Is there any way to write this code avoiding intermediate steps/views in PostgreSQL coming from different tables? - postgresql

Question

I am working in a large query I would like to eliminate intermediate
steps, so I am trying to write the two queries below in just one.
The first query (QUERY 1) select the grid id from a table called
tiles, from here i obtained an UUID who correspond to a value in a
second table so to obtain the real value of this grid id I have to
query a second query (QUERY 2). I have try to cast everything as I did
in the third query for other values, but this approach doesn't work.
Has someone an idea how can I manage to do this query (query 1 and 2)
just in one:
QUERY 1:
SELECT
jsonb_array_elements(grid_id_tile.tiledata -> '34cfea5d-c2c0-11ea-9026-02e7594ce0a0'::text) ->> 'resourceId'::text AS grid_id
FROM mv_geojson_geoms mv
LEFT JOIN tiles grid_id_tile ON tv1.resourceinstanceid = grid_id_tile.resourceinstanceid
WHERE (( SELECT resource_instances.graphid
FROM resource_instances
WHERE mv.resourceinstanceid = resource_instances.resourceinstanceid)) = '34cfe98e-c2c0-11ea-9026-02e7594ce0a0'::uuid;
QUERY 2:
SELECT grid_id.legacyid AS grid_id,
FROM table 1 (Where I have obtained the grid id)
LEFT JOIN resource_instances grid_id ON hb1.grid_id = grid_id.resourceinstanceid::text
QUERY 3:
( SELECT "values".value
FROM "values"
WHERE ((name_ft_tile.tiledata ->> '34cfea97-c2c0-11ea-9026-02e7594ce0a0'::text)::uuid) = "values".valueid) AS nametype,
FROM mv_geojson_geoms mv
LEFT JOIN tiles name_ft_tile ON mv.resourceinstanceid = name_ft_tile.resourceinstanceid AND (name_ft_tile.tiledata ->> '34cfea97-c2c0-11ea-9026-02e7594ce0a0'::text) <> ''::text
WHERE (( SELECT resource_instances.graphid
FROM resource_instances
WHERE mv.resourceinstanceid = resource_instances.resourceinstanceid)) = '34cfe98e-c2c0-11ea-9026-02e7594ce0a0'::uuid
Those are the type of data I am managing at the moment:
This is the table tiles where in the jsonb got the UUID from the feature i would like to get the gridid
This is the table resource instance where the legacyid is
So from the query 1 I get this result Gridid is a UUID
And from query 2 I get this result with the grid_id code
This is what I obtain and I would like to get directly the grid_id value without intermediate steps
The third query is a sample of similar approach I did so in one query I get the value instead of the UUID, and it is what I would like to do with the grid_id.
But when I run the similar code I get the error, because I get the element from an array:
ERROR: cannot extract elements from a scalar
CONTEXT: parallel worker
SQL state: 22023

Answer 1

You can literally inline the query 1 as a subquery where you've written "table 1 (Where I have obtained the grid id)":
SELECT grid_id.legacyid AS grid_id
FROM (
SELECT jsonb_array_elements(grid_id_tile.tiledata -> '34cfea5d-c2c0-11ea-9026-02e7594ce0a0'::text) ->> 'resourceId'::text AS grid_id
FROM mv_geojson_geoms mv
LEFT JOIN tiles grid_id_tile ON mv.resourceinstanceid = grid_id_tile.resourceinstanceid
JOIN resource_instances ON mv.resourceinstanceid = resource_instances.resourceinstanceid
WHERE resource_instances.graphid = '34cfe98e-c2c0-11ea-9026-02e7594ce0a0'::uuid;
) AS hb1
LEFT JOIN resource_instances grid_id ON hb1.grid_id = grid_id.resourceinstanceid::text;