The period is extended to the stream’s offset, up to a maximum of 14 days by default, regardless of the Snowflake edition for your account. If the data retention period for a table is less than 14 days, and a stream has not been consumed, Snowflake temporarily extends this period to prevent it from going stale. To avoid having a stream become stale, it is strongly recommended to regularly consume the changed data before its STALE_AFTER timestamp. The syntax to create Standard stream is as below Supported on standard tables, directory tables and views. delta) stream tracks all DML changes to the source object, including inserts, updates, and deletes (including table truncates). There are three different types of Streams supported in SnowflakeĪ Standard (i.e. Hence Snowflake also recommends creating separate stream for each consumer. Therefore, you can create any number of streams for an object without incurring significant cost. Only the subsequent changes made on the table are captured by Stream until they are again consumed by a consumer.Īs stream advances its offset only when it is involved in a DML transaction, the data consumed by streams is very minimal. Once the data in the Stream is consumed by a downstream table or a data pipeline in a DML transaction, the change data is no longer available in Stream. Streams work by keeping track of an offset, a pointer which indicates the point in time since you last read the stream which is referred as a transaction. Specifies the unique and immutable ID for the row, which can be used to track changes to specific rows over time. Updates to rows in the source object are represented as a pair of DELETE and INSERT records in the stream with a metadata column METADATA$ISUPDATE values set to TRUE. Indicates whether the operation was part of an UPDATE statement. Indicates the DML operation ( INSERT, DELETE) recorded. Standard tables, including shared tables.īelow are the additional metadata fields included in Streams along with Source object fields to track changes COLUMN NAME.Streams can be created to query change data on the following objects. The Change table mirrors the column structure of the tracked source object and includes additional metadata columns that describe each change event. What are Snowflake Streams?Ī Stream is a Snowflake object that provides Change Data Capture (CDC) capabilities to track the changes made to tables including inserts, updates, and deletes, as well as metadata about each change, so that actions can be taken using the changed data.Ī Stream creates a “ Change table” which tracks all the DML changes at the row level, between two transactional points of time in a table. In this article let us discuss about Snowflake’s own offering which provides CDC capabilities. There are several proven methods through which CDC can be implemented like making use of Audit Columns to identify the data that has been modified since the data last extracted. Change Data Capture (CDC) is a process that identifies and captures changes made to data in a database and then delivers those changes in real-time to a downstream process or system.
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