Student and Welch t-test

try use cmake version for croaring instead of amalgamation.sh

Add check for BOM

Revert "Optionally upload clickhouse binary in fast test"

Database or Table Engine description template update

Change error message in function if & ifNull

Add more context to error messages

Optionally upload clickhouse binary in fast test

Add total_rows/total_bytes support for Set/Join

Add ability to specify PRIMARY KEY without ORDER BY

01540_MemoryTracking is failing on CI for the following reasons:
- log_queries (fixed, by adding log_queries=0)
- profilers (fixed)
- but what can't be fixed is metric_log and so on, so we need separate
  instance with separate configuration (sigh).

Fix broken link in replication docs

Fix TwoLevelStringHashTable bug

Fixes for DDL queries

Atomic DROP DATABASE SYNC

v2: disable query profiling and logging in 01540_MemoryTracking
    (This should make MemoryTracker drift zero).

MemoryTracker assumes that for VariableContext::Thread new/delete may be
called from different threads, hence the amount of memory can go
negative.

However the MemoryTracker is nested, so even if the negative amount is
allowed for VariableContext::Thread it does not allowed for anything
upper, and hence the MemoryTracking will not be decremented properly.

Fix this, by passing initial size to the parent free.

This should fix memory drift for HTTP queries.

This should significantly reduce the MemoryTracking drift, test shows
that there is 0 drift after query storm (100 queries, via http/tcp/tcp
in one session).

TL;DR;

To track memory, clickhouse creates memory tracker object for each
thread **explicitly**, but until it is not created the memory
allocations are not under account.
There should not be lot of allocations w/o memory tracker, since most of
the time it is created early enough, but even this maybe enough to
trigger some problems.

Plus sometimes it is not possible to create it, for example some 3d
party library does not allow to do this explicitly:
- for example before #15740 allocations from librdkafka threads,
- or even worse, poco threads, they don't have any routines to do this.
This won't be a problem for `MemoryTracking` metric if the deallocation
will be done from the same thread w/o memory tracker (or vise versa),
but this is not always true.

NOTE, that this will slow down per-thread allocations w/o memory
tracker, since before this patch there were no memory tracking for them
while now they will be accounted in total_memory_tracker, and for
total_memory_tracker max_untracked_memory is always reached.
But this should not be significant.

Link dbms w/ atomic to fix undefined reference in unbundled build

* Update show.md

Update descriptions of show databases and show tables.

* Update show.md

Update 'identical query'.

* Update show.md

Внес поправки согласно комментариям.

* Update show.md

Внес поправки и перевел на русский язык.

* Update show.md

Внес мелкие поправки.
Co-authored-by: NDmitriy <sevirov@yandex-team.ru>