Remove intermittent errors while fetching Large CLOBs

Author: sharadraju

doc/src/release_notes.rst

@@ -45,6 +45,10 @@ Common Changes
 Thin Mode Changes
 ++++++++++++++++++
 
+#)  Fix for the intermittent error ``NJS-103`` seen while fetching large number
+    of CLOB columns whose metadata is split across multiple packets.
+    `Issue #1642 <https://github.com/oracle/node-oracledb/issues/1642>`__.
+
 #)  Fixed potential cursor issues when using DRCP.
 
 #)  Fixed bug in reading PLS_INTEGER type when used in PL/SQL records.

lib/thin/protocol/messages/withData.js

@@ -148,15 +148,16 @@ class MessageWithData extends Message {
       buf.skipUB1();
     }
     resultSet.metadata = [];
+    const metadata = [];
+    const queryVars = [];
     for (let i = 0; i < statement.numQueryVars; i++) {
       const variable = this.processColumnInfo(buf, i + 1);
       if (prevQueryVars && i < prevQueryVars.length) {
         this._adjustFetchType(prevQueryVars[i], variable);
       }
-      statement.queryVars.push(variable);
-      resultSet.metadata.push(variable.fetchInfo);
+      queryVars.push(variable);
+      metadata.push(variable.fetchInfo);
     }
-
     let numBytes = buf.readUB4();
     if (numBytes > 0) {
       buf.skipBytesChunked();                   // current date
@@ -170,6 +171,13 @@ class MessageWithData extends Message {
       buf.skipBytesChunked();
     }
 
+    /*
+     * The message state(resultSet) and statement state(queryVars) is modified
+     * at end of the DescribeInfo function so that an OutOfPacketsError
+     * won't cause partial information state to be stored.
+     */
+    resultSet.metadata = metadata;
+    statement.queryVars = queryVars;
     this.resultSetsToSetup.push(resultSet);
   }
 

test/columnMetadata.js

@@ -217,22 +217,23 @@ describe('9. columnMetadata.js', function() {
   });  // 9.2
 
   describe('9.3 Large number of columns', function() {
-    function genColumns(size) {
+    function genColumns(size, dbType) {
       const  buffer = [];
       for (var  i = 0; i < size; i++) {
-        buffer[i] = " column_" + i + " NUMBER";
+        buffer[i] = " column_" + i + dbType;
       }
       return buffer.join();
     }
 
     it('9.10 works with a large number of columns', async function() {
-      const column_size = 100;
-      const columns_string = genColumns(column_size);
+      const column_size = 300;
+      let columns_string = genColumns(column_size, " NUMBER");
       const table_name = "nodb_large_columns";
       const sqlSelect = "SELECT * FROM " + table_name;
       const sqlDrop = "DROP TABLE " + table_name + " PURGE";
 
-      const proc = "BEGIN \n" +
+      function generateProcedure() {
+        return "BEGIN \n" +
                "    DECLARE \n" +
                "        e_table_missing EXCEPTION; \n" +
                "        PRAGMA EXCEPTION_INIT(e_table_missing, -00942);\n " +
@@ -248,10 +249,25 @@ describe('9. columnMetadata.js', function() {
                "        ) \n" +
                "    '); \n" +
                "END; ";
+      }
 
-      await connection.execute(proc);
-      const result = await connection.execute(sqlSelect);
-      for (var i = 0; i < column_size; i++) {
+      // check NUMBER type column
+      await connection.execute(generateProcedure());
+
+      // Dont cache statment as we re-run with different
+      // column type with same table.
+      let result = await connection.execute(sqlSelect, [],
+        { keepInStmtCache: false });
+      for (let i = 0; i < column_size; i++) {
+        assert.strictEqual(result.metaData[i].name, 'COLUMN_' + i);
+      }
+      await connection.execute(sqlDrop);
+
+      // check CLOB type (GH Issue 1642)
+      columns_string = genColumns(column_size, " CLOB");
+      await connection.execute(generateProcedure());
+      result = await connection.execute(sqlSelect);
+      for (let i = 0; i < column_size; i++) {
         assert.strictEqual(result.metaData[i].name, 'COLUMN_' + i);
       }
       await connection.execute(sqlDrop);