Fix SimpleAggregateFunction for String longer MAX_SMALL_STRING_SIZE

SimpleAggregateFunction do not pass arena to the
add_function -> getAddressOfAddFunction(), hence next crash happens:
  (gdb) bt
  #0  DB::Arena::alloc (size=64, this=0x0) at ../dbms/src/Common/Arena.h:124
  #1  DB::SingleValueDataString::changeImpl (this=0x7f97424a27d8, value=..., arena=0x0) at ../dbms/src/AggregateFunctions/AggregateFunctionMinMaxAny.h:274
  #2  0x0000000005ea5319 in DB::AggregateFunctionNullUnary<true>::add (arena=<optimized out>, row_num=<optimized out>, columns=<optimized out>, place=<optimized out>, this=<optimized out>) at ../dbms/src/AggregateFunctions/AggregateFunctionNull.h:43
  #3  DB::IAggregateFunctionHelper<DB::AggregateFunctionNullUnary<true> >::addFree (that=<optimized out>, place=<optimized out>, columns=<optimized out>, row_num=<optimized out>, arena=<optimized out>) at ../dbms/src/AggregateFunctions/IAggregateFunction.h:131
  #4  0x000000000679772f in DB::AggregatingSortedBlockInputStream::addRow (this=this@entry=0x7f982de19c00, cursor=...) at ../dbms/src/Common/AlignedBuffer.h:31
  #5  0x0000000006797faa in DB::AggregatingSortedBlockInputStream::merge (this=this@entry=0x7f982de19c00, merged_columns=..., queue=...) at ../dbms/src/DataStreams/AggregatingSortedBlockInputStream.cpp:140
  #6  0x0000000006798979 in DB::AggregatingSortedBlockInputStream::readImpl (this=0x7f982de19c00) at ../dbms/src/DataStreams/AggregatingSortedBlockInputStream.cpp:78
  #7  0x000000000622db55 in DB::IBlockInputStream::read (this=0x7f982de19c00) at ../dbms/src/DataStreams/IBlockInputStream.cpp:56
  #8  0x0000000006613bee in DB::MergeTreeDataMergerMutator::mergePartsToTemporaryPart (this=this@entry=0x7f97ec65e1a0, future_part=..., merge_entry=..., time_of_merge=<optimized out>, disk_reservation=<optimized out>, deduplicate=<optimized out>) at /usr/include/c++/8/bits/shared_ptr_base.h:1018
  #9  0x000000000658f7a4 in DB::StorageReplicatedMergeTree::tryExecuteMerge (this=0x7f97ec65b810, entry=...) at /usr/include/c++/8/bits/unique_ptr.h:342
  #10 0x00000000065940ab in DB::StorageReplicatedMergeTree::executeLogEntry (this=0x7f97ec65b810, entry=...) at ../dbms/src/Storages/StorageReplicatedMergeTree.cpp:910
  <snip>

  (gdb) f 1
  (gdb) p MAX_SMALL_STRING_SIZE
  $1 = 48
  (gdb) p capacity
  $2 = 64
  (gdb) p value
  $3 = {data = 0x7f97242fcbd0 "HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH", size = 61}

v2: avoid leaking of allocated by Arena memory on the intermediate step

Fixes: 8f8d2c0 ("Merge pull request ClickHouse#4629 from bgranvea/simple_aggregate_function")

dbms/src/DataStreams/AggregatingSortedBlockInputStream.cpp

@@ -1,6 +1,7 @@
 #include <DataStreams/AggregatingSortedBlockInputStream.h>
 #include <Common/typeid_cast.h>
 #include <Common/StringUtils/StringUtils.h>
+#include <Common/Arena.h>
 #include <DataTypes/DataTypeAggregateFunction.h>
 #include <DataTypes/DataTypeCustomSimpleAggregateFunction.h>
 
@@ -134,6 +135,8 @@ void AggregatingSortedBlockInputStream::merge(MutableColumns & merged_columns, s
             for (auto & desc : columns_to_simple_aggregate)
                 desc.createState();
 
+            arena = std::make_unique<Arena>();
+
             ++merged_rows;
         }
 
@@ -169,7 +172,7 @@ void AggregatingSortedBlockInputStream::addRow(SortCursor & cursor)
     for (auto & desc : columns_to_simple_aggregate)
     {
         auto & col = cursor->all_columns[desc.column_number];
-        desc.add_function(desc.function.get(), desc.state.data(), &col, cursor->pos, nullptr);
+        desc.add_function(desc.function.get(), desc.state.data(), &col, cursor->pos, arena.get());
     }
 }
 

dbms/src/DataStreams/AggregatingSortedBlockInputStream.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <common/logger_useful.h>
+#include <memory>
 
 #include <Core/Row.h>
 #include <Core/ColumnNumbers.h>
@@ -13,6 +14,8 @@
 namespace DB
 {
 
+class Arena;
+
 /** Merges several sorted streams to one.
   * During this for each group of consecutive identical values of the primary key (the columns by which the data is sorted),
   * merges them into one row. When merging, the data is pre-aggregated - merge of states of aggregate functions,
@@ -63,6 +66,9 @@ class AggregatingSortedBlockInputStream : public MergingSortedBlockInputStream
      */
     void insertSimpleAggregationResult(MutableColumns & merged_columns);
 
+    /// Memory pool for SimpleAggregateFunction.
+    std::unique_ptr<Arena> arena;
+
     /// Stores information for aggregation of SimpleAggregateFunction columns
     struct SimpleAggregateDescription
     {

dbms/tests/queries/0_stateless/00915_simple_aggregate_function.reference

@@ -40,4 +40,5 @@ SimpleAggregateFunction(sum, Float64)
 8	16
 9	18
 1	1	2	2.2.2.2
+10	2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222	20	20.20.20.20
 SimpleAggregateFunction(anyLast, Nullable(String))	SimpleAggregateFunction(anyLast, LowCardinality(Nullable(String)))	SimpleAggregateFunction(anyLast, IPv4)

dbms/tests/queries/0_stateless/00915_simple_aggregate_function.sql

@@ -22,6 +22,9 @@ drop table if exists test.simple;
 create table test.simple (id UInt64,nullable_str SimpleAggregateFunction(anyLast,Nullable(String)),low_str SimpleAggregateFunction(anyLast,LowCardinality(Nullable(String))),ip SimpleAggregateFunction(anyLast,IPv4)) engine=AggregatingMergeTree order by id;
 insert into test.simple values(1,'1','1','1.1.1.1');
 insert into test.simple values(1,null,'2','2.2.2.2');
+-- String longer then MAX_SMALL_STRING_SIZE (actual string length is 100)
+insert into test.simple values(10,'10','10','10.10.10.10');
+insert into test.simple values(10,'2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222','20','20.20.20.20');
 
 select * from test.simple final;
 select toTypeName(nullable_str),toTypeName(low_str),toTypeName(ip) from test.simple limit 1;