Fix #5678 (#5681)

* Fix #5678

* Revert "Fix #5678"

This reverts commit 106b6ddd9535da6ec323226c1b9ad649022aeb1e.

* revert #5627

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -778,8 +778,6 @@ const buildWhereClause = ({ schema, query, index }): WhereClause => {
 
 export class PostgresStorageAdapter implements StorageAdapter {
   canSortOnJoinTables: boolean;
-  databaseVersion: string;
-  engine: string;
 
   // Private
   _collectionPrefix: string;
@@ -792,7 +790,6 @@ export class PostgresStorageAdapter implements StorageAdapter {
     this._client = client;
     this._pgp = pgp;
     this.canSortOnJoinTables = false;
-    this.engine = 'PostgreSQL';
   }
 
   handleShutdown() {
@@ -2279,12 +2276,6 @@ export class PostgresStorageAdapter implements StorageAdapter {
       })
       .then(data => {
         debug(`initializationDone in ${data.duration}`);
-        // databaseVersion
-        return this._client.query('SHOW server_version');
-      })
-      .then(versionData => {
-        // versionData is like [ { server_version: '11.3' } ]
-        this.databaseVersion = versionData[0].server_version;
       })
       .catch(error => {
         /* eslint-disable no-console */