ALTER TABLE SET PARAM

ALTER TABLE SET PARAM sets table parameters via SQL.

:::note

• Checking table metadata can be done via the tables() and table_columns() functions, as described in the meta functions documentation page.

:::

Syntax

maxUncommittedRows - defines the maximum number of uncommitted rows per-table to keep in memory before triggering a commit for a specific table.

The purpose of specifying maximum uncommitted rows per table is to reduce the occurrences of resource-intensive commits when ingesting out-of-order data.

The global setting for the same parameter is cairo.max.uncommitted.rows.

Example

The values for maximum uncommitted rows can be changed per each table with the following SQL:

ALTER TABLE my_table SET PARAM maxUncommittedRows = 10000

Checking the values per-table may be done using the tables() function:

SELECT id, name, maxUncommittedRows FROM tables();

For more details on retrieving table and column information, see the meta functions documentation.

Syntax

o3MaxLag allows for specifying the expected maximum lag of late-arriving records when ingesting out-of-order data. The purpose of specifying a commit lag per table is to reduce the occurrences of resource-intensive commits when ingesting out-of-order data. Incoming records will be kept in memory until for the duration specified in lag, then all records up to the boundary will be ordered and committed.

o3MaxLag expects a value with a modifier to specify the unit of time for the value:

To specify o3MaxLag value to 20 seconds:

ALTER TABLE my_table SET PARAM o3MaxLag = 20s;