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[PATCH v25 3/9] Row pattern recognition patch (rewriter).
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* [PATCH v25 3/9] Row pattern recognition patch (rewriter).
@ 2024-12-21 06:19  Tatsuo Ishii <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Tatsuo Ishii @ 2024-12-21 06:19 UTC (permalink / raw)

---
 src/backend/utils/adt/ruleutils.c | 103 ++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index be1f1f50b7..f58392f0aa 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -435,6 +435,10 @@ static void get_rule_groupingset(GroupingSet *gset, List *targetlist,
 								 bool omit_parens, deparse_context *context);
 static void get_rule_orderby(List *orderList, List *targetList,
 							 bool force_colno, deparse_context *context);
+static void get_rule_pattern(List *patternVariable, List *patternRegexp,
+							 bool force_colno, deparse_context *context);
+static void get_rule_define(List *defineClause, List *patternVariables,
+							bool force_colno, deparse_context *context);
 static void get_rule_windowclause(Query *query, deparse_context *context);
 static void get_rule_windowspec(WindowClause *wc, List *targetList,
 								deparse_context *context);
@@ -6667,6 +6671,67 @@ get_rule_orderby(List *orderList, List *targetList,
 	}
 }
 
+/*
+ * Display a PATTERN clause.
+ */
+static void
+get_rule_pattern(List *patternVariable, List *patternRegexp,
+				 bool force_colno, deparse_context *context)
+{
+	StringInfo	buf = context->buf;
+	const char *sep;
+	ListCell   *lc_var,
+			   *lc_reg = list_head(patternRegexp);
+
+	sep = "";
+	appendStringInfoChar(buf, '(');
+	foreach(lc_var, patternVariable)
+	{
+		char	   *variable = strVal((String *) lfirst(lc_var));
+		char	   *regexp = NULL;
+
+		if (lc_reg != NULL)
+		{
+			regexp = strVal((String *) lfirst(lc_reg));
+
+			lc_reg = lnext(patternRegexp, lc_reg);
+		}
+
+		appendStringInfo(buf, "%s%s", sep, variable);
+		if (regexp !=NULL)
+			appendStringInfoString(buf, regexp);
+
+		sep = " ";
+	}
+	appendStringInfoChar(buf, ')');
+}
+
+/*
+ * Display a DEFINE clause.
+ */
+static void
+get_rule_define(List *defineClause, List *patternVariables,
+				bool force_colno, deparse_context *context)
+{
+	StringInfo	buf = context->buf;
+	const char *sep;
+	ListCell   *lc_var,
+			   *lc_def;
+
+	sep = "  ";
+	Assert(list_length(patternVariables) == list_length(defineClause));
+
+	forboth(lc_var, patternVariables, lc_def, defineClause)
+	{
+		char	   *varName = strVal(lfirst(lc_var));
+		TargetEntry *te = (TargetEntry *) lfirst(lc_def);
+
+		appendStringInfo(buf, "%s%s AS ", sep, varName);
+		get_rule_expr((Node *) te->expr, context, false);
+		sep = ",\n  ";
+	}
+}
+
 /*
  * Display a WINDOW clause.
  *
@@ -6804,6 +6869,44 @@ get_rule_windowspec(WindowClause *wc, List *targetList,
 			appendStringInfoString(buf, "EXCLUDE GROUP ");
 		else if (wc->frameOptions & FRAMEOPTION_EXCLUDE_TIES)
 			appendStringInfoString(buf, "EXCLUDE TIES ");
+		/* RPR */
+		if (wc->rpSkipTo == ST_NEXT_ROW)
+			appendStringInfoString(buf,
+								   "\n  AFTER MATCH SKIP TO NEXT ROW ");
+		else if (wc->rpSkipTo == ST_PAST_LAST_ROW)
+			appendStringInfoString(buf,
+								   "\n  AFTER MATCH SKIP PAST LAST ROW ");
+		else if (wc->rpSkipTo == ST_FIRST_VARIABLE)
+			appendStringInfo(buf,
+							 "\n  AFTER MATCH SKIP TO FIRST %s ",
+							 wc->rpSkipVariable);
+		else if (wc->rpSkipTo == ST_LAST_VARIABLE)
+			appendStringInfo(buf,
+							 "\n  AFTER MATCH SKIP TO LAST %s ",
+							 wc->rpSkipVariable);
+		else if (wc->rpSkipTo == ST_VARIABLE)
+			appendStringInfo(buf,
+							 "\n  AFTER MATCH SKIP TO %s ",
+							 wc->rpSkipVariable);
+
+		if (wc->initial)
+			appendStringInfoString(buf, "\n  INITIAL");
+
+		if (wc->patternVariable)
+		{
+			appendStringInfoString(buf, "\n  PATTERN ");
+			get_rule_pattern(wc->patternVariable, wc->patternRegexp,
+							 false, context);
+		}
+
+		if (wc->defineClause)
+		{
+			appendStringInfoString(buf, "\n  DEFINE\n");
+			get_rule_define(wc->defineClause, wc->patternVariable,
+							false, context);
+			appendStringInfoChar(buf, ' ');
+		}
+
 		/* we will now have a trailing space; remove it */
 		buf->len--;
 	}
-- 
2.25.1


----Next_Part(Sat_Dec_21_18_20_04_2024_526)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="v25-0004-Row-pattern-recognition-patch-planner.patch"



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index a758e1a..d08b122 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -108,6 +108,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -200,6 +202,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -568,6 +571,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -921,16 +925,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -943,8 +968,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1374,6 +1399,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg17.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 9b7187e..21d21ea 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -115,6 +115,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -284,6 +286,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -703,6 +706,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -983,16 +987,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1005,8 +1030,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1924,6 +1949,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 8cf6ecf..0bbad25 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index acb508c..1d867d8 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg18.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index eedc5c8..c4d5cb1 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -282,6 +284,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -701,6 +704,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -981,16 +985,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1003,8 +1028,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1923,6 +1948,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 4bcd4e9..03fbd97 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 3e8929a..db2a21d 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc--






^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index 6cc2acb..7dfc311 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -113,6 +113,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -310,6 +312,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -739,6 +742,7 @@ executeJsonPath(JsonPath *path, void *vars, JsonPathGetVarCallback getVar,
 	cxt.lastGeneratedObjectId = 1 + countVars(vars);
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenceOfErrors(&cxt) && !result)
@@ -1017,16 +1021,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -1039,8 +1064,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1978,6 +2003,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index 81efebc..21f1362 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -785,6 +785,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index c1f4ab5..92abe13 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -150,6 +150,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg15.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread

* [PATCH] Collapse consecutive .** accessors for jsonpath exists queries
@ 2026-06-18 20:30  Andrey Rachitskiy <[email protected]>
  0 siblings, 0 replies; 297+ messages in thread

From: Andrey Rachitskiy @ 2026-06-18 20:30 UTC (permalink / raw)

When a jsonpath expression contains multiple consecutive .** (jpiAny)
accessors, each one triggers a full subtree traversal in executeAnyItem().
k consecutive .** operators can degrade performance to O(N^k) on a document
with N nodes, even though a chain like $.**.**.** is redundant for existence
semantics and equivalent to a single $.** with merged level bounds.

This was reported as a performance problem when expressions such as
$.**.**.**.**.* are evaluated with @? against deeply nested JSON: the same
query without the trailing .* completes in sub-millisecond time, while the
form with redundant .** segments can run for many minutes.  A similar pattern
in strict mode can also provoke very large memory allocation attempts.

Collapse consecutive jpiAny nodes at execution time for existence queries
(@? and jsonb_path_exists), merging their level bounds and performing a
single executeAnyItem() pass.

Author: Andrey Rachitskiy <[email protected]>
Reported-by: Andrey Rachitskiy <[email protected]>
Backpatch-through: 15
---
 src/backend/utils/adt/jsonpath_exec.c     | 47 +++++++++++++++++++---
 .../src/test/regress/expected/jsonb_jsonpath.out   | 40 ++++++++++++++++++
 src/test/regress/sql/jsonb_jsonpath.sql   | 11 +++++
 3 files changed, 93 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/adt/jsonpath_exec.c b/src/backend/utils/adt/jsonpath_exec.c
index ba9bbb6..74fc499 100644
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@@ -107,6 +107,8 @@ typedef struct JsonPathExecContext
 										 * ignored */
 	bool		throwErrors;	/* with "false" all suppressible errors are
 								 * suppressed */
+	bool		existsOnly;		/* @? / jsonb_path_exists: may collapse
+							 * redundant consecutive .** accessors */
 	bool		useTz;
 } JsonPathExecContext;
 
@@ -199,6 +201,7 @@ static JsonPathExecResult executeAnyItem(JsonPathExecContext *cxt,
 										 JsonPathItem *jsp, JsonbContainer *jbc, JsonValueList *found,
 										 uint32 level, uint32 first, uint32 last,
 										 bool ignoreStructuralErrors, bool unwrapNext);
+static uint32 mergeAnyBound(uint32 a, uint32 b);
 static JsonPathBool executePredicate(JsonPathExecContext *cxt,
 									 JsonPathItem *pred, JsonPathItem *larg, JsonPathItem *rarg,
 									 JsonbValue *jb, bool unwrapRightArg,
@@ -567,6 +570,7 @@ executeJsonPath(JsonPath *path, Jsonb *vars, Jsonb *json, bool throwErrors,
 	cxt.lastGeneratedObjectId = vars ? 2 : 1;
 	cxt.innermostArraySize = -1;
 	cxt.throwErrors = throwErrors;
+	cxt.existsOnly = (result == NULL);
 	cxt.useTz = useTz;
 
 	if (jspStrictAbsenseOfErrors(&cxt) && !result)
@@ -920,16 +924,37 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 
 		case jpiAny:
 			{
-				bool		hasNext = jspGetNext(jsp, &elem);
+				JsonPathItem elem;
+				bool		hasNext;
+				uint32		first;
+				uint32		last;
+
+				hasNext = jspGetNext(jsp, &elem);
+				first = jsp->content.anybounds.first;
+				last = jsp->content.anybounds.last;
+
+				/*
+				 * Consecutive .** accessors are redundant for existence
+				 * queries and multiply traversal cost.
+				 */
+				if (cxt->existsOnly)
+				{
+					while (hasNext && elem.type == jpiAny)
+					{
+						first = mergeAnyBound(first, elem.content.anybounds.first);
+						last = mergeAnyBound(last, elem.content.anybounds.last);
+						hasNext = jspGetNext(&elem, &elem);
+					}
+				}
 
 				/* first try without any intermediate steps */
-				if (jsp->content.anybounds.first == 0)
+				if (first == 0)
 				{
 					bool		savedIgnoreStructuralErrors;
 
 					savedIgnoreStructuralErrors = cxt->ignoreStructuralErrors;
 					cxt->ignoreStructuralErrors = true;
-					res = executeNextItem(cxt, jsp, &elem,
+					res = executeNextItem(cxt, jsp, hasNext ? &elem : NULL,
 										  jb, found, true);
 					cxt->ignoreStructuralErrors = savedIgnoreStructuralErrors;
 
@@ -942,8 +967,8 @@ executeItemOptUnwrapTarget(JsonPathExecContext *cxt, JsonPathItem *jsp,
 						(cxt, hasNext ? &elem : NULL,
 						 jb->val.binary.data, found,
 						 1,
-						 jsp->content.anybounds.first,
-						 jsp->content.anybounds.last,
+						 first,
+						 last,
 						 true, jspAutoUnwrap(cxt));
 				break;
 			}
@@ -1373,6 +1398,18 @@ executeNestedBoolItem(JsonPathExecContext *cxt, JsonPathItem *jsp,
 	return res;
 }
 
+
+/*
+ * Merge level bounds of two consecutive .** accessors.
+ */
+static uint32
+mergeAnyBound(uint32 a, uint32 b)
+{
+	if (a == PG_UINT32_MAX || b == PG_UINT32_MAX)
+		return PG_UINT32_MAX;
+	return a + b;
+}
+
 /*
  * Implementation of several jsonpath nodes:
  *  - jpiAny (.** accessor),
diff --git a/src/test/regress/expected/jsonb_jsonpath.out b/src/test/regress/expected/jsonb_jsonpath.out
index eafb421..5e1bd19 100644
--- a/src/test/regress/expected/jsonb_jsonpath.out
+++ b/src/test/regress/expected/jsonb_jsonpath.out
@@ -792,6 +792,46 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
  t
 (1 row)
 
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+ ?column? 
+----------
+ t
+(1 row)
+
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+ ?column? 
+----------
+ f
+(1 row)
+
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+ jsonb_path_exists 
+-------------------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+ ?column? 
+----------
+ t
+(1 row)
+
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
  jsonb_path_query 
 ------------------
diff --git a/src/test/regress/sql/jsonb_jsonpath.sql b/src/test/regress/sql/jsonb_jsonpath.sql
index 8163fc6..4c62fe2 100644
--- a/src/test/regress/sql/jsonb_jsonpath.sql
+++ b/src/test/regress/sql/jsonb_jsonpath.sql
@@ -155,6 +155,17 @@ select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{0 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to last}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{1 to 2}.b ? ( @ > 0)';
 select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**{2 to 3}.b ? ( @ > 0)';
+-- Redundant consecutive .** accessors are collapsed for existence queries
+-- (@? and jsonb_path_exists), avoiding multiplicative traversal cost.
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 0)';
+select jsonb '{"a": {"c": {"b": 1}}}' @? '$.**.**.b ? (@ > 99)';
+select jsonb_path_exists('{"a": {"c": {"b": 1}}}', '$.**.**.b ? (@ > 0)');
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'lax $.**.**.**.**';
+select ('[' || repeat('[', 50) || '0' || repeat(']', 50) || ']')::jsonb
+	@? 'strict $.**.**.**';
+
 
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.x))');
 select jsonb_path_query('{"g": {"x": 2}}', '$.g ? (exists (@.y))');
-- 
2.47.3

--MP_/BlgiDE/t55y8Vb7V2uvNybc
Content-Type: text/x-patch
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename=0001-collapse-consecutive-jsonpath-any-pg16.patch



^ permalink  raw  reply  [nested|flat] 297+ messages in thread