Improve performance of view default function lookup (rails-sqlserver#…

…1074) * Improve performance of view default function lookup (rails-sqlserver#1073) * Update CHANGELOG.md --------- Co-authored-by: David Genord II <[email protected]>
lavika · Sep 26, 2023 · 8de95b9 · 8de95b9
1 parent f95780f
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,9 @@
+## Unreleased
+
+#### Changed
+
+- [#1073](https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/pull/1073) Improve performance of view default function lookup
+
 ## v7.0.3.0
 
 #### Fixed

diff --git a/lib/active_record/connection_adapters/sqlserver/schema_statements.rb b/lib/active_record/connection_adapters/sqlserver/schema_statements.rb
@@ -371,6 +371,15 @@ def column_definitions(table_name)
           view_exists = view_exists?(table_name)
           view_tblnm  = view_table_name(table_name) if view_exists
 
+          if view_exists
+            results = sp_executesql %{
+              SELECT c.COLUMN_NAME AS [name], c.COLUMN_DEFAULT AS [default]
+              FROM #{database}.INFORMATION_SCHEMA.COLUMNS c
+              WHERE c.TABLE_NAME = #{quote(view_tblnm)}
+            }.squish, "SCHEMA", []
+            default_functions = results.each.with_object({}) {|row, out| out[row["name"]] = row["default"] }.compact
+          end
+
           sql = column_definitions_sql(database, identifier)
 
           binds = []
@@ -402,13 +411,8 @@ def column_definitions(table_name)
             ci[:default_function] = begin
               default = ci[:default_value]
               if default.nil? && view_exists
-                default = select_value %{
-                  SELECT c.COLUMN_DEFAULT
-                  FROM #{database}.INFORMATION_SCHEMA.COLUMNS c
-                  WHERE
-                    c.TABLE_NAME = '#{view_tblnm}'
-                    AND c.COLUMN_NAME = '#{views_real_column_name(table_name, ci[:name])}'
-                }.squish, "SCHEMA"
+                view_column = views_real_column_name(table_name, ci[:name])
+                default = default_functions[view_column] if view_column.present?
               end
               case default
               when nil