Textual JSON Objects That Represent Extended Scalar Values
Native binary JSON data (OSON format) extends the JSON language by adding scalar types, such as date, that correspond to SQL types and are not part of the JSON standard. Oracle Database also supports the use of textual JSON objects that represent JSON scalar values, including such nonstandard values.
When you create native binary JSON data from textual JSON data that contains such extended objects, they can optionally be replaced with corresponding (native binary) JSON scalar values.
An example of an extended object is {"$numberDecimal":31}
.
It represents a JSON scalar value of the nonstandard type decimal number, and
when interpreted as such it is replaced by a decimal number in native binary format.
For example, when you use the JSON data type constructor,
JSON
, if you use keyword EXTENDED
then recognized
extended objects in the textual input are replaced with corresponding scalar values in
the native binary JSON result. If you do not include keyword EXTENDED
then no such replacement occurs; the textual extended JSON objects are simply converted
as-is to JSON objects in the native binary format.
In the opposite direction, when you use Oracle SQL function
json_serialize
to serialize binary JSON data as textual JSON data
(VARCHAR2
, CLOB
, or BLOB
), you
can use keyword EXTENDED
to replace (native binary) JSON scalar values
with corresponding textual extended JSON objects.
Note:
If the database you use is an Oracle Autonomous Database then you can
use PL/SQL procedure DBMS_CLOUD.copy_collection
to create a JSON
document collection from a file of JSON data such as that produced by common NoSQL
databases, including Oracle NoSQL Database.
If you use ejson
as the value of the
type
parameter of the procedure, then recognized extended JSON
objects in the input file are replaced with corresponding scalar values in the
resulting native binary JSON collection. In the other direction, you can use
function json_serialize
with keyword EXTENDED
to
replace scalar values with extended JSON objects in the resulting textual JSON
data.
These are the two main use cases for extended objects:
-
Exchange (import/export):
-
Ingest existing JSON data (from somewhere) that contains extended objects.
-
Serialize native binary JSON data as textual JSON data with extended objects, for some use outside the database.
-
-
Inspection of native binary JSON data: see what you have by looking at corresponding extended objects.
For exchange purposes, you can ingest JSON data from a file produced by common NoSQL databases, including Oracle NoSQL Database, converting extended objects to native binary JSON scalars. In the other direction, you can export native binary JSON data as textual data, replacing Oracle-specific scalar JSON values with corresponding textual extended JSON objects.
Tip:
As an example of inspection, consider an object such as {"dob" :
"2000-01-02T00:00:00"}
as the result of serializing native JSON data.
Is "2000-01-02T00:00:00"
the result of serializing a native binary
value of type date, or is the native binary value just a string? Using
json_serialize
with keyword EXTENDED
lets you
know.
The mapping of extended object fields to scalar JSON types is, in general,
many-to-one: more than one kind of extended JSON object can be mapped to a given scalar
value. For example, the extended JSON objects {"$numberDecimal":"31"}
and {"$numberLong:"31"}
are both translated as the value 31 of
JSON-language scalar type number, and item method type()
returns
"number"
for each of those JSON scalars.
Item method type()
reports the JSON-language scalar type of
its targeted value (as a JSON string). Some scalar values are distinguishable
internally, even when they have the same scalar type. This generally allows function
json_serialize
(with keyword EXTENDED
) to
reconstruct the original extended JSON object. Such scalar values are distinguished
internally either by using different SQL types to implement them or by tagging
them with the kind of extended JSON object from which they were derived.
When json_serialize
reconstructs the original extended JSON
object the result is not always textually identical to the original, but it is
always semantically equivalent. For example,
{"$numberDecimal":"31"}
and
{"$numberDecimal":31}
are semantically equivalent, even
though the field values differ in type (string and number). They are translated to the
same internal value, and each is tagged as being derived from a
$numberDecimal
extended object (same tag). But when serialized, the
result for both is {"$numberDecimal":31}
. Oracle always uses
the most directly relevant type for the field value, which in this case is the
JSON-language value 31
, of scalar type number.
Table 6-1 presents correspondences among the various types used. It maps across
(1) types of extended objects used as input, (2) types reported by item method
type()
, (3) SQL types used internally, (4) standard JSON-language
types used as output by function json_serialize
, and (5) types of
extended objects output by json_serialize
when keyword
EXTENDED
is specified.
Table 6-1 Extended JSON Object Type Relations
Extended Object Type (Input) | Oracle JSON Scalar Type (Reported by type()) | SQL Scalar Type | Standard JSON Scalar Type (Output) | Extended Object Type (Output) |
---|---|---|---|---|
$numberDouble with value a JSON number,
a string representing the number, or one of these strings:
"Infinity" , "-Infinity" ,
"Inf" , "-Inf" ,
"Nan" Foot 1
|
double | BINARY_DOUBLE |
number |
$numberDouble with value a JSON number
or one of these strings: "Inf" ,
"-Inf" , "Nan" Foot 2 |
$numberFloat with value the same as for
$numberDouble |
float | BINARY_FLOAT |
number |
$numberFloat with value the same as for
$numberDouble |
$numberDecimal with value the same as
for $numberDouble |
number | NUMBER |
number |
$numberDecimal with value the same as
for $numberDouble |
$numberInt with value a signed 32-bit
integer or a string representing the number
|
number | NUMBER |
number |
$numberInt with value the same as for
$numberDouble |
$numberLong with value a JSON number or
a string representing the number
|
number | NUMBER |
number |
$numberLong with value the same as for
$numberDouble |
When the value is a string of base-64 characters, the
extended object can also have field |
binary | BLOB or RAW |
string Conversion is equivalent to the use of SQL function
|
One of the following:
|
$oid with value a string of 24 hexadecimal
characters
|
binary | RAW(12) |
string Conversion is equivalent to the use of SQL function
|
$rawid with value a string of 24 hexadecimal
characters
|
$rawhex with value a string with an even number of
hexadecimal characters
|
binary | RAW |
string Conversion is equivalent to the use of SQL function
|
$binary with value a string of base-64 characters,
right-padded with = characters
|
$rawid with value a string of 24 or 32 hexadecimal
characters
|
binary | RAW |
string Conversion is equivalent to the use of SQL function
|
$rawid |
$oracleDate with value an ISO 8601 date
string
|
date | DATE |
string |
$oracleDate with value an ISO 8601 date
string
|
$oracleTimestamp with value an ISO 8601 timestamp
string
|
timestamp | TIMESTAMP |
string |
$oracleTimestamp with value an ISO 8601 timestamp
string
|
$oracleTimestampTZ with value an ISO
8601 timestamp string with a numeric time zone offset or with
Z |
timestamp with time zone | TIMESTAMP WITH TIME ZONE |
string |
$oracleTimestampTZ with value an ISO
8601 timestamp string with a numeric time zone offset or with
Z |
|
timestamp with time zone | TIMESTAMP WITH TIME ZONE |
string |
$oracleTimestampTZ with value an ISO
8601 timestamp string with a numeric time zone offset or with
Z |
$intervalDaySecond with value an ISO 8601 interval
string as specified for SQL function
to_dsinterval |
daysecondInterval | INTERVAL DAY TO SECOND |
string |
$intervalDaySecond with value an ISO 8601 interval
string as specified for SQL function
to_dsinterval |
$intervalYearMonth with value an ISO
8601 interval string as specified for SQL function
to_yminterval |
yearmonthInterval | INTERVAL YEAR TO MONTH |
string |
$intervalYearMonth with value an ISO
8601 interval string as specified for SQL function
to_yminterval |
Two fields:
|
vector | VECTOR |
array of numbers |
Two fields:
|
Footnote 1 The string values are
interpreted case-insensitively. For example, "NAN"
"nan"
, and "nAn"
are accepted and
equivalent, and similarly "INF"
,
"inFinity"
, and "iNf"
.
Infinitely large ("Infinity"
or
"Inf"
) and small ("-Infinity"
or "-Inf"
) numbers are accepted with either the
full word or the abbreviation.
Footnote 2 On output, only these string values are used — no full-word Infinity or letter-case variants.
Parent topic: Load JSON