;

				APP_JUMB(mmexpr->op);
				JumbleExpr(jstate, (Node *) mmexpr->args);
			}
			break;
		case T_SQLValueFunction:
			{
				SQLValueFunction *svf = (SQLValueFunction *) node;

				APP_JUMB(svf->op);
				/* type is fully determined by op */
				APP_JUMB(svf->typmod);
			}
			break;
		case T_XmlExpr:
			{
				XmlExpr    *xexpr = (XmlExpr *) node;

				APP_JUMB(xexpr->op);
				JumbleExpr(jstate, (Node *) xexpr->named_args);
				JumbleExpr(jstate, (Node *) xexpr->args);
			}
			break;
		case T_NullTest:
			{
				NullTest   *nt = (NullTest *) node;

				APP_JUMB(nt->nulltesttype);
				JumbleExpr(jstate, (Node *) nt->arg);
			}
			break;
		case T_BooleanTest:
			{
				BooleanTest *bt = (BooleanTest *) node;

				APP_JUMB(bt->booltesttype);
				JumbleExpr(jstate, (Node *) bt->arg);
			}
			break;
		case T_CoerceToDomain:
			{
				CoerceToDomain *cd = (CoerceToDomain *) node;

				APP_JUMB(cd->resulttype);
				JumbleExpr(jstate, (Node *) cd->arg);
			}
			break;
		case T_CoerceToDomainValue:
			{
				CoerceToDomainValue *cdv = (CoerceToDomainValue *) node;

				APP_JUMB(cdv->typeId);
			}
			break;
		case T_SetToDefault:
			{
				SetToDefault *sd = (SetToDefault *) node;

				APP_JUMB(sd->typeId);
			}
			break;
		case T_CurrentOfExpr:
			{
				CurrentOfExpr *ce = (CurrentOfExpr *) node;

				APP_JUMB(ce->cvarno);
				if (ce->cursor_name)
					APP_JUMB_STRING(ce->cursor_name);
				APP_JUMB(ce->cursor_param);
			}
			break;
		case T_NextValueExpr:
			{
				NextValueExpr *nve = (NextValueExpr *) node;

				APP_JUMB(nve->seqid);
				APP_JUMB(nve->typeId);
			}
			break;
		case T_InferenceElem:
			{
				InferenceElem *ie = (InferenceElem *) node;

				APP_JUMB(ie->infercollid);
				APP_JUMB(ie->inferopclass);
				JumbleExpr(jstate, ie->expr);
			}
			break;
		case T_TargetEntry:
			{
				TargetEntry *tle = (TargetEntry *) node;

				APP_JUMB(tle->resno);
				APP_JUMB(tle->ressortgroupref);
				JumbleExpr(jstate, (Node *) tle->expr);
			}
			break;
		case T_RangeTblRef:
			{
				RangeTblRef *rtr = (RangeTblRef *) node;

				APP_JUMB(rtr->rtindex);
			}
			break;
		case T_JoinExpr:
			{
				JoinExpr   *join = (JoinExpr *) node;

				APP_JUMB(join->jointype);
				APP_JUMB(join->isNatural);
				APP_JUMB(join->rtindex);
				JumbleExpr(jstate, join->larg);
				JumbleExpr(jstate, join->rarg);
				JumbleExpr(jstate, join->quals);
			}
			break;
		case T_FromExpr:
			{
				FromExpr   *from = (FromExpr *) node;

				JumbleExpr(jstate, (Node *) from->fromlist);
				JumbleExpr(jstate, from->quals);
			}
			break;
		case T_OnConflictExpr:
			{
				OnConflictExpr *conf = (OnConflictExpr *) node;

				APP_JUMB(conf->action);
				JumbleExpr(jstate, (Node *) conf->arbiterElems);
				JumbleExpr(jstate, conf->arbiterWhere);
				JumbleExpr(jstate, (Node *) conf->onConflictSet);
				JumbleExpr(jstate, conf->onConflictWhere);
				APP_JUMB(conf->constraint);
				APP_JUMB(conf->exclRelIndex);
				JumbleExpr(jstate, (Node *) conf->exclRelTlist);
			}
			break;
		case T_List:
			foreach(temp, (List *) node)
			{
				JumbleExpr(jstate, (Node *) lfirst(temp));
			}
			break;
		case T_IntList:
			foreach(temp, (List *) node)
			{
				APP_JUMB(lfirst_int(temp));
			}
			break;
		case T_SortGroupClause:
			{
				SortGroupClause *sgc = (SortGroupClause *) node;

				APP_JUMB(sgc->tleSortGroupRef);
				APP_JUMB(sgc->eqop);
				APP_JUMB(sgc->sortop);
				APP_JUMB(sgc->nulls_first);
			}
			break;
		case T_GroupingSet:
			{
				GroupingSet *gsnode = (GroupingSet *) node;

				JumbleExpr(jstate, (Node *) gsnode->content);
			}
			break;
		case T_WindowClause:
			{
				WindowClause *wc = (WindowClause *) node;

				APP_JUMB(wc->winref);
				APP_JUMB(wc->frameOptions);
				JumbleExpr(jstate, (Node *) wc->partitionClause);
				JumbleExpr(jstate, (Node *) wc->orderClause);
				JumbleExpr(jstate, wc->startOffset);
				JumbleExpr(jstate, wc->endOffset);
			}
			break;
		case T_CommonTableExpr:
			{
				CommonTableExpr *cte = (CommonTableExpr *) node;

				/* we store the string name because RTE_CTE RTEs need it */
				APP_JUMB_STRING(cte->ctename);
				APP_JUMB(cte->ctematerialized);
				JumbleQueryInternal(jstate, castNode(Query, cte->ctequery));
			}
			break;
		case T_SetOperationStmt:
			{
				SetOperationStmt *setop = (SetOperationStmt *) node;

				APP_JUMB(setop->op);
				APP_JUMB(setop->all);
				JumbleExpr(jstate, setop->larg);
				JumbleExpr(jstate, setop->rarg);
			}
			break;
		case T_RangeTblFunction:
			{
				RangeTblFunction *rtfunc = (RangeTblFunction *) node;

				JumbleExpr(jstate, rtfunc->funcexpr);
			}
			break;
		case T_TableFunc:
			{
				TableFunc  *tablefunc = (TableFunc *) node;

				JumbleExpr(jstate, tablefunc->docexpr);
				JumbleExpr(jstate, tablefunc->rowexpr);
				JumbleExpr(jstate, (Node *) tablefunc->colexprs);
			}
			break;
		case T_TableSampleClause:
			{
				TableSampleClause *tsc = (TableSampleClause *) node;

				APP_JUMB(tsc->tsmhandler);
				JumbleExpr(jstate, (Node *) tsc->args);
				JumbleExpr(jstate, (Node *) tsc->repeatable);
			}
			break;
		default:
			/* Only a warning, since we can stumble along anyway */
			elog(WARNING, "unrecognized node type: %d",
				 (int) nodeTag(node));
			break;
	}
}

/*
 * Record location of constant within query string of query tree
 * that is currently being walked.
 */
static void
RecordConstLocation(JumbleState *jstate, int location)
{
	/* -1 indicates unknown or undefined location */
	if (location >= 0)
	{
		/* enlarge array if needed */
		if (jstate->clocations_count >= jstate->clocations_buf_size)
		{
			jstate->clocations_buf_size *= 2;
			jstate->clocations = (LocationLen *)
				repalloc(jstate->clocations,
						 jstate->clocations_buf_size *
						 sizeof(LocationLen));
		}
		jstate->clocations[jstate->clocations_count].location = location;
		/* initialize lengths to -1 to simplify third-party module usage */
		jstate->clocations[jstate->clocations_count].length = -1;
		jstate->clocations_count++;
	}
}