From 54b65446ec543edcd259ca7ae5a29f3beaeded22 Mon Sep 17 00:00:00 2001
From: Andrey Avtomonov <andreybavt@gmail.com>
Date: Sun, 24 May 2026 00:57:11 +0200
Subject: [PATCH] feat(connectors): add postgres maxConnections

---
 .../src/connectors/postgres/connector.test.ts | 42 ++++++++++++++++++-
 .../cli/src/connectors/postgres/connector.ts  | 26 +++++++++++-
 2 files changed, 66 insertions(+), 2 deletions(-)

diff --git a/packages/cli/src/connectors/postgres/connector.test.ts b/packages/cli/src/connectors/postgres/connector.test.ts
index 346c2ef2..052a589e 100644
--- a/packages/cli/src/connectors/postgres/connector.test.ts
+++ b/packages/cli/src/connectors/postgres/connector.test.ts
@@ -1,6 +1,6 @@
 import { describe, expect, it, vi } from 'vitest';
 import { createPostgresLiveDatabaseIntrospection } from '../../connectors/postgres/live-database-introspection.js';
-import { isKtxPostgresConnectionConfig, KtxPostgresScanConnector, postgresPoolConfigFromConfig, type KtxPostgresPoolFactory } from '../../connectors/postgres/connector.js';
+import { isKtxPostgresConnectionConfig, KtxPostgresScanConnector, postgresPoolConfigFromConfig, type KtxPostgresConnectionConfig, type KtxPostgresPoolFactory } from '../../connectors/postgres/connector.js';
 import { tableRefSet } from '../../context/scan/table-ref.js';
 
 interface FakeQueryResult {
@@ -154,6 +154,46 @@ describe('KtxPostgresScanConnector', () => {
     });
   });
 
+  it('defaults and validates Postgres maxConnections', () => {
+    const baseConnection: KtxPostgresConnectionConfig = {
+      driver: 'postgres',
+      host: 'db.example.test',
+      database: 'analytics',
+      username: 'reader',
+      password: 'test-password', // pragma: allowlist secret
+    };
+
+    expect(
+      postgresPoolConfigFromConfig({
+        connectionId: 'warehouse',
+        connection: baseConnection,
+      }),
+    ).toMatchObject({ max: 10 });
+
+    expect(
+      postgresPoolConfigFromConfig({
+        connectionId: 'warehouse',
+        connection: { ...baseConnection, maxConnections: 50 },
+      }),
+    ).toMatchObject({ max: 50 });
+
+    expect(
+      postgresPoolConfigFromConfig({
+        connectionId: 'warehouse',
+        connection: { ...baseConnection, maxConnections: '12' as never },
+      }),
+    ).toMatchObject({ max: 12 });
+
+    for (const maxConnections of [0, -1, 1.5, Number.NaN, 'abc' as never]) {
+      expect(() =>
+        postgresPoolConfigFromConfig({
+          connectionId: 'warehouse',
+          connection: { ...baseConnection, maxConnections },
+        }),
+      ).toThrow('connections.warehouse.maxConnections must be a positive integer');
+    }
+  });
+
   it('introspects schemas, tables, views, primary keys, comments, row counts, and foreign keys', async () => {
     const connector = new KtxPostgresScanConnector({
       connectionId: 'warehouse',
diff --git a/packages/cli/src/connectors/postgres/connector.ts b/packages/cli/src/connectors/postgres/connector.ts
index 5cb94bf4..9cf35799 100644
--- a/packages/cli/src/connectors/postgres/connector.ts
+++ b/packages/cli/src/connectors/postgres/connector.ts
@@ -43,6 +43,7 @@ export interface KtxPostgresConnectionConfig {
   sslmode?: string;
   sslMode?: string;
   rejectUnauthorized?: boolean;
+  maxConnections?: number;
   [key: string]: unknown;
 }
 
@@ -242,6 +243,23 @@ function numberValue(value: unknown): number | undefined {
   return typeof value === 'number' && Number.isFinite(value) ? value : undefined;
 }
 
+function positiveIntegerConfigValue(input: {
+  connection: KtxPostgresConnectionConfig;
+  key: keyof KtxPostgresConnectionConfig;
+  connectionId: string;
+  defaultValue: number;
+}): number {
+  const value = input.connection[input.key];
+  if (value === undefined) {
+    return input.defaultValue;
+  }
+  const numberValue = Number(value);
+  if (!Number.isInteger(numberValue) || numberValue < 1) {
+    throw new Error(`connections.${input.connectionId}.${String(input.key)} must be a positive integer`);
+  }
+  return numberValue;
+}
+
 function parsePostgresUrl(url: string): Partial<KtxPostgresConnectionConfig> {
   const parsed = new URL(url);
   const sslmode = parsed.searchParams.get('sslmode') ?? undefined;
@@ -299,6 +317,12 @@ export function postgresPoolConfigFromConfig(input: {
   const user = stringConfigValue(merged, 'username', env) ?? stringConfigValue(merged, 'user', env);
   const password = stringConfigValue(merged, 'password', env);
   const sslmode = normalizedSslMode(merged);
+  const maxConnections = positiveIntegerConfigValue({
+    connection: merged,
+    key: 'maxConnections',
+    connectionId: input.connectionId,
+    defaultValue: 10,
+  });
 
   if (!referencedUrl && !host) {
     throw new Error(`Native PostgreSQL connector requires connections.${input.connectionId}.host or url`);
@@ -311,7 +335,7 @@ export function postgresPoolConfigFromConfig(input: {
   }
 
   const config: KtxPostgresPoolConfig = {
-    max: 10,
+    max: maxConnections,
     idleTimeoutMillis: 30_000,
     connectionTimeoutMillis: 10_000,
     ...(referencedUrl && sslmode !== 'prefer' && sslmode !== 'disable'