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SQL/JSON: Fix JSON_TABLE() column deparsing

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The deparsing code in get_json_expr_options() unnecessarily emitted
the default column-specific ON ERROR / EMPTY behavior when the
top-level ON ERROR behavior in JSON_TABLE was set to ERROR. Fix that
by not overriding the column-specific default, determined based on
the column's JsonExprOp in get_json_table_columns(), with
JSON_BEHAVIOR_ERROR when that is the top-level ON ERROR behavior.

Note that this only removes redundancy; the current deparsing output
is not incorrect, just redundant.

Reviewed-by: Jian He <jian.universality@gmail.com>
Discussion: https://postgr.es/m/CACJufxEo4sUjKCYtda0_qt9tazqqKPmF1cqhW9KBOUeJFqQd2g@mail.gmail.com
Backpatch-through: 17
This commit is contained in:
Amit Langote 2024-09-06 10:12:16 +09:00
parent 3422f5f93f
commit 68222851d5
3 changed files with 27 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/utils/adt/ruleutils.c
View File

@ -11719,7 +11719,6 @@ get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
bool showimplicit)
{
StringInfo buf = context->buf;
JsonExpr *jexpr = castNode(JsonExpr, tf->docexpr);
ListCell *lc_colname;
ListCell *lc_coltype;
ListCell *lc_coltypmod;
@ -11772,6 +11771,10 @@ get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
if (ordinality)
continue;
/*
* Set default_behavior to guide get_json_expr_options() on whether to
* to emit the ON ERROR / EMPTY clauses.
*/
if (colexpr->op == JSON_EXISTS_OP)
{
appendStringInfoString(buf, " EXISTS");
@ -11795,9 +11798,6 @@ get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
default_behavior = JSON_BEHAVIOR_NULL;
}
if (jexpr->on_error->btype == JSON_BEHAVIOR_ERROR)
default_behavior = JSON_BEHAVIOR_ERROR;
appendStringInfoString(buf, " PATH ");
get_json_path_spec(colexpr->path_spec, context, showimplicit);

18
src/test/regress/expected/sqljson_jsontable.out
View File

@ -1132,3 +1132,21 @@ ERROR: invalid ON ERROR behavior for column "a"
LINE 1: ...M JSON_TABLE(jsonb '1', '$' COLUMNS (a int exists empty obje...
^
DETAIL: Only ERROR, TRUE, FALSE, or UNKNOWN is allowed in ON ERROR for EXISTS columns.
-- Test JSON_TABLE() column deparsing -- don't emit default ON ERROR / EMPTY
-- behavior
EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$'));
QUERY PLAN
-----------------------------------------------------------------------------------------------------
Table Function Scan on "json_table" (cost=0.01..1.00 rows=100 width=32)
Output: a
Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$'))
(3 rows)
EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') ERROR ON ERROR);
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------
Table Function Scan on "json_table" (cost=0.01..1.00 rows=100 width=32)
Output: a
Table Function Call: JSON_TABLE('"a"'::jsonb, '$' AS json_table_path_0 COLUMNS (a text PATH '$') ERROR ON ERROR)
(3 rows)

5
src/test/regress/sql/sqljson_jsontable.sql
View File

@ -542,3 +542,8 @@ SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int) NULL ON ERROR);
SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int true on empty));
SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int omit quotes true on error));
SELECT * FROM JSON_TABLE(jsonb '1', '$' COLUMNS (a int exists empty object on error));
-- Test JSON_TABLE() column deparsing -- don't emit default ON ERROR / EMPTY
-- behavior
EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$'));
EXPLAIN VERBOSE SELECT * from JSON_TABLE('"a"', '$' COLUMNS (a text PATH '$') ERROR ON ERROR);