Postgresql: Check if Schema Exists?

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星月不相逢 2021-02-01 12:24

I need to create, manage and drop schemas on the fly. If I go to create a schema that already exists, I want to (conditionally, via external means) drop and recreate it as speci

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  • 2021-02-01 12:28

    The following query will tell you whether a schema exists.

    SELECT schema_name FROM information_schema.schemata WHERE schema_name = 'name';
    
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  • 2021-02-01 12:28

    This one worked for me (Postgres 9.3):

    Select exists (SELECT 1 FROM information_schema.schemata where catalog_name = 'My_BD_with_UpperCase_characters_in_its_Name')
    
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  • 2021-02-01 12:31

    If you are a total purist or you want to gain some milisecs. I recommend you to make use of postgres native system catalog. One can avoid then nested loop which is caused by calling pg_catalog anyway...

    SELECT EXISTS(SELECT 1 FROM information_schema.schemata 
                  WHERE schema_name = 'name');
    

    querying information_schema

    If you querying pg_namespace directly:

    SELECT EXISTS(SELECT 1 FROM pg_namespace WHERE nspname = 'name');
    

    Planer's work is much simpler:

    enter image description here

    So your own solution was the best.

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  • 2021-02-01 12:32

    Somewhat related and perhaps of interest to others looking for conditional schema creation. I found myself using code like this in some of my creation scripts:

    DO $$
    BEGIN
    
        IF NOT EXISTS(
            SELECT schema_name
              FROM information_schema.schemata
              WHERE schema_name = 'pgcrypto'
          )
        THEN
          EXECUTE 'CREATE SCHEMA pgcrypto';
        END IF;
    
    END
    $$;
    
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  • 2021-02-01 12:37

    NONE of those will work if you have objects (tables,sprocs,views) within a particular schema - IT WILL FAIL during DROP...

    CREATE & MANAGE is the easy part.. It's the drop that will get you.. Anyways, I couldn't find a suitable answer, so I posted here for others..

    SEE LINK HERE: http://social.msdn.microsoft.com/Forums/en-US/transactsql/thread/4753d1b8-f547-44c6-b205-aa2dc22606ba/#6eb8238a-305e-40d5-858e-0fbd70454810

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  • 2021-02-01 12:39

    This can be one of the approaches. Drop the schema first and then create it.

    IF EXISTS:
    Do not throw an error if the schema does not exist. A notice is issued in this case.
    

    So,

    DROP SCHEMA IF EXISTS schema_Name
    Create SCHEMA schema_Name
    
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