SAP HANA - Execute

Overview

This Snap allows you to execute arbitrary SQL.

Tip: This Snap works only with single queries.
Warning: You can drop your database with it, so be careful.

Valid JSON paths that are defined in the where clause for queries/statements will be substituted with values from an incoming document. Documents will be written to the error view if the document is missing a value to be substituted into the query/statement.

If a SELECT query is executed, the query's results are merged into the incoming document and any existing keys will have their values overwritten. On the other hand, the original document is written if there are no results from the query.

Note: The SAP HANA Execute Snap is for simple DML (SELECT, INSERT, UPDATE, DELETE) type statements. For the comprehensive scripting functionality offered by the various databases, users should use stored procedure functionality offered by their chosen database in the Stored Procedure Snap.

Supported Accounts

Prerequisites

None.

Limitations

None.

Behavior changes

  • Starting May 2023, if the SQL statement starts with "SELECT" (case insensitive), the Snap regards it as a read-type query and executes once per input document. Otherwise, it regards it as a write-type query and executes in batch mode.

Known issues

None.

Snap views

Type Description Examples of upstream and downstream Snaps
Input This Snap has at most one document input view. If the input view is defined, then the where clause can substitute incoming values for a given expression.
Output This Snap has at most one document output view. 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 statement executed.
Learn more about Error handling.
Note: Database Write Snaps output all records of a batch (as configured in your account settings) to the error view if the write fails during batch processing.

Examples

Execute SQL query to retrieve data: Execute a SQL query to retrieve data from a table.

Snap settings

Note: Learn about the common controls in the Snap settings dialog.
Field/Field set 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: SAP HANA - Execute

Example: Execute custom query
SQL statement

String/Expression

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

Examples:



  • SELECT * FROM library WHERE id = $id AND book = $book
  • DELETE FROM library WHERE id = $id

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.
Note: Table name and column names must not be provided as bind parameters. Only values can be provided as bind parameters.

Examples:



  • "SELECT * FROM " + $tablename + " WHERE id = '$id' AND book = '$book'"
  • "DELETE FROM " + $tablename + " WHERE id = '$id'"
Tip: We recommend that you add a single query in the SQL Statement field.
Tip: When the SQL statement property is an expression, the pipeline parameters are shown in the suggest, but not the input schema.
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 has no single quotes: To pass value "Schaum Series", use 'Schaum Series'
  • If string contains single quotes: To pass value "O'Reilly's Publication", use 'O''Reilly''s Publication'

Default value: [None]
Query type

Dropdown list

 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 document to the output view under the key 'original'. This property applies only to the Execute Snaps with SELECT statement.

Default status: Selected
Ignore empty result

Checkbox

 Select this checkbox to ignore empty result; no document will be written to the output view when a SELECT operation does not produce any result.

If you deselect this checkbox and select the Pass through checkbox, the input document will be passed through to the output view.

Default status: Deselected
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.

Default value: Use account setting

Note: 'Auto commit' may be enabled for certain use cases if PostgreSQL jdbc driver is used in either Redshift, PostgreSQL or generic JDBC Snap. But the JDBC driver may cause out of memory issues when Select statements are executed. In those cases, "Auto commit" in Snap property should be set to 'False' and the Fetch size in the "Account setting" can be increased for optimal performance.
Number of retries

Integer

 Specify the maximum number of retry attempts the Snap must make in case of network failure.

When you set the Number of retries to more than 0, the Snap generates duplicate records when the connection is not established. To prevent duplicate records, we recommend that you follow one of the following:

  • Set the Number of retries to 0 (default value) to prevent duplicate records from being passed downstream while executing a pipeline.
  • Use a Primary key to prevent records from being inserted into the database.
  • Use an Upsert instead of an Insert statement.

Default value: 0

Example: 3
Retry interval (seconds)

Integer

 Specify 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
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, by extension, its downstream Snaps.

Default value: Execute only

Troubleshooting

None.