The query processor of metabase has many steps. To analyze the middleware in the default-middleware, you can write a simple middleware for tracking. The specific code is as follows
(ns metabase.query-processor.middleware.querylog
"Middleware for logging a query before it is processed.
(Various other middleware functions log the query as well in different stages.)"
(:require [clojure.tools.logging :as log]
[metabase.util :as u]
[clojure.pprint :refer [pprint]]))
(defn pprint-to-str
{
:style/indent 1}
[x]
(with-open [w (java.io.StringWriter.)]
(pprint x w)
(str w)))
; (defn- log-query* [query]
; (u/prog1 query
; (log/info (u/format-color 'blue "\nQuery (before preprocessing): %s\n%s" (u/pprint-to-str query)))))
(defn- log-query* [query]
(u/prog1 query
(log/info (u/format-color 'blue "\nQuery :%s" (pprint-to-str query)))))
(defn log-query
"Middleware that logs the query that will be ran."
[qp]
(fn [query rff context]
( qp (log-query* query) (log-query* rff) context) ))
Modify the default-middleware as follows
#'mbql-to-native/mbql->native ;; call driver's sql execution
#'querylog/log-query ;; log before
#'check-features/check-features
The output is as follows:
2021-03-03 14:24:43,684 INFO middleware.permissions :: Checking query permissions. Current user perms set = %s #{"/collection/2/" "/db/3/" "/collection/1/" "/" "/collection/3/" "/collection/root/" "/db/1/"}
2021-03-03 14:24:43,799 INFO middleware.querylog ::
Query :{
:type :native,
:native {
:query "select * from activity where user_id=?", :params ["1"]},
:database 3,
:middleware {
:js-int-to-string? true, :add-default-userland-constraints? true},
:info
{
:executed-by 1,
:context :ad-hoc,
:nested? false,
:query-hash [-75, -51, -33, -57, -53, 6, -74, 110, -126, 83, -10, -23, -20, 13, -91, -46, 8, -15, 106, 112, 48, -78, -115, 68, -44, -125, -29, -17, -118, -10, 55, 94]},
:constraints {
:max-results 10000, :max-results-bare-rows 2000},
:user-parameters [{
:type :category, :target [:variable [:template-tag "current_user_id"]], :value "1"}],
:query nil}
2021-03-03 14:24:43,811 INFO middleware.querylog ::
Query :#object[metabase.query_processor.middleware.limit$limit$fn__52796$fn__52797 0x6fe95fd7 "metabase.query_processor.middleware.limit$limit$fn__52796$fn__52797@6fe95fd7"]
Although query, rff and context can be tracked, we generally only need to pay attention to the change of query.