From ab0e6db5fe8aa5aac591ed2c04a17023dad712f2 Mon Sep 17 00:00:00 2001 From: jian he Date: Sun, 27 Sep 2026 00:04:56 +0800 Subject: [PATCH v3 1/1] Reset JsonExpr empty/error flags before NULL short-circuit SQL NULL context/path skips EEOP_JSONEXPR_PATH (JUMP_IF_NULL to CONST NULL) so jsonpath is not evaluated, then falls through to domain coercion and ON EMPTY / ON ERROR checks. empty/error were cleared only inside PATH, so a previous row's EMPTY/ERROR leaked onto the NULL row when DEFAULT was not NULL. Clear the flags in a new EEOP_JSONEXPR_RESET at the start of each JsonExpr evaluation. BUG #19621 Reported-by: Suyang Zhong Author: Andrey Rachitskiy Discussion: https://www.postgresql.org/message-id/19621-0a480d2dc74e6bd5%40postgresql.org Backpatch-through: 17 --- src/backend/executor/execExpr.c | 29 ++++----- src/backend/executor/execExprInterp.c | 23 ++++++- .../regress/expected/sqljson_queryfuncs.out | 61 +++++++++++++++++++ src/test/regress/sql/sqljson_queryfuncs.sql | 24 ++++++++ 4 files changed, 116 insertions(+), 21 deletions(-) diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c index 82e846a1f4f..18b33b24282 100644 --- a/src/backend/executor/execExpr.c +++ b/src/backend/executor/execExpr.c @@ -4807,6 +4807,17 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state, jsestate->args = lappend(jsestate->args, var); } + /* + * Adjust jump target addresses of JUMPs that we added above to point to + * the EEOP_JSONEXPR_PATH step, which returns NULL when either + * formatted_expr or pathspec is NULL. + */ + foreach(lc, jumps_return_null) + { + ExprEvalStep *as = &state->steps[lfirst_int(lc)]; + + as->d.jump.jumpdone = state->steps_len; + } /* Step for jsonpath evaluation; see ExecEvalJsonExprPath(). */ scratch->opcode = EEOP_JSONEXPR_PATH; scratch->resvalue = resv; @@ -4814,24 +4825,6 @@ ExecInitJsonExpr(JsonExpr *jsexpr, ExprState *state, scratch->d.jsonexpr.jsestate = jsestate; ExprEvalPushStep(state, scratch); - /* - * Step to return NULL after jumping to skip the EEOP_JSONEXPR_PATH step - * when either formatted_expr or pathspec is NULL. Adjust jump target - * addresses of JUMPs that we added above. - */ - foreach(lc, jumps_return_null) - { - ExprEvalStep *as = &state->steps[lfirst_int(lc)]; - - as->d.jump.jumpdone = state->steps_len; - } - scratch->opcode = EEOP_CONST; - scratch->resvalue = resv; - scratch->resnull = resnull; - scratch->d.constval.value = (Datum) 0; - scratch->d.constval.isnull = true; - ExprEvalPushStep(state, scratch); - escontext = jsexpr->on_error->btype != JSON_BEHAVIOR_ERROR ? &jsestate->escontext : NULL; diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c index 397219f7a3a..900946ae32e 100644 --- a/src/backend/executor/execExprInterp.c +++ b/src/backend/executor/execExprInterp.c @@ -4893,6 +4893,7 @@ ExecEvalJsonIsPredicate(ExprState *state, ExprEvalStep *op) /* * Evaluate a jsonpath against a document, both of which must have been * evaluated and their values saved in op->d.jsonexpr.jsestate. + * (If the document is NULL, the jsonpath evaluation is skipped) * * If an error occurs during JsonPath* evaluation or when coercing its result * to the RETURNING type, JsonExprState.error is set to true, provided the @@ -4919,9 +4920,6 @@ ExecEvalJsonExprPath(ExprState *state, ExprEvalStep *op, int jump_eval_coercion = jsestate->jump_eval_coercion; char *val_string = NULL; - item = jsestate->formatted_expr.value; - path = DatumGetJsonPathP(jsestate->pathspec.value); - /* Set error/empty to false. */ memset(&jsestate->error, 0, sizeof(NullableDatum)); memset(&jsestate->empty, 0, sizeof(NullableDatum)); @@ -4934,6 +4932,25 @@ ExecEvalJsonExprPath(ExprState *state, ExprEvalStep *op, } jsestate->escontext.error_occurred = false; + /* + * Return NULL if formatted_expr or pathspec is NULL, skipping ON ERROR + * and ON EMPTY. If the RETURNING type is a domain with constraints, the + * NULL must still be coerced to it so that the constraints are checked. + */ + if (jsestate->formatted_expr.isnull || jsestate->pathspec.isnull) + { + *op->resvalue = (Datum) 0; + *op->resnull = true; + + if (jump_eval_coercion >= 0) + return jump_eval_coercion; + else + return jsestate->jump_end; + } + + item = jsestate->formatted_expr.value; + path = DatumGetJsonPathP(jsestate->pathspec.value); + switch (jsexpr->op) { case JSON_EXISTS_OP: diff --git a/src/test/regress/expected/sqljson_queryfuncs.out b/src/test/regress/expected/sqljson_queryfuncs.out index fe8aa927b5e..c24d86fc35f 100644 --- a/src/test/regress/expected/sqljson_queryfuncs.out +++ b/src/test/regress/expected/sqljson_queryfuncs.out @@ -337,6 +337,16 @@ SELECT JSON_VALUE('"purple"'::jsonb, 'lax $[*]' RETURNING rgb); SELECT JSON_VALUE('"purple"'::jsonb, 'lax $[*]' RETURNING rgb ERROR ON ERROR); ERROR: value for domain rgb violates check constraint "rgb_check" +SELECT x IS NULL AS is_null, + json_value(x, 'strict $.a' RETURNING sqljsonb_int_not_null DEFAULT 1 ON ERROR) AS jv +FROM (VALUES ('1'::jsonb), (NULL), ('1'::jsonb)) v(x); + is_null | jv +---------+---- + f | 1 + t | 1 + f | 1 +(3 rows) + SELECT JSON_VALUE(jsonb '[]', '$'); json_value ------------ @@ -475,6 +485,57 @@ FROM 2 | -1 (3 rows) +-- SQL NULL must not reuse a previous row's ON EMPTY / ON ERROR result. +SELECT x IS NULL AS is_null, + json_value(x, '$.a' RETURNING int DEFAULT 42 ON EMPTY) AS jv +FROM (VALUES ('{}'), (NULL), ('{}')) v(x); + is_null | jv +---------+---- + f | 42 + t | + f | 42 +(3 rows) + +SELECT x IS NULL AS is_null, + json_value(x, 'strict $.a' RETURNING int DEFAULT 42 ON ERROR) AS jv +FROM (VALUES ('1'), (NULL), ('1')) v(x); + is_null | jv +---------+---- + f | 42 + t | + f | 42 +(3 rows) + +SELECT p IS NULL AS is_null, + json_value('{}', p RETURNING int DEFAULT 42 ON EMPTY) AS jv +FROM (VALUES ('$.a'::jsonpath), (NULL), ('$.a'::jsonpath)) v(p); + is_null | jv +---------+---- + f | 42 + t | + f | 42 +(3 rows) + +SELECT x IS NULL AS is_null, + json_query(x, '$.a' DEFAULT '"empty"' ON EMPTY) AS jq +FROM (VALUES ('{}'::jsonb), (NULL), ('{}'::jsonb)) v(x); + is_null | jq +---------+--------- + f | "empty" + t | + f | "empty" +(3 rows) + +SELECT x IS NULL AS is_null, + json_exists(x, 'strict $.a' TRUE ON ERROR) AS je +FROM (VALUES ('1'::jsonb), (NULL), ('1'::jsonb)) v(x); + is_null | je +---------+---- + f | t + t | + f | t +(3 rows) + SELECT JSON_VALUE(jsonb 'null', '$a' PASSING point ' (1, 2 )' AS a); json_value ------------ diff --git a/src/test/regress/sql/sqljson_queryfuncs.sql b/src/test/regress/sql/sqljson_queryfuncs.sql index 0767db9cfff..80fdb805f0f 100644 --- a/src/test/regress/sql/sqljson_queryfuncs.sql +++ b/src/test/regress/sql/sqljson_queryfuncs.sql @@ -80,6 +80,9 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple CREATE DOMAIN rgb AS rainbow CHECK (VALUE IN ('red', 'green', 'blue')); SELECT JSON_VALUE('"purple"'::jsonb, 'lax $[*]' RETURNING rgb); SELECT JSON_VALUE('"purple"'::jsonb, 'lax $[*]' RETURNING rgb ERROR ON ERROR); +SELECT x IS NULL AS is_null, + json_value(x, 'strict $.a' RETURNING sqljsonb_int_not_null DEFAULT 1 ON ERROR) AS jv +FROM (VALUES ('1'::jsonb), (NULL), ('1'::jsonb)) v(x); SELECT JSON_VALUE(jsonb '[]', '$'); SELECT JSON_VALUE(jsonb '[]', '$' ERROR ON ERROR); @@ -128,6 +131,27 @@ SELECT FROM generate_series(0, 2) x; +-- SQL NULL must not reuse a previous row's ON EMPTY / ON ERROR result. +SELECT x IS NULL AS is_null, + json_value(x, '$.a' RETURNING int DEFAULT 42 ON EMPTY) AS jv +FROM (VALUES ('{}'), (NULL), ('{}')) v(x); + +SELECT x IS NULL AS is_null, + json_value(x, 'strict $.a' RETURNING int DEFAULT 42 ON ERROR) AS jv +FROM (VALUES ('1'), (NULL), ('1')) v(x); + +SELECT p IS NULL AS is_null, + json_value('{}', p RETURNING int DEFAULT 42 ON EMPTY) AS jv +FROM (VALUES ('$.a'::jsonpath), (NULL), ('$.a'::jsonpath)) v(p); + +SELECT x IS NULL AS is_null, + json_query(x, '$.a' DEFAULT '"empty"' ON EMPTY) AS jq +FROM (VALUES ('{}'::jsonb), (NULL), ('{}'::jsonb)) v(x); + +SELECT x IS NULL AS is_null, + json_exists(x, 'strict $.a' TRUE ON ERROR) AS je +FROM (VALUES ('1'::jsonb), (NULL), ('1'::jsonb)) v(x); + SELECT JSON_VALUE(jsonb 'null', '$a' PASSING point ' (1, 2 )' AS a); SELECT JSON_VALUE(jsonb 'null', '$a' PASSING point ' (1, 2 )' AS a RETURNING point); SELECT JSON_VALUE(jsonb 'null', '$a' PASSING point ' (1, 2 )' AS a RETURNING point ERROR ON ERROR); -- 2.34.1