Optionally disable fetching of array types. (#205)

* Optionally disable fetching of array types.

* Document fetch_array_types

Author: JAForbes

README.md

@@ -71,6 +71,8 @@ const sql = postgres('postgres://username:password@host:port/database', {
   },
   target_session_attrs : null   // Use 'read-write' with multiple hosts to 
                                 // ensure only connecting to primary
+  fetch_array_types    : true   // Disable automatically fetching array types
+                                // on initial connection.
 })
 ```
 
@@ -96,6 +98,14 @@ Connecting to the specified hosts/ports will be tried in order, and on a success
 
 If you specify `target_session_attrs: 'read-write'` or `PGTARGETSESSIONATTRS=read-write` Postgres.js will only connect to a writeable host allowing for zero down time failovers.
 
+### Auto fetching of array types
+
+When Postgres.js first connects to the database it automatically fetches array type information.  
+
+If you have revoked access to `pg_catalog` this feature will no longer work and will need to be disabled.  
+
+You can disable fetching array types by setting `fetch_array_types` to `false` when creating an instance.
+
 ### Environment Variables for Options
 
 It is also possible to connect to the database without a connection string or any options. Postgres.js will fall back to the common environment variables used by `psql` as in the table below:

lib/index.js

@@ -62,7 +62,7 @@ function Postgres(a, b) {
 
   let ready = false
     , ended = null
-    , arrayTypesPromise
+    , arrayTypesPromise = options.fetch_types ? null : Promise.resolve([])
     , slots = max
     , listener
 
@@ -567,7 +567,8 @@ function parseOptions(a, b) {
     transform       : Object.assign({}, o.transform),
     connection      : Object.assign({ application_name: 'postgres.js' }, o.connection),
     target_session_attrs: o.target_session_attrs || url.query.target_session_attrs || env.PGTARGETSESSIONATTRS,
-    debug           : o.debug
+    debug           : o.debug,
+    fetch_types     : 'fetch_types' in o ? o.fetch_types : true
   },
     mergeUserTypes(o.types)
   )