UniDAC Using Google BigQuery data access provider with UniDAC in Delphi

This article provides a brief overview of the Google BigQuery database provider for UniDAC used to access Google BigQuery from Delphi and Lazarus. You will find the description of some useful features and how to get started quickly.

• Overview
• Compatibility
• Requirements
• Deployment
• Google Bigquery-specific options
  • TUniConnection
  • TUniSQL
  • TUniQuery, TUniTable, TUniStoredProc
  • TUniScript
  • TUniLoader
  • TUniDump

Overview

Main features of Google BigQuery data access provider are:

• Direct access to Google BigQuery without client library and additional tools
• Extended SQL Syntax

The full list of Database provider features can be found on the UniDAC features page.

Both Professional and Standard Editions of UniDAC include the Google BigQuery provider.

Compatibility

Google BigQuery provider supports Google BigQuery data types and API.

Requirements

Applications that use the Google BigQuery provider require Devart ODBC Driver for Google BigQuery to be installed on the client computer. The driver is sold and distributed separately from UniDAC.

Deployment

When an application was built without runtime packages (Link with runtime packages set to False in Project Options), you do not need to deploy any BPL files with it. For more information, see Deployment.
Note that UniDAC Trial requires deployment of additional BPL files regardless of Link with runtime packages.

Connecting to Google BigQuery

To connect to Google BigQuery using legacy authentication and Devart ODBC Driver, you should configure the driver and set up a DSN. In the TUniConnection component, specify the following parameters:

• Project ID
• Dataset ID
• Refresh Token

For more information on how to obtain Google BigQuery Refresh Token, see the article.

Google BigQuery-specific options

Though UniDAC is components that provide a unified interface to work with various database services, it also lets you tune behaviour for each server individually. For thin setup of a certain database service, UniDAC provides specific options. These options can be applied to such components as TUniConnection, TUniQuery, TUniTable, TUniStoredProc, TUniSQL, TUniScript via their SpecificOptions property. SpecificOptions is a sting list.

Below you will find the description of allowed options grouped by components.

TUniConnection

Option name	Description
ConnectionTimeout	The time to wait for a connection to open before raising an exception.
DataSetId	Allows referring the dataset by its name.
PrimaryKeyColumns	Contains unique keys that are used to identify all existing rows in the table.
ProjectID	Used to identify the projectы you have created from the existing ones.
RefreshToken	Used to supply an API key to log in to Google BigQuery.
UseUnicode	Enables or disables Unicode support. Affects character data fetched from the server. When set to True, all character data is stored as WideStrings, and TStringField is replaced by TWideStringField.
UTCDates	Use the UTCDates option to return the datetime values from the data source as UTC values.

Proxy connection options

Option name	Description
ProxyPassword	If Proxy User authorization is used, specify Proxy user password in this option.
ProxyPort	Specify the Proxy port here. You can learn Proxy Port in the same way as described above for the host.
ProxyServer	If you are using Proxy for connection to your network, specify the Proxy server address in this option. To learn your Proxy server address, open Control Panel->Internet Options->Connections->LAN settings.
ProxyUser	If Proxy User authorization is used, specify Proxy user name (ID) in this option.

TUniSQL

Option name	Description
CommandTimeout	The time to wait for a statement to be executed.

TUniQuery, TUniTable, TUniStoredProc

Option name	Description
CommandTimeout	The time to wait for a statement to be executed.
ExtendedFieldsInfo	If True, an additional query is performed to get information about the returned fields and tables they belong to. The default value is False.
FetchAll	If True, all records of a query are requested from database server when the dataset is being opened. If False, records are retrieved when a data-aware component or a program requests it. The default value is False.
FieldsAsString	If set to True, all non-BLOB fields are handled as strings. The default value is False.
UnknownAsString	If set to True, all Google BigQuery data types that are fetched as text and don't have the size limit, are mapped to TStringField with the default size 8192 bytes. If False (default value), such types are mapped to TMemoField. The TEXT data type is always mapped to TMemoField regardless of the value of this option.

TUniScript

The TUniDump component has no Google BigQuery-specific options.

TUniLoader

The TUniLoader component has no Google BigQuery-specific options.

TUniDump

The TUniDump component has no Google BigQuery-specific options.