Apply suggestions from code review

Accept obvious or agreed code review suggestions.

Co-authored-by: Rye Biesemeyer <yaauie@users.noreply.github.com>

Author: mashhurs

docs/index.asciidoc

@@ -119,17 +119,10 @@ Authorization to a secure Elasticsearch cluster requires `read` permission at in
 The `monitoring` permission at cluster level is necessary to perform periodic connectivity checks.
 
 [id="plugins-{type}s-{plugin}-esql"]
-==== ES|QL support
-{es} Query Language (ES|QL) provides a SQL-like interface for querying your {es} data.
+==== {esql} support
+{es} Query Language ({esql}) provides a SQL-like interface for querying your {es} data.
 
-To utilize the ES|QL feature with this plugin, the following version requirements must be met:
-[cols="1,2",options="header"]
-|===
-|Component |Minimum version
-|{es} |8.11.0 or newer
-|{ls} |8.17.4 or newer
-|This plugin |3.19.0+ (3.x series) or 4.3.0+ (4.x series)
-|===
+To use {esql}, this plugin needs to be installed in {ls} 8.17.4 or newer, and must be connected to {es} 8.11 or newer.
 
 To configure ES|QL query in the plugin, set your ES|QL query in the `query` parameter.
 

lib/logstash/filters/elasticsearch.rb

@@ -462,11 +462,10 @@ def validate_esql_query_and_params!
     named_params = original_query_params["named_params"] ||= []
     named_params_keys = named_params.map(&:keys).flatten
 
-    placeholders = @query.scan(/\?(\w+)/).flatten
+    placeholders = @query.scan(/(?<=[?])[a-z_][a-z0-9_]*/i)
     raise LogStash::ConfigurationError, "Number of placeholders in `query` and `named_params` do not match" unless placeholders.size == named_params_keys.size
 
     placeholders.each do |placeholder|
-      placeholder.delete_prefix!("?")
       raise LogStash::ConfigurationError, "Placeholder #{placeholder} not found in query" unless named_params_keys.include?(placeholder)
     end
   end

lib/logstash/filters/elasticsearch/esql_executor.rb

@@ -88,7 +88,7 @@ def add_requested_fields(event, columns, values)
             column_index = columns.find_index { |col| col['name'] == old_key }
             next unless column_index
 
-            row_values = values.map { |entry| entry[column_index] }&.compact # remove non-exist field values with compact
+            row_values = values[column_index]&.compact # remove non-exist field values with compact
             # TODO: set to the target field once target support is added
             event.set(new_key, row_values.one? ? row_values.first : row_values) if row_values&.size > 0
           end