Use GENERIC_PLAN for Postgres 16

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.2 (unreleased)
+
+- Use `GENERIC_PLAN` for Postgres 16
+
 ## 0.5.1 (2023-05-27)
 
 - Fixed `JSON::NestingError`

lib/dexter/indexer.rb

@@ -521,8 +521,8 @@ def conn
  raise Dexter::Abort, e.message
  end
 
- def execute(query, pretty: true, params: [])
- # use exec_params instead of exec for security
+ def execute(query, pretty: true, params: [], use_exec: false)
+ # use exec_params instead of exec when possible for security
  #
  # Unlike PQexec, PQexecParams allows at most one SQL command in the given string.
  # (There can be semicolons in it, but not more than one nonempty command.)
@@ -533,7 +533,11 @@ def execute(query, pretty: true, params: [])
  log colorize("[sql] #{query}#{params.any? ? " /*#{params.to_json}*/" : ""}", :cyan) if @log_sql
 
  @mutex.synchronize do
- conn.exec_params("#{query} /*dexter*/", params).to_a
+ if use_exec
+ conn.exec("#{query} /*dexter*/").to_a
+ else
+ conn.exec_params("#{query} /*dexter*/", params).to_a
+ end
  end
  end
 
@@ -543,7 +547,9 @@ def plan(query)
 
  # try to EXPLAIN normalized queries
  # https://dev.to/yugabyte/explain-from-pgstatstatements-normalized-queries-how-to-always-get-the-generic-plan-in--5cfi
- explain_normalized = query.include?("$1")
+ normalized = query.include?("$1")
+ generic_plan = normalized && server_version_num >= 160000
+ explain_normalized = normalized && !generic_plan
  if explain_normalized
  prepared_name = "dexter_prepared"
  execute("PREPARE #{prepared_name} AS #{safe_statement(query)}", pretty: false)
@@ -566,12 +572,14 @@ def plan(query)
  end
  end
 
+ explain_prefix = generic_plan ? "GENERIC_PLAN, " : ""
+
  # strip semi-colons as another measure of defense
- plan = JSON.parse(execute("EXPLAIN (FORMAT JSON) #{safe_statement(query)}", pretty: false).first["QUERY PLAN"], max_nesting: 1000).first["Plan"]
+ plan = JSON.parse(execute("EXPLAIN (#{explain_prefix}FORMAT JSON) #{safe_statement(query)}", pretty: false, use_exec: generic_plan).first["QUERY PLAN"], max_nesting: 1000).first["Plan"]
 
  if @log_explain
  # Pass format to prevent ANALYZE
- puts execute("EXPLAIN (FORMAT TEXT) #{safe_statement(query)}", pretty: false).map { |r| r["QUERY PLAN"] }.join("\n")
+ puts execute("EXPLAIN (#{explain_prefix}FORMAT TEXT) #{safe_statement(query)}", pretty: false, use_exec: generic_plan).map { |r| r["QUERY PLAN"] }.join("\n")
  end
 
  plan