3. Initializing node-oracledb

By default, node-oracledb runs in a ‘Thin’ mode which connects directly to Oracle Database. This mode does not need Oracle Client libraries. However, when the driver does use these libraries to communicate to Oracle Database, then node-oracledb is said to be in ‘Thick’ mode and has additional functionality available. See node-oracledb Thick Mode Architecture for the architecture diagram.

3.1. Enabling node-oracledb Thick Mode

To change from the default Thin mode to the Thick mode:

• Oracle Client libraries must be available. These need to be installed separately, see Installing node-oracledb.

  Various versions of Oracle Client libraries can be used. They do not have to match the version of Oracle Database. Node-oracledb can use the Client Libraries from:

  • an installation of Oracle Instant Client

  • or a full Oracle Client installation (installed by running the Oracle Universal installer runInstaller)

  • or an Oracle Database installation, if Node.js is running on the same machine as the database

• Your application must call the synchronous function oracledb.initOracleClient(), for example:

  const oracledb = require('oracledb');
  
  let clientOpts = {};
  if (process.platform === 'win32') {
    // Windows
    // If you use backslashes in the libDir string, you will
    // need to double them.
    clientOpts = { libDir: 'C:\\oracle\\instantclient_19_19' };
  } else if (process.platform === 'darwin' && process.arch === 'x64') {
    // macOS Intel
    clientOpts = { libDir: process.env.HOME + '/Downloads/instantclient_19_8' };
  }
  // else on other platforms like Linux the system library search path MUST always be
  // set before Node.js is started, for example with ldconfig or LD_LIBRARY_PATH.
  
  // enable node-oracledb Thick mode
  oracledb.initOracleClient(clientOpts);
  

  More details and options are shown in the later sections Enabling node-oracledb Thick Mode on Windows, Enabling node-oracledb Thick Mode on macOS, and Enabling node-oracledb Thick Mode on Linux and Related Platforms.

All connections in an application use the same mode.

Once the Thick mode is enabled, you cannot go back to the Thin mode except by removing calls to initOracleClient() and restarting the application.

See Finding the node-oracledb Mode to verify which mode is in use.

Notes on calling initOracleClient()

• The initOracleClient() function must be called before any standalone connection or connection pool is created. If a connection or pool is first created, then the Thick mode cannot be enabled.

• If you call initOracleClient() with a libDir attribute, the Oracle Client libraries are loaded immediately from that directory. If you call initOracleClient() but do not set the libDir attribute, the Oracle Client libraries are loaded immediately using the search heuristics discussed in later sections.

• If Oracle Client libraries cannot be loaded, then initOracleClient() will return an error DPI-1047: Cannot locate a 64-bit Oracle Client library. To resolve this, review the platform-specific instructions below. Alternatively, remove the call to initOracleClient() and use Thin mode. The features supported by Thin mode can be found in Oracle Database Features Supported by node-oracledb.

• If you set libDir on Linux and related platforms, you must still have configured the system library search path to include that directory before starting Node.js.

• On any operating system, if you set libDir to the library directory of a full database or full client installation (such as from running runInstaller), you will need to have previously set the Oracle environment, for example by setting the ORACLE_HOME environment variable. Otherwise you will get errors like ORA-1804. You should set this variable, and other Oracle environment variables, before starting Node.js, as shown in Oracle Environment Variables.

• The initOracleClient() function may be called multiple times in your application but must always pass the same arguments.

3.1.1. Enabling node-oracledb Thick Mode on Windows

On Windows, the alternative ways to enable Thick mode are:

• By passing the libDir parameter in a call to initOracleClient(), for example:

  const oracledb = require('oracledb');
  oracledb.initOracleClient({libDir: 'C:\\oracle\\instantclient_19_18'});
  

  If you use backslashes in the libDir string, you will need to double them.

  This directory should contain the libraries from an unzipped Instant Client ‘Basic’ or ‘Basic Light’ package. If you pass the library directory from a full client or database installation, such as Oracle Database “XE” Express Edition, then you will need to have previously set your environment to use that software installation otherwise files such as message files will not be located.

• Alternatively, copy the Oracle Instant Client libraries to the node_modules/oracledb/build/Release directory where the oracledb*.node binary is. This directory should contain the libraries from an unzipped Instant Client ‘Basic’ or ‘Basic Light’ package.

  Update your application to call oracledb.initOracleClient() which enables Thick mode:

  const oracledb = require('oracledb');
  oracledb.initOracleClient();
  

• Alternatively, add the Oracle Client library directory to the PATH environment variable. If you are running Node.js on the same machine as your database, and node-oracledb can therefore use the client libraries that are available in the Oracle Database software, this variable may already be set correctly. The directory must occur in PATH before any other Oracle directories. Restart any open command prompt windows.

  Update your application to call oracledb.initOracleClient() which enables Thick mode:

  const oracledb = require('oracledb');
  oracledb.initOracleClient();
  

• Alternatively, use SET to change your PATH in each command prompt window before you run node.

• Another way to set the PATH variable is to use a batch file that sets this variable before Node.js is executed, for example:

  REM mynode.bat
  SET PATH=C:\oracle\instantclient_19_18;%PATH%
  node %*
  

  Invoke this batch file every time you want to run Node.js.

  Update your application to call oracledb.initOracleClient() which enables Thick mode:

  const oracledb = require('oracledb');
  oracledb.initOracleClient();
  

3.1.2. Enabling node-oracledb Thick Mode on macOS

On macOS, the alternative ways to enable Thick mode are:

• By passing the libDir parameter in a call to initOracleClient().

  const oracledb = require('oracledb');
  oracledb.initOracleClient({libDir: process.env.HOME + '/Downloads/instantclient_19_8'});
  

  This directory should contain the libraries from an unzipped Instant Client ‘Basic’ or ‘Basic Light’ package.

• Alternatively, you can call initOracleClient() without passing a libDir parameter.

  const oracledb = require('oracledb');
  oracledb.initOracleClient();
  

  In this case, the Oracle Client libraries are first looked for in the directory where the oracledb*.node binary is. For example in node_modules/oracledb/build/Release. This directory should contain the libraries from an unzipped Instant Client ‘Basic’ or ‘Basic Light’ package. For example, use ln -s ~/Downloads/instantclient_19_8/libclntsh.dylibnode_modules/oracledb/build/Release/.

  If the libraries are not found, the library search path such as set in DYLD_LIBRARY_PATH (note this variable does not propagate to sub-shells) or files in /usr/local/lib may be used.

• Alternatively, create a symbolic link for the ‘client shared library’ in the node_modules/oracledb/build/Release directory where the oracledb*.node binary is. For example:

  ln -s ~/Downloads/instantclient_19_8/libclntsh.dylib node_modules/oracledb/build/Release
  

  This can be added to your package.json files:

  "scripts": {
      "postinstall": "ln -s $HOME/Downloads/instantclient_19_8/libclntsh.dylib $(npm root)/oracledb/build/Release"
  },
  

  Instead of linking, you can also copy all the required OCI libraries, for example:

  cp ~/Downloads/instantclient_19_8/{libclntsh.dylib.19.1,libclntshcore.dylib.19.1,libnnz19.dylib,libociei.dylib} node_modules/oracledb/build/Release
  cd node_modules/oracledb/build/Release/ && ln -s libclntsh.dylib.19.1 libclntsh.dylib
  

  With the libraries in place, your application can then enable Thick mode:

  const oracledb = require('oracledb');
  oracledb.initOracleClient();
  

• Alternatively, create a symbolic link for the ‘client shared library’ in /usr/local/lib. Note this may not work on all versions of macOS. If the lib sub-directory does not exist, you can create it. For example:

  mkdir /usr/local/lib
  ln -s ~/Downloads/instantclient_19_8/libclntsh.dylib /usr/local/lib
  

  Instead of linking, you can also copy all the required OCI libraries, for example:

  mkdir /usr/local/lib
  cp ~/Downloads/instantclient_19_8/{libclntsh.dylib.19.1,libclntshcore.dylib.19.1,libnnz19.dylib,libociei.dylib} /usr/local/lib/
  

  With the libraries in place, your application can then enable Thick mode:

  const oracledb = require('oracledb');
  oracledb.initOracleClient();
  

3.1.3. Enabling node-oracledb Thick Mode on Linux and Related Platforms

On Linux and related platforms, enable Thick mode by calling initOracleClient() without passing a libDir parameter.

const oracledb = require('oracledb');
oracledb.initOracleClient();

Oracle Client libraries are looked for in the operating system library search path, such as configured with ldconfig or set in the environment variable LD_LIBRARY_PATH. On some UNIX platforms an OS specific equivalent, such as LIBPATH or SHLIB_PATH, is used instead of LD_LIBRARY_PATH.

If the libraries are not found in the system library search path, then libraries in $ORACLE_HOME/lib will be used. Note that the environment variable ORACLE_HOME should only ever be set when you have a full database installation or full client installation (such as installed with the Oracle GUI installer). It should not be set if you are using Oracle Instant Client. If being used, the ORACLE_HOME variable and other necessary variables should be set before starting Node.js. See Oracle Environment Variables.

On Linux, node-oracledb Thick mode will not automatically load Oracle Client library files from the directory where the node-oracledb binary module is located. One of the above methods should be used instead.

Ensure that the Node.js process has directory and file access permissions for the Oracle Client libraries. OS restrictions may prevent the opening of Oracle Client libraries installed in unsafe paths, such as from a user directory. You may need to install the Oracle Client libraries under a directory like /opt or /usr/local.

3.1.4. Tracing Oracle Client Libraries Loading

To trace the loading of Oracle Client libraries, the environment variable DPI_DEBUG_LEVEL can be set to 64 before starting Node.js. For example, on Linux, you might use:

$ export DPI_DEBUG_LEVEL=64
$ node myapp.js 2> log.txt

On Windows you might set the variable like:

set DPI_DEBUG_LEVEL=64

3.2. Optional Oracle Configuration Files

3.2.1. Optional Oracle Net Configuration Files

Optional Oracle Net configuration files may be read by node-oracledb. These files affect connections and applications. The common files are:

Table 3.1 Optional Oracle Net Configuration Files

Name	Description
tnsnames.ora	Contains Oracle Net Service names and Oracle Net options for databases that can be connected to, see Net Service Names for Connection Strings. This file is only needed for advanced configuration. Not needed if connection strings use the Easy Connect syntax. The Oracle Net documentation on tnsnames.ora has more information.
sqlnet.ora	A configuration file controlling the network transport behavior. For example it can set call timeouts for high availability, or be used to encrypt network traffic, or be used to configure logging and tracing. The Oracle Net documentation on sqlnet.ora has more information. Many settings can alternatively be specified using Easy Connect syntax This file is only used in node-oracledb Thick mode. In the node-oracledb Thin mode, many settings can be defined in Easy Connect syntax, in getConnection() or createPool() calls, or in the tnsnames.ora file.

The documentation Connections and High Availability discusses some specific Oracle Net configuration options useful for node-oracledb applications.

See Using Optional Oracle Configuration Files to understand how node-oracledb locates the files.

3.2.2. Optional Oracle Client Configuration File

If the Oracle Client Libraries used by node-oracledb Thick mode are version 12, or later, then an optional oraaccess.xml file can be used to configure some behaviors of those libraries, such as statement caching and prefetching. This can be useful if the application cannot be altered. The file is read when node-oracledb starts. The file is read from the same directory as the Optional Oracle Net Configuration files.

Note

The oraaccess.xml files is only used in the node-oracledb Thick mode. See Enabling node-oracledb Thick Mode.

The following oraaccess.xml file sets the Oracle client ‘prefetch’ value to 1000 rows. This value affects every SQL query in the application:

<?xml version="1.0"?>
 <oraaccess xmlns="http://xmlns.oracle.com/oci/oraaccess"
  xmlns:oci="http://xmlns.oracle.com/oci/oraaccess"
  schemaLocation="http://xmlns.oracle.com/oci/oraaccess
  http://xmlns.oracle.com/oci/oraaccess.xsd">
  <default_parameters>
    <prefetch>
      <rows>1000</rows>
    </prefetch>
  </default_parameters>
</oraaccess>

Prefetching is a tuning feature, see Tuning Fetch Performance.

The oraaccess.xml file has other uses including:

• Changing the value of Fast Application Notification (FAN) events which affects notifications and Runtime Load Balancing (RLB).

• Configuring Client Result Caching parameters

• Turning on Client Statement Cache Auto-tuning

Refer to the documentation on oraaccess.xml for more information.

See Using Optional Oracle Configuration Files to understand how node-oracledb locates the file.

3.2.3. Using Optional Oracle Configuration Files

If you use optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml, then put the files in an accessible directory and follow the Thin or Thick mode instructions below.

The files should be in a directory accessible to Node.js, not on the database server host.

For node-oracledb Thin mode

In node-oracledb Thin mode, you must specify the directory that contains the tnsnames.ora file by either:

• Setting the TNS_ADMIN environment variable to the directory containing the file and then running your application. For example, in a terminal:

  export TNS_ADMIN=/opt/oracle/your_config_dir
  node myapp.js
  

• Or setting the configDir attribute to the directory containing the file when connecting or creating a connection pool. For example:

  const oracledb = require('oracledb');
  
  async function run() {
      const connection = await oracledb.getConnection({
          user          : "hr",
          password      : mypw,  // contains the hr schema password
          connectString : "myhost/FREEPDB1",
          configDir     : "/opt/oracle/your_config_dir"
      });
  

On Windows, if you use backslashes in the configDir string, you will need to double them.

Note

In Thin mode, you must explicitly set the directory because traditional “default” locations such as the Instant Client network/admin/ subdirectory, $ORACLE_HOME/network/admin/, or $ORACLE_BASE/homes/XYZ/network/admin/ (in a read-only Oracle Database home) are not automatically looked in.

For node-oracledb Thick mode

In node-oracledb Thick mode, the directory containing the optional files can be explicitly specified or a default location will be used. Do one of:

• Set the configDir attribute to the directory containing the files when enabling Thick mode with initOracleClient():

  const oracledb = require('oracledb');
  oracledb.initOracleClient({configDir: '/opt/oracle/your_config_dir'});
  

  On Windows, if you use backslashes in the configDir string, you will need to double them.

• If initOracleClient() is called to enable Thick mode but configDir is not specified, then default directories are searched. They include:

  • The directory specified by the TNS_ADMIN environment variable.

  • For Oracle Instant Client ZIP files, the network/admin subdirectory of Instant Client, for example /opt/oracle/instantclient_19_11/network/admin.

  • For Oracle Instant RPMs, the network/admin subdirectory of Instant Client, for example /usr/lib/oracle/19.18/client64/lib/network/admin.

  • When using libraries from a local Oracle Database or full client installation, in $ORACLE_HOME/network/admin or $ORACLE_BASE_HOME/network/admin.

3.2.4. Using the Optional Time Zone File

The name of the Oracle time zone file to use can be set in ORA_TZFILE.

Note

The Oracle time zone file and ORA_TZFILE environment variable are only used in the node-oracledb Thick mode.

If node-oracledb is using Oracle Client libraries from an Oracle Database or full Oracle Client software installation, and you want to use a non-default time zone file, then set ORA_TZFILE to the file name with a directory prefix, for example: export ORA_TZFILE=/opt/oracle/myconfig/timezone_31.dat.

Oracle Instant Client includes embedded small and big time zone ‘files’, for example timezone_32.dat and timezlrg_32.dat. The versions can be shown by running the utility genezi -v located in the Instant Client directory. The small file contains only the most commonly used time zones. By default the larger timezlrg_n.dat file is used. If you want to use the smaller timezone_n.dat file, then set the ORA_TZFILE environment variable to the name of the file without any directory prefix, for example export ORA_TZFILE=timezone_32.dat. With Oracle Instant Client 12.2 or later, you can also use an external time zone file. Create a subdirectory oracore/zoneinfo under the Instant Client directory, and move the file into it. Then set ORA_TZFILE to the file name, without any directory prefix. The genezi -v utility will show the time zone file in use.

The Oracle Database documentation contains more information about time zone files, see Choosing a Time Zone File.

3.3. Oracle Environment Variables for node-oracledb Thick Mode

Some common environment variables that influence node-oracledb in Thick mode are shown below. The variables that may be needed depend on how Node.js is installed, how you connect to the database, and what optional settings are desired. It is recommended to set Oracle variables in the environment before invoking Node.js, however they may also be set in application code as long as they are set before node-oracledb is first used. System environment variables like LD_LIBRARY_PATH must be set before Node.js starts.

Note

The variables listed below are only supported in the node-oracledb Thick mode, with the exception of the TNS_ADMIN and ORA_SDTZ which are also supported in the node-oracledb Thin mode.

Table 3.2 Common Oracle Environment Variables

Oracle Environment Variables	Purpose
LD_LIBRARY_PATH	The library search path for Linux and some UNIX platforms. Set this to the directory containing the Oracle Client libraries, for example /opt/oracle/instantclient_19_18 or $ORACLE_HOME/lib. The variable needs to be set in the environment before Node.js is invoked. The variable is not needed if the libraries are located by an alternative method, such as from running ldconfig. On some UNIX platforms an OS specific equivalent, such as LIBPATH or SHLIB_PATH is used instead of LD_LIBRARY_PATH.
PATH	The library search path for Windows should include the location where OCI.DLL is found. Not needed if you pass libDir when calling oracledb.initOracleClient().
TNS_ADMIN	The location of the optional Oracle Net configuration files and Oracle Client configuration files, including tnsnames.ora, sqlnet.ora, and oraaccess.xml, if they are not in a default location. The configDir value in a call to oracledb.initOracleClient() overrides TNS_ADMIN.
ORA_SDTZ	The default session time zone, see Fetching Dates and Timestamps.
ORA_TZFILE	The name of the Oracle time zone file to use. See the notes below.
ORACLE_HOME	The directory containing the Oracle Database software. This directory must be accessible by the Node.js process. This variable should not be set if node-oracledb uses Oracle Instant Client.
NLS_LANG	Determines the ‘national language support’ globalization options for node-oracledb. If not set, a default value will be chosen by Oracle. Note that node-oracledb will always uses the AL32UTF8 character set. See Globalization and National Language Support (NLS).
NLS_DATE_FORMAT, NLS_TIMESTAMP_FORMAT	See Fetching Numbers and Dates as String. The variables are ignored if NLS_LANG is not set.
NLS_NUMERIC_CHARACTERS	See Fetching Numbers and Dates as String. The variables are ignored if NLS_LANG is not set.

3.3.1. Scripts for Setting the Default Environment in a Database Installation

If you are using Linux, and node-oracledb is being run on the same computer as the database, you can set required Oracle environment variables, such as ORACLE_HOME and LD_LIBRARY_PATH in your shell by executing:

source /usr/local/bin/oraenv

Or, if you are using Oracle Database XE 11.2, by executing:

source /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh

Make sure the Node.js process has directory and file access permissions for the Oracle libraries and other files. Typically the home directory of the Oracle software owner will need permissions relaxed.

Note

The ORACLE_HOME and LD_LIBRARY_PATH environment variables are only used in the node-oracledb Thick mode.

3.4. Other node-oracledb Thick Mode Initialization

The oracledb.initOracleClient() function allows driverName and errorUrl attributes to be set. These are useful for applications whose end-users are not aware node-oracledb is being used. An example of setting the attributes is:

const oracledb = require('oracledb');
oracledb.initOracleClient({
    driverName: 'My Great App : 3.1.4'
    errorUrl: 'https://example.com/MyInstallInstructions.html',
});

The driverName value will be shown in Oracle Database views like V$SESSION_CONNECT_INFO. The convention for driverName is to separate the product name from the product version by a colon and single space characters. If this attribute is not specified, then the value “node-oracledb thk : version” is used, see Finding the node-oracledb Mode.

The errorUrl string will be shown in the exception raised if initOracleClient() cannot load Oracle Client libraries. This allows applications that use node-oracledb in Thick mode to refer users to application-specific installation instructions. If this attribute is not set, then the node-oracledb installation instructions are used.