Overview of result sets |V2.4.14|OceanBase Connector/J| docs|Distributed Database

Overview of result sets

Last Updated：2025-04-10 06:49:52 Updated

Result sets can be categorized into three types: full result sets, streaming result sets, and cursor result sets, based on the data reading method.

The following table describes the three result set types, including their advantages and disadvantages.

Result set type	Query method	Data reading method	Advantage	Disadvantage
Full result set	General query	All results are read at a time.	The application code is simple. When the data volume is small, result sets of this type are read faster than those of the other two types.	The out-of-memory (OOM) error will be reported when the data volume is large.
Streaming result set	Streaming query	Data is read from the socket row by row rather than all at a time.	The OOM error will not occur even when the data volume is large.	The execution occupies the database for a longer time and cannot be stopped once it starts. Therefore, it may cause network congestion.
Cursor result set	Cursor query	Multiple rows of data are read at a time. All results are obtained through multiple reads.	The OOM error will not occur even when the data volume is large. Compared with a streaming query, a single cursor query occupies a shorter DB time.	The execution is relatively slow. Compared with a streaming query, a cursor query consumes more server resources with a longer response time.

When the text protocol is executed, full result sets are used in OceanBase Database no matter in Oracle mode or MySQL mode.

The following table lists the trigger conditions of the three result set types in MySQL mode and Oracle mode.

Result set type	MySQL mode	Oracle mode
Cursor result set	The `&useCursorFetch=true` property is configured in the URL connection string. The result set type is `TYPE_FORWARD_ONLY`. The result set concurrency is `CONCUR_READ_ONLY`. The value of `FetchSize` is greater than 0.	The `&useServerPrepStmts=true` or `&useCursorFetch=true` property is configured in the URL connection string. Note: When `useCursorFetch` is set to `true`, `useServerPrepStmts` will be automatically set to `true`.
Streaming result set	The result set type is `TYPE_FORWARD_ONLY`. The result set concurrency is `CONCUR_READ_ONLY`. The value of `FetchSize` is the same as that of `Integer.MIN_VALUE`.	Not supported. Note: Streaming read is no longer supported in OceanBase Connector/J V2.2.7 or later in Oracle mode.
Full result set	Full result sets are used unless the trigger conditions for cursor result sets or streaming result sets are met.	The `&useServerPrepStmts=false` property is configured in the URL connection string.