diff --git a/apisix/core/table.lua b/apisix/core/table.lua
index 4346863079cf..ed9450a8d854 100644
--- a/apisix/core/table.lua
+++ b/apisix/core/table.lua
@@ -23,6 +23,7 @@ local newproxy     = newproxy
 local getmetatable = getmetatable
 local setmetatable = setmetatable
 local select       = select
+local tostring     = tostring
 local new_tab      = require("table.new")
 local nkeys        = require("table.nkeys")
 local ipairs       = ipairs
@@ -91,7 +92,7 @@ end
 -- @usage
 -- local arr = {"a", "b", "c"}
 -- local idx = core.table.array_find(arr, "b") -- idx = 2
-function _M.array_find(array, val)
+local function array_find(array, val)
     if type(array) ~= "table" then
         return nil
     end
@@ -104,6 +105,7 @@ function _M.array_find(array, val)
 
     return nil
 end
+_M.array_find = array_find
 
 
 -- only work under lua51 or luajit
@@ -117,19 +119,28 @@ end
 
 local deepcopy
 do
-    local function _deepcopy(orig, copied)
-        -- prevent infinite loop when a field refers its parent
-        copied[orig] = true
+    local function _deepcopy(orig, copied, parent, opts)
         -- If the array-like table contains nil in the middle,
         -- the len might be smaller than the expected.
         -- But it doesn't affect the correctness.
         local len = #orig
         local copy = new_tab(len, nkeys(orig) - len)
+        -- prevent infinite loop when a field refers its parent
+        copied[orig] = copy
         for orig_key, orig_value in pairs(orig) do
-            if type(orig_value) == "table" and not copied[orig_value] then
-                copy[orig_key] = _deepcopy(orig_value, copied)
-            else
+            local path = parent .. "." .. tostring(orig_key)
+            if opts and array_find(opts.shallows, path) then
                 copy[orig_key] = orig_value
+            else
+                if type(orig_value) == "table" then
+                    if copied[orig_value] then
+                        copy[orig_key] = copied[orig_value]
+                    else
+                        copy[orig_key] = _deepcopy(orig_value, copied, path, opts)
+                    end
+                else
+                    copy[orig_key] = orig_value
+                end
             end
         end
 
@@ -144,13 +155,13 @@ do
 
     local copied_recorder = {}
 
-    function deepcopy(orig)
+    function deepcopy(orig, opts)
         local orig_type = type(orig)
         if orig_type ~= 'table' then
             return orig
         end
 
-        local res = _deepcopy(orig, copied_recorder)
+        local res = _deepcopy(orig, copied_recorder, "self", opts)
         _M.clear(copied_recorder)
         return res
     end
diff --git a/apisix/init.lua b/apisix/init.lua
index 103a8c1d7584..4b2ad17e1ef5 100644
--- a/apisix/init.lua
+++ b/apisix/init.lua
@@ -246,15 +246,7 @@ local function parse_domain_in_route(route)
     -- don't modify the modifiedIndex to avoid plugin cache miss because of DNS resolve result
     -- has changed
 
-    local parent = route.value.upstream.parent
-    if parent then
-        route.value.upstream.parent = nil
-    end
-    route.dns_value = core.table.deepcopy(route.value)
-    if parent then
-        route.value.upstream.parent = parent
-        route.dns_value.upstream.parent = parent
-    end
+    route.dns_value = core.table.deepcopy(route.value, { shallows = { "self.upstream.parent"}})
     route.dns_value.upstream.nodes = new_nodes
     core.log.info("parse route which contain domain: ",
                   core.json.delay_encode(route, true))
diff --git a/apisix/plugin.lua b/apisix/plugin.lua
index 90d26f4ae37b..b3dadcb49588 100644
--- a/apisix/plugin.lua
+++ b/apisix/plugin.lua
@@ -584,7 +584,7 @@ end
 
 
 local function merge_service_route(service_conf, route_conf)
-    local new_conf = core.table.deepcopy(service_conf)
+    local new_conf = core.table.deepcopy(service_conf, { shallows = {"self.value.upstream.parent"}})
     new_conf.value.service_id = new_conf.value.id
     new_conf.value.id = route_conf.value.id
     new_conf.modifiedIndex = route_conf.modifiedIndex
@@ -658,7 +658,7 @@ end
 local function merge_service_stream_route(service_conf, route_conf)
     -- because many fields in Service are not supported by stream route,
     -- so we copy the stream route as base object
-    local new_conf = core.table.deepcopy(route_conf)
+    local new_conf = core.table.deepcopy(route_conf, { shallows = {"self.value.upstream.parent"}})
     if service_conf.value.plugins then
         for name, conf in pairs(service_conf.value.plugins) do
             if not new_conf.value.plugins then
@@ -706,7 +706,8 @@ local function merge_consumer_route(route_conf, consumer_conf, consumer_group_co
         return route_conf
     end
 
-    local new_route_conf = core.table.deepcopy(route_conf)
+    local new_route_conf = core.table.deepcopy(route_conf,
+                            { shallows = {"self.value.upstream.parent"}})
 
     if consumer_group_conf then
         for name, conf in pairs(consumer_group_conf.value.plugins) do
diff --git a/apisix/plugins/ai.lua b/apisix/plugins/ai.lua
index 39430c7ad014..278201d4e56e 100644
--- a/apisix/plugins/ai.lua
+++ b/apisix/plugins/ai.lua
@@ -69,7 +69,9 @@ local default_keepalive_pool = {}
 
 local function create_router_matching_cache(api_ctx)
     orig_router_http_matching(api_ctx)
-    return core.table.deepcopy(api_ctx)
+    return core.table.deepcopy(api_ctx, {
+        shallows = { "self.matched_route.value.upstream.parent" }
+    })
 end
 
 
diff --git a/t/core/table.t b/t/core/table.t
index c3ec5a7c0d1f..38616ae535bf 100644
--- a/t/core/table.t
+++ b/t/core/table.t
@@ -215,3 +215,147 @@ GET /t
 GET /t
 --- response_body
 ok
+
+
+
+=== TEST 8: deepcopy copy same table only once
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local tmp = { name = "tmp", priority = 1, enabled = true }
+            local origin = { a = { b = tmp }, c = tmp}
+            local copy = core.table.deepcopy(origin)
+            if not core.table.deep_eq(copy, origin) then
+                ngx.say("copy: ", json.encode(expect), ", origin: ", json.encode(actual))
+                return
+            end
+            if copy.a.b ~= copy.c then
+                ngx.say("copy.a.b should be the same as copy.c")
+                return
+            end
+            ngx.say("ok")
+        }
+    }
+--- request
+GET /t
+--- response_body
+ok
+
+
+
+=== TEST 9: reference same table
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local deepcopy = core.table.deepcopy
+            local tab1 = {name = "tab1"}
+            local tab2 = {
+                a = tab1,
+                b = tab1
+            }
+            local tab_copied = deepcopy(tab2)
+
+            ngx.say("table copied: ", require("toolkit.json").encode(tab_copied))
+
+            ngx.say("tab1 == tab2.a: ", tab1 == tab2.a)
+            ngx.say("tab2.a == tab2.b: ", tab2.a == tab2.b)
+
+            ngx.say("tab_copied.a == tab1: ", tab_copied.a == tab1)
+            ngx.say("tab_copied.a == tab_copied.b: ", tab_copied.a == tab_copied.b)
+        }
+    }
+--- request
+GET /t
+--- response_body
+table copied: {"a":{"name":"tab1"},"b":{"name":"tab1"}}
+tab1 == tab2.a: true
+tab2.a == tab2.b: true
+tab_copied.a == tab1: false
+tab_copied.a == tab_copied.b: true
+
+
+
+=== TEST 10: reference table self(root node)
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local deepcopy = core.table.deepcopy
+            local tab1 = {name = "tab1"}
+            local tab2 = {
+                a = tab1,
+            }
+            tab2.c = tab2
+
+            local tab_copied = deepcopy(tab2)
+
+            ngx.say("tab_copied.a == tab1: ", tab_copied.a == tab_copied.b)
+            ngx.say("tab_copied == tab_copied.c: ", tab_copied == tab_copied.c)
+        }
+    }
+--- request
+GET /t
+--- response_body
+tab_copied.a == tab1: false
+tab_copied == tab_copied.c: true
+
+
+
+=== TEST 11: reference table self(sub node)
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local deepcopy = core.table.deepcopy
+            local tab_org = {
+                a = {
+                    a2 = "a2"
+                },
+            }
+            tab_org.b = tab_org.a
+
+            local tab_copied = deepcopy(tab_org)
+            ngx.say("table copied: ", require("toolkit.json").encode(tab_copied))
+            ngx.say("tab_copied.a == tab_copied.b: ", tab_copied.a == tab_copied.b)
+        }
+    }
+--- request
+GET /t
+--- response_body
+table copied: {"a":{"a2":"a2"},"b":{"a2":"a2"}}
+tab_copied.a == tab_copied.b: true
+
+
+
+=== TEST 12: shallow copy
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+            local deepcopy = core.table.deepcopy
+            local t1 = {name = "tab1"}
+            local t2 = {name = "tab2"}
+            local tab = {
+                a = {b = {c = t1}},
+                x = {y = t2},
+            }
+            local tab_copied = deepcopy(tab, { shallows = { "self.a.b.c" }})
+
+            ngx.say("table copied: ", require("toolkit.json").encode(tab_copied))
+
+            ngx.say("tab_copied.a.b.c == tab.a.b.c1: ", tab_copied.a.b.c == tab.a.b.c)
+            ngx.say("tab_copied.a.b.c == t1: ", tab_copied.a.b.c == t1)
+            ngx.say("tab_copied.x.y == tab.x.y: ", tab_copied.x.y == tab.x.y)
+            ngx.say("tab_copied.x.y == t2: ", tab_copied.x.y == t2)
+        }
+    }
+--- request
+GET /t
+--- response_body
+table copied: {"a":{"b":{"c":{"name":"tab1"}}},"x":{"y":{"name":"tab2"}}}
+tab_copied.a.b.c == tab.a.b.c1: true
+tab_copied.a.b.c == t1: true
+tab_copied.x.y == tab.x.y: false
+tab_copied.x.y == t2: false