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JSON_TABLE

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This feature allows jsonb data to be treated as a table and thus used in
a FROM clause like other tabular data. Data can be selected from the
jsonb using jsonpath expressions, and hoisted out of nested structures
in the jsonb to form multiple rows, more or less like an outer join.

Nikita Glukhov

Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu (whose
name I previously misspelled), Himanshu Upadhyaya, Daniel Gustafsson,
Justin Pryzby.

Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru
This commit is contained in:
Andrew Dunstan
2022-04-04 15:36:03 -04:00
parent c42a6fc41d
commit 4e34747c88
31 changed files with 2605 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

228
src/backend/utils/adt/ruleutils.c
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@ -503,6 +503,8 @@ static char *flatten_reloptions(Oid relid);
static void get_reloptions(StringInfo buf, Datum reloptions);
static void get_json_path_spec(Node *path_spec, deparse_context *context,
bool showimplicit);
static void get_json_table_columns(TableFunc *tf, JsonTableParent *node,
deparse_context *context, bool showimplicit);
#define only_marker(rte) ((rte)->inh ? "" : "ONLY ")
@ -8516,7 +8518,8 @@ get_json_behavior(JsonBehavior *behavior, deparse_context *context,
/*
* get_json_expr_options
*
* Parse back common options for JSON_QUERY, JSON_VALUE, JSON_EXISTS.
* Parse back common options for JSON_QUERY, JSON_VALUE, JSON_EXISTS and
* JSON_TABLE columns.
*/
static void
get_json_expr_options(JsonExpr *jsexpr, deparse_context *context,
@ -9763,6 +9766,9 @@ get_rule_expr(Node *node, deparse_context *context,
case JSON_EXISTS_OP:
appendStringInfoString(buf, "JSON_EXISTS(");
break;
default:
elog(ERROR, "unexpected JsonExpr type: %d", jexpr->op);
break;
}
get_rule_expr(jexpr->formatted_expr, context, showimplicit);
@ -11039,16 +11045,14 @@ get_sublink_expr(SubLink *sublink, deparse_context *context)
/* ----------
* get_tablefunc - Parse back a table function
* get_xmltable - Parse back a XMLTABLE function
* ----------
*/
static void
get_tablefunc(TableFunc *tf, deparse_context *context, bool showimplicit)
get_xmltable(TableFunc *tf, deparse_context *context, bool showimplicit)
{
StringInfo buf = context->buf;
/* XMLTABLE is the only existing implementation. */
appendStringInfoString(buf, "XMLTABLE(");
if (tf->ns_uris != NIL)
@ -11139,6 +11143,220 @@ get_tablefunc(TableFunc *tf, deparse_context *context, bool showimplicit)
appendStringInfoChar(buf, ')');
}
/*
* get_json_nested_columns - Parse back nested JSON_TABLE columns
*/
static void
get_json_table_nested_columns(TableFunc *tf, Node *node,
deparse_context *context, bool showimplicit,
bool needcomma)
{
if (IsA(node, JsonTableSibling))
{
JsonTableSibling *n = (JsonTableSibling *) node;
get_json_table_nested_columns(tf, n->larg, context, showimplicit,
needcomma);
get_json_table_nested_columns(tf, n->rarg, context, showimplicit, true);
}
else
{
JsonTableParent *n = castNode(JsonTableParent, node);
if (needcomma)
appendStringInfoChar(context->buf, ',');
appendStringInfoChar(context->buf, ' ');
appendContextKeyword(context, "NESTED PATH ", 0, 0, 0);
get_const_expr(n->path, context, -1);
get_json_table_columns(tf, n, context, showimplicit);
}
}
/*
* get_json_table_columns - Parse back JSON_TABLE columns
*/
static void
get_json_table_columns(TableFunc *tf, JsonTableParent *node,
deparse_context *context, bool showimplicit)
{
StringInfo buf = context->buf;
JsonExpr *jexpr = castNode(JsonExpr, tf->docexpr);
ListCell *lc_colname;
ListCell *lc_coltype;
ListCell *lc_coltypmod;
ListCell *lc_colvarexpr;
int colnum = 0;
appendStringInfoChar(buf, ' ');
appendContextKeyword(context, "COLUMNS (", 0, 0, 0);
if (PRETTY_INDENT(context))
context->indentLevel += PRETTYINDENT_VAR;
forfour(lc_colname, tf->colnames,
lc_coltype, tf->coltypes,
lc_coltypmod, tf->coltypmods,
lc_colvarexpr, tf->colvalexprs)
{
char *colname = strVal(lfirst(lc_colname));
JsonExpr *colexpr;
Oid typid;
int32 typmod;
bool ordinality;
JsonBehaviorType default_behavior;
typid = lfirst_oid(lc_coltype);
typmod = lfirst_int(lc_coltypmod);
colexpr = castNode(JsonExpr, lfirst(lc_colvarexpr));
if (colnum < node->colMin)
{
colnum++;
continue;
}
if (colnum > node->colMax)
break;
if (colnum > node->colMin)
appendStringInfoString(buf, ", ");
colnum++;
ordinality = !colexpr;
appendContextKeyword(context, "", 0, 0, 0);
appendStringInfo(buf, "%s %s", quote_identifier(colname),
ordinality ? "FOR ORDINALITY" :
format_type_with_typemod(typid, typmod));
if (ordinality)
continue;
if (colexpr->op == JSON_EXISTS_OP)
{
appendStringInfoString(buf, " EXISTS");
default_behavior = JSON_BEHAVIOR_FALSE;
}
else
{
if (colexpr->op == JSON_QUERY_OP)
{
char typcategory;
bool typispreferred;
get_type_category_preferred(typid, &typcategory, &typispreferred);
if (typcategory == TYPCATEGORY_STRING)
appendStringInfoString(buf,
colexpr->format->format_type == JS_FORMAT_JSONB ?
" FORMAT JSONB" : " FORMAT JSON");
}
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);
get_json_expr_options(colexpr, context, default_behavior);
}
if (node->child)
get_json_table_nested_columns(tf, node->child, context, showimplicit,
node->colMax >= node->colMin);
if (PRETTY_INDENT(context))
context->indentLevel -= PRETTYINDENT_VAR;
appendContextKeyword(context, ")", 0, 0, 0);
}
/* ----------
* get_json_table - Parse back a JSON_TABLE function
* ----------
*/
static void
get_json_table(TableFunc *tf, deparse_context *context, bool showimplicit)
{
StringInfo buf = context->buf;
JsonExpr *jexpr = castNode(JsonExpr, tf->docexpr);
JsonTableParent *root = castNode(JsonTableParent, tf->plan);
appendStringInfoString(buf, "JSON_TABLE(");
if (PRETTY_INDENT(context))
context->indentLevel += PRETTYINDENT_VAR;
appendContextKeyword(context, "", 0, 0, 0);
get_rule_expr(jexpr->formatted_expr, context, showimplicit);
appendStringInfoString(buf, ", ");
get_const_expr(root->path, context, -1);
if (jexpr->passing_values)
{
ListCell *lc1, *lc2;
bool needcomma = false;
appendStringInfoChar(buf, ' ');
appendContextKeyword(context, "PASSING ", 0, 0, 0);
if (PRETTY_INDENT(context))
context->indentLevel += PRETTYINDENT_VAR;
forboth(lc1, jexpr->passing_names,
lc2, jexpr->passing_values)
{
if (needcomma)
appendStringInfoString(buf, ", ");
needcomma = true;
appendContextKeyword(context, "", 0, 0, 0);
get_rule_expr((Node *) lfirst(lc2), context, false);
appendStringInfo(buf, " AS %s",
quote_identifier((lfirst_node(String, lc1))->sval)
);
}
if (PRETTY_INDENT(context))
context->indentLevel -= PRETTYINDENT_VAR;
}
get_json_table_columns(tf, root, context, showimplicit);
if (jexpr->on_error->btype != JSON_BEHAVIOR_EMPTY)
get_json_behavior(jexpr->on_error, context, "ERROR");
if (PRETTY_INDENT(context))
context->indentLevel -= PRETTYINDENT_VAR;
appendContextKeyword(context, ")", 0, 0, 0);
}
/* ----------
* get_tablefunc - Parse back a table function
* ----------
*/
static void
get_tablefunc(TableFunc *tf, deparse_context *context, bool showimplicit)
{
/* XMLTABLE and JSON_TABLE are the only existing implementations. */
if (tf->functype == TFT_XMLTABLE)
get_xmltable(tf, context, showimplicit);
else if (tf->functype == TFT_JSON_TABLE)
get_json_table(tf, context, showimplicit);
}
/* ----------
* get_from_clause - Parse back a FROM clause
*