fix(pg): run a named statement with an empty text more than once

packages/pg/lib/native/query.js

@@ -136,8 +136,9 @@ NativeQuery.prototype.submit = function (client) {
     const values = (this.values || []).map(utils.prepareValue)
 
     // check if the client has already executed this named query
-    // if so...just execute it again - skip the planning phase
-    if (client.namedQueries[this.name]) {
+    // if so...just execute it again - skip the planning phase. By presence, not truth: a
+    // named statement with an empty text is prepared all the same
+    if (client.namedQueries[this.name] !== undefined) {
       if (this.text && client.namedQueries[this.name] !== this.text) {
         const err = new Error(`Prepared statements must be unique - '${this.name}' was used for a different statement`)
         return after(err)

packages/pg/lib/query.js

@@ -183,7 +183,12 @@ class Query extends EventEmitter {
   }
 
   hasBeenParsed(connection) {
-    return this.name && (connection.parsedStatements[this.name] || connection.submittedNamedStatements[this.name])
+    // by presence, not truth: a named statement with an empty text is parsed all the same
+    return (
+      this.name &&
+      (connection.parsedStatements[this.name] !== undefined ||
+        connection.submittedNamedStatements[this.name] !== undefined)
+    )
   }
 
   handlePortalSuspended(connection) {

packages/pg/test/integration/client/empty-query-tests.js

@@ -19,3 +19,17 @@ suite.test('callback supported', function (done) {
     client.end(done)
   })
 })
+
+// the name was recorded as parsed with its empty text, and then read as not parsed at all,
+// so the second run prepared it again and the server refused the duplicate
+suite.test('a named empty statement can run more than once', async function () {
+  const client = helper.client()
+  try {
+    for (let i = 0; i < 2; i++) {
+      const result = await client.query({ text: '', name: 'empty' })
+      assert.empty(result.rows)
+    }
+  } finally {
+    await client.end()
+  }
+})