[PECO-1260] Support results compression (#216)

* [PECO-1260] Support results compression

Signed-off-by: Levko Kravets <levko.ne@gmail.com>

* Fix existing tests

Signed-off-by: Levko Kravets <levko.ne@gmail.com>

* Add tests

Signed-off-by: Levko Kravets <levko.ne@gmail.com>

* Rename option to align with other connectors

Signed-off-by: Levko Kravets <levko.ne@gmail.com>

---------

Signed-off-by: Levko Kravets <levko.ne@gmail.com>

Author: kravets-levko

lib/DBSQLClient.ts

@@ -84,6 +84,8 @@ export default class DBSQLClient extends EventEmitter implements IDBSQLClient, I
 
       useCloudFetch: false,
       cloudFetchConcurrentDownloads: 10,
+
+      useLZ4Compression: true,
     };
   }
 

lib/DBSQLOperation/index.ts

@@ -377,14 +377,14 @@ export default class DBSQLOperation implements IOperation {
         case TSparkRowSetType.ARROW_BASED_SET:
           resultSource = new ArrowResultConverter(
             this.context,
-            new ArrowResultHandler(this.context, this._data, metadata.arrowSchema),
+            new ArrowResultHandler(this.context, this._data, metadata.arrowSchema, metadata.lz4Compressed),
             metadata.schema,
           );
           break;
         case TSparkRowSetType.URL_BASED_SET:
           resultSource = new ArrowResultConverter(
             this.context,
-            new CloudFetchResultHandler(this.context, this._data),
+            new CloudFetchResultHandler(this.context, this._data, metadata.lz4Compressed),
             metadata.schema,
           );
           break;

lib/DBSQLSession.ts

@@ -184,6 +184,7 @@ export default class DBSQLSession implements IDBSQLSession {
       ...getArrowOptions(clientConfig),
       canDownloadResult: options.useCloudFetch ?? clientConfig.useCloudFetch,
       parameters: getQueryParameters(this.sessionHandle, options.namedParameters, options.ordinalParameters),
+      canDecompressLZ4Result: clientConfig.useLZ4Compression,
     });
     const response = await this.handleResponse(operationPromise);
     const operation = this.createOperation(response);

lib/contracts/IClientContext.ts

@@ -15,6 +15,8 @@ export interface ClientConfig {
 
   useCloudFetch: boolean;
   cloudFetchConcurrentDownloads: number;
+
+  useLZ4Compression: boolean;
 }
 
 export default interface IClientContext {

lib/result/ArrowResultHandler.ts

@@ -1,4 +1,4 @@
-import { Buffer } from 'buffer';
+import LZ4 from 'lz4';
 import { TRowSet } from '../../thrift/TCLIService_types';
 import IClientContext from '../contracts/IClientContext';
 import IResultsProvider, { ResultsProviderFetchNextOptions } from './IResultsProvider';
@@ -10,10 +10,18 @@ export default class ArrowResultHandler implements IResultsProvider<Array<Buffer
 
   private readonly arrowSchema?: Buffer;
 
-  constructor(context: IClientContext, source: IResultsProvider<TRowSet | undefined>, arrowSchema?: Buffer) {
+  private readonly isLZ4Compressed: boolean;
+
+  constructor(
+    context: IClientContext,
+    source: IResultsProvider<TRowSet | undefined>,
+    arrowSchema?: Buffer,
+    isLZ4Compressed?: boolean,
+  ) {
     this.context = context;
     this.source = source;
     this.arrowSchema = arrowSchema;
+    this.isLZ4Compressed = isLZ4Compressed ?? false;
   }
 
   public async hasMore() {
@@ -31,9 +39,9 @@ export default class ArrowResultHandler implements IResultsProvider<Array<Buffer
     const rowSet = await this.source.fetchNext(options);
 
     const batches: Array<Buffer> = [];
-    rowSet?.arrowBatches?.forEach((arrowBatch) => {
-      if (arrowBatch.batch) {
-        batches.push(arrowBatch.batch);
+    rowSet?.arrowBatches?.forEach(({ batch }) => {
+      if (batch) {
+        batches.push(this.isLZ4Compressed ? LZ4.decode(batch) : batch);
       }
     });
 

lib/result/CloudFetchResultHandler.ts

@@ -1,4 +1,4 @@
-import { Buffer } from 'buffer';
+import LZ4 from 'lz4';
 import fetch, { RequestInfo, RequestInit } from 'node-fetch';
 import { TRowSet, TSparkArrowResultLink } from '../../thrift/TCLIService_types';
 import IClientContext from '../contracts/IClientContext';
@@ -9,13 +9,16 @@ export default class CloudFetchResultHandler implements IResultsProvider<Array<B
 
   private readonly source: IResultsProvider<TRowSet | undefined>;
 
+  private readonly isLZ4Compressed: boolean;
+
   private pendingLinks: Array<TSparkArrowResultLink> = [];
 
   private downloadTasks: Array<Promise<Buffer>> = [];
 
-  constructor(context: IClientContext, source: IResultsProvider<TRowSet | undefined>) {
+  constructor(context: IClientContext, source: IResultsProvider<TRowSet | undefined>, isLZ4Compressed?: boolean) {
     this.context = context;
     this.source = source;
+    this.isLZ4Compressed = isLZ4Compressed ?? false;
   }
 
   public async hasMore() {
@@ -42,7 +45,12 @@ export default class CloudFetchResultHandler implements IResultsProvider<Array<B
     }
 
     const batch = await this.downloadTasks.shift();
-    return batch ? [batch] : [];
+    const batches = batch ? [batch] : [];
+
+    if (this.isLZ4Compressed) {
+      return batches.map((buffer) => LZ4.decode(buffer));
+    }
+    return batches;
   }
 
   private async downloadLink(link: TSparkArrowResultLink): Promise<Buffer> {