How to Retrieve the Size of All Tables in a Database

sql-queries-4/physical-vs-logical-deletion/cascading-deletion-challenges.sql

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+ALTER TABLE Registration
+ DROP CONSTRAINT registration_student_id_fkey;
+
+ALTER TABLE Registration
+ ADD CONSTRAINT registration_student_id_fkey
+ FOREIGN KEY (student_id)
+ REFERENCES Student (id)
+ ON DELETE CASCADE;
+
+DELETE FROM Student WHERE id = 1007;
+
+
+ALTER TABLE Exam
+DROP CONSTRAINT exam_student_id_fkey;
+
+ALTER TABLE Exam
+ADD CONSTRAINT exam_student_id_fkey
+FOREIGN KEY (student_id)
+REFERENCES Student (id)
+ON DELETE CASCADE;
+
+DELETE FROM Student WHERE id = 1007;
+
+SELECT * FROM student limit 10;

sql-queries-4/physical-vs-logical-deletion/manual-deletion.sql

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+DELETE FROM Exam WHERE student_id = 1007; 
+DELETE FROM Registration WHERE student_id = 1007; 
+
+DELETE FROM Student WHERE id = 1007;

sql-queries-4/physical-vs-logical-deletion/physical-deletion.sql

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+DELETE FROM department WHERE id = 1;
+
+SELECT * FROM department;

sql-queries-4/physical-vs-logical-deletion/using-deleted_at Column.sql

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+ALTER TABLE Student ADD COLUMN IF NOT EXISTS deleted_at TIMESTAMP;
+
+UPDATE Student SET deleted_at = CURRENT_TIMESTAMP WHERE id = 1011;
+
+SELECT * FROM Student WHERE id = 1011;

sql-queries-4/physical-vs-logical-deletion/using-is_deleted Column.sql

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+ALTER TABLE Student ADD COLUMN is_deleted BOOLEAN DEFAULT FALSE;
+
+UPDATE Student SET is_deleted = TRUE WHERE id = 1010;
+
+SELECT * FROM Student WHERE is_deleted = FALSE;

sql-queries-4/retrieve-size-table/using pg_table_size-function-postgres.sql

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+SELECT
+    schemaname AS schema_name,
+    tablename AS table_name,
+    pg_size_pretty(pg_table_size(schemaname || '.' || tablename)) AS table_size
+FROM
+    pg_tables
+WHERE
+    schemaname NOT IN ('information_schema', 'pg_catalog')
+ORDER BY
+    pg_table_size(schemaname || '.' || tablename) DESC;

sql-queries-4/retrieve-size-table/using-custom-query-postgres.sql

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+SELECT
+    relname AS table_name,
+    pg_size_pretty(pg_total_relation_size(relid)) AS total_size,
+    pg_size_pretty(pg_relation_size(relid)) AS data_size,
+    pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) AS index_size
+FROM
+    pg_stat_user_tables
+ORDER BY
+    pg_total_relation_size(relid) DESC;

sql-queries-4/retrieve-size-table/using-information-schema-mysql.sql

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+SELECT
+    table_schema AS 'Database',
+    table_name AS 'Table',
+    ROUND((data_length + index_length) / 1024 / 1024, 2) AS 'Size (MB)'
+FROM
+    information_schema.tables
+WHERE
+    table_schema = 'University'
+ORDER BY
+    (data_length + index_length) DESC;

sql-queries-4/retrieve-size-table/using-information-schema-postgres.sql

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+SELECT
+    table_schema,
+    table_name,
+    pg_size_pretty(pg_total_relation_size(table_schema || '.' || table_name)) AS table_size
+FROM
+    information_schema.tables
+WHERE
+    table_schema NOT IN ('information_schema', 'pg_catalog')
+ORDER BY
+    pg_total_relation_size(table_schema || '.' || table_name) DESC;

sql-queries-4/retrieve-size-table/using-show-table-status-mysql.sql

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+SHOW TABLE STATUS FROM University;

sql-queries-4/retrieve-size-table/using-sp_spaceused-sql-server.sql

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+EXEC sp_MSforeachtable 'EXEC sp_spaceused ''?''';
+

sql-queries-4/retrieve-size-table/using-sys.dm_db_partition_stats-sql-server.sql

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+SELECT
+    t.name AS table_name,
+    SUM(a.total_pages) * 8 AS total_space_kb,
+    SUM(a.used_pages) * 8 AS used_space_kb,
+    (SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS unused_space_kb
+FROM
+    sys.tables t
+INNER JOIN
+    sys.indexes i ON t.object_id = i.object_id
+INNER JOIN
+    sys.partitions p ON i.object_id = p.object_id AND i.index_id = p.index_id
+INNER JOIN
+    sys.allocation_units a ON p.partition_id = a.container_id
+GROUP BY
+    t.name
+ORDER BY
+    total_space_kb DESC;