perf: pre allocate array instead of push item (brianc#3250)

* fix: typo

* perf: pre allocate array instead of push item

* perf: refractoring missing push

* perf: avoid useless varible declaration

* perf: short control flow

* fix: lint

* more precise bench

* fix: lint

Author: nigrosimone

packages/pg-native/bench/index.js

@@ -19,7 +19,7 @@ var warmup = function (fn, cb) {
 var native = Native()
 native.connectSync()
 
-var queryText = 'SELECT generate_series(0, 1000)'
+var queryText = 'SELECT generate_series(0, 1000) as X, generate_series(0, 1000) as Y, generate_series(0, 1000) as Z'
 var client = new pg.Client()
 client.connect(function () {
   var pure = function (cb) {
@@ -36,12 +36,12 @@ client.connect(function () {
   }
 
   var run = function () {
-    var start = Date.now()
+    console.time('pure')
     warmup(pure, function () {
-      console.log('pure done', Date.now() - start)
-      start = Date.now()
+      console.timeEnd('pure')
+      console.time('native')
       warmup(nativeQuery, function () {
-        console.log('native done', Date.now() - start)
+        console.timeEnd('native')
       })
     })
   }

packages/pg-native/lib/build-result.js

@@ -18,46 +18,43 @@ class Result {
 
   consumeFields(pq) {
     const nfields = pq.nfields()
+    this.fields = new Array(nfields)
     for (var x = 0; x < nfields; x++) {
-      this.fields.push({
+      this.fields[x] = {
         name: pq.fname(x),
         dataTypeID: pq.ftype(x),
-      })
+      }
     }
   }
 
   consumeRows(pq) {
     const tupleCount = pq.ntuples()
+    this.rows = new Array(tupleCount)
     for (var i = 0; i < tupleCount; i++) {
-      const row = this._arrayMode ? this.consumeRowAsArray(pq, i) : this.consumeRowAsObject(pq, i)
-      this.rows.push(row)
+      this.rows[i] = this._arrayMode ? this.consumeRowAsArray(pq, i) : this.consumeRowAsObject(pq, i)
     }
   }
 
   consumeRowAsObject(pq, rowIndex) {
     const row = {}
     for (var j = 0; j < this.fields.length; j++) {
-      const value = this.readValue(pq, rowIndex, j)
-      row[this.fields[j].name] = value
+      row[this.fields[j].name] = this.readValue(pq, rowIndex, j)
     }
     return row
   }
 
   consumeRowAsArray(pq, rowIndex) {
-    const row = []
+    const row = new Array(this.fields.length)
     for (var j = 0; j < this.fields.length; j++) {
-      const value = this.readValue(pq, rowIndex, j)
-      row.push(value)
+      row[j] = this.readValue(pq, rowIndex, j)
     }
     return row
   }
 
   readValue(pq, rowIndex, colIndex) {
     var rawValue = pq.getvalue(rowIndex, colIndex)
-    if (rawValue === '') {
-      if (pq.getisnull(rowIndex, colIndex)) {
-        return null
-      }
+    if (rawValue === '' && pq.getisnull(rowIndex, colIndex)) {
+      return null
     }
     const dataTypeId = this.fields[colIndex].dataTypeID
     return this._types.getTypeParser(dataTypeId)(rawValue)

packages/pg/lib/result.js

@@ -37,7 +37,7 @@ class Result {
     if (match) {
       this.command = match[1]
       if (match[3]) {
-        // COMMMAND OID ROWS
+        // COMMAND OID ROWS
         this.oid = parseInt(match[2], 10)
         this.rowCount = parseInt(match[3], 10)
       } else if (match[2]) {