Generic JDBC Execute

Overview

You can use this Snap to execute a SQL statement/query against a SQL database. This Snap also supports DCL commands (Grant and Revoke).

Note:

  • This Snap works only with single queries.

  • This Snap only supports conversion of standard JDBC specification 4.1 types listed here. Learn more about the JDBC 4.1 specification. If you want database-specific conversion, then a database specific Snap pack should be used. For example, for handling TIMESTAMPTZ and TIMESTAMPLTZ formats, you should use the Oracle Snap Pack.

  • The Generic JDBC - Execute Snap is used for simple DDL (SELECT, INSERT, UPDATE, DELETE) type statements. This Snap also supports DML operations (CREATE, ALTER, INSERT, and SELECT) when using AWS Athena database.



Known issues

  • If a SELECT query in the SQL statement field in the Snap Settings contains duplicate column names, then the query result displays the column name twice, with the latter prefixed with the table name. If the column name occurs more than twice, the second entry is still prefixed with the table name, but it displays the value of the column mentioned last in the query. The example below illustrates this behavior.

    Incorrect results for SELECT queries with duplicate column names

    Example

    Consider the following query, where the column name "name" is repeated three times:

    select id, name, city, location, id as name, city as name, location as name from address

    Expected output:

    The Generic JDBC - Execute Snap's output should reflect the correct query result containing all the six fields, as shown in the image below:



    Actual Output:

    The Snap's output displays the repeat occurrence of the column "name" only once, prefixed with the table name "address" as shown in the image below. Further, it holds the value of the table column "location", which was mentioned last in the SELECT query.



    To avoid this issue, we recommend that you give unique column names in the query.

  • The metadata output in the second output preview is not displayed in table format when your target database is AWS Athena.

  • The suggestions list is not populated for Table name field when your target database is AWS Athena.

  • When the SQL statement property is an expression, the Pipeline parameters are shown in the suggest, but not the input schema.

  • When the Generic JDBC - Execute Snap connects to the Sybase database to retrieve BigTime-type data, the Snap displays both date and time for the data type.

Behavior changes

Improved the output for the CLOB data type when used with the SELECT statement in the Generic JDBC - Execute Snap. This update has resulted in the following Behavior change:

  • Previously, the output for a Teradata object displayed as shown below:
    "col_clob": "com.teradata.jdbc.jdk6.JDK6_SQL_Clob@2f8e6bdd"
  • With 442patches32366, the output now reflects the actual content inserted, as shown below:
    "col_clob": "This is a CLOB text"

Snap views

View Description Examples of upstream and downstream Snaps
Input The input data typically includes the SQL query that you want to execute on your database. The specific format of the input data can vary depending on the design of your pipeline and the data source you are using, but typically it can be the SQL query. In addition to the SQL query, you may also need to provide additional parameters that need to be substituted in the query.
Output If an output view is available and an update/insert/merge/delete statement was executed, then the original document that was used to create the statement will be output with the status of the executed statement.
Error

Error handling is a generic way to handle errors without losing data or failing the Snap execution. You can handle the errors that the Snap might encounter when running the pipeline by choosing one of the following options from the When errors occur list under the Views tab. The available options are:

  • Stop Pipeline Execution Stops the current pipeline execution when an error occurs.
  • Discard Error Data and Continue Ignores the error, discards that record, and continues with the remaining records.
  • Route Error Data to Error View Routes the error data to an error view without stopping the Snap execution.

Learn more about Error handling in Pipelines.

Snap settings

Legend:
  • Expression icon (): Allows using pipeline parameters to set field values dynamically (if enabled). SnapLogic Expressions are not supported. If disabled, you can provide a static value.
  • SnapGPT (): Generates SnapLogic Expressions based on natural language using SnapGPT. Learn more.
  • Suggestion icon (): Populates a list of values dynamically based on your Snap configuration. You can select only one attribute at a time using the icon. Type into the field if it supports a comma-separated list of values.
  • Upload : Uploads files. Learn more.
Learn more about the icons in the Snap settings dialog.
Field / Field set Type Description
Label String

Required. Specify a unique name for the Snap. Modify this to be more appropriate, especially if more than one of the same Snaps is in the pipeline.

Default value: Generic JDBC - Execute

Example: Execute EmployeeRecords
SQL statement String/Expression

Required. Specify the SQL statement to execute on the server.

Note: We recommend you to add a single query in the SQL Statement field.

There are two possible scenarios that you encounter when working with SQL statements in SnapLogic.

Tip: Scenarios to successfully execute your SQL statements
Scenario 1: Executing SQL statements without expressions.If the expression toggle of the SQL statement field is not selected:
  • The SQL statement must not be within quotes.
  • The $<variable_name> parts of the SQL statement are expressions. In the below example, $id and $book.
  • email = '[email protected]' or email = $email

  • emp=$emp

Additionally, the JSON path is allowed only in the WHERE clause. If the SQL statement starts with SELECT (case-insensitive), the Snap regards it as a select-type query and executes once per input document. If not, it regards it as write-type query and executes in batch mode.

Scenario 2: Executing SQL queries with expressions. If the expression toggle of the SQL statement field is selected:

  • The SQL statement must be within quotes.

  • The + $<variable_name> + parts of the SQL statement are expressions, and must not be within quotes. In the below example, $tablename.

  • The $<variable_name> parts of the SQL statement are bind parameter, and must be within quotes. In the below example, $id and $book.

  • "EMPNO=$EMPNO and ENAME=$EMPNAME"

  • "emp='" + $emp + "'"

  • "EMPNO=" + $EMPNO + " and ENAME='" + $EMPNAME+ "'"

Note: Table name and column names must not be provided as bind parameters. Only values can be provided as bind parameters.
We recommend you use the Oracle - Stored Procedure Snap for invoking procedures when using Oracle database with this Snap due to the following limitation while invoking procedures:
  • Procedures have to invoked as a PL/SQL block (with older JDBC JARs). However, with this approach the output parameters cannot be sent to the output view. Besides, the latest oracle JDBC drivers do not support PL/SQL.
Note:

  • The non-expression form uses bind parameters, so it is much faster than executing N arbitrary SQL expressions.

  • Using expressions that join strings together to create SQL queries or conditions has a potential SQL injection risk and hence unsafe. Ensure that you understand all implications and risks involved before using concatenation of strings with '=' Expression enabled.

  • The '$' sign and identifier characters, such as double quotes (“), single quotes ('), or back quotes (`), are reserved characters and should not be used in comments or for purposes other than their originally intended purpose.

Warning: Single quotes in values must be escaped.

Any relational database (RDBMS) treats single quotes (') as special symbols. So, single quotes in the data or values passed through a DML query may cause the Snap to fail when the query is executed. Ensure that you pass two consecutive single quotes in place of one within these values to escape the single quote through these queries.

For example:

If String To pass this value Use
Has no single quotes Schaum Series 'Schaum Series'
Contains single quotes O'Reilly's Publication 'O''Reilly''s Publication'

Values can be substituted into the query/statement by using a JSON path using a $ to start the path.

For example, for the given document data:
{
    "firstName": "John"
}

During design time if you specify query such as,select * from users where first_name = $firstName,

then the run-time query is: select * from users where first_name = "John"

Note: To invoke procedures when using Oracle database with this Snap, we recommend you use the Oracle Stored Procedure Snap.

Default value: N/A

Example: INSERT into SnapLogic.book (id, book) VALUES ($id,$book)
Query Type Dropdown list/Expression

Select the type of query for your SQL statement (Read or Write).

When Auto is selected, the Snap tries to determine the query type automatically.

If the execution result of the query is not as expected, you can change the query type to Read or Write.

Default value: Auto

Example: Read
Pass through Checkbox

Select this checkbox to pass the input data to the output view under the key 'original'. This property applies only to the Execute Snaps with SELECT statement.

Default status: Deselected
Ignore empty result Checkbox

Select this checkbox to ignore empty result; no document is written to the output view when a SELECT operation does not produce any result. If you deselect this checkbox and select the Pass through option, the input document is passed through to the output view.Default value:

Default status: Deselected
Number of retries Integer/Expression
Specify the maximum number of attempts to be made to receive a response. The request is terminated if the attempts do not result in a response.
Note:

If you provide a string value, the Snap displays the following error:

Invalid type (STRING) for property, expecting a value of type integer

You can use a string value only when the field is expression-enabled.

Default value: 0

Example: 3
Retry interval (seconds) Integer/Expression Specifies the time interval between two successive retry requests. A retry happens only when the previous attempt resulted in an exception.

Default value: 1

Example: 10
Auto commit Dropdown list Select one of the options for this property to override the state of the Auto commit property on the account. The Auto commit at the Snap-level has three values: True, False, and Use account setting. The expected functionality for these modes are:
  • True - The Snap will execute with auto-commit enabled regardless of the value set for Auto commit in the Account used by the Snap.
  • False - The Snap will execute with auto-commit disabled regardless of the value set for Auto commit in the Account used by the Snap.

  • Use account setting - The Snap will execute with Auto commit property value inherited by the Account used by the Snap.

Note:
  • Auto commit may be enabled for certain use cases if the PostgreSQL JDBC driver is used in either Redshift, PostgreSQL, or the generic JDBC Snap. However, the JDBC driver may cause out of memory issues when SELECT statements are executed. In those cases, Auto commit in the Snap property should be set to False and the Fetch size in the Account settings can be increased for optimal performance.
  • For a DB Execute Snap, assume that a stream of documents are passed to the input view of the Snap and the SQL statement property has JSON paths in the WHERE clause. If the number of documents are large, the Snap executes in more than one batch rather than executing one per each document. Each batch would contain a certain number of WHERE clause values. If Auto commit is turned on, a failure would only roll back the records in the current batch. If Auto commit is turned off, the entire operation would be rolled back. For a single execute statement (with no input view), the setting has no practical effect.
Warning: Behavior of DML Queries in Database Execute Snap when auto-commit is false

DDL queries used in the Database Execute Snap will be committed by the Database itself, regardless of the Auto-commit setting.When Auto commit is set to false for the DML queries, the commit is called at the end of the Snap's execution.

The Auto commit needs to be true in a scenario where the downstream Snap does depend on the data processed on an Upstream Database Execute Snap containing a DML query. When the Auto commit is set to the Use account setting on the Snap, the account level commit needs to be enabled.

Default value: Use account setting

Example: True
Snap execution Dropdown list
Choose one of the three modes in which the Snap executes. Available options are:
  • Validate & Execute: Performs limited execution of the Snap and generates a data preview during pipeline validation. Subsequently, performs full execution of the Snap (unlimited records) during pipeline runtime.
  • Execute only: Performs full execution of the Snap during pipeline execution without generating preview data.
  • Disabled: Disables the Snap and all Snaps that are downstream from it.

Default value: Execute only

Example: Validate & Execute

Examples