Why would postgres views not be visible to PGadmin browser, Psycopg2? - postgresql

Question

I've created some views in my postgres database. I know they're there, because I can query them through the query tool in PGAdmin4 (and they are persistent between restarting the machine hosting the database), but they are neither visible in the schema browser nor queryable through psycopg2.
For larger context, I'm trying to extract some text from a large collection of documents which are stored in a database. (The database is a copy of the data received from a third party, and fully normalized, etc.) I'd like to do my NLP nonsense in Python, while defining a lot of document categorizations through SQL views so the categorizations are consistent, persistent, and broadly shareable to my team.
Googling has not turned up anything relevant here, so I'm wondering if there is a basic configuration issue that I've missed. (I am much more experienced with SQLServer than with postgres.)
Example:
[Assume I'm connected to database DB, schema SC, which has tables T1, T2, T3.]
-- in PGAdmin4 window
CREATE VIEW v_my_view as
SELECT T1.field1, T2.field2
FROM T1
JOIN T2
on T1.field3 = T2.field3
Restart host machine (so definitely new PGAdmin session), the following works:
-- in pgadmin4 window
SELECT *
FROM v_my_view
-- 123456 results returned
...but even though that works, in the pgadmin4 browser panel, the 'views' folder is empty (right underneath the tables folder that proudly shows T1 and T2).
Within psycopg2:
import psycopg2
import pandas as pd
sqluser = 'me'
sqlpwd = 'secret'
dbname = 'DB'
schema_name = 'SC'
pghost = 'localhost'
def q(query):
cnxn = psycopg2.connect(dbname=dbname, user=sqluser, password=sqlpwd, host=pghost)
cursor = cnxn.cursor()
cursor.execute('SET search_path to ' + schema_name)
return pd.read_sql_query(query, cnxn)
view_query = """select *
from v_my_view
limit 100;"""
table_query = """select *
from SC.T1
limit 100;"""
# This works
print(f"Result: {q(table_query)}")
# This does not; error is: relation 'v_my_view' does not exist
# (Same result if view is prefixed with schema name)
# print(f"Result: {q(view_query)}")
Software versions:
pgadmin 4.23
postgres: I'm connected to 10.13 (Ubuntu 10.13-1-pgdg18.04+1), though 12
is also installed.
psycopg2: 2.8.5

Answer 1

Turns out this was a noob mistake. Views are created to the first schema of the search path (which can be checked by executing show search_path;, which in my case was set to "$user", public despite attempting to set it to the appropriate schema name). So the views were getting created against a different schema from the one I was working with/where the tables were defined.
Created views are all visible in the left-hand browser once I look under the correct schema.
The following modification to the psycopg2 code returns the expected results:
import psycopg2
import pandas as pd
sqluser = 'me'
sqlpwd = 'secret'
dbname = 'DB'
schema_name = 'SC'
pghost = 'localhost'
def q(query):
cnxn = psycopg2.connect(dbname=dbname, user=sqluser, password=sqlpwd, host=pghost)
cursor = cnxn.cursor()
cursor.execute('SET search_path to ' + schema_name)
return pd.read_sql_query(query, cnxn)
# NOTE I am explicitly indicating the 'public' schema here
view_query = """select *
from public.v_my_view
limit 100;"""
table_query = """select *
from SC.T1
limit 100;"""
# This works
print(f"Result: {q(table_query)}")
# This works too once I specify the right schema:
print(f"Result: {q(view_query)}")

Answer 2

Try refresh Object on the PGAdmin toolbar. This should refresh the view.
Thanks
Amar