Ppl help command

[YANG-DB]

Description

Add PPL -help command to assist grammar explaining and assisting users on different dialects and semantic

search -help

results in:

SEARCH Command:

Syntax:
   (SEARCH)? fromClause
   | (SEARCH)? fromClause logicalExpression
   | (SEARCH)? logicalExpression fromClause

Description:
The SEARCH command is used to retrieve data from a specified source. It can be used with or without additional filters.
- You can specify the data source using the FROM clause.
- You can add filters using logical expressions.
- The order of FROM clause and logical expression can be interchanged.

Issues Resolved

• [FEATURE]Add help command to PPL for a descriptive of grammar #658

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[YANG-DB]

@LantaoJin
I would appreciate your feedback on the approach i've drafter here for adding help parameter attribute for each command, for example the following would provide information and examples for the search command:

search -help

This would be done for all commands we want to add the help description to.

Implementation concepts and consideration

• Added a dedicated AstCommandDescriptionVisitor which is an additional visitor (to the ASTBuilder ) that is only responsible of the commands decoration visiting.
• The result is that AstStatementBuilder now hold a chain of visitors that run on each query and produce a plan (or not if they dont apply)
• FlintPPLSparkExtensions was added with injectPlannerStrategy to override the standard queries in case of a PrintLiteralCommandDescriptionLogicalPlan plan and to avoid reaching to the underlying SQL engine and responding with the actual planner's text that was generated during the former stage

Please let me know if this sounds reasonable and if you have any suggestions to make this simpler
Thanks

[LantaoJin]

Hi @YANG-DB , I haven't get the point what is the help command for.

The result is that AstStatementBuilder now hold a chain of visitors that run on each query and produce a plan (or not if they dont apply)

Seems you are going to add a debug or explain command to display the translated Spark unresolved plan tree. help sounds like a customer towards command to show usage of PPL.

If your proposal is for debug or explain purpose, I think the display info not only includes the unresolved plan, but also the physical plan (which will reach to the underlying SQL engine) with a trigger.

What confused me is the usage in description. It definitely is a help command. Beside the syntax, we can add some usage or examples.

For the debug or explain command, we need to display a generated plan for the PPL query user provided.

SEARCH explain=index
| <ppl command1>
| <ppl command2

or

EXPLAIN source=index
| <ppl command1>
| <ppl command2

[YANG-DB]

@YANG-DB plz resolve conflict

[YANG-DB]

closing this as it has not gained sufficient attention