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import time
from mcp_database_universal.engines.base import (
BaseEngine, DBInfo, ColumnInfo, TableInfo, TableDetail,
IndexInfo, ForeignKeyInfo, TableStats, QueryResult,
_named_to_pyformat,
)
class PostgresEngine(BaseEngine):
def __init__(
self,
host: str = "localhost",
port: int = 5432,
database: str = "postgres",
user: str = "",
password: str = "",
read_only: bool = True,
):
self.host = host
self.port = port
self.database = database
self.user = user
self.password = password
self._read_only = read_only
self._conn = None
async def connect(self) -> None:
try:
import psycopg
except ImportError:
raise RuntimeError(
"PostgreSQL engine requires psycopg. "
"Install with: pip install 'mcp-database-universal[postgres]'"
)
self._conn = await psycopg.AsyncConnection.connect(
host=self.host,
port=self.port,
dbname=self.database,
user=self.user,
password=self.password,
autocommit=True,
)
async def disconnect(self) -> None:
if self._conn:
await self._conn.close()
self._conn = None
def _ensure_conn(self):
if self._conn is None:
raise RuntimeError("Not connected. Call connect() first.")
return self._conn
async def get_db_info(self) -> DBInfo:
conn = self._ensure_conn()
cur = await conn.execute("SELECT version()")
row = await cur.fetchone()
version = row[0] if row else "unknown"
try:
cur = await conn.execute(
"SELECT pg_size_pretty(pg_database_size(current_database()))"
)
row2 = await cur.fetchone()
size = row2[0] if row2 else "unknown"
except Exception:
size = "unknown"
return DBInfo(engine="postgresql", version=version, name=self.database, size_approx=size)
async def get_tables(self) -> list[TableInfo]:
conn = self._ensure_conn()
cur = await conn.execute("""
SELECT t.table_name
FROM information_schema.tables t
WHERE t.table_schema = 'public' AND t.table_type = 'BASE TABLE'
ORDER BY t.table_name
""")
rows = await cur.fetchall()
tables = []
for row in rows:
name = row[0]
try:
cur = await conn.execute(f'SELECT COUNT(*) FROM "{name}"')
cnt = await cur.fetchone()
row_count = cnt[0] if cnt else 0
except Exception:
row_count = 0
try:
cur = await conn.execute("""
SELECT COUNT(*) FROM information_schema.columns
WHERE table_schema = 'public' AND table_name = %s
""", [name])
cols = await cur.fetchone()
col_count = cols[0] if cols else 0
except Exception:
col_count = 0
tables.append(TableInfo(
name=name,
row_count=row_count,
column_count=col_count,
))
return tables
async def get_table_detail(self, table: str) -> TableDetail:
conn = self._ensure_conn()
cur = await conn.execute("""
SELECT c.column_name, c.data_type, c.is_nullable, c.column_default,
CASE WHEN pk.column_name IS NOT NULL THEN true ELSE false END as is_pk
FROM information_schema.columns c
LEFT JOIN (
SELECT ku.column_name
FROM information_schema.table_constraints tc
JOIN information_schema.key_column_usage ku
ON tc.constraint_name = ku.constraint_name
WHERE tc.table_name = %s AND tc.constraint_type = 'PRIMARY KEY'
) pk ON c.column_name = pk.column_name
WHERE c.table_schema = 'public' AND c.table_name = %s
ORDER BY c.ordinal_position
""", [table, table])
col_rows = await cur.fetchall()
columns = []
pk_name = None
for c in col_rows:
is_pk = c[4]
if is_pk:
pk_name = c[0]
columns.append(ColumnInfo(
name=c[0],
type=c[1],
nullable=(c[2] == "YES"),
default=c[3],
is_primary_key=is_pk,
))
cur = await conn.execute("""
SELECT
kcu.column_name,
ccu.table_name AS foreign_table_name,
ccu.column_name AS foreign_column_name
FROM information_schema.table_constraints tc
JOIN information_schema.key_column_usage kcu
ON tc.constraint_name = kcu.constraint_name
JOIN information_schema.constraint_column_usage ccu
ON tc.constraint_name = ccu.constraint_name
WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name = %s
""", [table])
fk_rows = await cur.fetchall()
foreign_keys = []
fk_cols = set()
for fk in fk_rows:
foreign_keys.append(ForeignKeyInfo(
column=fk[0],
references_table=fk[1],
references_column=fk[2],
))
fk_cols.add(fk[0])
for col in columns:
if col.name in fk_cols:
col.is_foreign_key = True
for fk in foreign_keys:
if fk.column == col.name:
col.foreign_key_table = fk.references_table
col.foreign_key_column = fk.references_column
break
cur = await conn.execute("""
SELECT indexname, indexdef
FROM pg_indexes
WHERE tablename = %s AND schemaname = 'public'
""", [table])
idx_rows = await cur.fetchall()
indexes = []
for idx in idx_rows:
name = idx[0]
unique = "UNIQUE" in (idx[1] or "").upper()
indexes.append(IndexInfo(name=name, columns=[], unique=unique))
try:
cur = await conn.execute(f'SELECT * FROM "{table}" LIMIT 5')
sample_rows = await cur.fetchall()
if sample_rows:
cols_d = [d.name for d in cur.description] if cur.description else []
sample_data = [dict(zip(cols_d, row)) for row in sample_rows]
else:
sample_data = []
except Exception:
sample_data = []
stats = await self.get_table_stats(table)
return TableDetail(
name=table,
columns=columns,
indexes=indexes,
primary_key=pk_name,
foreign_keys=foreign_keys,
sample_data=sample_data,
stats=stats,
)
async def execute_query(self, sql: str, params: dict | None = None) -> QueryResult:
conn = self._ensure_conn()
start = time.monotonic()
try:
sql, params = self._translate_params(sql, params)
if params:
cur = await conn.execute(sql, params)
else:
cur = await conn.execute(sql)
rows = await cur.fetchall()
columns = [desc.name for desc in cur.description] if cur.description else []
elapsed = int((time.monotonic() - start) * 1000)
result_rows = [dict(zip(columns, row)) for row in rows]
return QueryResult(
columns=columns,
rows=result_rows,
row_count=len(result_rows),
truncated=False,
execution_time_ms=elapsed,
sql=sql,
)
except Exception as e:
elapsed = int((time.monotonic() - start) * 1000)
return QueryResult(
sql=sql,
execution_time_ms=elapsed,
warning=f"Error: {str(e)}",
)
async def get_sample_data(self, table: str, limit: int = 5) -> QueryResult:
return await self.execute_query(f'SELECT * FROM "{table}" LIMIT {limit}')
async def get_table_stats(self, table: str) -> TableStats:
conn = self._ensure_conn()
try:
cur = await conn.execute(f'SELECT COUNT(*) FROM "{table}"')
row = await cur.fetchone()
row_count = row[0] if row else 0
except Exception:
row_count = 0
try:
cur = await conn.execute(
"SELECT pg_size_pretty(pg_total_relation_size(%s))", [table]
)
row = await cur.fetchone()
total_size = row[0] if row else "unknown"
except Exception:
total_size = "unknown"
return TableStats(
row_count=row_count,
total_size=total_size,
)
def is_read_only(self) -> bool:
return self._read_only
|