Why is my Apps Script deletion loop running so slowly? Can I improve performance?

问题

My company collects manufacturing data a few dozen times a day through Google Form responses. Right now the Sheet I'll be referencing is near 10,000 rows. Recently I frankensteined some Google Apps Script code (from other SO threads and forums) to delete rows from a large spreadsheet that are older than 7 days. During trials (on a copy of the Sheet) the script deleted 3-4 rows per second. Now, the code is deleting only one row every 7-8 seconds. I don't know why my code is running so slowly. Is there something wrong with my loop?

I've tried this code on a couple of other Sheets during development and it worked perfectly fine. When the script was first applied to the target Sheet it operated as expected. However, when I went to run it again a few days ago the script executed extremely slowly.

The function that deletes the rows is triggered by a custom menu option that is loaded once the Sheet is opened in the browser.

function onOpen() {
  SpreadsheetApp.getUi()
                .createMenu('Delete')
                .addItem('Delete Rows Older than 7 Days', 'deleteOldEntries')
                .addToUi();
}

function deleteOldEntries() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getSheetByName("Form Responses 1");    //name of the sheet
  //var sheet = ss.getActiveSheet();
  var datarange = sheet.getDataRange();
  var lastrow = datarange.getLastRow();
  var values = datarange.getValues();   //get all data in a 2D array

  var currentDate = new Date();   //today
  var weekOld = Date.now() + -7*24*3600*1000;   //for dates longer than 7 days, change only the 7 to a higher number
  for (i=lastrow;i>=2;i--) {
    var tempDate = values[i-1][0];  //2D arrays are organized as [row][column]; arrays are 0 indexed so row1 = values[0] and col12 = [11]
    if ((tempDate!="") && (tempDate <= (weekOld)))
    {
      sheet.deleteRow(i);
    }
  }
}

I expect the performance to at least be a few rows per second, but actual performance has slowed to 6-7 rows per minute. The script times out at 30 minutes, which is a preset time limit by Google (if I'm not mistaken).

Thanks in advance!

EDIT: Here is the partial Execution Transcript from the last run of the code (the whole execution transcript was quite long). Almost all entries from the last run, conducted this morning, seem to be just above 4 seconds.

[19-05-31 08:57:24:875 EDT] Sheet.deleteRow([5681]) [4.048 seconds]
[19-05-31 08:57:29:295 EDT] Sheet.deleteRow([5680]) [4.419 seconds]
[19-05-31 08:57:34:013 EDT] Sheet.deleteRow([5679]) [4.718 seconds]
[19-05-31 08:57:38:561 EDT] Sheet.deleteRow([5678]) [4.547 seconds]
[19-05-31 08:57:42:991 EDT] Sheet.deleteRow([5677]) [4.43 seconds]
[19-05-31 08:57:47:599 EDT] Sheet.deleteRow([5676]) [4.607 seconds]
[19-05-31 08:57:52:122 EDT] Sheet.deleteRow([5675]) [4.522 seconds]
[19-05-31 08:57:56:683 EDT] Sheet.deleteRow([5674]) [4.56 seconds]
[19-05-31 08:58:00:950 EDT] Sheet.deleteRow([5673]) [4.266 seconds]
[19-05-31 08:58:05:450 EDT] Sheet.deleteRow([5672]) [4.5 seconds]
[19-05-31 08:58:10:349 EDT] Sheet.deleteRow([5671]) [4.898 seconds]
[19-05-31 08:58:14:736 EDT] Sheet.deleteRow([5670]) [4.387 seconds]
[19-05-31 08:58:19:697 EDT] Sheet.deleteRow([5669]) [4.96 seconds]
[19-05-31 08:58:28:412 EDT] Sheet.deleteRow([5668]) [8.714 seconds]
[19-05-31 08:58:33:601 EDT] Sheet.deleteRow([5667]) [5.189 seconds]
[19-05-31 08:58:38:845 EDT] Sheet.deleteRow([5666]) [5.243 seconds]
[19-05-31 08:58:43:313 EDT] Sheet.deleteRow([5665]) [4.468 seconds]
[19-05-31 08:58:47:964 EDT] Sheet.deleteRow([5664]) [4.65 seconds]
[19-05-31 08:58:52:947 EDT] Sheet.deleteRow([5663]) [4.982 seconds]
[19-05-31 08:58:58:172 EDT] Sheet.deleteRow([5662]) [5.223 seconds]
[19-05-31 08:59:03:036 EDT] Sheet.deleteRow([5661]) [4.864 seconds]
[19-05-31 08:59:07:957 EDT] Sheet.deleteRow([5660]) [4.92 seconds]
[19-05-31 08:59:12:727 EDT] Sheet.deleteRow([5659]) [4.769 seconds]
[19-05-31 08:59:12:800 EDT] Execution failed: Exceeded maximum execution time [1,803.124 seconds total runtime]

回答1:

You need to use batch operations.

Snippet:

  var thisBatch = 0;//added
  for (i=lastrow;i>=2;i--) {
    var tempDate = values[i-1][0];  
    if ((tempDate!="") && (tempDate <= (weekOld)))
    {
        ++thisBatch;//increment this batch
    } else if(thisBatch){ // previous batch ended
        sheet.deleteRows(i+1, thisBatch); //delete next row and all of that batch 
        thisBatch = 0;
    }
  }
 thisBatch ? sheet.deleteRows(i+1, thisBatch) : null;//to remove any batch after remaining after end of loop

If that's still slow, you need to use Advanced Google services to access the sheets api and issue Delete Dimension Request. Also trim your sheet by deleting all empty rows at the bottom of the sheet manually.

来源：https://stackoverflow.com/questions/56395779/why-is-my-apps-script-deletion-loop-running-so-slowly-can-i-improve-performance

标签

performance

google-apps-script

google-sheets