DTM - Stands for Data Transformation Manager. This is a unix process /windows service which runs on Informatica server and does the actual processing of the ETL code.
DTM process - Creates threads to initialize the session, read, write, and transform data, and handle pre- and post-session operations
DTM process is the second process associated with a session run
The primary purpose of the DTM process is to create and manage threads that carry out the session tasks
The DTM allocates process memory for the session and divides it into buffers. This is also known as buffer memory.
It creates the main thread, which is called the master thread
The master thread creates and manages all other threads
If you partition a session, the DTM creates a set of threads for each partition to allow concurrent processing.
When the Informatica Server writes messages to the session log, it includes the thread type and thread ID.
The Integration Service process starts the DTM process to run a session. The DTM process is also known as the pmdtm process. The DTM is the process associated with the session task. The DTM process performs the following tasks:
Retrieves and validates session information from the repository.
Performs pushdown optimization when the session is configured for pushdown optimization.
Adds partitions to the session when the session is configured for dynamic partitioning.
Forms partition groups when the session is configured to run on a grid.
Expands the service process variables, session parameters, and mapping variables and parameters.
Creates the session log.
Validates source and target code pages.
Verifies connection object permissions.
Runs pre-session shell commands, stored procedures, and SQL.
Sends a request to start worker DTM processes on other nodes when the session is configured to run on a grid.
Creates and runs mapping, reader, writer, and transformation threads to extract, transform, and load data.
Runs post-session stored procedures, SQL, and shell commands.