SQL/JSON in PostgreSQL

Hi

2017-02-28 20:08 GMT+01:00 Oleg Bartunov <obartunov@gmail.com>:

Hi there,

Attached patch is an implementation of SQL/JSON data model from SQL-2016
standard (ISO/IEC 9075-2:2016(E)), which was published 2016-12-15 and is
available only for purchase from ISO web site (
https://www.iso.org/standard/63556.html). Unfortunately I didn't find any
public sources of the standard or any preview documents, but Oracle
implementation of json support in 12c release 2 is very close (
http://docs.oracle.com/database/122/ADJSN/json-in-oracle-database.htm),
also we used https://livesql.oracle.com/ to understand some details.

Postgres has already two json data types - json and jsonb and implementing
another json data type, which strictly conforms the standard, would be not
a good idea. Moreover, SQL standard doesn’t describe data type, but only
data model, which “comprises SQL/JSON items and SQL/JSON sequences. The
components of the SQL/JSON data model are:

1) An SQL/JSON item is defined recursively as any of the following:

a) An SQL/JSON scalar, defined as a non-null value of any of the following
predefined (SQL) types:

character string with character set Unicode, numeric, Boolean, or datetime.

b) An SQL/JSON null, defined as a value that is distinct from any value of
any SQL type.

NOTE 122 — An SQL/JSON null is distinct from the SQL null value.

c) An SQL/JSON array, defined as an ordered list of zero or more SQL/JSON
items, called the SQL/JSON

elements of the SQL/JSON array.

d) An SQL/JSON object, defined as an unordered collection of zero or more
SQL/JSON members….

“

Our jsonb corresponds to SQL/JSON with UNIQUE KEYS and implicit ordering
of keys and our main intention was to provide support of jsonb as a most
important and usable data type.

We created repository for reviewing (ask for write access) -
https://github.com/postgrespro/sqljson/tree/sqljson

Examples of usage can be found in src/test/regress/sql/sql_json.sql

The whole documentation about json support should be reorganized and
added, and we plan to do this before release. We need help of community
here.

Our goal is to provide support of main features of SQL/JSON to release 10,
as we discussed at developers meeting in Brussels (Andrew Dunstan has
kindly agreed to review the patch).

We had not much time to develop the complete support, because of standard
availability), but hope all major features are here, namely, all nine
functions as described in the standard (but see implementation notes below):

“All manipulation (e.g., retrieval, creation, testing) of SQL/JSON items
is performed through a number of SQL/JSON functions. There are nine such
functions, categorized as SQL/JSON retrieval functions and SQL/JSON
construction functions. The SQL/JSON retrieval functions are characterized
by operating on JSON data and returning an SQL value (possibly a Boolean
value) or a JSON value. The SQL/JSON construction functions return JSON
data created from operations on SQL data or other JSON data.

The SQL/JSON retrieval functions are:

— <JSON value function>: extracts an SQL value of a predefined type from a
JSON text.

— <JSON query>: extracts a JSON text from a JSON text.

— <JSON table>: converts a JSON text to an SQL table.

— <JSON predicate>: tests whether a string value is or is not properly
formed JSON text.

— <JSON exists predicate>: tests whether an SQL/JSON path expression
returns any SQL/JSON items.

The SQL/JSON construction functions are:

— <JSON object constructor>: generates a string that is a serialization of
an SQL/JSON object.

— <JSON array constructor>: generates a string that is a serialization of
an SQL/JSON array.

— <JSON object aggregate constructor>: generates, from an aggregation of
SQL data, a string that is a serialization

of an SQL/JSON object.

— <JSON array aggregate constructor>: generates, from an aggregation of
SQL data, a string that is a serialization

of an SQL/JSON array.

A JSON-returning function is an SQL/JSON construction function or
JSON_QUERY.”

The standard describes SQL/JSON path language, which used by SQL/JSON
query operators to query JSON. It defines path language as string literal.
We implemented the path language as JSONPATH data type, since other
approaches are not friendly to planner and executor.

The functions and JSONPATH provide a new functionality for json support,
namely, ability to operate (in standard specified way) with json structure
at SQL-language level - the often requested feature by the users.

The patch is consists of about 15000 insertions (about 5000 lines are from
tests), passes all regression tests and doesn’t touches critical parts, so
we hope with community help to bring it to committable state.

Authors: Nikita Glukhov, Teodor Sigaev, Oleg Bartunov and Alexander
Korotkov

Implementation notes:

1.

We didn’t implemented ‘datetime’ support, since it’s not clear from
standard.
2.

JSON_OBJECT/JSON_OBJECTAGG (KEY <key> VALUE <value>, ...) doesn’t
implemented, only (<key>:<value>, …) and (<key> VALUE <value>, …) are
supported, because of grammar conflicts with leading KEY keyword.
3.

FORMAT (JSON|JSONB)) in JSON_ARRAYAGG with subquery doesn’t
supported, because of grammar conflicts with non-reserved word FORMAT.
4.

JSONPATH implemented only for jsonb data type , so JSON_EXISTS(),
JSON_VALUE(), JSON_QUERY() and JSON_TABLE() doesn’t works if context item
is of json data type.
5.

Some methods and predicates for JSONPATH not yet implemented, for
example .type(), .size(), .keyvalue(), predicates like_regex, starts
with, etc. They are not key features and we plan to make them in next
release.
6.

JSONPATH doesn’t support expression for index array, like [2+3 to
$upperbound], only simple constants like [5, 7 to 12] are supported.
7.

JSONPATH extensions to standard: .** (wildcard path accessor), .key
(member accessor without leading @).
8.

FORMAT JSONB extension to standard for returning jsonb - standard
specifies possibility of returning custom type.
9.

JSON_EXISTS(), JSON_VALUE(), JSON_QUERY() are implemented using new
executor node JsonExpr.
10.

JSON_TABLE() is transformed into joined subselects with JSON_VALUE()
and JSON_QUERY() in target list.
11.

JSON_OBJECT(), JSON_ARRAY() constructors and IS JSON predicate are
transformed into raw function calls.
12.

Added explicit casts bytea=>jsonb and jsonb=>bytea (for jsonb=>bytea
output using RETURNING bytea FORMAT JSONB and corresponding bytea=>jsonb
input using <jsonb_bytea_expr> FORMAT JSONB).

Good work - it will be pretty big patch.

There is a intersection with implementation of XMLTABLE. I prepared a
executor infrastructure. So it can little bit reduce size of this patch.

Taking only Oracle as origin can be risk - in details Oracle doesn't
respects owns proposal to standard.

This is last commitfest for current release cycle - are you sure, so is
good idea to push all mentioned features?

Regards

Pavel

On Tue, Feb 28, 2017 at 10:55 PM, Pavel Stehule <pavel.stehule@gmail.com>
wrote:

Hi

2017-02-28 20:08 GMT+01:00 Oleg Bartunov <obartunov@gmail.com>:

Hi there,

Attached patch is an implementation of SQL/JSON data model from SQL-2016
standard (ISO/IEC 9075-2:2016(E)), which was published 2016-12-15 and is
available only for purchase from ISO web site (
https://www.iso.org/standard/63556.html). Unfortunately I didn't find
any public sources of the standard or any preview documents, but Oracle
implementation of json support in 12c release 2 is very close (
http://docs.oracle.com/database/122/ADJSN/json-in-oracle-database.htm),
also we used https://livesql.oracle.com/ to understand some details.

Postgres has already two json data types - json and jsonb and
implementing another json data type, which strictly conforms the standard,
would be not a good idea. Moreover, SQL standard doesn’t describe data
type, but only data model, which “comprises SQL/JSON items and SQL/JSON
sequences. The components of the SQL/JSON data model are:

1) An SQL/JSON item is defined recursively as any of the following:

a) An SQL/JSON scalar, defined as a non-null value of any of the
following predefined (SQL) types:

character string with character set Unicode, numeric, Boolean, or
datetime.

b) An SQL/JSON null, defined as a value that is distinct from any value
of any SQL type.

NOTE 122 — An SQL/JSON null is distinct from the SQL null value.

c) An SQL/JSON array, defined as an ordered list of zero or more SQL/JSON
items, called the SQL/JSON

elements of the SQL/JSON array.

d) An SQL/JSON object, defined as an unordered collection of zero or more
SQL/JSON members….

“

Our jsonb corresponds to SQL/JSON with UNIQUE KEYS and implicit ordering
of keys and our main intention was to provide support of jsonb as a most
important and usable data type.

We created repository for reviewing (ask for write access) -
https://github.com/postgrespro/sqljson/tree/sqljson

Examples of usage can be found in src/test/regress/sql/sql_json.sql

The whole documentation about json support should be reorganized and
added, and we plan to do this before release. We need help of community
here.

Our goal is to provide support of main features of SQL/JSON to release
10, as we discussed at developers meeting in Brussels (Andrew Dunstan has
kindly agreed to review the patch).

We had not much time to develop the complete support, because of standard
availability), but hope all major features are here, namely, all nine
functions as described in the standard (but see implementation notes below):

“All manipulation (e.g., retrieval, creation, testing) of SQL/JSON items
is performed through a number of SQL/JSON functions. There are nine such
functions, categorized as SQL/JSON retrieval functions and SQL/JSON
construction functions. The SQL/JSON retrieval functions are characterized
by operating on JSON data and returning an SQL value (possibly a Boolean
value) or a JSON value. The SQL/JSON construction functions return JSON
data created from operations on SQL data or other JSON data.

The SQL/JSON retrieval functions are:

— <JSON value function>: extracts an SQL value of a predefined type from
a JSON text.

— <JSON query>: extracts a JSON text from a JSON text.

— <JSON table>: converts a JSON text to an SQL table.

— <JSON predicate>: tests whether a string value is or is not properly
formed JSON text.

— <JSON exists predicate>: tests whether an SQL/JSON path expression
returns any SQL/JSON items.

The SQL/JSON construction functions are:

— <JSON object constructor>: generates a string that is a serialization
of an SQL/JSON object.

— <JSON array constructor>: generates a string that is a serialization of
an SQL/JSON array.

— <JSON object aggregate constructor>: generates, from an aggregation of
SQL data, a string that is a serialization

of an SQL/JSON object.

— <JSON array aggregate constructor>: generates, from an aggregation of
SQL data, a string that is a serialization

of an SQL/JSON array.

A JSON-returning function is an SQL/JSON construction function or
JSON_QUERY.”

The standard describes SQL/JSON path language, which used by SQL/JSON
query operators to query JSON. It defines path language as string literal.
We implemented the path language as JSONPATH data type, since other
approaches are not friendly to planner and executor.

The functions and JSONPATH provide a new functionality for json support,
namely, ability to operate (in standard specified way) with json structure
at SQL-language level - the often requested feature by the users.

The patch is consists of about 15000 insertions (about 5000 lines are
from tests), passes all regression tests and doesn’t touches critical
parts, so we hope with community help to bring it to committable state.

Authors: Nikita Glukhov, Teodor Sigaev, Oleg Bartunov and Alexander
Korotkov

Implementation notes:

1.

We didn’t implemented ‘datetime’ support, since it’s not clear from
standard.
2.

JSON_OBJECT/JSON_OBJECTAGG (KEY <key> VALUE <value>, ...) doesn’t
implemented, only (<key>:<value>, …) and (<key> VALUE <value>, …) are
supported, because of grammar conflicts with leading KEY keyword.
3.

FORMAT (JSON|JSONB)) in JSON_ARRAYAGG with subquery doesn’t
supported, because of grammar conflicts with non-reserved word FORMAT.
4.

JSONPATH implemented only for jsonb data type , so JSON_EXISTS(),
JSON_VALUE(), JSON_QUERY() and JSON_TABLE() doesn’t works if context item
is of json data type.
5.

Some methods and predicates for JSONPATH not yet implemented, for
example .type(), .size(), .keyvalue(), predicates like_regex, starts
with, etc. They are not key features and we plan to make them in next
release.
6.

JSONPATH doesn’t support expression for index array, like [2+3 to
$upperbound], only simple constants like [5, 7 to 12] are supported.
7.

JSONPATH extensions to standard: .** (wildcard path accessor), .key
(member accessor without leading @).
8.

FORMAT JSONB extension to standard for returning jsonb - standard
specifies possibility of returning custom type.
9.

JSON_EXISTS(), JSON_VALUE(), JSON_QUERY() are implemented using new
executor node JsonExpr.
10.

JSON_TABLE() is transformed into joined subselects with JSON_VALUE()
and JSON_QUERY() in target list.
11.

JSON_OBJECT(), JSON_ARRAY() constructors and IS JSON predicate are
transformed into raw function calls.
12.

Added explicit casts bytea=>jsonb and jsonb=>bytea (for jsonb=>bytea
output using RETURNING bytea FORMAT JSONB and corresponding bytea=>jsonb
input using <jsonb_bytea_expr> FORMAT JSONB).

Good work - it will be pretty big patch.

There is a intersection with implementation of XMLTABLE. I prepared a
executor infrastructure. So it can little bit reduce size of this patch.

we considered your XMLTABLE patch, but it's itself pretty big and in
unknown state.

Taking only Oracle as origin can be risk - in details Oracle doesn't
respects owns proposal to standard.

we used an original standard document ! I suggest Oracle to those, who
don't have access to standard. Yes, there are some problem in Oracle's
implementation.

This is last commitfest for current release cycle - are you sure, so is
good idea to push all mentioned features?

This would be a great feature for Release 10 and I understand all risks.
Hopefully, community will help us. We have resources to continue our work
and will do as much as possible to satisfy community requirements. It's not
our fault, that standard was released so late :)

Good work - it will be pretty big patch.

There is a intersection with implementation of XMLTABLE. I prepared a
executor infrastructure. So it can little bit reduce size of this patch.

we considered your XMLTABLE patch, but it's itself pretty big and in
unknown state.

It is big, but it is hard to expect so JSON_TABLE can be shorter if you are
solve all commiters requests.

Last patch should be near to final state.

Taking only Oracle as origin can be risk - in details Oracle doesn't
respects owns proposal to standard.

we used an original standard document ! I suggest Oracle to those, who
don't have access to standard. Yes, there are some problem in Oracle's
implementation.

This is last commitfest for current release cycle - are you sure, so is
good idea to push all mentioned features?

This would be a great feature for Release 10 and I understand all risks.
Hopefully, community will help us. We have resources to continue our work
and will do as much as possible to satisfy community requirements. It's not
our fault, that standard was released so late :)

It is not your fault. Ok, I am looking for patches.

Regards

Pavel

1.

Added explicit casts bytea=>jsonb and jsonb=>bytea (for jsonb=>bytea
output using RETURNING bytea FORMAT JSONB and corresponding bytea=>jsonb
input using <jsonb_bytea_expr> FORMAT JSONB).

This point has sense in Oracle, where JSON is blob. But it is little bit
obscure in PostgreSQL context.

Regards

Pavel

Hi Oleg,

On 2/28/17 2:55 PM, Pavel Stehule wrote:

2017-02-28 20:08 GMT+01:00 Oleg Bartunov <obartunov@gmail.com

Attached patch is an implementation of SQL/JSON data model from
SQL-2016 standard (ISO/IEC 9075-2:2016(E)), which was published
2016-12-15 and is available only for purchase from ISO web site
(https://www.iso.org/standard/63556.html
<https://www.iso.org/standard/63556.html&gt;). Unfortunately I didn't
find any public sources of the standard or any preview documents,
but Oracle implementation of json support in 12c release 2 is very
close
(http://docs.oracle.com/database/122/ADJSN/json-in-oracle-database.htm
<http://docs.oracle.com/database/122/ADJSN/json-in-oracle-database.htm&gt;),
also we used https://livesql.oracle.com/ to understand some details.

<...>

This is last commitfest for current release cycle - are you sure, so is
good idea to push all mentioned features?

Implementing standards is always a goal of the PostgreSQL community, but
this is a very large patch arriving very late in the release cycle with
no prior discussion.

That the patch proposed follows a standard which will not be available
to the majority of reviewers is very worrisome, let alone the sheer
size. While much of the code is new, I see many changes to core data
structures that could very easily be destabilizing.

I propose we move this patch to the 2017-07 CF so further development
and review can be done without haste and as the standard becomes more
accessible.

Regards,
--
-David
david@pgmasters.net

--
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2017-03-03 21:49 GMT+01:00 David Steele <david@pgmasters.net>:

Hi Oleg,

On 2/28/17 2:55 PM, Pavel Stehule wrote:

2017-02-28 20:08 GMT+01:00 Oleg Bartunov <obartunov@gmail.com

Attached patch is an implementation of SQL/JSON data model from
SQL-2016 standard (ISO/IEC 9075-2:2016(E)), which was published
2016-12-15 and is available only for purchase from ISO web site
(https://www.iso.org/standard/63556.html
<https://www.iso.org/standard/63556.html&gt;). Unfortunately I didn't
find any public sources of the standard or any preview documents,
but Oracle implementation of json support in 12c release 2 is very
close
(http://docs.oracle.com/database/122/ADJSN/json-in-

oracle-database.htm

<http://docs.oracle.com/database/122/ADJSN/json-in-

oracle-database.htm>),

also we used https://livesql.oracle.com/ to understand some

details.

<...>

This is last commitfest for current release cycle - are you sure, so is
good idea to push all mentioned features?

Implementing standards is always a goal of the PostgreSQL community, but
this is a very large patch arriving very late in the release cycle with
no prior discussion.

That the patch proposed follows a standard which will not be available
to the majority of reviewers is very worrisome, let alone the sheer
size. While much of the code is new, I see many changes to core data
structures that could very easily be destabilizing.

I propose we move this patch to the 2017-07 CF so further development
and review can be done without haste and as the standard becomes more
accessible.

Although I would to see these features in Postgres early I have same
feeling. Is it a question if some features can be implemented easy and can
be merged early?

The implementation of some JSON generation functions can be easy and the
verification should not be hard. Different situation is in JSON querying
functions. Merging JSONPath in first commitfest is better.

Regards

Pavel

On Fri, Mar 3, 2017 at 11:49 PM, David Steele <david@pgmasters.net> wrote:

Hi Oleg,

On 2/28/17 2:55 PM, Pavel Stehule wrote:

2017-02-28 20:08 GMT+01:00 Oleg Bartunov <obartunov@gmail.com

Attached patch is an implementation of SQL/JSON data model from
SQL-2016 standard (ISO/IEC 9075-2:2016(E)), which was published
2016-12-15 and is available only for purchase from ISO web site
(https://www.iso.org/standard/63556.html
<https://www.iso.org/standard/63556.html&gt;). Unfortunately I didn't
find any public sources of the standard or any preview documents,
but Oracle implementation of json support in 12c release 2 is very
close
(http://docs.oracle.com/database/122/ADJSN/json-in-

oracle-database.htm

<http://docs.oracle.com/database/122/ADJSN/json-in-

oracle-database.htm>),

also we used https://livesql.oracle.com/ to understand some

details.

<...>

This is last commitfest for current release cycle - are you sure, so is
good idea to push all mentioned features?

Implementing standards is always a goal of the PostgreSQL community, but
this is a very large patch arriving very late in the release cycle with
no prior discussion.

We discussed this in Brussels, but I agree, the patch is rather big.

That the patch proposed follows a standard which will not be available
to the majority of reviewers is very worrisome, let alone the sheer
size. While much of the code is new, I see many changes to core data
structures that could very easily be destabilizing.

I don't know when the standard will be publicly available.

I propose we move this patch to the 2017-07 CF so further development
and review can be done without haste and as the standard becomes more
accessible.

I wanted to have one more good feature in 10 and let postgres be on par
with other competitors. SQL/JSON adds many interesting features and users
will be dissapointed if we postpone it for next two years. Let's wait for
reviewers, probably they will find the patch is not very intrusive. We
have a plenty of time and we dedicate one full-time developer for this
project.

Hi,

On 2017-03-07 12:21:59 +0300, Oleg Bartunov wrote:

On 2017-03-03 15:49:38 -0500, David Steele wrote:

I propose we move this patch to the 2017-07 CF so further development
and review can be done without haste and as the standard becomes more
accessible.

+1

I wanted to have one more good feature in 10 and let postgres be on par
with other competitors. SQL/JSON adds many interesting features and users
will be dissapointed if we postpone it for next two years. Let's wait for
reviewers, probably they will find the patch is not very intrusive.

I think it's way too late to late for a patch of this size for 10. And I
don't think it's fair to a lot of other patches of significant size that
have been submitted way earlier, that also need reviewing resources, to
say that we can just see whether it'll get the required resources.

We have a plenty of time and we dedicate one full-time developer for
this project.

How about having that, and perhaps others, developer participate in
reviewing patches and getting to the bottom of the commitfest? Should
we end up being done early, we can look at this patch... There's not
been review activity corresponding to the amount of submissions from
pgpro...

- Andres

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Hi,

about the datetime issue: as far as I know, JSON does not define a
serialization format for dates and timestamps.

On the other hand, YAML (as a superset of JSON) already supports a
language-independent date(time) serialization format
(http://yaml.org/type/timestamp.html).

I haven't had a glance into the SQL/JSON standard yet and a quick search
didn't reveal anything. However, reading your test case here
https://github.com/postgrespro/sqljson/blob/5a8a241/src/test/regress/sql/sql_json.sql#L411
it seems as if you intend to parse all strings in the form of
"YYYY-MM-DD" as dates. This is problematic in case a string happens to
look like this but is not intended to be a date.

Just for the sake of completeness: YAML solves this issue by omitting
the quotation marks around the date string (just as JSON integers have
no quotations marks around them).

Regards,
Sven

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On 3/7/17 11:38 AM, Andres Freund wrote:

<...>

We have a plenty of time and we dedicate one full-time developer for
this project.

How about having that, and perhaps others, developer participate in
reviewing patches and getting to the bottom of the commitfest? Should
we end up being done early, we can look at this patch... There's not
been review activity corresponding to the amount of submissions from
pgpro...

This patch has been moved to CF 2017-07.

--
-David
david@pgmasters.net

--
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On Wed, Mar 8, 2017 at 12:43 AM, Sven R. Kunze <srkunze@mail.de> wrote:

Hi,

about the datetime issue: as far as I know, JSON does not define a
serialization format for dates and timestamps.

On the other hand, YAML (as a superset of JSON) already supports a
language-independent date(time) serialization format (
http://yaml.org/type/timestamp.html).

I haven't had a glance into the SQL/JSON standard yet and a quick search
didn't reveal anything. However, reading your test case here
https://github.com/postgrespro/sqljson/blob/5a8a241/src/
test/regress/sql/sql_json.sql#L411 it seems as if you intend to parse all
strings in the form of "YYYY-MM-DD" as dates. This is problematic in case a
string happens to look like this but is not intended to be a date.

SQL/JSON defines methods in jsonpath, in particularly,

| datetime <left paren> [ <JSON datetime template> ] <right paren>
| keyvalue <left paren> <right paren>

<JSON datetime template> ::=
<JSON path string literal>

datetime template is also specified in the standard (very rich)

<datetime template> ::=
{ <datetime template part> }...
<datetime template part> ::=
<datetime template field>
| <datetime template delimiter>
<datetime template field> ::=
<datetime template year>
| <datetime template rounded year>
| <datetime template month>
| <datetime template day of month>
| <datetime template day of year>
| <datetime template 12-hour>
| <datetime template 24-hour>
| <datetime template minute>
| <datetime template second of minute>
| <datetime template second of day>
| <datetime template fraction>
| <datetime template am/pm>
| <datetime template time zone hour>
| <datetime template time zone minute>
<datetime template delimiter> ::=
<minus sign>
| <period>
| <solidus>
| <comma>
| <apostrophe>
| <semicolon>
| <colon>
| <space>
<datetime template year> ::=
YYYY | YYY | YY | Y
<datetime template rounded year> ::=
RRRR | RR
<datetime template month> ::=
MM
<datetime template day of month> ::=
DD
<datetime template day of year> ::=
DDD
<datetime template 12-hour> ::=
HH | HH12
<datetime template 24-hour> ::=
HH24
<datetime template minute> ::=
MI
<datetime template second of minute> ::=
SS
<datetime template second of day> ::=
SSSSS
<datetime template fraction> ::=
FF1 | FF2 | FF3 | FF4 | FF5 | FF6 | FF7 | FF8 | FF9
<datetime template am/pm> ::=
A.M. | P.M.
<datetime template time zone hour> ::=
TZH
<datetime template time zone minute> ::=
TZM

Just for the sake of completeness: YAML solves this issue by omitting the
quotation marks around the date string (just as JSON integers have no
quotations marks around them).

interesting idea, but need to dig the standard first.

On Wed, Mar 8, 2017 at 7:05 AM, David Steele <david@pgmasters.net> wrote:

On 3/7/17 11:38 AM, Andres Freund wrote:

<...>

We have a plenty of time and we dedicate one full-time developer for

this project.

How about having that, and perhaps others, developer participate in
reviewing patches and getting to the bottom of the commitfest? Should
we end up being done early, we can look at this patch... There's not
been review activity corresponding to the amount of submissions from
pgpro...

This patch has been moved to CF 2017-07.

Yes, after committing XMLTABLE, we anyway need to extend its infrastructure
to support JSON_TABLE.

Small point of order: YAML is not strictly a super-set of JSON.

Editorializing slightly, I have not seen much interest in the world for
YAML support though I'd be interested in evidence to the contrary.

On Tue, Mar 7, 2017 at 1:43 PM, Sven R. Kunze <srkunze@mail.de> wrote:

Hi,

about the datetime issue: as far as I know, JSON does not define a
serialization format for dates and timestamps.

On the other hand, YAML (as a superset of JSON) already supports a
language-independent date(time) serialization format (
http://yaml.org/type/timestamp.html).

I haven't had a glance into the SQL/JSON standard yet and a quick search
didn't reveal anything. However, reading your test case here
https://github.com/postgrespro/sqljson/blob/5a8a241/src/
test/regress/sql/sql_json.sql#L411 it seems as if you intend to parse all
strings in the form of "YYYY-MM-DD" as dates. This is problematic in case a
string happens to look like this but is not intended to be a date.

Just for the sake of completeness: YAML solves this issue by omitting the
quotation marks around the date string (just as JSON integers have no
quotations marks around them).

Regards,
Sven

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Peter van Hardenberg
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"Everything was beautiful, and nothing hurt."—Kurt Vonnegut

On Wed, Mar 8, 2017 at 11:48 AM, Peter van Hardenberg <pvh@pvh.ca> wrote:

Small point of order: YAML is not strictly a super-set of JSON.

Editorializing slightly, I have not seen much interest in the world for
YAML support though I'd be interested in evidence to the contrary.

The world of configuration management seems to for some reason run off
YAML, but that's the only places I've seen it recently (ansible, puppet
etc).

That said if we're introducing something new, it's usually better to copy
from another format than to invite your own.

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Work: http://www.redpill-linpro.com/

On Tue, Mar 7, 2017 at 2:38 PM, Andres Freund <andres@anarazel.de> wrote:

On 2017-03-07 12:21:59 +0300, Oleg Bartunov wrote:

On 2017-03-03 15:49:38 -0500, David Steele wrote:

I propose we move this patch to the 2017-07 CF so further development
and review can be done without haste and as the standard becomes more
accessible.

+1

I agree that this should not go into v10. February 28th is not the
right time for a large, never-before-seen patch to show up with
expectations of getting committed for the current cycle.

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On 08.03.2017 20:48, Peter van Hardenberg wrote:

Small point of order: YAML is not strictly a super-set of JSON.

I haven't read the whole standard, but from what I can see the standard
considers JSON an official subset of itself:
http://www.yaml.org/spec/1.2/spec.html

Regards,
Sven

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On Thu, Mar 9, 2017 at 12:48 PM, Sven R. Kunze <srkunze@mail.de> wrote:

On 08.03.2017 20:48, Peter van Hardenberg wrote:

Small point of order: YAML is not strictly a super-set of JSON.

I haven't read the whole standard, but from what I can see the standard
considers JSON an official subset of itself:
http://www.yaml.org/spec/1.2/spec.html

But there's apparent sophistry, like this, in that spec:

SON's RFC4627 requires that mappings keys merely “SHOULD” be unique,
while YAML insists they “MUST” be. Technically, YAML therefore
complies with the JSON spec, choosing to treat duplicates as an error.
In practice, since JSON is silent on the semantics of such duplicates,
the only portable JSON files are those with unique keys, which are
therefore valid YAML files.

I don't see how YAML can impose a stronger requirement than JSON and
yet claim to be a superset; a JSON document that doesn't meet that
requirement will be legal (if stupid) as JSON but illegal as YAML.

Also, even if the superset thing were true on a theoretical plane, I'm
not sure it would do us much good in practice. If we start using
YAML-specific constructs, we won't have valid JSON any more. If we
use only things that are legal in JSON, YAML's irrelevant.

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On 08.03.2017 20:52, Magnus Hagander wrote:

On Wed, Mar 8, 2017 at 11:48 AM, Peter van Hardenberg <pvh@pvh.ca
<mailto:pvh@pvh.ca>> wrote:

Small point of order: YAML is not strictly a super-set of JSON.

Editorializing slightly, I have not seen much interest in the
world for YAML support though I'd be interested in evidence to the
contrary.

The world of configuration management seems to for some reason run off
YAML, but that's the only places I've seen it recently (ansible,
puppet etc).

SaltStack uses YAML for their tools, too. I personally can empathize
with them (as a user of configuration management) about this as writing
JSON would be nightmare with all the quoting, commas, curly braces etc.
But that's my own preference maybe.

(Btw. does "run off" mean like or avoid? At least my dictionaries tend
to the latter.)

That said if we're introducing something new, it's usually better to
copy from another format than to invite your own.

From my day-to-day work I can tell, the date(time) type is the only
missing piece of JSON to make it perfect for business applications
(besides, maybe, a "currency" type).

Regards,
Sven

On 09.03.2017 18:58, Robert Haas wrote:

Also, even if the superset thing were true on a theoretical plane, I'm
not sure it would do us much good in practice. If we start using
YAML-specific constructs, we won't have valid JSON any more. If we
use only things that are legal in JSON, YAML's irrelevant.

That's true. I just wanted to share my view of the "date guessing" part
of pgpro's commits.
I don't have a good solution for it either, I can only tell that where I
work we do have same issues: either we guess by looking at the string
value or we know that "this particular key" must be a date.
Unsatisfied with either solution, we tend to use YAML for our APIs if
possible.

Regards,
Sven

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