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Fix get_table_bloat_info and list_user_permissions SQL error of MCP server #2064

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Fix get_table_bloat_info and list_user_permissions SQL error of MCP server #2064

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27 changes: 15 additions & 12 deletions mcp-server/src/cbmcp/database.py
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Original file line number Diff line number Diff line change
Expand Up @@ -416,13 +416,15 @@ async def list_user_permissions(self, username: str) -> list[dict]:
"n.nspname as schema_name, "
"c.relname as object_name, "
"c.relkind as object_type, "
"p.perm as permission "
"p.privilege_type as permission "
"FROM pg_class c "
"JOIN pg_namespace n ON n.oid = c.relnamespace "
"CROSS JOIN LATERAL aclexplode(c.relacl) p "
"WHERE p.grantee = (SELECT oid FROM pg_user WHERE usename = $1) "
"CROSS JOIN LATERAL aclexplode(coalesce(c.relacl, "
"acldefault((CASE WHEN c.relkind = 'S' THEN 's' ELSE 'r' END)::\"char\", c.relowner))) p "
"WHERE p.grantee = (SELECT usesysid FROM pg_user WHERE usename = $1) "

@MisterRaindrop MisterRaindrop Sep 30, 2026

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Could we also handle a NULL relacl here? For a newly created table, relacl is normally NULL, which means the object has its default privileges rather than no privileges. aclexplode(c.relacl) therefore produces no rows, so this function can still report no permissions for the table owner.

information_schema.table_privileges handles this with aclexplode(coalesce(relacl, acldefault('r', relowner))). Could we apply equivalent handling here? It would also be helpful to clarify whether this function is intended to return only direct grants or effective permissions including PUBLIC and inherited role privileges.

@fairyfar fairyfar Oct 8, 2026

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Good catch! I've fixed this.

"AND c.relkind IN ('r', 'v', 'm', 'f', 'p', 'S') "
"AND n.nspname NOT LIKE 'pg_%' "
"ORDER BY n.nspname, c.relname",
"ORDER BY n.nspname, c.relname, p.privilege_type",
username
)
return [
Expand Down Expand Up @@ -643,15 +645,16 @@ async def get_table_bloat_info(self) -> list[dict]:
async with self.get_connection() as conn:
records = await conn.fetch(
"SELECT "
"schemaname, "
"relname as tablename, "
"pg_size_pretty(pg_total_relation_size(schemaname||'.'||relname)) as total_size, "
"round(100 * (relpages - (relpages * fillfactor / 100)) / relpages, 2) as bloat_ratio "
"FROM pg_class c "
"n.nspname AS schemaname, "
"c.relname AS tablename, "
"pg_size_pretty(pg_total_relation_size(c.oid)) AS total_size, "
"round(100.0 * s.n_dead_tup / GREATEST(s.n_live_tup + s.n_dead_tup, 1), 2)::float8 AS bloat_ratio "
"FROM pg_stat_user_tables s "
"JOIN pg_class c ON c.oid = s.relid "
"JOIN pg_namespace n ON n.oid = c.relnamespace "
"JOIN pg_stat_user_tables s ON s.relid = c.oid "
"WHERE c.relkind = 'r' AND n.nspname NOT LIKE 'pg_%' "
"ORDER BY bloat_ratio DESC "
"WHERE c.relkind = 'r' "
"AND n.nspname NOT LIKE 'pg_%' "
"ORDER BY bloat_ratio DESC, n.nspname, c.relname "
"LIMIT 20"
)
return [
Expand Down
2 changes: 1 addition & 1 deletion mcp-server/tests/test_cbmcp.py
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Original file line number Diff line number Diff line change
Expand Up @@ -236,7 +236,7 @@ async def test_get_index_usage(self, client):
async def test_get_table_bloat_info(self, client):
"""Test getting table bloat information"""
try:
result = await client.call_tool("get_table_bloat_info", {"schema": "public", "limit": 5})
result = await client.call_tool("get_table_bloat_info", {})
assert result is not None
assert hasattr(result, 'structured_content')
except Exception as e:
Expand Down
5 changes: 1 addition & 4 deletions mcp-server/tests/test_database_tools.py
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Original file line number Diff line number Diff line change
Expand Up @@ -145,10 +145,7 @@ async def test_get_index_usage(self, client):
async def test_get_table_bloat_info(self, client):
"""Test table bloat information"""
try:
result = await client.call_tool("get_table_bloat_info", {
"schema": "public",
"limit": 5
})
result = await client.call_tool("get_table_bloat_info", {})
assert result is not None
assert hasattr(result, 'structured_content')
except Exception as e:
Expand Down
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