add: typing for key deps

Author: steve-chavez

.gitignore

@@ -9,4 +9,3 @@ pgbench_log.*
 .history
 tags
 pgrst_schema_cache--*.sql
-!pgrst_schema_cache--*--*.sql

sql/pgrst_schema_cache.sql

@@ -44,12 +44,47 @@ where traint.contype = 'f'
 and traint.conparentid = 0
 order by traint.conrelid, traint.conname;
 
+
 -- type for the array of (column_name, view_columns[]), otherwise the creation of the function would fail
 CREATE TYPE col_dep AS (
   col          text,
   view_columns text[]
 );
 
+CREATE TYPE key_dep_type AS enum(
+  'p',     -- pk dependency
+  'f_ref', -- fk dependency
+  'f'      -- fk reference dependency
+);
+
+-- | A view foreign key or primary key dependency detected on its source table
+-- Each column of the key could be referenced multiple times in the view, e.g.
+--
+-- create view projects_view as
+-- select
+--   id as id_1,
+--   id as id_2,
+--   id as id_3,
+--   name
+-- from projects
+--
+-- In this case, the keyDepCols mapping maps projects.id to all three of the columns:
+--
+-- [('id', ['id_1', 'id_2', 'id_3'])]
+--
+-- Depending on key type, we can then choose how to handle this case. Primary keys
+-- can arbitrarily choose one of the columns, but for foreign keys we need to create
+-- relationships for each possible combinations.
+CREATE TYPE view_key_dependency AS (
+  table_schema        text,
+  table_name          text,
+  view_schema         text,
+  view_name           text,
+  constraint_name     text,
+  key_dep             key_dep_type,
+  column_dependencies col_dep[]
+);
+
 -- Same query as PostgREST's allViewsKeyDependencies
 --  Returns all the views' primary keys and foreign keys dependencies
 -- query explanation at:
@@ -58,16 +93,8 @@ CREATE TYPE col_dep AS (
 create or replace function all_views_key_dependencies
 ( db_schemas           regnamespace[] default '{public}'
 , db_extra_search_path regnamespace[] default '{public}'
-)
-returns table (
-  table_schema      text,
-  table_name        text,
-  view_schema       text,
-  view_name         text,
-  constraint_name   text,
-  constraint_type   text,
-  column_dependencies col_dep[]    -- array of (col, view_columns[])
-) as $func$
+) returns setof view_key_dependency as $$
+
 with recursive
 pks_fks as (
   -- pk + fk referencing col
@@ -247,7 +274,7 @@ select
   rep.view_schema,
   rep.view_name,
   pks_fks.conname as constraint_name,
-  pks_fks.contype as constraint_type,
+  pks_fks.contype::key_dep_type as constraint_type,
   array_agg(row(col.attname, view_columns)::col_dep order by pks_fks.ord) as column_dependencies
 from repeated_references rep
 join pks_fks using (resorigtbl, resorigcol)
@@ -257,5 +284,5 @@ join pg_namespace sch on sch.oid = tbl.relnamespace
 group by sch.nspname, tbl.relname, rep.view_schema, rep.view_name, pks_fks.conname, pks_fks.contype, pks_fks.ncol
 -- make sure we only return key for which all columns are referenced in the view - no partial PKs or FKs
 having ncol = array_length(array_agg(row(col.attname, view_columns) order by pks_fks.ord), 1)
-$func$
-language sql stable;
+
+$$ language sql stable;