because plugin code is not only about encryption anymore
(also loads provider plugins), and xb_ prefix prevents name
clashes with the server code (that mariabackup links with).

prefer backup-my.cnf from the incremental-dir over the one in target-dir

* Change InnoDB message text to mention compression.
* make "not loaded compression provider" warning to be issued
  also when current_thd == 0.

make mariabackup to load not only encryption but also provider plugins.

like

==31311==ERROR: AddressSanitizer: odr-violation (0x7f3cda2e1480):
  [1] size=8 'provider_service_lz4' libservices/provider_service_lz4.c:14:17
  [2] size=8 'provider_service_lz4' sql/sql_plugin_services.ic:301:33

bzip2/lz4/lzma/lzo/snappy compression is now provided via *services*

they're almost like normal services, but in include/providers/
and they're supposed to provide exactly the same interface
as original compression libraries (but not everything,
only enough of if for the code to compile).

the services are implemented via dummy functions that return
corresponding error values (LZMA_PROG_ERROR, LZO_E_INTERNAL_ERROR, etc).

the actual compression libraries are linked into corresponding
provider plugins. Providers are daemon plugins that when loaded
replace service pointers to point to actual compression functions.

That is, run-time dependency on compression libraries is now on plugins,
and the server doesn't need any compression libraries to run, but
will automatically support the compression when a plugin is loaded.

InnoDB and Mroonga use compression plugins now. RocksDB doesn't,
because it comes with standalone utility binaries that cannot
load plugins.

if plugin->deinit() returns a failure, it is no longer ignored, it
means that the plugin isn't ready to be unloaded from memory yet.
So it's marked "dying", deinitialized as much as possible,
but stays in memory until shutdown.

also:

* increment MARIA_PLUGIN_INTERFACE_VERSION
* rewrite ha_rocksdb to use the new approach, update the test

* reduce code duplication

It turns out that WFRM_WRITE_EXTRACTED was added only in a debug
assertion and in a comment, as part of
commit b7bba721.

mysql_write_frm(): Correctly enclose code inside
#ifdef WITH_PARTITION_STORAGE_ENGINE
so that cmake -DPLUGIN_PARTITION=NO builds can succeed.
This was broken in
commit b7bba721.

Adding 10.4 specific tests.

Also fixes:
MDEV-25399 Assertion `name.length == strlen(name.str)' failed in Item_func_sp::make_send_field

Also fixes a problem that in this scenario:

SET NAMES binary;
SELECT 'some not well-formed utf8 string';

the auto-generated column name copied the binary string value directly
to the Item name, without checking utf8 well-formedness.

After this change auto-generated column names work as follows:
- Zero bytes 0x00 are copied to the name using HEX notation
- In case of "SET NAMES binary", all bytes sequences that do not make
  well-formed utf8 characters are copied to the name using HEX notation.

ALTER TABLE IMPORT doesn't properly handle instant alter metadata.
This patch makes IMPORT read, parse and apply instant alter metadata at the
very beginning of operation. So, cases when source table has some metadata
and destination table doesn't have it now works fine.

DISCARD already removes instant metadata so importing normal table into
instant table worked fine before this patch.

decrypt_decompress(): decrypts and decompresses page if needed

handle_instant_metadata(): this should be the first thing to read source
table. Basically, it applies instant metadata to a destination
dict_table_t object. This is the first thing to read FSP flags so
all possible checks of it were moved to this function.

PageConverter::update_index_page(): it doesn't now read instant metadata.
This logic were moved into handle_instant_metadata()

row_import::match_flags(): this is a first part row_import::match_schema().
As a separate function it's used by handle_instant_metadata().

fil_space_t::is_full_crc32_compressed(): added convenient function

ha_innobase::discard_or_import_tablespace(): do not reload table definition
to read instant metadata because handle_instant_metadata() does it better.
The reverted code was originally added in
4e7ee166

ANONYMOUS_VAR: this is a handy thing to use along with make_scope_exit()

full_crc32_import.test shows different results, because no
dict_table_close() and dict_table_open_on_id() happens.
Thus, SHOW CREATE TABLE shows a little bit older table definition.

ER_TRUNCATED_WRONG_VALUE

Part 1: Fix for DELETE without ORDER BY

Analysis: m_current_row_for_warning doesn't increment and assumes default
value which is then used by ROW_NUMBER.
Fix: Increment m_current_row_for_warning for each processed row.

CHECK violation

Analysis: When there is constraint fail we return non-zero value for
view_check_option(). So we continue the loop which doesn't increment the
counter because it increments at the end of the loop.
Fix: Increment m_current_row_for_warning() at the beginning of loop. This
will also fix similar bugs if any, about counter not incrementing
correctly because of continue.

ER_WRONG_VALUE_COUNT_ON_ROW for the 1st row

Analysis: Current row for warning does not increment for prepare phase
Fix: Increment current row for warning if number of fields in the table and
row values dont match and number of values in rows is greater than number
of fields

MDEV-26842: ROW_NUMBER is not set and differs from the message upon WARN_DATA_TRUNCATED produced by inplace ALTER

Analysis: When row number is passed as parameter to set_warning() it is only
used for error/warning text but m_current_row_for_warning is not updated.
Hence default value of m_current_row_for_warning is assumed.
Fix: update m_current_row_for_warning when error/warning occurs.

just a test case

in case of a bulk insert the server sends all rows to the engine, and
then the engine replies that there was ER_DUP_ENTRY somewhere.

the exact number of the row that caused the error is unknown.

to remove

Sql_condition*
raise_condition(const Sql_condition *cond)
{
  Sql_condition *raised= raise_condition(cond->get_sql_errno(),
                                         cond->get_sqlstate(),
                                         cond->get_level(),
                                         *cond,
                                         cond->get_message_text());
  return raised;
}

otherwise how can we know that the row counter is incremented?

Analysis: Parser was missing ROW_NUMBER as syntax for SIGNAL and RESIGNAL.
Fix: Fix parser and fix how m_row_number is copied like other attributes
to avoid ROW_NUMBER from assuming default value.

Wrong assertion leftover removed. m_sql_cmd can be allocated by any
ALTER subcommand and before allocation it is checked for NULL first.

Syntax for CONVERT TABLE

ALTER TABLE tbl_name CONVERT TABLE tbl_name TO PARTITION partition_name partition_spec

Examples:

    ALTER TABLE t1 CONVERT TABLE tp2 TO PARTITION p2 VALUES LESS THAN MAX_VALUE();

New ALTER_PARTITION_CONVERT_IN command for
fast_alter_partition_table() is done in alter_partition_convert_in()
function which basically does ha_rename_table().

Table structure and data check is basically the same as in EXCHANGE
PARTITION command. And these are done by
compare_table_with_partition() and check_table_data().

Atomic DDL is done by the scheme from MDEV-22166 (see the
corresponding commit message). The only differnce is that it also has
to drop source table frm and that is done by WFRM_DROP_CONVERTED_FROM.

Initial patch was done by Dmitry Shulga <dmitry.shulga@mariadb.com>