ALTER TABLE SET PARAM

The following keywords allow for setting table parameters via SQL. This is useful for configuring out-of-order ILP data ingestion on a per-table basis. For more information on these values including details on why these settings should be applied, see the documentation for out-of-order data commits and ILP commit strategy.

info

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

Syntax

The following two sections describe table parameters relating to out-of-order ingestion. For context on commit lag and max uncommitted rows, see the guide for configuring commit lag of out-of-order data and ILP commit strategy.

commitLag

commitLag 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.

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

unit	description
us	microseconds
s	seconds
m	minutes
h	hours
d	days

To specify commitLag value to 20 seconds:

ALTER TABLE my_table SET PARAM commitLag = 20s

maxUncommittedRows

maxUncommittedRows allows for specifying the maximum number of uncommitted rows per-table to keep in memory before triggering a commit. The purpose of specifying maximum uncommitted rows per table is to reduce the occurrences of resource-intensive commits when ingesting out-of-order data.

Example

The values for maximum uncommitted rows and a time range for commit lag can changed per each table with the following SQL:

Altering out-of-order parameters via SQL

ALTER TABLE my_table SET PARAM maxUncommittedRows = 10000

ALTER TABLE my_table SET PARAM commitLag = 20s

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

List table metadata

SELECT id, name, maxUncommittedRows, commitLag FROM tables();

id	name	maxUncommittedRows	commitLag
1	my_table	10000	20000000

info

commitLag is returned in microseconds

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