Hints

Keyword	flag	Description	Scenario	Example
[HINT_LOCAL]	[1]	Obtains only the calculation results on the local server	in a distributed cluster	select [HINT_LOCAL] sum(*) from pt
[HINT_HASH]	[32]	Groups data with the hash algorithm by default	with a group by clause	select [HINT_HASH] count(*) from t group by sym
[HINT_SNAPSHO T]	[64]	Queries data from a snapshot engine of a DFS table	when querying a snapshot engine registered with registerSnapshotEngine	select [HINT_SNAPSHOT] * from loadTable(dbName,tableName)
[HINT_KEEPORD ER]	[128 ]	Keeps the order of output records consistent with the input	with a context by clause	select [HINT_KEEPORDER] cumsu(vol) from t context by date, sym
[HINT_SEQ]	[512 ]	Executes queries on partitions serially to save the concurrency overhead	when memory is limited	timer select [HINT_SEQ] avg(vol) from t
[HINT_NOMERGE ]	[102 4]	Skips the merge step of intermediate results from map clause to improve the performance. Instead of returning the merged results in an in-memory table, only the handles of DFS tables are returned.	when the intermediate results do not need to be returned	select [HINT_NOMERGE] price from pt context by ticker
[HINT_PRELOAD ]	[409 6]	Loads all data into memory before filtering with where-conditions	with a where clause	select [HINT_PRELOAD] sum(price) from t where volume > 100000
[HINT_EXPLAIN ]	[327 68]	Prints the query execution plan to monitor the real-time performance and execution order of a SQL query	for SQL performance tuning. See [HINT_EXPLAIN]	select [HINT_EXPLAIN] * from tb where id > 20
[HINT_SORT]	[524 288]	Applies sorting algorithm to data grouping	with a group by clause	select [HINT_SORT] avg(price) from trades group by sym
[HINT_VECTORI ZED]	[419 4304]	Applies vectorization to data grouping	with a group by clause	select [HINT_VECTORIZED] sum(price) from trades group by sym