View and configure runtime parameters

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What are runtime parameters?

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How to view runtime parameters?

SHOW ALL;

          Name                  |     Setting     |        Description
--------------------------------+-----------------+--------------------------------------
 implicit_flush                 | false           | If set to `true`, every INSERT/UPDATE/DELETE statement will block until the entire dataflow is refreshed.
 create_compaction_group_for_mv | false           | If set to `true`, RisingWave will create dedicated compaction groups when creating these materialized views.
 query_mode                     | auto            | A temporary config variable to force query running in either local or distributed mode. If the value is auto, the system will decide for you automatically.
 ...

SHOW parameter_name;

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How to configure runtime parameters?

SET parameter_name { TO | = } { value | 'value' | DEFAULT};

ALTER SYSTEM SET session_param_name TO session_param_value;

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Usage examples

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Configuring backfill parallelism

SET STREAMING_PARALLELISM = 3;
SET STREAMING_PARALLELISM_FOR_BACKFILL = 2;
SET BACKFILL_RATE_LIMIT = 1;
SET BACKGROUND_DDL = true;

CREATE TABLE t(v int);
INSERT INTO t SELECT * FROM generate_series(1, 10);

CREATE MATERIALIZED VIEW m AS SELECT * FROM t;

-- While backfill is running, check parallelism
SHOW JOBS;
SELECT name, parallelism FROM rw_fragment_parallelism WHERE name = 'm';
-- Output: parallelism = 2 (using streaming_parallelism_for_backfill)

-- After backfill completes, check parallelism again
SHOW JOBS;
SELECT name, parallelism FROM rw_fragment_parallelism WHERE name = 'm';
-- Output: parallelism = 3 (switched to streaming_parallelism)

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Adaptive parallelism strategies

• streaming_parallelism — the global policy.
• streaming_parallelism_for_<type> — per-job-type overrides, where <type> is one of table, materialized_view, index, source, or sink.

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Accepted values

• <n>: A positive integer, for example 4. Pins the job to a fixed parallelism. The effective parallelism is still capped by streaming_max_parallelism.
• adaptive (or 0): Uses all available worker parallelism in the resource group. Maximizes resource utilization for high-throughput workloads.
• bounded(<n>): Adaptive scheduling with an upper bound of <n>, for example bounded(4). The job scales with the resource group but never exceeds <n> parallel workers.
• ratio(<r>): Adaptive scheduling using a fraction of the available worker parallelism, where 0 < r ≤ 1, for example ratio(0.5).
• default: Falls back to the built-in default.
  • For streaming_parallelism, default resolves to bounded(64).
  • For streaming_parallelism_for_table and streaming_parallelism_for_source, default resolves to bounded(4) when streaming_parallelism is also default; otherwise it follows the resolved global value.
  • For the other streaming_parallelism_for_<type> parameters, default follows the resolved global value.

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Examples

SET streaming_parallelism = 'ratio(0.5)';

SET streaming_parallelism = 8;

SET streaming_parallelism = 'bounded(16)';

SET streaming_parallelism_for_table = 'adaptive';
SET streaming_parallelism_for_materialized_view = 'bounded(8)';
SET streaming_parallelism_for_sink = 'ratio(0.3)';

SET streaming_parallelism_for_table = 'bounded(2)';
CREATE TABLE my_table (id INT, value VARCHAR);

SET streaming_parallelism_for_materialized_view = DEFAULT;
-- or equivalently
SET streaming_parallelism_for_materialized_view = 'default';

ALTER SYSTEM SET streaming_parallelism TO 'bounded(4)';

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Important notes

• Per-job-type parameters (streaming_parallelism_for_<type>) take precedence over the global streaming_parallelism. When a per-type parameter is default, it inherits from the resolved global value, with the exceptions for table and source noted above.
• The resolved policy is persisted with the streaming job at creation time and remains effective even if session or system-level settings change later.
• The concrete policy for each job is visible in system catalogs and diagnostics. Fixed parallelism displays as an integer (for example, 4); adaptive policies display as adaptive, bounded(<n>), or ratio(<r>). This applies to pg_catalog.pg_settings, rw_streaming_parallelism, rw_streaming_jobs, rw_table_fragments, and diagnose-style output.
• ALTER TABLE|SOURCE|SINK|INDEX|MATERIALIZED VIEW ... SET PARALLELISM accepts the same value forms (adaptive, 0, a fixed integer, bounded(<n>), ratio(<r>)). Fragment-level ALTER ... SET PARALLELISM remains limited to adaptive and fixed integers.