Message-ID: <gh-pgjdbc-pgjdbc-538-c1346193264@github.com>
From: "lukaseder (@lukaseder)" <noreply+lukaseder@github.com>
To: "pgjdbc/pgjdbc" <noreply+pgjdbc-pgjdbc@github.com>
Date: Mon, 12 Dec 2022 09:57:27 +0000
Subject: Re: [pgjdbc/pgjdbc] issue #538: Why getSchemaName return empty string or exists getBaseSchemaName and getColumnName return getColumnLabel?
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I wonder if this could be implemented relatively easily by now? It was implemented for `PgResultSetMetaData::getTableName`, in case of which a query like this one is issued:

```sql
SELECT
  c.oid,
  a.attnum,
  a.attname,
  c.relname,
  n.nspname,
  a.attnotnull OR (t.typtype = 'd' AND t.typnotnull),
  a.attidentity != '' OR pg_catalog.pg_get_expr(d.adbin, d.adrelid) LIKE '%nextval(%'
FROM
  pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON
  (c.relnamespace = n.oid)
JOIN pg_catalog.pg_attribute a ON
  (c.oid = a.attrelid)
JOIN pg_catalog.pg_type t ON
  (a.atttypid = t.oid)
LEFT JOIN pg_catalog.pg_attrdef d ON
  (d.adrelid = a.attrelid
    AND d.adnum = a.attnum)
JOIN (...) vals ON
  (c.oid = vals.oid AND a.attnum = vals.attnum)
```

That query produces the schema name (`n.nspname`) and the information is cached. Since users are likely going to call `PgResultSetMetaData::getTableName` as well when they call `PgResultSetMetaData::getSchemaName`, I suspect there wouldn't be any additional overhead?