Update PostgreSQL connection pool handling

packages/query/CHANGELOG.md

@@ -8,6 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 - Revert yargs version
 
+### Changed
+- Update how idle psql pool connections are handled (#2520)
+
 ## [2.14.0] - 2024-08-05
 ### Changed
 - Update dependencies (#2518)

packages/query/src/configure/configure.module.ts

@@ -13,10 +13,14 @@ import {debugPgClient} from './x-postgraphile/debugClient';
 async function ensurePool(poolConfig: PoolConfig): Promise<Pool> {
   const pgPool = new Pool(poolConfig);
   try {
-    await pgPool.connect();
+    const pgClient = await pgPool.connect();
+    // Release the client back to the pool as it's no longer needed
+    pgClient.release();
   } catch (e: any) {
     if (JSON.stringify(e.message).includes(CONNECTION_SSL_ERROR_REGEX)) {
       poolConfig.ssl = undefined;
+      // end the pool and recreate it without ssl
+      await pgPool.end();
       return ensurePool(poolConfig);
     }
   }

packages/query/src/graphql/graphql.module.ts

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-3.0
 
 import assert from 'assert';
+import {setInterval} from 'timers';
 import PgPubSub from '@graphile/pg-pubsub';
 import {Module, OnModuleDestroy, OnModuleInit} from '@nestjs/common';
 import {HttpAdapterHost} from '@nestjs/core';
@@ -127,6 +128,18 @@ export class GraphqlModule implements OnModuleInit, OnModuleDestroy {
     }
   }
 
+  private setupKeepAlive(pgClient) {
+    setInterval(() => {
+      (async () => {
+        try {
+          await pgClient.query('SELECT 1');
+        } catch (err) {
+          getLogger('db').error('Schema listener client keep-alive query failed: ', err);
+        }
+      })();
+    }, this.config.get('sl-keep-alive-interval'));
+  }
+
   private async createServer() {
     const app = this.httpAdapterHost.httpAdapter.getInstance();
     const httpServer = this.httpAdapterHost.httpAdapter.getHttpServer();
@@ -165,6 +178,14 @@ export class GraphqlModule implements OnModuleInit, OnModuleDestroy {
         const pgClient = await this.pgPool.connect();
         await pgClient.query(`LISTEN "${hashName(dbSchema, 'schema_channel', '_metadata')}"`);
 
+        // Set up a keep-alive interval to prevent the connection from being killed
+        this.setupKeepAlive(pgClient);
+
+        pgClient.on('error', (err: Error) => {
+          getLogger('db').error('PostgreSQL schema listener client error: ', err);
+          process.exit(1);
+        });
+
         pgClient.on('notification', (msg) => {
           if (msg.payload === 'schema_updated') {
             void this.schemaListener(dbSchema, options);

packages/query/src/yargs.ts

@@ -151,6 +151,12 @@ export function getYargsOption() {
         type: 'boolean',
         default: false,
       },
+      'sl-keep-alive-interval': {
+        demandOption: false,
+        describe: 'Schema listener keep-alive interval in milliseconds',
+        type: 'number',
+        default: 180000,
+      },
     });
 }