Obtains only the calculation results on the local server

in a distributed cluster

select [HINT_LOCAL] sum(*) from pt



Groups data with the hash algorithm by default

with a group by clause

select [HINT_HASH] count(*) from t group by sym



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)


[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


[512 ]

Executes queries on partitions serially to save the concurrency overhead

when memory is limited

timer select [HINT_SEQ] avg(vol) from t


[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


[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


[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


[524 288]

Applies sorting algorithm to data grouping

with a group by clause

select [HINT_SORT] avg(price) from trades group by sym


[419 4304]

Applies vectorization to data grouping

with a group by clause

select [HINT_VECTORIZED] sum(price) from trades group by sym