Add no_prepare option - fixes #93 and #76

Author: porsager

README.md

@@ -54,6 +54,7 @@ const sql = postgres('postgres://username:password@host:port/database', {
   max             : 10,         // Max number of connections
   idle_timeout    : 0,          // Idle connection timeout in seconds
   connect_timeout : 30,         // Connect timeout in seconds
+  no_prepare      : false,      // No automatic creation of prepared statements
   types           : [],         // Array of custom types, see more below
   onnotice        : fn          // Defaults to console.log
   onparameter     : fn          // (key, value) when server param change
@@ -532,6 +533,10 @@ Any query which was already sent over the wire will be rejected if the connectio
 
 There are no guarantees about queries executing in order unless using a transaction with `sql.begin()` or setting `max: 1`. Of course doing a series of queries, one awaiting the other will work as expected, but that's just due to the nature of js async/promise handling, so it's not necessary for this library to be concerned with ordering.
 
+## Prepared statements
+
+Prepared statements will automatically be created for any queries where it can be inferred that the query is static. This can be disabled by using the `no_prepare` option. For instance — this is useful when [using PGBouncer in `transaction mode`](https://github.com/porsager/postgres/issues/93).
+
 <details><summary><code>sql.unsafe</code> - Advanced unsafe use cases</summary>
 
 ### Unsafe queries `sql.unsafe(query, [args], [options]) -> promise`

lib/index.js

@@ -167,6 +167,7 @@ function Postgres(a, b) {
 
   function query(query, connection, xs, args) {
     query.origin = options.debug ? new Error().stack : cachedError(xs)
+    query.dynamic = query.dynamic || options.no_prepare
     if (!query.raw && (!Array.isArray(xs) || !Array.isArray(xs.raw)))
       return nested(xs, args)
 
@@ -238,7 +239,7 @@ function Postgres(a, b) {
   function fetchArrayTypes(connection) {
     return arrayTypesPromise || (arrayTypesPromise =
       new Promise((resolve, reject) => {
-        send(connection, { resolve, reject, raw: true }, `
+        send(connection, { resolve, reject, raw: true, dynamic: true }, `
           select b.oid, b.typarray
           from pg_catalog.pg_type a
           left join pg_catalog.pg_type b on b.oid = a.typelem
@@ -528,10 +529,11 @@ function parseOptions(a, b) {
     ssl             : o.ssl || url.ssl || false,
     idle_timeout    : o.idle_timeout || url.query.idle_timeout || env.PGIDLE_TIMEOUT || warn(o.timeout),
     connect_timeout : o.connect_timeout || url.query.connect_timeout || env.PGCONNECT_TIMEOUT || 30,
+    no_prepare      : o.no_prepare,
     onnotice        : o.onnotice,
     onparameter     : o.onparameter,
     transform       : Object.assign({}, o.transform),
-    connection  : Object.assign({ application_name: 'postgres.js' }, o.connection),
+    connection      : Object.assign({ application_name: 'postgres.js' }, o.connection),
     debug           : o.debug
   },
     mergeUserTypes(o.types)

tests/index.js

@@ -1048,3 +1048,15 @@ t('Insert array in sql()', async() => {
     await sql`drop table tester`
   ]
 })
+
+t('Automatically creates prepared statements', async() => {
+  const sql = postgres({ no_prepare: false })
+  const result = await sql`select * from pg_prepared_statements`
+  return [result[0].statement, 'select * from pg_prepared_statements']
+})
+
+t('no_prepare: true disables prepared transactions', async() => {
+  const sql = postgres({ no_prepare: true })
+  const result = await sql`select * from pg_prepared_statements`
+  return [0, result.count]
+})