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JSON_TABLE: Add support for NESTED paths and columns

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A NESTED path allows to extract data from nested levels of JSON
objects given by the parent path expression, which are projected as
columns specified using a nested COLUMNS clause, just like the parent
COLUMNS clause.  Rows comprised from a NESTED columns are "joined"
to the row comprised from the parent columns.  If a particular NESTED
path evaluates to 0 rows, then the nested COLUMNS will emit NULLs,
making it an OUTER join.

NESTED columns themselves may include NESTED paths to allow
extracting data from arbitrary nesting levels, which are likewise
joined against the rows at the parent level.

Multiple NESTED paths at a given level are called "sibling" paths
and their rows are combined by UNIONing them, that is, after being
joined against the parent row as described above.

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: 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

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+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
This commit is contained in:
Amit Langote
2024-04-08 15:58:58 +09:00
parent f6a2529920
commit bb766cde63
17 changed files with 1209 additions and 33 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.c
View File

@@ -132,11 +132,21 @@ if (sqlca.sqlcode < 0) sqlprint();}
printf("Found foo=%d\n", foo);
{ ECPGdisconnect(__LINE__, "CURRENT");
#line 26 "sqljson_jsontable.pgc"
{ ECPGdo(__LINE__, 0, 1, NULL, 0, ECPGst_normal, "select foo from json_table ( jsonb '[{\"foo\":\"1\"}]' , '$[*]' as p0 columns ( nested '$' as p1 columns ( nested path '$' as p11 columns ( foo int ) ) ) ) jt ( foo )", ECPGt_EOIT,
ECPGt_int,&(foo),(long)1,(long)1,sizeof(int),
ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EORT);
#line 31 "sqljson_jsontable.pgc"
if (sqlca.sqlcode < 0) sqlprint();}
#line 26 "sqljson_jsontable.pgc"
#line 31 "sqljson_jsontable.pgc"
printf("Found foo=%d\n", foo);
{ ECPGdisconnect(__LINE__, "CURRENT");
#line 34 "sqljson_jsontable.pgc"
if (sqlca.sqlcode < 0) sqlprint();}
#line 34 "sqljson_jsontable.pgc"
return 0;

8
src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.stderr
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@@ -12,5 +12,13 @@
[NO_PID]: sqlca: code: 0, state: 00000
[NO_PID]: ecpg_get_data on line 20: RESULT: 1 offset: -1; array: no
[NO_PID]: sqlca: code: 0, state: 00000
[NO_PID]: ecpg_execute on line 26: query: select foo from json_table ( jsonb '[{"foo":"1"}]' , '$[*]' as p0 columns ( nested '$' as p1 columns ( nested path '$' as p11 columns ( foo int ) ) ) ) jt ( foo ); with 0 parameter(s) on connection ecpg1_regression
[NO_PID]: sqlca: code: 0, state: 00000
[NO_PID]: ecpg_execute on line 26: using PQexec
[NO_PID]: sqlca: code: 0, state: 00000
[NO_PID]: ecpg_process_output on line 26: correctly got 1 tuples with 1 fields
[NO_PID]: sqlca: code: 0, state: 00000
[NO_PID]: ecpg_get_data on line 26: RESULT: 1 offset: -1; array: no
[NO_PID]: sqlca: code: 0, state: 00000
[NO_PID]: ecpg_finish: connection ecpg1_regression closed
[NO_PID]: sqlca: code: 0, state: 00000

1
src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.stdout
View File

@@ -1 +1,2 @@
Found foo=1
Found foo=1

8
src/interfaces/ecpg/test/sql/sqljson_jsontable.pgc
View File

@@ -23,6 +23,14 @@ EXEC SQL END DECLARE SECTION;
)) jt (foo);
printf("Found foo=%d\n", foo);
EXEC SQL SELECT foo INTO :foo FROM JSON_TABLE(jsonb '[{"foo":"1"}]', '$[*]' AS p0
COLUMNS (
NESTED '$' AS p1 COLUMNS (
NESTED PATH '$' AS p11 COLUMNS ( foo int )
)
)) jt (foo);
printf("Found foo=%d\n", foo);
EXEC SQL DISCONNECT;
return 0;