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Rostislav Dugin
Rostislav Dugin

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PostgreSQL backups: comparing pg_dump speed in different formats and with different compression levels

I made a backup using pg_dump and restored it 21 times. I made backups in 4 different formats using 1 to 7 compression levels for each format. I recorded the results and compared the different types to understand which methods are more effective for my use case.

Details and measurements are below.

Table of content:

  • Why do I need this measurement?
  • Backup formats and compression types in pg_dump
  • PostgreSQL configuration
  • Data preparation
  • Measurement results
  • Conclusions based on measurements
  • Conclusion

Why do I need this measurement?

I had a very specific task: to find the best backup format using the standard pg_dump. “Best” means the optimal ratio of backup creation speed, recovery speed and final file size.

I used this information in my open source project for PostgreSQL backups called Postgresus. There is an overview article about it on dev.to:

Postgresus image

There were additional requirements:

  • the backup must be compressed before being sent to my server to minimize network usage;

  • the backup file itself must be a single file (rather than, for example, a directory) so it can be streamed to a disk, S3 or the cloud;

  • the method of creating a backup should not require any database configuration in advance (therefore, PgBackRest, WAL-G, and pg_basebackup were ruled out) in order to be easy to integrate into an open source project and work with any database (installed locally, in Docker, in DBaaS, with a read replica, etc.).

Backup formats and compression types in pg_dump

pg_dump supports 4 formats:

Format Compression Single file? Parallel backup Parallel restore
Plain (SQL)
Custom (-Fc)
Directory (-Fd)
Tar (-Ft)

I was most interested in the custom format and directory format. They support parallel processing of backups. The custom format cannot create a backup in parallel (only restore), but writes it to a single file. The directory format can both back up and restore in parallel, but writes everything to a directory.

For these formats the following compression types are supported:

Name Feature (in theory) Compression / Decompression Speed (in theory) Compression Ratio (in theory)
gzip Standard compression algorithm Medium / High 2–3×
lz4 Compression algorithm optimized for higher speed than gzip Very High / Very High 1.5–2×
zstd Relatively new (2016) algorithm developed at Facebook: balance of speed and compression High / High 3–5×

The compression characteristics described are based on perfectly prepared data. In the case of a database, compression does not take up 100% of the time with 100% CPU utilization. There are many database-specific operations that are likely to slow down compression (especially “on the fly”).

Before the test, I assumed that a custom format with gzip compression would be the best option for me (as a happy medium) and had cautious hopes for zstd (as a more modern format). By the way, zstd only began to be supported in PostgreSQL 15.

PostgreSQL configuration

I launched two PostgreSQL instances in Docker Compose: one for creating backups (with data) and one for restoring from them. I didn’t use the standard ports because they are already in use by my local versions of PostgreSQL.

docker-compose.yml

version: "3.8" services: db: image: postgres:17 container_name: db environment: POSTGRES_DB: testdb POSTGRES_USER: postgres POSTGRES_PASSWORD: testpassword ports: - "7000:7000" command: -p 7000 volumes: - ./pgdata:/var/lib/postgresql/data healthcheck: test: ["CMD-SHELL", "pg_isready -U postgres -d testdb -p 7000"] interval: 10s timeout: 5s retries: 5 restart: unless-stopped db-restore: image: postgres:17 container_name: db-restore environment: POSTGRES_DB: testdb POSTGRES_USER: postgres POSTGRES_PASSWORD: testpassword ports: - "7001:7001" command: -p 7001 volumes: - ./pgdata-restore:/var/lib/postgresql/data healthcheck: test: ["CMD-SHELL", "pg_isready -U postgres -d testdb -p 7001"] interval: 10s timeout: 5s retries: 5 restart: unless-stopped depends_on: - db 
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Then I updated postgresql.conf a little to use more computer resources. I have an AMD Ryzen 9 7950X (16 cores, 32 threads), 64 GB of RAM and a 1 TB NVMe drive. I configured the database to use 4 threads and 16 GB of memory via PgTune.

postgresql.conf

# DB Version: 17 # OS Type: linux # DB Type: web # Total Memory (RAM): 16 GB # CPUs num: 4 # Connections num: 100 # Data Storage: ssd  max_connections = 100 shared_buffers = 4GB effective_cache_size = 12GB maintenance_work_mem = 1GB checkpoint_completion_target = 0.9 wal_buffers = 16MB default_statistics_target = 100 random_page_cost = 1.1 effective_io_concurrency = 200 work_mem = 40329kB huge_pages = off min_wal_size = 1GB max_wal_size = 4GB max_worker_processes = 4 max_parallel_workers_per_gather = 2 max_parallel_workers = 4 max_parallel_maintenance_workers = 2 listen_addresses = '*' 
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Data preparation

To begin with, I created a database with 3 tables and 9 indexes with a total size of ~11 GB. The data is as diverse as possible. I am more than sure that pg_dump works better with some types of data and worse with others. But my project is aimed at a wide audience, so it is important to measure the “average across the board.”

Below is the tables structure.

Tables:

Table name Purpose Columns
large_test_table Employees and users with various data types 18 columns including name, email, address, salary, etc.
orders Order data and history of changes 13 columns including user_id, order_number, amounts, etc.
activity_logs User activity logs with large text fields 13 columns including user_id, action, details, timestamps, etc.

Indexes:

Table Index Name Column Purpose
large_test_table idx_large_test_name name Search by name
large_test_table idx_large_test_email email Search by email
large_test_table idx_large_test_created_at created_at Search by time range
large_test_table idx_large_test_department department Filter by department
orders idx_orders_user_id user_id Search user’s orders
orders idx_orders_order_date order_date Search by date/time
orders idx_orders_status status Search by status
activity_logs idx_activity_user_id user_id Search by ID
activity_logs idx_activity_timestamp timestamp Search by date
activity_logs idx_activity_action action Search by action

The data is generated and inserted into the database using a Python script. The algorithm is as follows:

  • 25,000 rows of data are generated;
  • 100,000 rows are inserted into each table in turn using COPY;
  • when the database reaches 10 GB in size, indexes are created.

Script to fill database with data
#!/usr/bin/env python3 """ Script to populate PostgreSQL database with ~10GB of test data for backup performance testing. Inserts 1 million rows into each of 3 tables until reaching 10GB target. """ import psycopg2 import random import string import time import io from datetime import datetime, timedelta import sys # Database connection parameters DB_CONFIG = { "host": "localhost", "port": 7000, "database": "testdb", "user": "postgres", "password": "testpassword", } # Target database size in bytes (10GB) TARGET_SIZE_GB = 10 TARGET_SIZE_BYTES = TARGET_SIZE_GB * 1024 * 1024 * 1024 # Rows per table per round ROWS_PER_TABLE = 100000 def generate_random_string(length): """Generate a random string of specified length.""" return "".join(random.choices(string.ascii_letters + string.digits + " ", k=length)) def generate_random_date(): """Generate a random date within the last 5 years.""" start_date = datetime.now() - timedelta(days=5 * 365) random_days = random.randint(0, 5 * 365) return start_date + timedelta(days=random_days) def create_tables(cursor): """Create the 3 test tables with various data types.""" print("Creating 3 tables...") # Table 1: Large table with mixed data types  cursor.execute(""" CREATE TABLE IF NOT EXISTS large_test_table ( id BIGSERIAL PRIMARY KEY, name VARCHAR(100), description TEXT, email VARCHAR(255), phone VARCHAR(20), address TEXT, city VARCHAR(100), country VARCHAR(100), postal_code VARCHAR(20), birth_date DATE, created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP, updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP, salary DECIMAL(10,2), is_active BOOLEAN DEFAULT TRUE, rating FLOAT, notes TEXT, department VARCHAR(100), employee_id VARCHAR(50) ) """) # Table 2: Orders table for transactional data  cursor.execute(""" CREATE TABLE IF NOT EXISTS orders ( id BIGSERIAL PRIMARY KEY, user_id BIGINT, order_number VARCHAR(50) UNIQUE, total_amount DECIMAL(12,2), order_date TIMESTAMP, status VARCHAR(20), shipping_address TEXT, notes TEXT, payment_method VARCHAR(50), shipping_method VARCHAR(50), discount_amount DECIMAL(10,2), product_list TEXT, customer_notes TEXT ) """) # Table 3: Activity logs with lots of text data  cursor.execute(""" CREATE TABLE IF NOT EXISTS activity_logs ( id BIGSERIAL PRIMARY KEY, user_id BIGINT, action VARCHAR(100), details TEXT, ip_address INET, user_agent TEXT, timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP, session_id VARCHAR(100), browser VARCHAR(50), operating_system VARCHAR(50), referrer TEXT, response_time INTEGER, error_message TEXT ) """) print("3 tables created successfully!") def create_indexes(cursor): """Create indexes for all 3 tables.""" print("Creating indexes...") # Indexes for large_test_table  cursor.execute( "CREATE INDEX IF NOT EXISTS idx_large_test_name ON large_test_table(name)" ) cursor.execute( "CREATE INDEX IF NOT EXISTS idx_large_test_email ON large_test_table(email)" ) cursor.execute( "CREATE INDEX IF NOT EXISTS idx_large_test_created_at ON large_test_table(created_at)" ) cursor.execute( "CREATE INDEX IF NOT EXISTS idx_large_test_department ON large_test_table(department)" ) # Indexes for orders  cursor.execute("CREATE INDEX IF NOT EXISTS idx_orders_user_id ON orders(user_id)") cursor.execute( "CREATE INDEX IF NOT EXISTS idx_orders_order_date ON orders(order_date)" ) cursor.execute("CREATE INDEX IF NOT EXISTS idx_orders_status ON orders(status)") # Indexes for activity_logs  cursor.execute( "CREATE INDEX IF NOT EXISTS idx_activity_user_id ON activity_logs(user_id)" ) cursor.execute( "CREATE INDEX IF NOT EXISTS idx_activity_timestamp ON activity_logs(timestamp)" ) cursor.execute( "CREATE INDEX IF NOT EXISTS idx_activity_action ON activity_logs(action)" ) print("Indexes created successfully!") def drop_indexes(cursor): """Drop indexes for faster bulk loading.""" print("Dropping indexes for bulk loading...") indexes_to_drop = [ "idx_large_test_name", "idx_large_test_email", "idx_large_test_created_at", "idx_large_test_department", "idx_orders_user_id", "idx_orders_order_date", "idx_orders_status", "idx_activity_user_id", "idx_activity_timestamp", "idx_activity_action", ] for index in indexes_to_drop: try: cursor.execute(f"DROP INDEX IF EXISTS {index}") except: pass print("Indexes dropped!") def print_progress(inserted, total, start_time, operation_name): """Print detailed progress information.""" current_time = time.time() elapsed = current_time - start_time rate = inserted / elapsed if elapsed > 0 else 0 percentage = (inserted / total) * 100 if rate > 0: eta_seconds = (total - inserted) / rate eta_minutes = eta_seconds / 60 eta_str = f"ETA: {eta_minutes:.1f}m" else: eta_str = "ETA: calculating..." print( f"{operation_name}: {inserted:,} / {total:,} ({percentage:.1f}%) | " f"Rate: {rate:,.0f} rows/sec | Elapsed: {elapsed / 60:.1f}m | {eta_str}" ) def populate_large_table_batch(cursor, count=ROWS_PER_TABLE): """Populate large_test_table with specified number of rows.""" print(f"Inserting {count:,} rows into large_test_table...") batch_size = 25000 inserted = 0 start_time = time.time() while inserted < count: current_batch_size = min(batch_size, count - inserted) data_buffer = io.StringIO() for i in range(current_batch_size): name = ( generate_random_string(random.randint(20, 100)) .replace("\t", " ") .replace("\n", " ") ) description = ( generate_random_string(random.randint(100, 500)) .replace("\t", " ") .replace("\n", " ") ) email = f"{generate_random_string(10)}@{generate_random_string(10)}.com" phone = f"+1-{random.randint(100, 999)}-{random.randint(100, 999)}-{random.randint(1000, 9999)}" address = ( generate_random_string(random.randint(50, 200)) .replace("\t", " ") .replace("\n", " ") ) city = ( generate_random_string(random.randint(10, 50)) .replace("\t", " ") .replace("\n", " ") ) country = ( generate_random_string(random.randint(5, 30)) .replace("\t", " ") .replace("\n", " ") ) postal_code = f"{random.randint(10000, 99999)}" birth_date = generate_random_date().date() salary = f"{random.randint(30000, 150000) + random.random():.2f}" is_active = "t" if random.choice([True, False]) else "f" rating = f"{random.uniform(1.0, 5.0):.2f}" notes = ( generate_random_string(random.randint(50, 300)) .replace("\t", " ") .replace("\n", " ") ) department = random.choice( ["HR", "Engineering", "Sales", "Marketing", "Finance", "Operations"] ) employee_id = ( f"EMP-{random.randint(1000, 9999)}-{generate_random_string(4)}" ) data_buffer.write( f"{name}\t{description}\t{email}\t{phone}\t{address}\t{city}\t{country}\t{postal_code}\t{birth_date}\t{salary}\t{is_active}\t{rating}\t{notes}\t{department}\t{employee_id}\n" ) data_buffer.seek(0) cursor.copy_from( data_buffer, "large_test_table", columns=( "name", "description", "email", "phone", "address", "city", "country", "postal_code", "birth_date", "salary", "is_active", "rating", "notes", "department", "employee_id", ), sep="\t", ) inserted += current_batch_size if inserted % 100000 == 0: print_progress(inserted, count, start_time, "Large table") elapsed = time.time() - start_time print( f"Completed large_test_table: {inserted:,} rows in {elapsed:.2f}s ({inserted / elapsed:,.0f} rows/sec)" ) def populate_orders_batch(cursor, count=ROWS_PER_TABLE): """Populate orders table with specified number of rows.""" print(f"Inserting {count:,} rows into orders...") batch_size = 25000 inserted = 0 start_time = time.time() while inserted < count: current_batch_size = min(batch_size, count - inserted) data_buffer = io.StringIO() for i in range(current_batch_size): user_id = random.randint(1, 10000000) order_number = f"ORD-{time.time_ns()}-{i:06d}" total_amount = f"{random.uniform(10.0, 5000.0):.2f}" order_date = generate_random_date() status = random.choice( ["pending", "processing", "shipped", "delivered", "cancelled"] ) shipping_address = ( generate_random_string(random.randint(100, 300)) .replace("\t", " ") .replace("\n", " ") ) notes = ( generate_random_string(random.randint(50, 200)) .replace("\t", " ") .replace("\n", " ") if random.random() > 0.5 else "" ) payment_method = random.choice(["credit_card", "paypal", "bank_transfer"]) shipping_method = random.choice(["standard", "express", "overnight"]) discount_amount = ( f"{random.uniform(0, 50) if random.random() > 0.7 else 0:.2f}" ) product_list = ( generate_random_string(random.randint(200, 800)) .replace("\t", " ") .replace("\n", " ") ) customer_notes = ( generate_random_string(random.randint(100, 400)) .replace("\t", " ") .replace("\n", " ") ) data_buffer.write( f"{user_id}\t{order_number}\t{total_amount}\t{order_date}\t{status}\t{shipping_address}\t{notes}\t{payment_method}\t{shipping_method}\t{discount_amount}\t{product_list}\t{customer_notes}\n" ) data_buffer.seek(0) cursor.copy_from( data_buffer, "orders", columns=( "user_id", "order_number", "total_amount", "order_date", "status", "shipping_address", "notes", "payment_method", "shipping_method", "discount_amount", "product_list", "customer_notes", ), sep="\t", ) inserted += current_batch_size if inserted % 100000 == 0: print_progress(inserted, count, start_time, "Orders") elapsed = time.time() - start_time print( f"Completed orders: {inserted:,} rows in {elapsed:.2f}s ({inserted / elapsed:,.0f} rows/sec)" ) def populate_activity_logs_batch(cursor, count=ROWS_PER_TABLE): """Populate activity_logs table with specified number of rows.""" print(f"Inserting {count:,} rows into activity_logs...") batch_size = 25000 inserted = 0 start_time = time.time() actions = [ "login", "logout", "view_product", "add_to_cart", "checkout", "update_profile", "search", "download", ] while inserted < count: current_batch_size = min(batch_size, count - inserted) data_buffer = io.StringIO() for i in range(current_batch_size): user_id = random.randint(1, 10000000) action = random.choice(actions) details = ( generate_random_string(random.randint(100, 500)) .replace("\t", " ") .replace("\n", " ") ) ip_address = f"{random.randint(1, 255)}.{random.randint(1, 255)}.{random.randint(1, 255)}.{random.randint(1, 255)}" user_agent = f"Mozilla/5.0 ({generate_random_string(50)}) {generate_random_string(30)}".replace( "\t", " " ).replace("\n", " ") timestamp = generate_random_date() session_id = generate_random_string(32) browser = random.choice(["Chrome", "Firefox", "Safari", "Edge"]) operating_system = random.choice( ["Windows", "macOS", "Linux", "iOS", "Android"] ) referrer = ( f"https://{generate_random_string(10)}.com" if random.random() > 0.3 else "" ) response_time = random.randint(50, 5000) error_message = ( generate_random_string(random.randint(100, 300)) .replace("\t", " ") .replace("\n", " ") if random.random() > 0.8 else "" ) data_buffer.write( f"{user_id}\t{action}\t{details}\t{ip_address}\t{user_agent}\t{timestamp}\t{session_id}\t{browser}\t{operating_system}\t{referrer}\t{response_time}\t{error_message}\n" ) data_buffer.seek(0) cursor.copy_from( data_buffer, "activity_logs", columns=( "user_id", "action", "details", "ip_address", "user_agent", "timestamp", "session_id", "browser", "operating_system", "referrer", "response_time", "error_message", ), sep="\t", ) inserted += current_batch_size if inserted % 100000 == 0: print_progress(inserted, count, start_time, "Activity logs") elapsed = time.time() - start_time print( f"Completed activity_logs: {inserted:,} rows in {elapsed:.2f}s ({inserted / elapsed:,.0f} rows/sec)" ) def get_database_size_bytes(cursor): """Get the current database size in bytes.""" cursor.execute("SELECT pg_database_size('testdb')") return cursor.fetchone()[0] def get_database_size_mb(cursor): """Get the current database size in MB.""" size_bytes = get_database_size_bytes(cursor) return size_bytes / (1024 * 1024) def format_size_mb(size_bytes): """Format size in bytes to MB string.""" return f"{size_bytes / (1024 * 1024):.1f}MB" def main(): """Main function to populate the database until reaching 10GB.""" print("Starting database population for backup performance testing...") print(f"Target: {TARGET_SIZE_GB * 1024:.0f}MB of data") print( f"Strategy: Insert {ROWS_PER_TABLE:,} rows into each of 3 tables per round until target reached" ) print("-" * 80) try: # Connect to database  print("Connecting to database...") conn = psycopg2.connect(**DB_CONFIG) conn.autocommit = False cursor = conn.cursor() initial_size_mb = get_database_size_mb(cursor) print(f"Initial database size: {initial_size_mb:.1f}MB") overall_start_time = time.time() # Create tables  create_tables(cursor) conn.commit() # Drop indexes for faster loading  drop_indexes(cursor) conn.commit() round_number = 1 current_size_bytes = get_database_size_bytes(cursor) # Keep adding rounds of 1M rows per table until we reach 10GB  while current_size_bytes < TARGET_SIZE_BYTES: print(f"\n{'=' * 20} ROUND {round_number} {'=' * 20}") round_start_time = time.time() # Populate all 3 tables with 1M rows each  populate_large_table_batch(cursor) conn.commit() populate_orders_batch(cursor) conn.commit() populate_activity_logs_batch(cursor) conn.commit() # Check current size  current_size_bytes = get_database_size_bytes(cursor) current_size_mb = format_size_mb(current_size_bytes) round_elapsed = time.time() - round_start_time print(f"\nRound {round_number} completed in {round_elapsed:.2f}s") print(f"Current database size: {current_size_mb}") print( f"Progress: {(current_size_bytes / TARGET_SIZE_BYTES) * 100:.1f}% of target ({TARGET_SIZE_GB * 1024:.0f}MB)" ) if current_size_bytes >= TARGET_SIZE_BYTES: print(f"✅ Target size reached!") break round_number += 1 # Recreate indexes  print(f"\n{'=' * 20} CREATING INDEXES {'=' * 20}") index_start_time = time.time() create_indexes(cursor) conn.commit() index_elapsed = time.time() - index_start_time print(f"Indexes created in {index_elapsed:.2f}s") # Final statistics  overall_elapsed = time.time() - overall_start_time final_size_mb = get_database_size_mb(cursor) print(f"\n{'=' * 60}") print("DATABASE POPULATION COMPLETED!") print(f"Final database size: {final_size_mb:.1f}MB") print(f"Total rounds: {round_number}") print( f"Total time: {overall_elapsed:.2f} seconds ({overall_elapsed / 60:.2f} minutes)" ) # Show table statistics  cursor.execute(""" SELECT relname, n_tup_ins as "Rows", round(pg_total_relation_size('public.'||relname)::numeric / (1024*1024), 1) as "Size_MB" FROM pg_stat_user_tables ORDER BY pg_total_relation_size('public.'||relname) DESC """) print(f"\nTable Statistics:") print(f"{'Table':<20} | {'Rows':<12} | {'Size':<10}") print("-" * 50) for row in cursor.fetchall(): print(f"{row[0]:<20} | {row[1]:>12,} | {row[2]:.1f}MB") cursor.close() conn.close() except psycopg2.Error as e: print(f"Database error: {e}") sys.exit(1) except Exception as e: print(f"Error: {e}") sys.exit(1) if __name__ == "__main__": main() 
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Measurement results

After 21 creations and restores, I obtained the following table with data that includes:

  • backup creation speed;
  • restore speed from backup;
  • total time;
  • backup size relative to the original database size.

The table with raw CSV data:

tool,format,compression_method,compression_level,backup_duration_seconds,restore_duration_seconds,total_duration_seconds,backup_size_bytes,database_size_bytes,restored_db_size_bytes,compression_ratio,backup_success,restore_success,backup_error,restore_error,timestamp pg_dump,plain,none,0,100.39210295677185,735.2188968658447,835.6109998226166,9792231003,11946069139,11922173075,0.8197031918249641,True,True,,,2025-07-29T09:56:20.611844 pg_dump,custom,none,0,264.56927490234375,406.6467957496643,671.216070652008,6862699613,11946069139,11943709843,0.5744734550878778,True,True,,,2025-07-29T10:07:37.226681 pg_dump,custom,gzip,1,214.07211470603943,383.0168492794037,597.0889639854431,7074031563,11946069139,11943611539,0.5921639562511493,True,True,,,2025-07-29T10:17:39.801883 pg_dump,custom,gzip,5,260.6179132461548,393.76623010635376,654.3841433525085,6866440205,11946069139,11943718035,0.5747865783384196,True,True,,,2025-07-29T10:28:40.167485 pg_dump,custom,gzip,9,272.3802499771118,385.1409020423889,657.5211520195007,6856264586,11946069139,11943619731,0.5739347819121977,True,True,,,2025-07-29T10:39:42.912960 pg_dump,custom,lz4,1,84.0079517364502,379.6986663341522,463.7066180706024,9146843234,11946069139,11943685267,0.765678075990583,True,True,,,2025-07-29T10:47:32.131593 pg_dump,custom,lz4,5,150.24981474876404,393.44346714019775,543.6932818889618,8926348325,11946069139,11943718035,0.7472205477078983,True,True,,,2025-07-29T10:56:41.333595 pg_dump,custom,lz4,12,220.93980932235718,418.26913809776306,639.2089474201202,8923243046,11946069139,11943767187,0.7469606062188722,True,True,,,2025-07-29T11:07:26.574678 pg_dump,custom,zstd,1,87.83108067512512,419.07846903800964,506.90954971313477,6835388679,11946069139,11943767187,0.5721872692570225,True,True,,,2025-07-29T11:15:59.917828 pg_dump,custom,zstd,5,102.42366409301758,413.64263129234314,516.0662953853607,6774137561,11946069139,11944357011,0.567059966100871,True,True,,,2025-07-29T11:24:42.075008 pg_dump,custom,zstd,15,844.7868592739105,388.23959374427795,1233.0264530181885,6726189591,11946069139,11943636115,0.5630462633973209,True,True,,,2025-07-29T11:45:17.885163 pg_dump,custom,zstd,22,5545.566084384918,404.1370210647583,5949.7031054496765,6798947241,11946069139,11943750803,0.5691367731000038,True,True,,,2025-07-29T13:24:30.014902 pg_dump,directory,none,0,114.9900906085968,395.2716040611267,510.2616946697235,6854332396,11946069139,11943693459,0.5737730391684116,True,True,,,2025-07-29T13:33:05.944191 pg_dump,directory,lz4,1,53.48561334609985,384.92091369628906,438.4065270423889,9146095976,11946069139,11943668883,0.7656155233641663,True,True,,,2025-07-29T13:40:30.590719 pg_dump,directory,lz4,5,83.44352841377258,410.42058181762695,493.86411023139954,8925601067,11946069139,11943718035,0.7471579950814815,True,True,,,2025-07-29T13:48:50.201990 pg_dump,directory,lz4,12,114.15110802650452,400.04946303367615,514.2005710601807,8922495788,11946069139,11943758995,0.7468980535924554,True,True,,,2025-07-29T13:57:30.419171 pg_dump,directory,zstd,1,57.22735643386841,414.4600088596344,471.6873652935028,6835014976,11946069139,11943750803,0.5721559867493079,True,True,,,2025-07-29T14:05:28.529630 pg_dump,directory,zstd,5,60.121564865112305,398.27933716773987,458.4009020328522,6773763858,11946069139,11943709843,0.5670286835931563,True,True,,,2025-07-29T14:13:13.472761 pg_dump,directory,zstd,15,372.43965554237366,382.9877893924713,755.427444934845,6725815888,11946069139,11943644307,0.5630149808896062,True,True,,,2025-07-29T14:25:54.580924 pg_dump,directory,zstd,22,2637.47145485878,394.4939453601837,3031.9654002189636,6798573538,11946069139,11943660691,0.5691054905922891,True,True,,,2025-07-29T15:16:29.450828 pg_dump,tar,none,0,126.3212628364563,664.1294028759003,790.4506657123566,9792246784,11946069139,11942759571,0.8197045128452776,True,True,,,2025-07-29T15:29:45.280592 
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Script for measurement
 python #!/usr/bin/env python3 """ Comprehensive PostgreSQL backup performance testing script. Tests pg_dump with all possible formats and compression levels. """ import subprocess import time import os import shutil import json import csv from datetime import datetime from pathlib import Path import psycopg2 import argparse def log_with_timestamp(message): """Print a message with timestamp.""" timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S") print(f"[{timestamp}] {message}") # PostgreSQL binary path PG_BIN_PATH = Path("./postgresql-17/bin") # Database connection parameters DB_CONFIG = { "host": "localhost", "port": 7000, "database": "testdb", "user": "postgres", "password": "testpassword", } # Restore database connection parameters RESTORE_DB_CONFIG = { "host": "localhost", "port": 7001, "database": "testdb", "user": "postgres", "password": "testpassword", } # Test configurations PG_DUMP_FORMATS = [ ("plain", "sql"), ("custom", "dump"), ("directory", "dir"), ("tar", "tar"), ] COMPRESSION_LEVELS = { "gzip": [1, 5, 9], "lz4": [1, 5, 12], "zstd": [1, 5, 15, 22], } # Available compression methods (depends on PostgreSQL version) COMPRESSION_METHODS = ["none", "gzip", "lz4", "zstd"] # Results storage results: list[dict] = [] def ensure_backup_directory(): """Ensure backup directory exists and is clean.""" backup_dir = Path("./backups") if backup_dir.exists(): shutil.rmtree(backup_dir) backup_dir.mkdir(exist_ok=True) return backup_dir def get_database_size(): """Get current database size in bytes.""" try: conn = psycopg2.connect(**DB_CONFIG) cursor = conn.cursor() cursor.execute("SELECT pg_database_size('testdb')") size = cursor.fetchone()[0] cursor.close() conn.close() return size except Exception as e: log_with_timestamp(f"Error getting database size: {e}") return 0 def get_restore_database_size(): """Get restore database size in bytes.""" try: conn = psycopg2.connect(**RESTORE_DB_CONFIG) cursor = conn.cursor() cursor.execute("SELECT pg_database_size('testdb')") size = cursor.fetchone()[0] cursor.close() conn.close() return size except Exception as e: log_with_timestamp(f"Error getting restore database size: {e}") return 0 def clean_restore_database(): """Clean the restore database by dropping and recreating it.""" import time try: # Connect to postgres database to drop/create testdb restore_config = RESTORE_DB_CONFIG.copy() restore_config["database"] = "postgres" conn = psycopg2.connect(**restore_config) conn.autocommit = True cursor = conn.cursor() # Terminate any existing connections to testdb with retry logic max_attempts = 5 for attempt in range(max_attempts): try: # Get count of active connections first cursor.execute(""" SELECT COUNT(*) FROM pg_stat_activity WHERE datname = 'testdb' AND pid <> pg_backend_pid() """) active_connections = cursor.fetchone()[0] if active_connections == 0: break log_with_timestamp( f"Found {active_connections} active connections to testdb, terminating..." ) # Terminate connections cursor.execute(""" SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = 'testdb' AND pid <> pg_backend_pid() """) # Fetch all results to ensure the query completes terminated_pids = cursor.fetchall() log_with_timestamp(f"Terminated {len(terminated_pids)} connections") # Wait a bit for connections to actually close time.sleep(2) except Exception as term_error: log_with_timestamp( f"Warning: Error terminating connections (attempt {attempt + 1}): {term_error}" ) if attempt < max_attempts - 1: time.sleep(1) else: # Continue anyway, maybe we can still drop the database break # Try to drop database with retry logic drop_attempts = 3 for attempt in range(drop_attempts): try: cursor.execute("DROP DATABASE IF EXISTS testdb") log_with_timestamp("Database testdb dropped successfully") break except Exception as drop_error: if ( "is being accessed by other users" in str(drop_error) and attempt < drop_attempts - 1 ): log_with_timestamp( f"Database still in use, waiting and retrying... (attempt {attempt + 1})" ) time.sleep(3) else: raise drop_error # Create fresh database cursor.execute("CREATE DATABASE testdb") cursor.close() conn.close() log_with_timestamp("✓ Restore database cleaned and recreated") return True except Exception as e: log_with_timestamp(f"✗ Error cleaning restore database: {e}") return False def wait_for_restore_db(): """Wait for restore database to be ready.""" import time max_attempts = 30 for attempt in range(max_attempts): try: conn = psycopg2.connect(**RESTORE_DB_CONFIG) conn.close() return True except: if attempt < max_attempts - 1: time.sleep(1) else: log_with_timestamp("✗ Restore database not ready after 30 seconds") return False def restore_pg_dump(backup_path, format_name): """Restore a pg_dump backup.""" env = os.environ.copy() env["PGPASSWORD"] = RESTORE_DB_CONFIG["password"] if format_name == "plain": # Use psql for plain format command = [ str(PG_BIN_PATH / "psql.exe"), "-h", RESTORE_DB_CONFIG["host"], "-p", str(RESTORE_DB_CONFIG["port"]), "-U", RESTORE_DB_CONFIG["user"], "-d", RESTORE_DB_CONFIG["database"], "-f", str(backup_path), "-v", "ON_ERROR_STOP=1", ] else: # Use pg_restore for custom, directory, tar formats command = [ str(PG_BIN_PATH / "pg_restore.exe"), "-h", RESTORE_DB_CONFIG["host"], "-p", str(RESTORE_DB_CONFIG["port"]), "-U", RESTORE_DB_CONFIG["user"], "-d", RESTORE_DB_CONFIG["database"], "--verbose", str(backup_path), ] # Add parallel processing for custom and directory formats if format_name in ["custom", "directory"]: command.extend(["-j", "4"]) else: # Only add --single-transaction for tar format (not parallel) command.insert(-1, "--single-transaction") return run_command(command, env=env) def get_file_size(filepath): """Get file or directory size in bytes.""" if os.path.isfile(filepath): return os.path.getsize(filepath) elif os.path.isdir(filepath): total_size = 0 for dirpath, dirnames, filenames in os.walk(filepath): for filename in filenames: file_path = os.path.join(dirpath, filename) total_size += os.path.getsize(file_path) return total_size return 0 def format_size(size_bytes): """Format size in GB with 1 decimal place.""" size_gb = size_bytes / (1024.0 * 1024.0 * 1024.0) return f"{size_gb:.1f} GB" def format_minutes(seconds): """Format time in minutes with 1 decimal place.""" minutes = seconds / 60.0 return f"{minutes:.1f} mins" def run_command(command, timeout=7200, env=None): """Run a command and measure execution time.""" log_with_timestamp(f"Running: {' '.join(command)}") start_time = time.time() try: # Set environment variables for password if env is None: env = os.environ.copy() env["PGPASSWORD"] = DB_CONFIG["password"] result = subprocess.run( command, capture_output=True, text=True, timeout=timeout, env=env ) end_time = time.time() duration = end_time - start_time if result.returncode != 0: log_with_timestamp(f"Command failed with return code {result.returncode}") log_with_timestamp(f"STDERR: {result.stderr}") return None, duration, result.stderr return result, duration, None except subprocess.TimeoutExpired: log_with_timestamp(f"Command timed out after {timeout} seconds") return None, timeout, "Command timed out" except Exception as e: end_time = time.time() duration = end_time - start_time log_with_timestamp(f"Command failed with exception: {e}") return None, duration, str(e) def test_pg_dump(skip_restore=False): """Test pg_dump with all format and compression combinations.""" log_with_timestamp("\n" + "=" * 60) log_with_timestamp("TESTING PG_DUMP") log_with_timestamp("=" * 60) backup_dir = Path("./backups") for format_name, extension in PG_DUMP_FORMATS: log_with_timestamp(f"\nTesting pg_dump format: {format_name}") # Test without compression test_name = f"pg_dump_{format_name}_no_compression" output_path = backup_dir / f"{test_name}.{extension}" command = [ str(PG_BIN_PATH / "pg_dump.exe"), "-h", DB_CONFIG["host"], "-p", str(DB_CONFIG["port"]), "-U", DB_CONFIG["user"], "-d", DB_CONFIG["database"], "-f", str(output_path), "--format", format_name, "--verbose", ] if format_name == "directory": # For directory format, create the directory first output_path.mkdir(exist_ok=True) # Replace the path after -f flag with the directory path for i, item in enumerate(command): if item == "-f" and i + 1 < len(command): command[i + 1] = str(output_path) break # Add parallel processing for directory format command.extend(["-j", "4"]) # Perform backup result, backup_duration, error = run_command(command) if result is not None: backup_size = get_file_size(output_path) db_size = get_database_size() compression_ratio = backup_size / db_size if db_size > 0 else 0 # Clean restore database and perform restore restore_success = False restore_duration = 0 restore_error = None restored_db_size = 0 if not skip_restore: if clean_restore_database() and wait_for_restore_db(): restore_result, restore_duration, restore_error = restore_pg_dump( output_path, format_name ) if restore_result is not None and restore_result.returncode == 0: restore_success = True restored_db_size = get_restore_database_size() else: restore_success = True # Mark as successful if skipped restore_error = "Skipped" results.append( { "tool": "pg_dump", "format": format_name, "compression_method": "none", "compression_level": 0, "backup_duration_seconds": backup_duration, "restore_duration_seconds": restore_duration, "total_duration_seconds": backup_duration + restore_duration, "backup_size_bytes": backup_size, "database_size_bytes": db_size, "restored_db_size_bytes": restored_db_size, "compression_ratio": compression_ratio, "backup_success": True, "restore_success": restore_success, "backup_error": None, "restore_error": restore_error, "timestamp": datetime.now().isoformat(), } ) if skip_restore: log_with_timestamp( f"✓ {test_name}: Backup {format_minutes(backup_duration)}, " f"{format_size(backup_size)}, ratio: {compression_ratio:.3f} (restore skipped)" ) else: log_with_timestamp( f"✓ {test_name}: Backup {format_minutes(backup_duration)}, Restore {format_minutes(restore_duration)}, " f"{format_size(backup_size)}, ratio: {compression_ratio:.3f}" ) else: results.append( { "tool": "pg_dump", "format": format_name, "compression_method": "none", "compression_level": 0, "backup_duration_seconds": backup_duration, "restore_duration_seconds": 0, "total_duration_seconds": backup_duration, "backup_size_bytes": 0, "database_size_bytes": get_database_size(), "restored_db_size_bytes": 0, "compression_ratio": 0, "backup_success": False, "restore_success": False, "backup_error": error, "restore_error": "Backup failed", "timestamp": datetime.now().isoformat(), } ) log_with_timestamp(f"✗ {test_name}: BACKUP FAILED - {error}") # Test with compression (only for formats that support it) if format_name in ["custom", "directory"]: for compression_method in COMPRESSION_METHODS[1:]: # Skip 'none' if compression_method == "gzip" and format_name == "directory": continue # Directory format doesn't support gzip compression directly compression_levels = COMPRESSION_LEVELS.get(compression_method, [1]) for level in compression_levels: test_name = ( f"pg_dump_{format_name}_{compression_method}_level_{level}" ) output_path = backup_dir / f"{test_name}.{extension}" command = [ str(PG_BIN_PATH / "pg_dump.exe"), "-h", DB_CONFIG["host"], "-p", str(DB_CONFIG["port"]), "-U", DB_CONFIG["user"], "-d", DB_CONFIG["database"], "-f", str(output_path), "--format", format_name, "--verbose", ] # Add compression options if format_name == "custom": if compression_method == "gzip": command.extend(["-Z", str(level)]) else: command.extend( [ "--compress", f"{compression_method}:{level}", ] ) elif format_name == "directory": output_path.mkdir(exist_ok=True) # For directory format, replace the path after -f for i, item in enumerate(command): if item == "-f" and i + 1 < len(command): command[i + 1] = str(output_path) break if ( compression_method != "gzip" ): # Directory format supports lz4 and zstd command.extend( [ "--compress", f"{compression_method}:{level}", ] ) # Add parallel processing for directory format command.extend(["-j", "4"]) # Perform backup result, backup_duration, error = run_command(command) if result is not None: backup_size = get_file_size(output_path) db_size = get_database_size() compression_ratio = backup_size / db_size if db_size > 0 else 0 # Clean restore database and perform restore restore_success = False restore_duration = 0 restore_error = None restored_db_size = 0 if not skip_restore: if clean_restore_database() and wait_for_restore_db(): restore_result, restore_duration, restore_error = ( restore_pg_dump(output_path, format_name) ) if ( restore_result is not None and restore_result.returncode == 0 ): restore_success = True restored_db_size = get_restore_database_size() else: restore_success = True # Mark as successful if skipped restore_error = "Skipped" results.append( { "tool": "pg_dump", "format": format_name, "compression_method": compression_method, "compression_level": level, "backup_duration_seconds": backup_duration, "restore_duration_seconds": restore_duration, "total_duration_seconds": backup_duration + restore_duration, "backup_size_bytes": backup_size, "database_size_bytes": db_size, "restored_db_size_bytes": restored_db_size, "compression_ratio": compression_ratio, "backup_success": True, "restore_success": restore_success, "backup_error": None, "restore_error": restore_error, "timestamp": datetime.now().isoformat(), } ) if skip_restore: log_with_timestamp( f"✓ {test_name}: Backup {format_minutes(backup_duration)}, " f"{format_size(backup_size)}, ratio: {compression_ratio:.3f} (restore skipped)" ) else: log_with_timestamp( f"✓ {test_name}: Backup {format_minutes(backup_duration)}, Restore {format_minutes(restore_duration)}, " f"{format_size(backup_size)}, ratio: {compression_ratio:.3f}" ) else: results.append( { "tool": "pg_dump", "format": format_name, "compression_method": compression_method, "compression_level": level, "backup_duration_seconds": backup_duration, "restore_duration_seconds": 0, "total_duration_seconds": backup_duration, "backup_size_bytes": 0, "database_size_bytes": get_database_size(), "restored_db_size_bytes": 0, "compression_ratio": 0, "backup_success": False, "restore_success": False, "backup_error": error, "restore_error": "Backup failed", "timestamp": datetime.now().isoformat(), } ) log_with_timestamp(f"✗ {test_name}: BACKUP FAILED - {error}") def save_tabular_results(): """Save tabular test results to a CSV file.""" timestamp = datetime.now().strftime("%Y%m%d_%H%M%S") # Save as tabular CSV csv_file = f"backup_performance_tabular_{timestamp}.csv" with open(csv_file, "w", newline="") as f: writer = csv.writer(f) # Write header writer.writerow( [ "format", "backup duration mins", "restore duration mins", "total duration mins", "backup size GB", "db size GB", "restored DB size GB", "db size % from original", ] ) # Write data rows for r in sorted( results, key=lambda x: ( x["format"], x["compression_method"], x["compression_level"], ), ): if not r["backup_success"]: continue format_str = f"{r['format']} {r['compression_method']}" if r["compression_method"] != "none": format_str += f" {r['compression_level']}" backup_mins = round(r["backup_duration_seconds"] / 60.0, 1) restore_mins = round(r["restore_duration_seconds"] / 60.0, 1) total_mins = round(backup_mins + restore_mins, 1) backup_gb = round(r["backup_size_bytes"] / (1024.0 * 1024.0 * 1024.0), 1) db_gb = round(r["database_size_bytes"] / (1024.0 * 1024.0 * 1024.0), 1) restored_db_gb = round( r["restored_db_size_bytes"] / (1024.0 * 1024.0 * 1024.0), 1 ) db_size_percent = round((backup_gb / db_gb) * 100) if db_gb > 0 else 0 writer.writerow( [ format_str, backup_mins, restore_mins, total_mins, backup_gb, db_gb, restored_db_gb, db_size_percent, ] ) print(f"Tabular results saved to {csv_file}") def save_results(): """Save test results to JSON and CSV files.""" timestamp = datetime.now().strftime("%Y%m%d_%H%M%S") # Save as JSON json_file = f"backup_performance_results_{timestamp}.json" with open(json_file, "w") as f: json.dump(results, f, indent=2) print(f"\nResults saved to {json_file}") # Save as CSV csv_file = f"backup_performance_results_{timestamp}.csv" if results: fieldnames = results[0].keys() with open(csv_file, "w", newline="") as f: writer = csv.DictWriter(f, fieldnames=fieldnames) writer.writeheader() writer.writerows(results) print(f"Results saved to {csv_file}") # Save tabular results save_tabular_results() def print_summary(): """Print a summary of test results.""" print("\n" + "=" * 80) print("PERFORMANCE TEST SUMMARY") print("=" * 80) if not results: print("No results to display.") return # Check if any tests had restore attempts restore_attempted = any( r["restore_error"] != "Skipped" for r in results if r["backup_success"] ) if restore_attempted: successful_tests = [ r for r in results if r["backup_success"] and r["restore_success"] ] backup_only_success = [ r for r in results if r["backup_success"] and not r["restore_success"] and r["restore_error"] != "Skipped" ] failed_tests = [r for r in results if not r["backup_success"]] print(f"Total tests: {len(results)}") print(f"Complete success (backup + restore): {len(successful_tests)}") print(f"Backup only success: {len(backup_only_success)}") print(f"Complete failures: {len(failed_tests)}") if successful_tests: print(f"\nBest compression ratios (complete success):") best_compression = sorted( successful_tests, key=lambda x: x["compression_ratio"] )[:5] for test in best_compression: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Ratio: {test['compression_ratio']:.3f}, Backup: {format_minutes(test['backup_duration_seconds'])}, " f"Restore: {format_minutes(test['restore_duration_seconds'])}, Total: {format_minutes(test['total_duration_seconds'])}" ) print(f"\nFastest total time (backup + restore):") fastest_total = sorted( successful_tests, key=lambda x: x["total_duration_seconds"] )[:5] for test in fastest_total: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Total: {format_minutes(test['total_duration_seconds'])}, Ratio: {test['compression_ratio']:.3f}" ) print(f"\nFastest backup times:") fastest_backup = sorted( successful_tests, key=lambda x: x["backup_duration_seconds"] )[:5] for test in fastest_backup: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Backup: {format_minutes(test['backup_duration_seconds'])}, Restore: {format_minutes(test['restore_duration_seconds'])}" ) print(f"\nFastest restore times:") fastest_restore = sorted( successful_tests, key=lambda x: x["restore_duration_seconds"] )[:5] for test in fastest_restore: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Restore: {format_minutes(test['restore_duration_seconds'])}, Backup: {format_minutes(test['backup_duration_seconds'])}" ) if backup_only_success: print(f"\nBackup-only successes (restore failed):") for test in backup_only_success: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Backup: {format_minutes(test['backup_duration_seconds'])}, Restore Error: {test['restore_error']}" ) if failed_tests: print(f"\nComplete failures:") for test in failed_tests: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Backup Error: {test['backup_error']}" ) else: # Restore was skipped for all tests successful_tests = [r for r in results if r["backup_success"]] failed_tests = [r for r in results if not r["backup_success"]] print(f"Total tests: {len(results)}") print(f"Successful backups: {len(successful_tests)}") print(f"Failed backups: {len(failed_tests)}") print("Note: Restore tests were skipped") if successful_tests: print(f"\nBest compression ratios:") best_compression = sorted( successful_tests, key=lambda x: x["compression_ratio"] )[:5] for test in best_compression: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Ratio: {test['compression_ratio']:.3f}, Backup: {format_minutes(test['backup_duration_seconds'])}" ) print(f"\nFastest backup times:") fastest_backup = sorted( successful_tests, key=lambda x: x["backup_duration_seconds"] )[:5] for test in fastest_backup: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Backup: {format_minutes(test['backup_duration_seconds'])}, Ratio: {test['compression_ratio']:.3f}" ) if failed_tests: print(f"\nFailed backups:") for test in failed_tests: print( f" {test['tool']} {test['format']} {test['compression_method']}:{test['compression_level']} - " f"Backup Error: {test['backup_error']}" ) def print_tabular_report(): """Print a tabular report of results similar to the requested format.""" if not results: print("No results to display.") return print("\n" + "=" * 120) print("TABULAR PERFORMANCE REPORT") print("=" * 120) # Print header print( f"{'format':<20}{'backup duration mins':<20}{'restore duration mins':<25}{'total duration mins':<20}" f"{'backup size GB':<15}{'db size GB':<15}{'restored DB size GB':<20}{'db size % from original':<25}" ) print("-" * 120) # Group results by format and compression method+level for r in sorted( results, key=lambda x: (x["format"], x["compression_method"], x["compression_level"]), ): if not r["backup_success"]: continue format_str = f"{r['format']} {r['compression_method']}" if r["compression_method"] != "none": format_str += f" {r['compression_level']}" backup_mins = r["backup_duration_seconds"] / 60.0 restore_mins = r["restore_duration_seconds"] / 60.0 total_mins = backup_mins + restore_mins backup_gb = r["backup_size_bytes"] / (1024.0 * 1024.0 * 1024.0) db_gb = r["database_size_bytes"] / (1024.0 * 1024.0 * 1024.0) restored_db_gb = r["restored_db_size_bytes"] / (1024.0 * 1024.0 * 1024.0) db_size_percent = (backup_gb / db_gb) * 100 if db_gb > 0 else 0 print( f"{format_str:<20}{backup_mins:.1f}{'':<14}{restore_mins:.1f}{'':<19}{total_mins:.1f}{'':<14}" f"{backup_gb:.1f}{'':<9}{db_gb:.1f}{'':<9}{restored_db_gb:.1f}{'':<14}{db_size_percent:.0f}" ) def main(): """Main function to run pg_dump backup performance tests.""" parser = argparse.ArgumentParser( description="PostgreSQL pg_dump backup performance testing" ) parser.add_argument( "--skip-gzip", action="store_true", help="Skip gzip compression tests" ) parser.add_argument( "--skip-lz4", action="store_true", help="Skip lz4 compression tests" ) parser.add_argument( "--skip-zstd", action="store_true", help="Skip zstd compression tests" ) parser.add_argument( "--skip-restore", action="store_true", help="Skip restore tests" ) args = parser.parse_args() # Filter compression methods based on skip flags global COMPRESSION_METHODS filtered_compression_methods = ["none"] # Always include 'none' if not args.skip_gzip: filtered_compression_methods.append("gzip") if not args.skip_lz4: filtered_compression_methods.append("lz4") if not args.skip_zstd: filtered_compression_methods.append("zstd") COMPRESSION_METHODS = filtered_compression_methods log_with_timestamp("PostgreSQL pg_dump Backup Performance Testing") log_with_timestamp("=" * 60) log_with_timestamp( f"Source Database: {DB_CONFIG['database']} on {DB_CONFIG['host']}:{DB_CONFIG['port']}" ) log_with_timestamp( f"Restore Database: {RESTORE_DB_CONFIG['database']} on {RESTORE_DB_CONFIG['host']}:{RESTORE_DB_CONFIG['port']}" ) log_with_timestamp(f"Database size: {format_size(get_database_size())}") log_with_timestamp(f"Compression methods: {', '.join(COMPRESSION_METHODS)}") log_with_timestamp( f"Restore tests: {'Skipped' if args.skip_restore else 'Enabled'}" ) log_with_timestamp(f"Test started: {datetime.now()}") # Ensure backup directory is ready backup_dir = ensure_backup_directory() log_with_timestamp(f"Backup directory: {backup_dir.absolute()}") try: # Run pg_dump tests only test_pg_dump(skip_restore=args.skip_restore) # Save and display results save_results() print_summary() print_tabular_report() except KeyboardInterrupt: log_with_timestamp("\nTest interrupted by user") if results: save_results() print_summary() print_tabular_report() except Exception as e: log_with_timestamp(f"\nTest failed with error: {e}") if results: save_results() print_summary() print_tabular_report() log_with_timestamp(f"\nTest completed: {datetime.now()}") if __name__ == "__main__": main() 
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I had to remove the results for zstd with compression level 15 and zstd with compression level 22 from the charts. They breaks the charts significantly due to the long compression time, while not providing any noticeable increase in compression.

So, measurements.

Backup speed in seconds (lower is better):

Backup speed in seconds

Restore speed from backup in seconds (lower is better):

Restore speed from backup in seconds

Total time for creation and restoration from backup in seconds (lower is better):

Total backup size as a percentage of the original database size (smaller is better):

otal backup size as a percentage of the original database size

Conclusions based on measurements

Before talking about conclusions, I would like to make an important disclaimer: the test was performed on synthetic data, and the results with “real-world” data will differ significantly. The trend will be the same, but the time difference will be greater.

The measurements show that there is no radical difference in speed between the plain format, custom format and directory format on synthetic data. Despite the fact that the custom format is restored in parallel mode relative to plain, and the directory format also creates the copy itself in parallel.

The difference in speed between the custom format and plain is ~30%. Between the custom and directory formats, it is only ~20%. I would suppose that the test data lacked a sufficient number of independent tables and objects — otherwise, the gap between the formats would have been multiple times greater.

So, based on the measurements, I can make the following conclusions:

  • The fastest backup format is directory-based.

The custom format is faster than plain and tar in terms of total time under any circumstances. The directory format is faster than custom under any circumstances. If parallel mode enabled, of course.

Moreover, in terms of backup creation speed, the directory format is more than twice as fast as the custom format. This is very important, considering that <u>we make backups more often than we restore from them</u>.

  • The most useful in terms of the “speed and compression level” ratio was zstd with a compression level of 5.

In terms of backup creation speed, it is only surpassed by uncompressed formats. In terms of recovery speed, it is on average ~4% slower than other formats. At the same time, it has maximum compression comparable to gzip with compression level 9, but outperforms it in speed by ~18%. Taking into account the error margin on synthetic data.

  • zstd 15 and zstd 22 turned out to be useless in this particular test. They gave compression levels roughly the same as gzip 9, but took 2-8x times longer to produce the result.

I think that with a database of at least 1 TB without synthetic data and cold storage, they will show completely different results and may turn out to be very cost-effective (especially if you need to make hundreds of backups and store them for a long time).

Conclusion

The measurement showed that the most optimal format for my task was a custom format with zstd compression and a compression level of 5. I get the maximum total speed with almost maximum compression and a single backup file.

After implementing zstd 5 instead of gzip 6 in the project, the backup size was reduced by almost half with a slightly shorter backup time. At the same time, unlike synthetic data, a 4.7 GB database was compressed to 276 MB (17 times smaller!):

Size decrease

I hope that my test will be useful to those who develop backup tools or regularly dump databases using pg_dump scripts. Perhaps in the future, I will conduct the same test, but with a more diverse data set.

And once again, if you need to create regular backups, I have an open source project for this task. I would be extremely grateful for a star on GitHub ❤️, as the first stars are hard to come by.


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