initial code

sql/00_read_only_connection_check.sql

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+-- Run the whole file when connected to the countydata database.
+-- The explicit read-only transaction protects against accidental writes.
+BEGIN TRANSACTION READ ONLY;
+
+SELECT
+    current_database() AS database_name,
+    current_user AS database_user,
+    current_setting('transaction_read_only') AS transaction_read_only,
+    version() AS postgres_version;
+
+SELECT
+    ssl,
+    version AS tls_version,
+    cipher,
+    bits
+FROM pg_stat_ssl
+WHERE pid = pg_backend_pid();
+
+SELECT
+    n.nspname AS schema_name,
+    c.relname AS relation_name,
+    CASE c.relkind
+        WHEN 'r' THEN 'table'
+        WHEN 'p' THEN 'partitioned table'
+        WHEN 'v' THEN 'view'
+        WHEN 'm' THEN 'materialized view'
+        WHEN 'f' THEN 'foreign table'
+        ELSE c.relkind::text
+    END AS relation_type,
+    COALESCE(s.n_live_tup, c.reltuples)::bigint AS estimated_rows
+FROM pg_class AS c
+JOIN pg_namespace AS n ON n.oid = c.relnamespace
+LEFT JOIN pg_stat_user_tables AS s ON s.relid = c.oid
+WHERE c.relkind IN ('r', 'p', 'v', 'm', 'f')
+  AND n.nspname NOT IN ('pg_catalog', 'information_schema')
+  AND n.nspname NOT LIKE 'pg_toast%'
+ORDER BY n.nspname, c.relname;
+
+ROLLBACK;