Batch Operations and Utilities

def execute_batch(cur, sql, argslist, page_size=100):
    """
    Execute SQL with multiple parameter sets efficiently.
    
    Parameters:
    - cur: Database cursor
    - sql (str): SQL statement with placeholders
    - argslist (sequence): Sequence of parameter tuples
    - page_size (int): Number of parameters to execute per batch
    """

def execute_values(cur, sql, argslist, template=None, page_size=100, fetch=False):
    """
    Execute INSERT with VALUES clause efficiently.
    
    Parameters:
    - cur: Database cursor
    - sql (str): SQL statement with VALUES placeholder
    - argslist (sequence): Sequence of parameter tuples
    - template (str, optional): Values template (default: %s placeholders)
    - page_size (int): Number of rows per batch
    - fetch (bool): Return results from RETURNING clause
    
    Returns:
    list: Results if fetch=True
    """

import psycopg2
from psycopg2.extras import execute_batch, execute_values

conn = psycopg2.connect("host=localhost dbname=mydb user=myuser")

# Prepare batch data
users = [
    ("Alice", "alice@example.com", 28),
    ("Bob", "bob@example.com", 32),
    ("Charlie", "charlie@example.com", 24),
    ("Diana", "diana@example.com", 30)
]

# execute_batch - efficient multiple executions
with conn.cursor() as cur:
    execute_batch(
        cur,
        "INSERT INTO users (name, email, age) VALUES (%s, %s, %s)",
        users,
        page_size=2  # Process 2 rows at a time
    )
    print(f"Inserted {cur.rowcount} users with execute_batch")

# execute_values - efficient VALUES clause insertion  
with conn.cursor() as cur:
    execute_values(
        cur,
        "INSERT INTO users (name, email, age) VALUES %s",
        users,
        template=None,  # Use default (%s, %s, %s)
        page_size=100
    )
    print(f"Inserted {cur.rowcount} users with execute_values")

# execute_values with RETURNING clause
with conn.cursor() as cur:
    results = execute_values(
        cur,
        "INSERT INTO users (name, email, age) VALUES %s RETURNING id, name",
        users,
        fetch=True
    )
    for user_id, name in results:
        print(f"Created user {name} with ID {user_id}")

# Performance comparison with large datasets
import time

large_dataset = [("User {}".format(i), f"user{i}@example.com", 25+i%40) for i in range(10000)]

# Regular executemany (slower)
start_time = time.time()
with conn.cursor() as cur:
    cur.executemany(
        "INSERT INTO users_test (name, email, age) VALUES (%s, %s, %s)",
        large_dataset
    )
executemany_time = time.time() - start_time

# execute_batch (faster)
start_time = time.time() 
with conn.cursor() as cur:
    execute_batch(
        cur,
        "INSERT INTO users_test2 (name, email, age) VALUES (%s, %s, %s)",
        large_dataset,
        page_size=1000
    )
batch_time = time.time() - start_time

# execute_values (fastest for inserts)
start_time = time.time()
with conn.cursor() as cur:
    execute_values(
        cur,
        "INSERT INTO users_test3 (name, email, age) VALUES %s",
        large_dataset,
        page_size=1000
    )
values_time = time.time() - start_time

print(f"executemany: {executemany_time:.2f}s")
print(f"execute_batch: {batch_time:.2f}s")
print(f"execute_values: {values_time:.2f}s")

conn.commit()
conn.close()

def make_dsn(dsn=None, **kwargs):
    """
    Build connection string from parameters.
    
    Parameters:
    - dsn (str, optional): Base connection string
    - **kwargs: Connection parameters to add/override
    
    Returns:
    str: Complete connection string
    """

def parse_dsn(dsn):
    """
    Parse connection string into components.
    
    Parameters:
    - dsn (str): Connection string to parse
    
    Returns:
    dict: Dictionary of connection parameters
    """

from psycopg2.extensions import make_dsn, parse_dsn

# Build connection string from parameters
dsn = make_dsn(
    host="localhost",
    port=5432,
    dbname="mydb",
    user="myuser",
    password="secret"
)
print(dsn)  # "host=localhost port=5432 dbname=mydb user=myuser password=secret"

# Add to existing DSN
base_dsn = "host=localhost dbname=mydb"
full_dsn = make_dsn(base_dsn, user="newuser", password="newpass", connect_timeout=10)
print(full_dsn)

# Parse connection string
params = parse_dsn("host=localhost port=5432 dbname=mydb user=myuser sslmode=require")
print(params)
# {'host': 'localhost', 'port': '5432', 'dbname': 'mydb', 'user': 'myuser', 'sslmode': 'require'}

# Use parsed parameters to modify connection
params['password'] = 'newsecret'
params['connect_timeout'] = '30'
new_dsn = make_dsn(**params)

# Connect using built DSN
conn = psycopg2.connect(new_dsn)

def quote_ident(name, scope=None):
    """
    Quote SQL identifier safely.
    
    Parameters:
    - name (str): Identifier name to quote
    - scope (connection/cursor, optional): Quoting context
    
    Returns:
    str: Properly quoted identifier
    """

from psycopg2.extensions import quote_ident

# Quote table and column names safely
table_name = quote_ident("user data")  # "user data"
column_name = quote_ident("email-address")  # "email-address"

# Safe dynamic query building
def build_select_query(table, columns, condition_column=None):
    """Build SELECT query with safe identifier quoting."""
    quoted_table = quote_ident(table)
    quoted_columns = [quote_ident(col) for col in columns]
    
    query = f"SELECT {', '.join(quoted_columns)} FROM {quoted_table}"
    
    if condition_column:
        quoted_condition = quote_ident(condition_column)
        query += f" WHERE {quoted_condition} = %s"
    
    return query

# Usage
query = build_select_query("user accounts", ["full name", "email-addr"], "user id")
print(query)
# SELECT "full name", "email-addr" FROM "user accounts" WHERE "user id" = %s

with conn.cursor() as cur:
    cur.execute(query, (123,))
    results = cur.fetchall()

def wait_select(conn):
    """
    Wait callback for select-based waiting.
    
    Parameters:
    - conn: Database connection
    """

def set_wait_callback(f):
    """
    Set global wait callback function.
    
    Parameters:
    - f (callable): Wait callback function
    """

def get_wait_callback():
    """
    Get current wait callback function.
    
    Returns:
    callable: Current wait callback
    """

import psycopg2
from psycopg2.extensions import set_wait_callback, get_wait_callback, wait_select
import select

# Custom wait callback with logging
def logging_wait_callback(conn):
    """Wait callback that logs polling activity."""
    print(f"Waiting for connection {conn}")
    wait_select(conn)
    print(f"Connection {conn} ready")

# Set custom wait callback
original_callback = get_wait_callback()
set_wait_callback(logging_wait_callback)

# Asynchronous connection (will use custom callback)
async_conn = psycopg2.connect(
    "host=localhost dbname=mydb user=myuser",
    async_=True
)

# Poll until connection is ready
while async_conn.poll() != psycopg2.extensions.POLL_OK:
    # Custom callback is used during polling
    pass

print("Async connection established")

# Restore original callback
set_wait_callback(original_callback)

async_conn.close()

def encrypt_password(password, user, scope=None, algorithm=None):
    """
    Encrypt password using PostgreSQL methods.
    
    Parameters:
    - password (str): Plain text password
    - user (str): Username
    - scope (connection, optional): Connection for server-side encryption
    - algorithm (str, optional): Encryption algorithm
    
    Returns:
    str: Encrypted password string
    """

from psycopg2.extensions import encrypt_password

# Client-side password encryption
encrypted = encrypt_password("mysecret", "myuser")
print(f"Encrypted password: {encrypted}")

# Use encrypted password in user management
conn = psycopg2.connect("host=localhost dbname=postgres user=admin password=adminpass")

with conn.cursor() as cur:
    # Create user with encrypted password
    cur.execute(
        "CREATE USER %s WITH PASSWORD %s",
        (psycopg2.sql.Identifier("newuser"), encrypted)
    )

conn.commit()
conn.close()

# execute_batch parameters
cur: cursor  # Database cursor
sql: str  # SQL statement with placeholders
argslist: sequence  # Sequence of parameter tuples
page_size: int  # Batch size (default: 100)

# execute_values parameters  
cur: cursor  # Database cursor
sql: str  # SQL with VALUES placeholder
argslist: sequence  # Parameter tuples sequence
template: str | None  # Values template (default: None)
page_size: int  # Batch size (default: 100)
fetch: bool  # Return results (default: False)

# make_dsn parameters
dsn: str | None  # Base DSN (default: None)
**kwargs: dict  # Connection parameters

# Connection parameter names
host: str  # Database host
port: int  # Database port
dbname: str  # Database name
user: str  # Username
password: str  # Password
sslmode: str  # SSL mode
connect_timeout: int  # Connection timeout
application_name: str  # Application name

# Wait callback function signature
def wait_callback(conn) -> None:
    """Custom wait callback for async operations."""

# Polling result constants
POLL_OK: int  # 0 - Operation complete
POLL_READ: int  # 1 - Wait for read
POLL_WRITE: int  # 2 - Wait for write  
POLL_ERROR: int  # 3 - Error occurred