perf: use LATERAL instead of CTE for json body

* add pgbench test for INSERT and RPC
* use LATERAL for RPC and INSERT
* add tests for inlining

test/pgbench/1652/new.sql

@@ -0,0 +1,20 @@
+WITH pgrst_source AS (
+  SELECT pgrst_call.*
+  FROM (
+    SELECT '{"id": 4}'::json as json_data
+  ) pgrst_payload,
+  LATERAL (
+    SELECT CASE WHEN json_typeof(pgrst_payload.json_data) = 'array' THEN pgrst_payload.json_data ELSE json_build_array(pgrst_payload.json_data) END AS val
+  ) pgrst_uniform_json,
+  LATERAL (
+    SELECT * FROM json_to_recordset(pgrst_uniform_json.val) AS _("id" integer) LIMIT 1
+  ) pgrst_body,
+  LATERAL "test"."get_projects_below"("id" := pgrst_body.id) pgrst_call
+)
+SELECT
+  null::bigint AS total_result_set,
+  pg_catalog.count(_postgrest_t) AS page_total,
+  coalesce(json_agg(_postgrest_t), '[]')::character varying AS body,
+  nullif(current_setting('response.headers', true), '') AS response_headers,
+  nullif(current_setting('response.status', true), '') AS response_status
+FROM (SELECT "projects".* FROM "pgrst_source" AS "projects") _postgrest_t;

test/pgbench/1652/old.sql

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+WITH pgrst_source AS (
+  WITH
+  pgrst_payload AS (SELECT '{"id": 4}'::json AS json_data),
+  pgrst_body AS ( SELECT CASE WHEN json_typeof(json_data) = 'array' THEN json_data ELSE json_build_array(json_data) END AS val FROM pgrst_payload),
+  pgrst_args AS ( SELECT * FROM json_to_recordset((SELECT val FROM pgrst_body)) AS _("id" integer) )
+  SELECT "get_projects_below".*
+  FROM "test"."get_projects_below"("id" := (SELECT "id" FROM pgrst_args LIMIT 1))
+)
+SELECT
+  null::bigint AS total_result_set,
+  pg_catalog.count(_postgrest_t) AS page_total,
+  coalesce(json_agg(_postgrest_t), '[]')::character varying AS body,
+  nullif(current_setting('response.headers', true), '') AS response_headers,
+  nullif(current_setting('response.status', true), '') AS response_status
+FROM (SELECT "projects".* FROM "pgrst_source" AS "projects") _postgrest_t;

test/pgbench/2677/new.sql

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+INSERT INTO "test"."complex_items"("arr_data", "field-with_sep", "id", "name")
+SELECT pgrst_body."arr_data", pgrst_body."field-with_sep", pgrst_body."id", pgrst_body."name"
+FROM (
+  SELECT '[{"id": 4, "name": "Vier"}, {"id": 5, "name": "Funf", "arr_data": null}, {"id": 6, "name": "Sechs", "arr_data": [1, 2, 3], "field-with_sep": 6}]'::json as json_data
+) pgrst_payload,
+LATERAL (
+  SELECT CASE WHEN json_typeof(pgrst_payload.json_data) = 'array' THEN pgrst_payload.json_data ELSE json_build_array(pgrst_payload.json_data) END AS val
+) pgrst_uniform_json,
+LATERAL (
+  SELECT * FROM json_to_recordset (pgrst_uniform_json.val) AS _ ("arr_data" integer[], "field-with_sep" integer, "id" bigint, "name" text)
+) pgrst_body
+RETURNING "test"."complex_items".*

test/pgbench/2677/old.sql

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+WITH
+pgrst_payload AS (SELECT '[{"id": 4, "name": "Vier"}, {"id": 5, "name": "Funf", "arr_data": null}, {"id": 6, "name": "Sechs", "arr_data": [1, 2, 3], "field-with_sep": 6}]'::json AS json_data),
+pgrst_body AS ( SELECT CASE WHEN json_typeof(json_data) = 'array' THEN json_data ELSE json_build_array(json_data) END AS val FROM pgrst_payload)
+INSERT INTO "test"."complex_items"("arr_data", "field-with_sep", "id", "name")
+SELECT "arr_data", "field-with_sep", "id", "name"
+FROM json_to_recordset ((SELECT val FROM pgrst_body)) AS _ ("arr_data" integer[], "field-with_sep" integer, "id" bigint, "name" text)
+RETURNING "test"."complex_items".*

test/pgbench/README.md

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+## pgbench tests
+
+Can be used as:
+
+```
+postgrest-with-postgresql-15 -f test/pgbench/fixtures.sql pgbench -n -T 10 -f test/pgbench/2677/old.sql
+postgrest-with-postgresql-15 -f test/pgbench/fixtures.sql pgbench -n -T 10 -f test/pgbench/2677/new.sql
+```

test/pgbench/fixtures.sql

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+\ir ../spec/fixtures/load.sql
+
+ALTER TABLE test.complex_items
+    DROP CONSTRAINT complex_items_pkey;
+
+ALTER TABLE test.complex_items
+    ALTER COLUMN "field-with_sep" DROP NOT NULL;