set_var HINT in SQL.System Variable | Description | Parameter Type | Default Value | Value Range | Scope | SET_VAR Hint Supported |
libra_enable_runtime_filter | Whether to enable Runtime Filter. | BOOL | ON | ON: Enable Runtime Filter. OFF: Disables the Runtime Filter. | Global & Session | Yes |
libra_runtime_filter_type | Set the type of Runtime Filter that can be assigned. | VARCHAR | MIN_MAX,BLOOM_FILTER,IN_FILTER,TOPN_FILTER | BLOOM_FILTER: Builds a Bloom Filter based on the JOIN KEY from the JOIN BUILD side to filter data from the Probe side. MIN_MAX: Builds the maximum and minimum values based on the JOIN KEY from the JOIN BUILD side to filter data from the Probe side. IN_FILTER: Builds a value list based on the JOIN KEY from the JOIN BUILD side to filter data from the Probe side; TOPN_FILTER: A Runtime Filter based on TopN; Empty string: Disables the Runtime Filter feature. | Global & Session | Yes |
libra_enable_cost_based_runtime_filter | Enable or disable the cost-based Runtime Filter. | BOOL | ON | ON: Enables cost-based Runtime Filter assignment. OFF: Disables cost-based Runtime Filter assignment. | Global & Session | Yes |
libra_max_in_runtime_filter_ndv | The maximum NDV (Number of Distinct Values) value on the BUILD side when generating an IN type Runtime Filter in a cost-based Runtime Filter. | INT | 1024 | [0, MaxInt64] | Global & Session | Yes |
runtime_filter_wait_time_ms | The maximum time for the first wait for RF Ready on the RF USE side. | INT | 100 | Any integer | Global & Session | Yes |
runtime_filter_wait_time_ms indicates an infinite wait until the query times out or is interrupted.System Variable | Description | Parameter Type | Default Value | Value Range | Scope | SET_VAR Hint Supported |
libra_enable_late_materialization | Whether to enable late materialization. | BOOL | ON | ON: Enable late materialization. OFF: Disables late materialization. | Global & Session | Yes |
System Variable | Description | Parameter Type | Default Value | Value Range | Scope | SET_VAR Hint Supported |
max_threads | Query the degree of parallelism during execution. | INT | 0 | 0 - MaxInt64 (Recommended not to exceed twice the number of CPU cores). | Global & Session | Yes |
0 for max_threads indicates that the system automatically determines the parallelism based on the number of CPU cores on the node.System Variable | Description | Parameter Type | Default Value | Value Range | Scope | SET_VAR Hint Supported |
max_bytes_before_external_agg_uniq_exact | When count distinct uses the calculation function uniqExact, the system starts to spill the HashSet to external storage when it exceeds the limit. The default value is 0, and no external storage calculation is performed. | INT | 0 | [0, MaxInt64] | Global & Session | Yes |
agg_uniq_exact_set_one_bucket_max_temp_file_size | When count distinct uses the calculation function uniqExact, the system needs to switch to a new file for writing if the maximum value of the file flushed to disk per bucket is exceeded. | INT | 68719476736 | [0, MaxInt64] | Global & Session | Yes |
count_distinct_implementation | The function name used for count distinct calculation. | VARCHAR | uniqExact | uniqExact: an in-memory, precise CountDistinct calculation method; uniqExactDisk: a precise CountDistinct calculation method with the feature of being flushed to disk; uniq: an approximate CountDistinct calculation method. | Global & Session | Yes |
join_build_concurrency | Specifies the parallelism used for Join Build. The default value is 0, which indicates that Default or a specified MaxThreads is used. | INT | 0 | [0, MaxInt64] | Global & Session | Yes |
enable_local_tunnel | Whether local communication optimization between the Sender and Receiver is supported. | BOOL | ON | ON: Enable Local Channel intra-host communication optimization; OFF: Disable Local Channel intra-host communication optimization. | Global & Session | Yes |
mpp_max_packet_size | The maximum size of data packets sent by the Sender. | INT | 0 | [0, MaxInt64], where 0 indicates no limit | Global & Session | Yes |
tunnel_buffer_size | The number of BUFFERs in the sending queue at the Sender end. | INT | 1 | [0, MaxInt64] | Global & Session | Yes |
pipeline_executor_use_thread_manager | Whether the Pipeline model uses a dynamic thread pool model. | BOOL | OFF | ON: Enable the Pipeline model to use a dynamic thread pool; OFF: Disable the Pipeline model from using a dynamic thread pool. | Global & Session | Yes |
enable_order_by_push_down | Enable or disable the order by push down feature. | BOOL | ON | ON: Enable the order by push down feature; OFF: Disable the order by push down feature. | Global & Session | Yes |
max_block_size | Set the number of rows of the data Block transferred in the Pipeline execution engine. | INT | 65409 | [1, MaxInt64] | Global & Session | Yes |
shuffle_after_join | Specifies whether to shuffle data to multiple Pipelines after a Join. | BOOL | OFF | ON: Enable the data shuffling feature; OFF: Disable the data shuffling feature. | Global & Session | Yes |
SET_VAR HINT in SQL to temporarily adjust system variables within a single query, as shown in the following example:SELECT /*+ SET_VAR(libra_enable_runtime_filter = ON) SET_VAR(max_threads = 8) */a.id, b.nameFROM table_a a JOIN table_b b ON a.id = b.id;
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