MDEV-28992 Spider group by handler: Push down TIMESTAMPDIFF function

Also removed ITEM_FUNC_TIMESTAMPDIFF_ARE_PUBLIC.

Similar to pr#2225, with the testcase adapted from that patch:

--8<---------------cut here---------------start------------->8---
From 884f7c6df16236748ca975339e0b1c267e195309 Mon Sep 17 00:00:00 2001
From: "Norio Akagi (norakagi)" <norakagi@amazon.com>
Date: Wed, 3 Aug 2022 23:30:34 -0700
Subject: [PATCH] [MDEV-28992] Push down TIMESTAMP_DIFF in spider

This changes so that TIMESTAMP_DIFF function in a query is pushed down and works natively in Spider.
Instead of directly accessing item's member, now we can rely on a public accessor method to make it work.
Unit tests are added under spider.pushdown_timestamp_diff.

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.
--8<---------------cut here---------------end--------------->8---

storage/spider/mysql-test/spider/feature/r/pushdown_timestamp_diff.result

+#
+# MDEV-28992 Spider: Push down TIMESTAMPDIFF function
+#
+for master_1
+for child2
+for child3
+set spider_same_server_link= 1;
+CREATE SERVER srv FOREIGN DATA WRAPPER mysql
+OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+create table t2 (
+a INT,
+b CHAR(1),
+c DATETIME,
+PRIMARY KEY(a)
+);
+CREATE TABLE t1 (
+a INT,
+b CHAR(1),
+c DATETIME,
+PRIMARY KEY(a)
+) ENGINE=Spider COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+INSERT INTO t1 (a, b, c) VALUES
+(1, 'a', '2018-11-01 10:21:39'),
+(2, 'b', '2015-06-30 23:59:59'),
+(3, 'c', '2013-11-01 01:01:01');
+interval year
+explain select a, b, timestampdiff(year, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(year, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(year, '2000-01-01 00:00:00', c)
+1	a	18
+2	b	15
+3	c	13
+interval quarter
+explain select a, b, timestampdiff(quarter, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(quarter, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(quarter, '2000-01-01 00:00:00', c)
+1	a	75
+2	b	61
+3	c	55
+interval month
+explain select a, b, timestampdiff(month, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(month, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(month, '2000-01-01 00:00:00', c)
+1	a	226
+2	b	185
+3	c	166
+interval week
+explain select a, b, timestampdiff(week, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(week, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(week, '2000-01-01 00:00:00', c)
+1	a	982
+2	b	808
+3	c	721
+interval day
+explain select a, b, timestampdiff(day, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(day, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(day, '2000-01-01 00:00:00', c)
+1	a	6879
+2	b	5659
+3	c	5053
+internal hour
+explain select a, b, timestampdiff(hour, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(hour, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(hour, '2000-01-01 00:00:00', c)
+1	a	165106
+2	b	135839
+3	c	121273
+internal minute
+explain select a, b, timestampdiff(minute, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(minute, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(minute, '2000-01-01 00:00:00', c)
+1	a	9906381
+2	b	8150399
+3	c	7276381
+internal second
+explain select a, b, timestampdiff(second, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(second, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(second, '2000-01-01 00:00:00', c)
+1	a	594382899
+2	b	489023999
+3	c	436582861
+internal microsecond
+explain select a, b, timestampdiff(microsecond, '2000-01-01 00:00:00', c) from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select a, b, timestampdiff(microsecond, '2000-01-01 00:00:00', c) from t1;
+a	b	timestampdiff(microsecond, '2000-01-01 00:00:00', c)
+1	a	594382899000000
+2	b	489023999000000
+3	c	436582861000000
+drop table t1, t2;
+drop server srv;
+for master_1
+for child2
+for child3

storage/spider/mysql-test/spider/feature/t/pushdown_timestamp_diff.test

+--echo #
+--echo # MDEV-28992 Spider: Push down TIMESTAMPDIFF function
+--echo #
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+set spider_same_server_link= 1;
+evalp CREATE SERVER srv FOREIGN DATA WRAPPER mysql
+OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+
+create table t2 (
+  a INT,
+  b CHAR(1),
+  c DATETIME,
+  PRIMARY KEY(a)
+);
+CREATE TABLE t1 (
+  a INT,
+  b CHAR(1),
+  c DATETIME,
+  PRIMARY KEY(a)
+) ENGINE=Spider COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+
+INSERT INTO t1 (a, b, c) VALUES
+  (1, 'a', '2018-11-01 10:21:39'),
+  (2, 'b', '2015-06-30 23:59:59'),
+  (3, 'c', '2013-11-01 01:01:01');
+
+--echo interval year
+let $query=
+select a, b, timestampdiff(year, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo interval quarter
+let $query=
+select a, b, timestampdiff(quarter, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo interval month
+let $query=
+select a, b, timestampdiff(month, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo interval week
+let $query=
+select a, b, timestampdiff(week, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo interval day
+let $query=
+select a, b, timestampdiff(day, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo internal hour
+let $query=
+select a, b, timestampdiff(hour, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo internal minute
+let $query=
+select a, b, timestampdiff(minute, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo internal second
+let $query=
+select a, b, timestampdiff(second, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+--echo internal microsecond
+let $query=
+select a, b, timestampdiff(microsecond, '2000-01-01 00:00:00', c) from t1;
+eval explain $query;
+eval $query;
+
+drop table t1, t2;
+drop server srv;
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log

storage/spider/spd_db_handlersocket.cc

@@ -3178,14 +3178,13 @@ int spider_db_handlersocket_util::open_item_func(
             alias, alias_length, dbton_id, use_fields, fields));
         } else if (!strncasecmp("timestampdiff", func_name, func_name_length))
         {
-#ifdef ITEM_FUNC_TIMESTAMPDIFF_ARE_PUBLIC
           Item_func_timestamp_diff *item_func_timestamp_diff =
             (Item_func_timestamp_diff *) item_func;
           if (str)
           {
             const char *interval_str;
             uint interval_len;
-            switch (item_func_timestamp_diff->int_type)
+            switch (item_func_timestamp_diff->get_int_type())
             {
               case INTERVAL_YEAR:
                 interval_str = SPIDER_SQL_YEAR_STR;
@@ -3257,9 +3256,6 @@ int spider_db_handlersocket_util::open_item_func(
               SPIDER_SQL_CLOSE_PAREN_LEN);
           }
           DBUG_RETURN(0);
-#else
-          DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
-#endif
         }
       } else if (func_name_length == 14)
       {

storage/spider/spd_db_mysql.cc

@@ -5533,14 +5533,6 @@ int spider_db_mbase_util::open_item_func(
     alias_length, use_fields, fields));
 }
 
-static bool item_func_is_timestampdiff(
-  const char *func_name,
-  int func_name_length
-) {
-  return func_name_length == 13 &&
-    !strncasecmp("timestampdiff", func_name, func_name_length);
-}
-
 static bool not_func_should_be_skipped(
   Item_func *item_func
 ){
@@ -5610,10 +5602,6 @@ int spider_db_mbase_util::check_item_func(
   Item_func::Functype func_type = item_func->functype();
   DBUG_PRINT("info",("spider functype = %d", func_type));
 
-  const char *func_name = (char*) item_func->func_name();
-  int func_name_length = strlen(func_name);
-  DBUG_PRINT("info",("spider func_name = %s", func_name));
-
   /* The blacklist of the functions that cannot be pushed down */
   switch (func_type)
   {
@@ -5628,14 +5616,6 @@ int spider_db_mbase_util::check_item_func(
       break;
     case Item_func::FUNC_SP:
     case Item_func::UDF_FUNC:
-      /* Notes on merging regarding MDEV-29447: please refer to the
-      following commits for build error or merge conflicts:
-      10.5: d7b564da2a634dcf86798d6b86bd127e7eef9286
-      10.6: 1ed20b993b0dd4e95450cab2e8347e5bf4617a69
-      10.9: dd316b6e20265cfd832bb5585cb4c96e716387c8
-      10.10-11: 3f67f110ba1b23a89c5ede0fbeeb203cf5e164f4
-      11.0-1: 17ba6748afa8834df5658361088e6c8e65aca16f
-      Please remove this comment after merging. */
       use_pushdown_udf= spider_param_use_pushdown_udf(
           spider->trx->thd, spider->share->use_pushdown_udf);
       if (!use_pushdown_udf)
@@ -5645,12 +5625,6 @@ int spider_db_mbase_util::check_item_func(
       if (spider_db_check_ft_idx(item_func, spider) == MAX_KEY)
         DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
       break;
-#ifndef ITEM_FUNC_TIMESTAMPDIFF_ARE_PUBLIC
-    case Item_func::UNKNOWN_FUNC:
-      if (item_func_is_timestampdiff(func_name, func_name_length))
-        DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
-      break;
-#endif
     default:
       break;
   }
@@ -6015,12 +5989,11 @@ int spider_db_mbase_util::print_item_func(
             alias, alias_length, dbton_id, use_fields, fields));
         } else if (!strncasecmp("timestampdiff", func_name, func_name_length))
         {
-#ifdef ITEM_FUNC_TIMESTAMPDIFF_ARE_PUBLIC
           Item_func_timestamp_diff *item_func_timestamp_diff =
             (Item_func_timestamp_diff *) item_func;
           const char *interval_str;
           uint interval_len;
-          switch (item_func_timestamp_diff->int_type)
+          switch (item_func_timestamp_diff->get_int_type())
           {
           case INTERVAL_YEAR:
             interval_str = SPIDER_SQL_YEAR_STR;
@@ -6071,7 +6044,7 @@ int spider_db_mbase_util::print_item_func(
           str->q_append(SPIDER_SQL_OPEN_PAREN_STR, SPIDER_SQL_OPEN_PAREN_LEN);
           str->q_append(interval_str, interval_len);
           str->q_append(SPIDER_SQL_COMMA_STR, SPIDER_SQL_COMMA_LEN);
-          
+
           if ((error_num = spider_db_print_item_type(item_list[0], NULL, spider,
                                                      str, alias, alias_length, dbton_id, use_fields, fields)))
             DBUG_RETURN(error_num);
@@ -6092,9 +6065,6 @@ int spider_db_mbase_util::print_item_func(
                           SPIDER_SQL_CLOSE_PAREN_LEN);
           }
           DBUG_RETURN(0);
-#else
-          DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
-#endif
         }
       } else if (func_name_length == 14)
       {

storage/spider/spd_db_oracle.cc

@@ -3424,14 +3424,13 @@ int spider_db_oracle_util::open_item_func(
             alias, alias_length, dbton_id, use_fields, fields));
         } else if (!strncasecmp("timestampdiff", func_name, func_name_length))
         {
-#ifdef ITEM_FUNC_TIMESTAMPDIFF_ARE_PUBLIC
           Item_func_timestamp_diff *item_func_timestamp_diff =
             (Item_func_timestamp_diff *) item_func;
           if (str)
           {
             const char *interval_str;
             uint interval_len;
-            switch (item_func_timestamp_diff->int_type)
+            switch (item_func_timestamp_diff->get_int_type())
             {
               case INTERVAL_YEAR:
                 interval_str = SPIDER_SQL_YEAR_STR;
@@ -3503,9 +3502,6 @@ int spider_db_oracle_util::open_item_func(
               SPIDER_SQL_CLOSE_PAREN_LEN);
           }
           DBUG_RETURN(0);
-#else
-          DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
-#endif
         }
       } else if (func_name_length == 14)
       {