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resultset2.js
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resultset2.js
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/* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. */
/******************************************************************************
*
* You may not use the identified files except in compliance with the Apache
* License, Version 2.0 (the "License.")
*
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
* See the License for the specific language governing permissions and
* limitations under the License.
*
* NAME
* resultset2.js
*
* DESCRIPTION
* Executes a query and uses a result set to fetch batches of rows
* with getRows(). Also shows setting the prefetch size.
* Uses Oracle's sample HR schema.
*
*****************************************************************************/
var oracledb = require('oracledb');
var dbConfig = require('./dbconfig.js');
// Prefetching is a tuning feature for optimizing row transfer from
// the Oracle Database to node-oracledb with Result Sets. The default
// prefetch size is 100. The prefetch size does not affect how, or
// when, rows are returned by node-oracledb to the application.
// Buffering is handled by the underlying Oracle client libraries.
// Benchmark to choose the optimal size for each application or query.
//
//oracledb.prefetchRows = 100;
var numRows = 10; // number of rows to return from each call to getRows()
oracledb.getConnection(
{
user : dbConfig.user,
password : dbConfig.password,
connectString : dbConfig.connectString
},
function(err, connection)
{
if (err) { console.error(err.message); return; }
connection.execute(
"SELECT employee_id, last_name " +
"FROM employees " +
"WHERE ROWNUM < 25 " +
"ORDER BY employee_id",
[], // no bind variables
{
resultSet: true, // return a result set. Default is false
prefetchRows: 25 // the prefetch size can be set for each query
},
function(err, result)
{
if (err) {
console.error(err.message);
doRelease(connection);
return;
}
console.log(result);
fetchRowsFromRS(connection, result.resultSet, numRows);
});
});
function fetchRowsFromRS(connection, resultSet, numRows)
{
resultSet.getRows( // get numRows rows
numRows,
function (err, rows)
{
if (err) {
console.log(err);
doClose(connection, resultSet); // always close the result set
} else if (rows.length === 0) { // no rows, or no more rows
doClose(connection, resultSet); // always close the result set
} else if (rows.length > 0) {
console.log("fetchRowsFromRS(): Got " + rows.length + " rows");
console.log(rows);
fetchRowsFromRS(connection, resultSet, numRows);
}
});
}
function doRelease(connection)
{
connection.release(
function(err)
{
if (err) { console.error(err.message); }
});
}
function doClose(connection, resultSet)
{
resultSet.close(
function(err)
{
if (err) { console.error(err.message); }
doRelease(connection);
});
}