Added support for explaining normalized queries with Postgres 16

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 3.4.0 (unreleased)
 
+- Added support for explaining normalized queries with Postgres 16
 - Added Docker image for `linux/arm64`
 
 ## 3.3.4 (2023-09-05)

app/controllers/pg_hero/home_controller.rb

@@ -292,12 +292,14 @@ def explain
       # need to prevent CSRF and DoS
       if request.post? && @query.present?
         begin
+          generic_plan = @database.server_version_num >= 160000 && @query.include?("$1")
+
           explain_options =
             case params[:commit]
             when "Analyze"
               {analyze: true}
             when "Visualize"
-              if @explain_analyze_enabled
+              if @explain_analyze_enabled && !generic_plan
                 {analyze: true, costs: true, verbose: true, buffers: true, format: "json"}
               else
                 {costs: true, verbose: true, format: "json"}
@@ -306,6 +308,8 @@ def explain
               {}
             end
 
+          explain_options[:generic_plan] = true if generic_plan
+
           if explain_options[:analyze] && !@explain_analyze_enabled
             render_text "Explain analyze not enabled", status: :bad_request
             return
@@ -319,7 +323,7 @@ def explain
           @error =
             if message == "Unsafe statement"
               "Unsafe statement"
-            elsif message.start_with?("PG::ProtocolViolation: ERROR:  bind message supplies 0 parameters")
+            elsif message.start_with?("PG::UndefinedParameter") || message.include?("EXPLAIN options ANALYZE and GENERIC_PLAN cannot be used together")
               "Can't explain queries with bind parameters"
             elsif message.start_with?("PG::SyntaxError")
               "Syntax error with query"

lib/pghero/methods/explain.rb

@@ -12,19 +12,20 @@ def explain(sql)
           if (sql.sub(/;\z/, "").include?(";") || sql.upcase.include?("COMMIT")) && !explain_safe?
             raise ActiveRecord::StatementInvalid, "Unsafe statement"
           end
-          explanation = select_all("EXPLAIN #{sql}").map { |v| v[:"QUERY PLAN"] }.join("\n")
+          explanation = execute("EXPLAIN #{sql}").map { |v| v["QUERY PLAN"] }.join("\n")
         end
 
         explanation
       end
 
       # TODO rename to explain in 4.0
       # note: this method is not affected by the explain option
-      def explain_v2(sql, analyze: nil, verbose: nil, costs: nil, settings: nil, buffers: nil, wal: nil, timing: nil, summary: nil, format: "text")
+      def explain_v2(sql, analyze: nil, verbose: nil, costs: nil, settings: nil, generic_plan: nil, buffers: nil, wal: nil, timing: nil, summary: nil, format: "text")
         options = []
         add_explain_option(options, "ANALYZE", analyze)
         add_explain_option(options, "VERBOSE", verbose)
         add_explain_option(options, "SETTINGS", settings)
+        add_explain_option(options, "GENERIC_PLAN", generic_plan)
         add_explain_option(options, "COSTS", costs)
         add_explain_option(options, "BUFFERS", buffers)
         add_explain_option(options, "WAL", wal)

lib/pghero/methods/query_stats.rb

@@ -319,7 +319,7 @@ def combine_query_stats(grouped_stats)
       end
 
       def explainable?(query)
-        query =~ /select/i && !query.include?("?)") && !query.include?("= ?") && !query.include?("$1") && query !~ /limit \?/i
+        query =~ /select/i && (server_version_num >= 160000 || (!query.include?("?)") && !query.include?("= ?") && !query.include?("$1") && query !~ /limit \?/i))
       end
 
       # removes comments

test/controller_test.rb

@@ -62,6 +62,18 @@ def test_explain_only
     refute_match /Execution Time/i, response.body
   end
 
+  def test_explain_only_normalized
+    post pg_hero.explain_path, params: {query: "SELECT $1"}
+    assert_response :success
+    if explain_normalized?
+      assert_match "Result  (cost=0.00..0.01 rows=1 width=32)", response.body
+      refute_match /Planning Time/i, response.body
+      refute_match /Execution Time/i, response.body
+    else
+      assert_match "Can't explain queries with bind parameters", response.body
+    end
+  end
+
   def test_explain_only_not_enabled
     with_explain(false) do
       post pg_hero.explain_path, params: {query: "SELECT 1"}
@@ -88,6 +100,14 @@ def test_explain_analyze
     assert_match /Execution Time/i, response.body
   end
 
+  def test_explain_analyze_normalized
+    with_explain("analyze") do
+      post pg_hero.explain_path, params: {query: "SELECT $1", commit: "Analyze"}
+    end
+    assert_response :success
+    assert_match "Can't explain queries with bind parameters", response.body
+  end
+
   def test_explain_analyze_timeout
     with_explain("analyze") do
       with_explain_timeout(0.01) do
@@ -122,6 +142,21 @@ def test_explain_visualize_analyze
     assert_match "Actual Total Time", response.body
   end
 
+  def test_explain_visualize_normalized
+    with_explain("analyze") do
+      post pg_hero.explain_path, params: {query: "SELECT $1", commit: "Visualize"}
+    end
+    assert_response :success
+
+    if explain_normalized?
+      assert_match "https://tatiyants.com/pev/#/plans/new", response.body
+      assert_match ""Node Type": "Result"", response.body
+      refute_match "Actual Total Time", response.body
+    else
+      assert_match "Can't explain queries with bind parameters", response.body
+    end
+  end
+
   def test_tune
     get pg_hero.tune_path
     assert_response :success

test/explain_test.rb

@@ -54,6 +54,16 @@ def test_explain_v2_analyze
     end
   end
 
+  def test_explain_v2_generic_plan
+    assert_raises(ActiveRecord::StatementInvalid) do
+      database.explain_v2("SELECT $1")
+    end
+
+    if explain_normalized?
+      assert_match "Result", database.explain_v2("SELECT $1", generic_plan: true)
+    end
+  end
+
   def test_explain_v2_format_text
     assert_match "Result  (cost=", database.explain_v2("SELECT 1", format: "text")
   end

test/test_helper.rb

@@ -21,6 +21,10 @@ def with_explain_timeout(value)
       yield
     end
   end
+
+  def explain_normalized?
+    database.server_version_num >= 160000
+  end
 end
 
 logger = ActiveSupport::Logger.new(ENV["VERBOSE"] ? STDERR : nil)