agmission/Development/server/docs/APPLICATION_DETAIL_SCHEMA_CHANGES.md

Application Detail Schema Changes

Removed Fields

createdDate Field (Removed)

• Reason: Redundant with MongoDB ObjectId timestamp
• Storage Impact: Saves ~8+GB storage (and 14+GB indexes) on billion+ documents
• Index Impact: Eliminates unnecessary index maintenance

Migration Guide

Getting Creation Time

Instead of using createdDate, extract timestamp from _id:

// Old way:
const createdDate = appDetail.createdDate;

// New way:
const createdDate = appDetail._id.getTimestamp();

// Using utility function:
const utils = require('../helpers/utils');
const createdDate = utils.getDateTSFromObjectId(appDetail._id);

Time-based Queries

Use ObjectId ranges for time-based filtering:

const mongoose = require('mongoose');

// Create ObjectId from date
function createObjectIdFromDate(date) {
  const timestamp = Math.floor(new Date(date).getTime() / 1000);
  return new mongoose.Types.ObjectId(timestamp.toString(16) + '0000000000000000');
}

// Query by date range
const startObjectId = createObjectIdFromDate(startDate);
const endObjectId = createObjectIdFromDate(endDate);

const results = await AppDetail.find({
  _id: { $gte: startObjectId, $lt: endObjectId }
});

Updated Files

• model/application_detail.js - Removed createdDate field and index
• scripts/cleanOrphanedAppDetails.js - Updated to use _id.getTimestamp()
• helpers/utils.js - Added getDateTSFromObjectId() utility function

Performance Benefits

• Storage: ~8+GB (and 14+GB indexes) saved on billion documents
• Write Performance: Reduced index maintenance overhead
• Query Performance: Uses existing _id index for time queries