Bug #31310238: SUPPORT SORTING MULTIPLE TABLES [patch 2/5, implementation] [noclose]

Make filesort support sorting a join of multiple tables, not just a single
table. The biggest change is that the sort types that depend on row IDs
need to support multiple ones instead of just one -- this means that we
can do such sorts without having to materialize them (StreamingIterator
already took care of most of the common cases, although with a fair bit
of unneccessary copying).

Filesort now takes in the estimate for number of rows (only used for
excluding priority queue, if there are so few rows that we assume multiple
buffers are not needed) from the estimates in the access path instead of asking
the table, since there's not necessarily “one table” anymore. For some tests,
this actually gives a more precise estimate, although it's likely to be fairly
inconsequential in practice.

Nothing in the executor currently sets up access paths with such multi-table
sorts, since fields are always resolved to the temporary table (so it's not
just a matter of changing), but the new optimizer will.

Change-Id: I5304035b1fa36b622e7d58d5464d6b3ec0e50ba8

Author: Steinar H. Gunderson

mysql-test/r/window_functions_explain.result

@@ -16724,8 +16724,8 @@ join_optimization": {
                           "memory_available": 262144,
                           "key_size": "XXX",
                           "row_size": "XXX",
-                          "max_rows_per_buffer": 34,
-                          "num_rows_estimate": 34,
+                          "max_rows_per_buffer": "NNN",
+                          "num_rows_estimate": 40,
                           "num_rows_found": 24,
                           "num_initial_chunks_spilled_to_disk": 0,
                           "peak_memory_used": "NNN",
@@ -16754,8 +16754,8 @@ join_optimization": {
                     "memory_available": 262144,
                     "key_size": "XXX",
                     "row_size": "XXX",
-                    "max_rows_per_buffer": 34,
-                    "num_rows_estimate": 34,
+                    "max_rows_per_buffer": "NNN",
+                    "num_rows_estimate": 18446744073709551615,
                     "num_rows_found": 24,
                     "num_initial_chunks_spilled_to_disk": 0,
                     "peak_memory_used": "NNN",
@@ -16784,8 +16784,8 @@ join_optimization": {
               "memory_available": 262144,
               "key_size": "XXX",
               "row_size": "XXX",
-              "max_rows_per_buffer": 34,
-              "num_rows_estimate": 34,
+              "max_rows_per_buffer": "NNN",
+              "num_rows_estimate": 18446744073709551615,
               "num_rows_found": 24,
               "num_initial_chunks_spilled_to_disk": 0,
               "peak_memory_used": "NNN",

mysql-test/suite/opt_trace/include/general2.inc

@@ -679,6 +679,7 @@ insert into t1 values(1),(2),(3);
 create database mysqltest2;
 create table mysqltest2.t2(a int);
 insert into mysqltest2.t2 values(1),(2);
+analyze table t1, mysqltest2.t2;
 --sorted_result
 select * from t1,mysqltest2.t2;
 SELECT * FROM INFORMATION_SCHEMA.OPTIMIZER_TRACE;

mysql-test/suite/opt_trace/r/filesort_pack.result

@@ -214,7 +214,7 @@ select * from t1 order by c1	{
               "key_size": 1022,
               "row_size": 66561,
               "max_rows_per_buffer": 14,
-              "num_rows_estimate": 215,
+              "num_rows_estimate": 15,
               "num_rows_found": 0,
               "num_initial_chunks_spilled_to_disk": 0,
               "peak_memory_used": 0,
@@ -372,7 +372,7 @@ select * from t1 order by c1	{
               "key_size": 1022,
               "row_size": 66561,
               "max_rows_per_buffer": 14,
-              "num_rows_estimate": 215,
+              "num_rows_estimate": 15,
               "num_rows_found": 0,
               "num_initial_chunks_spilled_to_disk": 0,
               "peak_memory_used": 0,
@@ -530,7 +530,7 @@ select * from t1 order by c1	{
               "key_size": 1022,
               "row_size": 66561,
               "max_rows_per_buffer": 14,
-              "num_rows_estimate": 215,
+              "num_rows_estimate": 15,
               "num_rows_found": 0,
               "num_initial_chunks_spilled_to_disk": 0,
               "peak_memory_used": 0,