I don't think it's SQL Standard, but essentially it takes a text value containing JSON data (one record or an array) and converts it into a relational table:
https://docs.oracle.com/database/121/SQLRF/functions092.htm I've managed to get most of this working, now I seem to be failing to put the syntax together correctly for the query I currently have: - A UDF ("HTTP_GET") which can make HTTP calls and return the data as a String - A table type for Collection<Map<String, Object>> ("MapCollectionTable") - A TableFunctionImpl ("JsonTableFunction"), which takes a JSON string, reads it with Jackson, and converts it into a "MapCollectionTable" The following work: SELECT HTTP_GET('https://jsonplaceholder.typicode.com/posts') SELECT * FROM TABLE( JSON_TABLE('[{ "id": "1", "name": "foo" }, { "id": "2", "name": "bar" }]')) But trying to combine them fails =/ SELECT * FROM TABLE( JSON_TABLE(HTTP_GET('https://jsonplaceholder.typicode.com/posts'))) The TableFunctionImpl is receiving "null" for the JSON value I guess it's maybe expecting static data? Calcite JSON_TABLE wip 2 (github.com) <https://gist.github.com/GavinRay97/fbd16dd2b893cb59c720e6d514c5e39a#file-main-java> On Tue, May 31, 2022 at 2:44 PM Julian Hyde <[email protected]> wrote: > What is JSON_TABLE? Is it in the SQL standard? Can you give a simple > example? > > On Tue, May 31, 2022 at 10:03 AM Gavin Ray <[email protected]> wrote: > > > > I dug up some examples from Github of using the "TableFunctionImpl" > class: > > > > mat-calcite-plugin/TableFunctions.java at > > a57a5ba80768066714c22bd9e8a9b529d4cb9a6b · vlsi/mat-calcite-plugin > > (github.com) > > < > https://github.com/vlsi/mat-calcite-plugin/blob/a57a5ba80768066714c22bd9e8a9b529d4cb9a6b/MatCalcitePlugin/src/com/github/vlsi/mat/calcite/functions/TableFunctions.java > > > > Calcite_sql_driver/MazeTable.java at > > 6819088123e67631367ca927b112b58e4eb90829 · dream001/Calcite_sql_driver > > (github.com) > > < > https://github.com/dream001/Calcite_sql_driver/blob/6819088123e67631367ca927b112b58e4eb90829/src/test/java/com/yonyou/calcite/MazeTable.java > > > > > > Currently trying to get a TableFunction that just returns a Map<String, > > Object> as a relation to work > > Have the below -- calling this shows that the function IS invoked, but > the > > data it gives back is garbage: > > > > Calcite JSON_TABLE WIP (github.com) > > <https://gist.github.com/GavinRay97/b42c69992a0d0c3a01f1c7e1b9ab1999> > > > > This is the output of main() > > > > json = {"id":1, "name":"John"} > > json = {"id":1, "name":"John"} > > json = {"id":1, "name":"John"} > > EXPR$0: id > > EXPR$0: id > > > > I'm doing something wrong here for sure, lol. > > > > > > On Tue, May 31, 2022 at 11:35 AM Gavin Ray <[email protected]> > wrote: > > > > > I'm interested in implementing JSON_TABLE functionality for Calcite > > > > > > This opens up some neat usecases, like adding HTTP request UDF's > > > then using JSON_TABLE to convert the result into a table: > > > > > > SELECT JSON_TABLE( > > > HTTP_GET('http://localhost:8080/api/v1/users/1')) > > > > > > Adding support for all of the functionality seems difficult, > > > but I'm wondering whether this could be done as a "SqlTableFunction" > UDF? > > > > > > I'm thinking it might be possible if the JSON_TABLE udf > > > expects Map<String, Object> and does inference based on that? > > > > > > Something like: > > > > > > WITH users AS ( > > > SELECT HTTP_GET('http://localhost:8080/api/v1/users') > > > ) SELECT > > > id, > > > name > > > FROM > > > JSON_TABLE(JSON_PATH(users, "$.0")) > > > > > > Does anyone have ideas or see issues with this approach? > > > Thank you =) > > > > > > > > > > > > >
