Add query for schemas, tables, and views inventory in Redshift

schema_memory_usage.sql

@@ -0,0 +1,106 @@
+-- =============================================================================
+-- QUERY: Schema-Level Storage Summary
+-- =============================================================================
+-- This query provides a summary of each schema in the database, showing
+-- the number of tables, views, total storage size, and row counts.
+-- It also flags schemas that are empty or contain only views.
+--
+-- USE CASE: Database capacity planning, identifying unused schemas,
+--           storage allocation review, schema cleanup decisions.
+--
+-- OUTPUT COLUMNS:
+--   schema_name   - The name of the schema
+--   table_count   - Number of tables in the schema
+--   view_count    - Number of views in the schema
+--   size_mb       - Total size of all tables in MB
+--   size_gb       - Total size of all tables in GB
+--   total_rows    - Sum of all rows across all tables
+--   schema_status - 'empty', 'views_only', or 'has_tables'
+--
+-- NOTE: The schema_status column helps identify schemas that may be
+--       candidates for cleanup (empty) or that only contain view definitions.
+-- =============================================================================
+
+-- -----------------------------------------------------------------------------
+-- CTE 1: all_schemas
+-- -----------------------------------------------------------------------------
+-- Get a complete list of all user-created schemas from pg_namespace.
+-- This ensures we capture schemas that might be empty or only have views,
+-- which wouldn't appear in svv_table_info.
+-- -----------------------------------------------------------------------------
+WITH all_schemas AS (
+    SELECT nspname AS schema_name
+    FROM pg_namespace
+    WHERE nspname NOT IN (
+        'pg_catalog',        -- PostgreSQL system catalog
+        'information_schema', -- SQL standard metadata schema
+        'pg_internal',       -- Redshift internal schema
+        'pg_auto_copy',      -- Redshift auto-copy schema
+        'pg_automv',         -- Redshift auto materialized views
+        'pg_mv',             -- Redshift materialized views metadata
+        'pg_s3'              -- Redshift Spectrum S3 schema
+    )
+    AND nspname NOT LIKE 'pg_temp%'   -- Exclude temporary schemas
+    AND nspname NOT LIKE 'pg_toast%'  -- Exclude TOAST storage schemas
+),
+
+-- -----------------------------------------------------------------------------
+-- CTE 2: table_sizes
+-- -----------------------------------------------------------------------------
+-- Aggregate table statistics by schema from svv_table_info.
+-- This gives us the count of tables, total size, and total rows per schema.
+-- Schemas with no tables won't appear here (handled by LEFT JOIN later).
+-- -----------------------------------------------------------------------------
+table_sizes AS (
+    SELECT 
+        "schema" AS schema_name,
+        COUNT(DISTINCT "table") AS table_count,
+        ROUND(SUM(size)::NUMERIC, 2) AS size_mb,
+        ROUND(SUM(size)::NUMERIC / 1024, 2) AS size_gb,
+        ROUND(SUM(tbl_rows)::NUMERIC, 0) AS total_rows
+    FROM svv_table_info
+    WHERE "schema" NOT IN ('pg_catalog', 'information_schema', 'pg_internal')
+    GROUP BY "schema"
+),
+
+-- -----------------------------------------------------------------------------
+-- CTE 3: view_counts
+-- -----------------------------------------------------------------------------
+-- Count views per schema using pg_class (relkind = 'v' indicates a view).
+-- This is joined with pg_namespace to get the schema name.
+-- Schemas with no views won't appear here (handled by LEFT JOIN later).
+-- -----------------------------------------------------------------------------
+view_counts AS (
+    SELECT 
+        n.nspname AS schema_name,
+        COUNT(*) AS view_count
+    FROM pg_class c
+    JOIN pg_namespace n ON c.relnamespace = n.oid
+    WHERE c.relkind = 'v'  -- 'v' = view in pg_class
+    AND n.nspname NOT IN ('pg_catalog', 'information_schema', 'pg_internal')
+    GROUP BY n.nspname
+)
+
+-- -----------------------------------------------------------------------------
+-- Main SELECT: Join all CTEs and calculate schema_status
+-- -----------------------------------------------------------------------------
+-- LEFT JOINs ensure we get all schemas even if they have no tables or views.
+-- COALESCE converts NULLs to 0 for schemas missing from table_sizes or view_counts.
+-- The CASE statement determines the schema_status based on object counts.
+-- -----------------------------------------------------------------------------
+SELECT 
+    s.schema_name,
+    COALESCE(t.table_count, 0) AS table_count,
+    COALESCE(v.view_count, 0) AS view_count,
+    COALESCE(t.size_mb, 0) AS size_mb,
+    COALESCE(t.size_gb, 0) AS size_gb,
+    COALESCE(t.total_rows, 0) AS total_rows,
+    CASE 
+        WHEN COALESCE(t.table_count, 0) = 0 AND COALESCE(v.view_count, 0) = 0 THEN 'empty'
+        WHEN COALESCE(t.table_count, 0) = 0 AND COALESCE(v.view_count, 0) > 0 THEN 'views_only'
+        ELSE 'has_tables'
+    END AS schema_status
+FROM all_schemas s
+LEFT JOIN table_sizes t ON s.schema_name = t.schema_name
+LEFT JOIN view_counts v ON s.schema_name = v.schema_name
+ORDER BY s.schema_name ASC;

sql/table_memory_usage.sql

@@ -0,0 +1,95 @@
+-- =============================================================================
+-- QUERY: Individual Tables and Views Inventory
+-- =============================================================================
+-- This query returns a comprehensive list of all tables and views in the 
+-- Redshift database, along with their size and row count information.
+-- 
+-- USE CASE: Database inventory, storage analysis, identifying large tables,
+--           finding unused objects, or auditing database contents.
+--
+-- OUTPUT COLUMNS:
+--   schema_name  - The schema containing the object
+--   table_name   - The name of the table or view
+--   object_type  - Either 'table' or 'view'
+--   size_mb      - Size in megabytes (0 for views since they don't store data)
+--   size_gb      - Size in gigabytes (0 for views)
+--   row_count    - Number of rows (0 for views)
+--
+-- NOTE: Views show 0 for size and row_count because views are stored queries,
+--       not physical data. They don't consume storage space.
+-- =============================================================================
+
+-- -----------------------------------------------------------------------------
+-- PART 1: Get all tables from svv_table_info
+-- -----------------------------------------------------------------------------
+-- svv_table_info is a Redshift system view that contains information about
+-- all user-defined tables including their size and row counts.
+-- We exclude system schemas that contain internal Redshift objects.
+-- -----------------------------------------------------------------------------
+SELECT 
+    schema_name::VARCHAR(256),
+    table_name::VARCHAR(256),
+    object_type::VARCHAR(10),
+    size_mb::NUMERIC(18,2),
+    size_gb::NUMERIC(18,2),
+    row_count::BIGINT
+FROM (
+    SELECT 
+        "schema" AS schema_name,
+        "table" AS table_name,
+        'table' AS object_type,
+        ROUND(size::NUMERIC, 2) AS size_mb,
+        ROUND(size::NUMERIC / 1024, 2) AS size_gb,
+        tbl_rows AS row_count
+    FROM svv_table_info
+    WHERE "schema" NOT IN (
+        'pg_catalog',        -- PostgreSQL system catalog
+        'information_schema', -- SQL standard metadata schema
+        'pg_internal',       -- Redshift internal schema
+        'pg_auto_copy',      -- Redshift auto-copy schema
+        'pg_automv',         -- Redshift auto materialized views
+        'pg_mv',             -- Redshift materialized views metadata
+        'pg_s3'              -- Redshift Spectrum S3 schema
+    )
+) t
+
+UNION ALL
+
+-- -----------------------------------------------------------------------------
+-- PART 2: Get all views from pg_views
+-- -----------------------------------------------------------------------------
+-- pg_views is a system catalog that lists all views in the database.
+-- Views don't have size or row count since they're just stored SQL queries
+-- that execute against underlying tables when called.
+-- -----------------------------------------------------------------------------
+SELECT 
+    schema_name::VARCHAR(256),
+    table_name::VARCHAR(256),
+    object_type::VARCHAR(10),
+    size_mb::NUMERIC(18,2),
+    size_gb::NUMERIC(18,2),
+    row_count::BIGINT
+FROM (
+    SELECT 
+        schemaname AS schema_name,
+        viewname AS table_name,
+        'view' AS object_type,
+        0 AS size_mb,
+        0 AS size_gb,
+        0 AS row_count
+    FROM pg_views
+    WHERE schemaname NOT IN (
+        'pg_catalog',
+        'information_schema',
+        'pg_internal',
+        'pg_auto_copy',
+        'pg_automv',
+        'pg_mv',
+        'pg_s3'
+    )
+) v
+
+-- -----------------------------------------------------------------------------
+-- Sort by schema, then object type (tables first), then object name
+-- -----------------------------------------------------------------------------
+ORDER BY 1, 3, 2;