使用 Nodejs 将大数据保存到 SQL 服务器的最佳方法

Question

I have a buffer data which is approximately 320MB. I am trying to save it into SQL server table from node.js.

What is the best way I can do this? When I try to insert the buffer data directly I am getting Cannot create a string longer than 0x1fffffe8 characters .

What can I do to save it?

This is my buffer data

<Buffer 53 6f 75 72 63 65 53 63 68 65 6d 61 2c 43 6f 75 6e 74 72 79 4e 61 6d 65 2c 49 44 2c 41 4d 54 5f 45 58 43 4c 5f 54 41 58 2c 41 4d 54 5f 49 4e 43 4c 5f ... 340629006 more bytes>

I am trying to save this data to database using sequelize as below

const DBMODEL = require("../../../models/SaveBufferData")

module.exports = async (req, res) => {

try{
var bufdata = req.file.buffer;

 var fdata = fs.writeFile('files/uploaded_files/' + req.body.fileName, bufdata, "utf8", function (err) {
          console.log('errrrr',err)
          stream = fs.createReadStream('files/uploaded_files/' + req.body.fileName);
          
        // Read and display the file data on console
        stream.on('data', function (chunk) {
            console.log(chunk);
        });
        stream.on('end', function(){
          console.log('stream ended')
      })
      
      stream.on('open', function(){
          console.log('File opened')
      });
        })
var response = await DBMODEL.SaveBufferData(req.body.fileId, bufdata);

} catch (error) {
   console.log('errorerror',error)
   res.status(500).json(ResponseManager(false, error.message));
 }
 

I ended up with the below error

node:buffer:669
slice: (buf, start, end) => buf.hexSlice(start, end),
                                ^

Error: Cannot create a string longer than 0x1fffffe8 characters
    at Object.slice (node:buffer:669:37)
    at Buffer.toString (node:buffer:811:14)
    at BLOB._stringify (C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\data-types.js:423:23)
    at BLOB.stringify (C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\data-types.js:22:19)
    at escape (C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\sql-string.js:40:48)
    at C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\sql-string.js:101:14
    at String.replace (<anonymous>)
    at Object.formatNamedParameters (C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\sql-string.js:96:14)
    at Object.formatNamedParameters (C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\utils.js:112:20)
    at Sequelize.query (C:\IWA-BACKEND\PRIMS-local\PRIMS - Iwa\BACKEND\node_modules\sequelize\dist\lib\sequelize.js:283:21) {
  code: 'ERR_STRING_TOO_LONG'
}

Answer 1

Looking at the call-stack, this is what I diagnose is happening:

1. You are passing a file as a buffer (from multer I guess) to the sequelize node module
2. sequelize node module is calling Blob.stringify

step 2) is where you are probably hitting node string length upper limits

Try the following to test this hypothesis

-> try this endpoint with a file of a smaller size and keep incrementing the size of the said file,

if this endpoint succeeds for smaller file sizes and fails after a certain file size is reached, we are can mention with high probability that the file to buffer to string conversion is the issue (as in we are hitting the ceiling of allowed size of string by either the node process or the system memory)