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Add SQL/JSON query functions

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This introduces the following SQL/JSON functions for querying JSON
data using jsonpath expressions:

JSON_EXISTS(), which can be used to apply a jsonpath expression to a
JSON value to check if it yields any values.

JSON_QUERY(), which can be used to to apply a jsonpath expression to
a JSON value to get a JSON object, an array, or a string.  There are
various options to control whether multi-value result uses array
wrappers and whether the singleton scalar strings are quoted or not.

JSON_VALUE(), which can be used to apply a jsonpath expression to a
JSON value to return a single scalar value, producing an error if it
multiple values are matched.

Both JSON_VALUE() and JSON_QUERY() functions have options for
handling EMPTY and ERROR conditions, which can be used to specify
the behavior when no values are matched and when an error occurs
during jsonpath evaluation, respectively.

Author: Nikita Glukhov <n.gluhov@postgrespro.ru>
Author: Teodor Sigaev <teodor@sigaev.ru>
Author: Oleg Bartunov <obartunov@gmail.com>
Author: Alexander Korotkov <aekorotkov@gmail.com>
Author: Andrew Dunstan <andrew@dunslane.net>
Author: Amit Langote <amitlangote09@gmail.com>
Author: Peter Eisentraut <peter@eisentraut.org>
Author: Jian He <jian.universality@gmail.com>

Reviewers have included (in no particular order):

Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup,
Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson,
Justin Pryzby, Álvaro Herrera, Jian He, Anton A. Melnikov,
Nikita Malakhov, Peter Eisentraut, Tomas Vondra

Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru
Discussion: https://postgr.es/m/20220616233130.rparivafipt6doj3@alap3.anarazel.de
Discussion: https://postgr.es/m/abd9b83b-aa66-f230-3d6d-734817f0995d%40postgresql.org
Discussion: https://postgr.es/m/CA+HiwqHROpf9e644D8BRqYvaAPmgBZVup-xKMDPk-nd4EpgzHw@mail.gmail.com
Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
This commit is contained in:
Amit Langote
2024-03-21 17:06:27 +09:00
parent a145f424d5
commit 6185c9737c
34 changed files with 4815 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

322
src/backend/utils/adt/jsonpath_exec.c
View File

@ -229,6 +229,12 @@ static JsonPathExecResult appendBoolResult(JsonPathExecContext *cxt,
JsonPathItem *jsp, JsonValueList *found, JsonPathBool res);
static void getJsonPathItem(JsonPathExecContext *cxt, JsonPathItem *item,
JsonbValue *value);
static JsonbValue *GetJsonPathVar(void *cxt, char *varName, int varNameLen,
JsonbValue *baseObject, int *baseObjectId);
static int CountJsonPathVars(void *cxt);
static void JsonItemFromDatum(Datum val, Oid typid, int32 typmod,
JsonbValue *res);
static void JsonbValueInitNumericDatum(JsonbValue *jbv, Datum num);
static void getJsonPathVariable(JsonPathExecContext *cxt,
JsonPathItem *variable, JsonbValue *value);
static int countVariablesFromJsonb(void *varsJsonb);
@ -2860,6 +2866,155 @@ getJsonPathItem(JsonPathExecContext *cxt, JsonPathItem *item,
}
}
/*
* Returns the computed value of a JSON path variable with given name.
*/
static JsonbValue *
GetJsonPathVar(void *cxt, char *varName, int varNameLen,
JsonbValue *baseObject, int *baseObjectId)
{
JsonPathVariable *var = NULL;
List *vars = cxt;
ListCell *lc;
JsonbValue *result;
int id = 1;
foreach(lc, vars)
{
JsonPathVariable *curvar = lfirst(lc);
if (!strncmp(curvar->name, varName, varNameLen))
{
var = curvar;
break;
}
id++;
}
if (var == NULL)
{
*baseObjectId = -1;
return NULL;
}
result = palloc(sizeof(JsonbValue));
if (var->isnull)
{
*baseObjectId = 0;
result->type = jbvNull;
}
else
JsonItemFromDatum(var->value, var->typid, var->typmod, result);
*baseObject = *result;
*baseObjectId = id;
return result;
}
static int
CountJsonPathVars(void *cxt)
{
List *vars = (List *) cxt;
return list_length(vars);
}
/*
* Initialize JsonbValue to pass to jsonpath executor from given
* datum value of the specified type.
*/
static void
JsonItemFromDatum(Datum val, Oid typid, int32 typmod, JsonbValue *res)
{
switch (typid)
{
case BOOLOID:
res->type = jbvBool;
res->val.boolean = DatumGetBool(val);
break;
case NUMERICOID:
JsonbValueInitNumericDatum(res, val);
break;
case INT2OID:
JsonbValueInitNumericDatum(res, DirectFunctionCall1(int2_numeric, val));
break;
case INT4OID:
JsonbValueInitNumericDatum(res, DirectFunctionCall1(int4_numeric, val));
break;
case INT8OID:
JsonbValueInitNumericDatum(res, DirectFunctionCall1(int8_numeric, val));
break;
case FLOAT4OID:
JsonbValueInitNumericDatum(res, DirectFunctionCall1(float4_numeric, val));
break;
case FLOAT8OID:
JsonbValueInitNumericDatum(res, DirectFunctionCall1(float8_numeric, val));
break;
case TEXTOID:
case VARCHAROID:
res->type = jbvString;
res->val.string.val = VARDATA_ANY(val);
res->val.string.len = VARSIZE_ANY_EXHDR(val);
break;
case DATEOID:
case TIMEOID:
case TIMETZOID:
case TIMESTAMPOID:
case TIMESTAMPTZOID:
res->type = jbvDatetime;
res->val.datetime.value = val;
res->val.datetime.typid = typid;
res->val.datetime.typmod = typmod;
res->val.datetime.tz = 0;
break;
case JSONBOID:
{
JsonbValue *jbv = res;
Jsonb *jb = DatumGetJsonbP(val);
if (JsonContainerIsScalar(&jb->root))
{
bool result PG_USED_FOR_ASSERTS_ONLY;
result = JsonbExtractScalar(&jb->root, jbv);
Assert(result);
}
else
JsonbInitBinary(jbv, jb);
break;
}
case JSONOID:
{
text *txt = DatumGetTextP(val);
char *str = text_to_cstring(txt);
Jsonb *jb;
jb = DatumGetJsonbP(DirectFunctionCall1(jsonb_in,
CStringGetDatum(str)));
pfree(str);
JsonItemFromDatum(JsonbPGetDatum(jb), JSONBOID, -1, res);
break;
}
default:
ereport(ERROR,
errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("could not convert value of type %s to jsonpath",
format_type_be(typid)));
}
}
/* Initialize numeric value from the given datum */
static void
JsonbValueInitNumericDatum(JsonbValue *jbv, Datum num)
{
jbv->type = jbvNumeric;
jbv->val.numeric = DatumGetNumeric(num);
}
/*
* Get the value of variable passed to jsonpath executor
*/
@ -3596,3 +3751,170 @@ compareDatetime(Datum val1, Oid typid1, Datum val2, Oid typid2,
return DatumGetInt32(DirectFunctionCall2(cmpfunc, val1, val2));
}
/*
* Executor-callable JSON_EXISTS implementation
*
* Returns NULL instead of throwing errors if 'error' is not NULL, setting
* *error to true.
*/
bool
JsonPathExists(Datum jb, JsonPath *jp, bool *error, List *vars)
{
JsonPathExecResult res;
res = executeJsonPath(jp, vars,
GetJsonPathVar, CountJsonPathVars,
DatumGetJsonbP(jb), !error, NULL, true);
Assert(error || !jperIsError(res));
if (error && jperIsError(res))
*error = true;
return res == jperOk;
}
/*
* Executor-callable JSON_QUERY implementation
*
* Returns NULL instead of throwing errors if 'error' is not NULL, setting
* *error to true. *empty is set to true if no match is found.
*/
Datum
JsonPathQuery(Datum jb, JsonPath *jp, JsonWrapper wrapper, bool *empty,
bool *error, List *vars)
{
JsonbValue *singleton;
bool wrap;
JsonValueList found = {0};
JsonPathExecResult res;
int count;
res = executeJsonPath(jp, vars,
GetJsonPathVar, CountJsonPathVars,
DatumGetJsonbP(jb), !error, &found, true);
Assert(error || !jperIsError(res));
if (error && jperIsError(res))
{
*error = true;
*empty = false;
return (Datum) 0;
}
/* WRAP or not? */
count = JsonValueListLength(&found);
singleton = count > 0 ? JsonValueListHead(&found) : NULL;
if (singleton == NULL)
wrap = false;
else if (wrapper == JSW_NONE || wrapper == JSW_UNSPEC)
wrap = false;
else if (wrapper == JSW_UNCONDITIONAL)
wrap = true;
else if (wrapper == JSW_CONDITIONAL)
wrap = count > 1 ||
IsAJsonbScalar(singleton) ||
(singleton->type == jbvBinary &&
JsonContainerIsScalar(singleton->val.binary.data));
else
{
elog(ERROR, "unrecognized json wrapper %d", wrapper);
wrap = false;
}
if (wrap)
return JsonbPGetDatum(JsonbValueToJsonb(wrapItemsInArray(&found)));
/* No wrapping means only one item is expected. */
if (count > 1)
{
if (error)
{
*error = true;
return (Datum) 0;
}
ereport(ERROR,
(errcode(ERRCODE_MORE_THAN_ONE_SQL_JSON_ITEM),
errmsg("JSON path expression in JSON_QUERY should return singleton item without wrapper"),
errhint("Use WITH WRAPPER clause to wrap SQL/JSON item sequence into array.")));
}
if (singleton)
return JsonbPGetDatum(JsonbValueToJsonb(singleton));
*empty = true;
return PointerGetDatum(NULL);
}
/*
* Executor-callable JSON_VALUE implementation
*
* Returns NULL instead of throwing errors if 'error' is not NULL, setting
* *error to true. *empty is set to true if no match is found.
*/
JsonbValue *
JsonPathValue(Datum jb, JsonPath *jp, bool *empty, bool *error, List *vars)
{
JsonbValue *res;
JsonValueList found = {0};
JsonPathExecResult jper PG_USED_FOR_ASSERTS_ONLY;
int count;
jper = executeJsonPath(jp, vars, GetJsonPathVar, CountJsonPathVars,
DatumGetJsonbP(jb),
!error, &found, true);
Assert(error || !jperIsError(jper));
if (error && jperIsError(jper))
{
*error = true;
*empty = false;
return NULL;
}
count = JsonValueListLength(&found);
*empty = (count == 0);
if (*empty)
return NULL;
/* JSON_VALUE expects to get only singletons. */
if (count > 1)
{
if (error)
{
*error = true;
return NULL;
}
ereport(ERROR,
(errcode(ERRCODE_MORE_THAN_ONE_SQL_JSON_ITEM),
errmsg("JSON path expression in JSON_VALUE should return singleton scalar item")));
}
res = JsonValueListHead(&found);
if (res->type == jbvBinary && JsonContainerIsScalar(res->val.binary.data))
JsonbExtractScalar(res->val.binary.data, res);
/* JSON_VALUE expects to get only scalars. */
if (!IsAJsonbScalar(res))
{
if (error)
{
*error = true;
return NULL;
}
ereport(ERROR,
(errcode(ERRCODE_SQL_JSON_SCALAR_REQUIRED),
errmsg("JSON path expression in JSON_VALUE should return singleton scalar item")));
}
if (res->type == jbvNull)
return NULL;
return res;
}