[IMPALA-8826] Impala Doc: Add docs for PLAN_ROOT_SINK and result spooling

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 3.4.0
• Component/s: Docs
• Labels: future_release_doc in_34
• Epic Color: ghx-label-6
• Assignee: Alexandra Rodoni
• Reporter: Sahil Takiar
• Created: 02/Aug/19 16:34
• Updated: 07/Oct/19 23:35
• Resolved: 07/Oct/19 23:35

Description

Currently, I don't see many docs explaining what a PLAN_ROOT_SINK is, even though it shows up in explain plans and runtime profiles. After more of the changes in IMPALA-8656 are merged, understanding what PLAN_ROOT_SINK is will be more important, because it will start taking up a memory reservation and possibly spilling to disk.

I don't see any docs on data sinks in general, so perhaps it would be useful to create a dedicated page for explaining data sinks and how they work. We can start by documenting the PLAN_ROOT_SINK as that may be the most commonly used one.

We should document all the changes being made in IMPALA-8656 as well.

Query option:
SPOOL_QUERY_RESULTS
MAX_RESULT_SPOOLING_MEM
MAX_SPILLED_RESULT_SPOOLING_MEM
FETCH_ROWS_TIMEOUT_MS (https://issues.apache.org/jira/browse/IMPALA-7312)

Issue Links

• links to: Impala Result Spooling Doc Notes