DB2 DDL Parser using ANTLR 3 -

i trying build antlr 3 grammar db2 ddl statement (create table) , finding decision can match input such "data" using multiple alternatives: 1, 2. following db2 ddl documentation document.

i have mapped syntax diagrams grammar. problem there optional clauses , path can same point , hence multiple alternatives. have used backtrack option want other solution of this. can please me in regard.

please have @ grammar:

unit: create_table_statement ;  create_table_statement: create_table_statement_rest ;  create_table_statement_rest:   create table id create_table_opts   organize_by_items?   data capture (none|changes) in_tbspc_cyc   tablespace_opts? distribution_clause?   partitioning_clause? compress_ny_val_compression   with_restrict_on_drop? not_logged_init?   ccsid_ascii_unicode? (security policy name)?   (options lparen add name name (comma name name)* rparen)? ;  with_restrict_on_drop: restrict on drop ;  not_logged_init:   not logged ;  ccsid_ascii_unicode:   ccsid (ascii|unicode) ;  create_table_opts:   element_list   |of name typed_table_opts?   |materialized_query_definition   |staging_table_definition   |like name copy_opts?  ;  organize_by_items:   organize (dimensions_item|key_sequence_items) ;  dimensions_item:   dimensions? lparen id (comma id)* rparen ;  key_sequence_items:   key sequence sequence_key_spec ;  sequence_key_spec:   lparen seq_key_spec_one (comma seq_key_spec_one) rparen (allow|disallow) overflow (pctfree digit)? ;  seq_key_spec_one:   id (starting from? constant)? ending at? digit ;  in_tbspc_cyc:   in (name (comma name)*) no? cycle? ;  tablespace_opts:   //tablespace_opt_one?    (index in name)? (log in name (comma name)*)? ;  distribution_clause:   distribute distribute_by_opts ;  distribute_by_opts:   distribution_item_one   |distribution_item_two ;  distribute_by:   distribute ;  distribution_item_one:   hash lparen id (comma id)* rparen ;  distribution_item_two:   replication ;  tablespace_opt_one:   index in name log in name ;  element_list:   lparen      element_list_items (comma element_list_items)*   rparen ;  materialized_query_definition:   (id (comma id)*)? lparen fullselect rparen materialized_query_table_opts ;  staging_table_definition:   (lparen name (comma name)* rparen) name propagate immediate ;  fullselect:  ;  materialized_query_table_opts:   no data copy_opts? | refreshable_table_opts ;  element_list_items:   column_definition|referential_constraint|check_constraint ;  column_definition:   name data_type? column_opts? ;  copy_opts:   ((including|excluding) column? defaults)? (excluding|including) identity (column attributes)? ;  refreshable_table_opts:   data deferred refresh (deferred|immediate) (enable|disable) query optimization (maintained (system|user|federated_tool))? ;  data_type:   smallint   |integer|int   |bigint   |float (lparen digit rparen)?   |real   |double precision?   |(decimal|dec|numeric|num) (lparen digit (comma integer)? rparen)?   |(dt_char|dt_vchar|long varchar) (for bit data)?   |((blob|binary large object)|(clob|(character|char) large object|dbclob) (lparen digit (k|m|g) rparen)?)   |graphic (lparen digit rparen)   |vargraphic (lparen digit rparen)   |long vargraphic   |date   |time   |timestamp   |xml   //|name   //added name instead of 2 below replaced   //|distinct_type_name   //|structured_type_name   |ref name   |(lparen sysproc dot rparen)? db2securitylabel ;  dt_char :   (character|char)(lparen digit rparen)?     ; dt_vchar    :     (varchar|((char|character) varying))lparen digit rparen      ; distinct_type_name :    name ; structured_type_name : name     ;  column_opts:   column_options_items+ ;   column_options_items:   not null   |lob_opts   |scope name   |((constraint name)? ((primary key|unique)| references_clause|(check_condition constraint_attributes)))   |generated_column_spec   |(inline length digit)   |(compress system default)   |(column secured id) ;  lob_opts:   not? logged not? compact ;  generated_column_spec:   default_clause|generated_by_identity|generated_by_exp ;  default_clause:   with? default default_values? ;  default_values:   default_values_items   |cast_function lparen default_values_items rparen   |null ;  default_values_items : constant |datetime_special_register |user_special_register |current schema  ;  datetime_special_register:   current date   |current time   |current timestamp ;  user_special_register:   current user   |session_user   |system_user ;  cast_function:   //needs figured out ;  generated_by_identity:   generated (always|(by default)) identity_opts? ;  identity_opts:   identity lparen identity_options_items (identity_options_items)* rparen ;  identity_options_items:   start digit   |increment digit   |no minvalue   |minvalue digit   |no maxvalue   |maxvalue digit   |no cycle   |cycle   | (no cache | cache digit)//cache 20 needs seen   |no order   |order ;  generated_by_exp:   generated always? generation_expression ;  generation_expression:   //needs figured out ;  unique_constraint:   (constraint name)? (unique|primary key) lparen name (comma name)* rparen ;  referential_constraint:   (constraint id)? foreign key lparen id (comma id)* rparen references_clause ;  references_clause:   references  name (lparen id (comma id)* rparen)? rule_clause constraint_attributes ;  rule_clause:   on delete (no action | restrict|cascade|set null) on update (no action|restrict) ;  check_constraint:   (constraint name) check check_condition constraint_attributes ;  check_condition:   search_condition|functional_dependency ;  constraint_attributes:   not? enforced (enable|disable) query optimization  ;  search_condition:   //needs done ;  functional_dependency:   (id | (lparen id (comma id)* rparen)) determined (id | (lparen id (comma id)* rparen)) ;  typed_table_opts:   (hierarchy name|under_clause)? typed_element_list? ;  typed_table_options_item2:   under_clause ;  under_clause:   under name inherit select privileges ;  typed_element_list:   lparen typed_element_list_items (comma typed_element_list_items)* rparen ;  typed_element_list_items:   oid_column_definition | with_opts | unique_constraint | check_constraint ;  oid_column_definition:   ref name user generated ;  with_opts:   name options column_opts ;  partitioning_clause:   part_by_range range_partition_spec  ;  part_by_range:   partition range? ; compress_ny_val_compression: compress (no|yes) (value compression)? ;  range_partition_spec:   lparen partition_expression (comma partition_expression)* rparen lparen partition_element (comma partition_element)* rparen ;  partition_element:   partition_boundry_element   |start_with_boundry_spec ;  partition_boundry_element:   (partition name)? boundary_spec (in name)? ;  start_with_boundry_spec:   boundary_spec every (duration_with_paren|duration_without_paren) ;  duration_with_paren:   lparen constant duration_label rparen ;  duration_without_paren:   constant duration_label ;  partition_expression:   nulls (last|first) ;  boundary_spec:   boundary_spec_path_one|boundary_spec_path_two ;  boundary_spec_path_one:   starting_clause ending_clause ;  boundary_spec_path_two:   ending_clause ;  starting_clause:   starting from? (starting_ending_with_repeat|starting_ending_without_repeat) (inclusive|exclusive) ;  ending_clause:   ending at? (starting_ending_with_repeat|starting_ending_without_repeat) (inclusive|exclusive) ;  starting_ending_with_repeat:   lparen starting_ending_clause_values (comma starting_ending_clause_values)* rparen ;  starting_ending_without_repeat:   starting_ending_clause_values ;  duration_label:   year|years|month|months|day|days|hour|hours|minute|minutes|second|seconds|microsecond|microseconds ;  starting_ending_clause_values:   constant|minvalue|maxvalue ;  constant:   digit ;  name    :   id;  ///////////////////////////////////////////////end parser rules///////////////////////////////////////////////////  ///////////////////////////////////////////////lexer rules///////////////////////////////////////////////////////  ws      :   ( '\t' | ' ' | '\r' | '\n' )+   { $channel = hidden; } ;  comma      :  ','     ;    equal:        '='; string_literal 

: ('n'|'u')?'\''( ~('\'') | '\'\'' )* '\'' ;

id  :   ('a'..'z'|'a'..'z'|'_') ('a'..'z'|'a'..'z'|'0'..'9'|'_')* ; digit : '0'..'9'+ ; 

any in regard appreciated.