[IGNITE-6020] SQL: client should request first pages on query execution instead of first cursor read

• Type: Task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.1
• Component/s: sql
• Assignee: Unassigned
• Reporter: Vladimir Ozerov
• Created: 10/Aug/17 08:13
• Updated: 14/Feb/19 08:18

Description

Currently we request first data blocks form server nodes on first cursor access. However, user code might want to execute a query, and access the cursor after some delay, in hope that asynchronous execution will do the trick.

For this reason, we should start requesting pages eagerly on "execute" command rather than on cursor access.

try (QueryCursor cursor = cache.execute(...)) { // <-- Should be here
    ...
    for (List<Object> row : cursor) {           // <-- But currently here
        ...
    }
}

Issue Links

• is a child of: IGNITE-11203 SQL: global refactoring