virajjasani opened a new pull request, #2102:
URL: https://github.com/apache/phoenix/pull/2102

   Jira: PHOENIX-7463
   
   PHOENIX-7330 introduces BSON as Data type in Phoenix. It also introduces 
complex expressions BSON_CONDITION_EXPRESSION() and BSON_UPDATE_EXPRESSION() to 
evaluate various WHERE clause based conditions and to perform full or partial 
document updates.
   
   BSON_CONDITION_EXPRESSION() has two flavors of expressions:
   
   Document style condition expression
   
   - SQL style condition expression with placeholder values
   - The Document style condition expression already comes in AST (Abstract 
Syntax Tree) form and hence the tree is directly parsed to evaluate the given 
condition.
   
   The SQL style condition expression has statement that needs to be evaluated. 
This style of expressions do have substantial difference from what we use in 
Phoenix SQL based WHERE clause. The expression also has BSON specific functions.
   
   PHOENIX-7330 uses MVEL based expression evaluation language to evaluate the 
given statement. MVEL also internally parses the string into AST tree before 
evaluating it. While this works well, it has some disadvantages:
   
   - The approach has dependency on regex based string conversions.
   - Adding more internal functions for BSON might require significant changes 
and potentially more regex overhead.
   
   The purpose of this Jira it to introduce new ANTLR grammar for BSON's SQL 
style condition expressions such that it can be extended to support more 
complex BSON functions in future. ANTLR is a powerful parser framework and it 
is already in use for Phoenix SQL use cases. While the same ANTLR grammar rules 
are not fully applicable to BSON conditions and internal functions (e.g. 
field_exists()), creating new grammar rules for BSON (Document) data type 
should be beneficial.


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