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The assertion failed in handler::ha_reset upon SELECT under READ UNCOMMITTED from table with index on virtual column. This was the debug-only failure, though the problem is mush wider: * MY_BITMAP is a structure containing my_bitmap_map, the latter is a raw bitmap. * read_set, write_set and vcol_set of TABLE are the pointers to MY_BITMAP * The rest of MY_BITMAPs are stored in TABLE and TABLE_SHARE * The pointers to the stored MY_BITMAPs, like orig_read_set etc, and sometimes all_set and tmp_set, are assigned to the pointers. * Sometimes tmp_use_all_columns is used to substitute the raw bitmap directly with all_set.bitmap * Sometimes even bitmaps are directly modified, like in TABLE::update_virtual_field(): bitmap_clear_all(&tmp_set) is called. The last three bullets in the list, when used together (which is mostly always) make the program flow cumbersome and impossible to follow, notwithstanding the errors they cause, like this MDEV-17556, where tmp_set pointer was assigned to read_set, write_set and vcol_set, then its bitmap was substituted with all_set.bitmap by dbug_tmp_use_all_columns() call, and then bitmap_clear_all(&tmp_set) was applied to all this. To untangle this knot, the rule should be applied: * Never substitute bitmaps! This patch is about this. orig_*, all_set bitmaps are never substituted already. This patch changes the following function prototypes: * tmp_use_all_columns, dbug_tmp_use_all_columns to accept MY_BITMAP** and to return MY_BITMAP * instead of my_bitmap_map* * tmp_restore_column_map, dbug_tmp_restore_column_maps to accept MY_BITMAP* instead of my_bitmap_map* These functions now will substitute read_set/write_set/vcol_set directly, and won't touch underlying bitmaps.
== Summary ==
This directory contains RocksDB-based Storage Engine (RDBSE) for MySQL,
also known as "MyRocks".
== Resources ==
https://github.com/facebook/mysql-5.6/wiki/Getting-Started-with-MyRocks
https://www.facebook.com/groups/MyRocks/
== Coding Conventions ==
The baseline for MyRocks coding conventions for the code in storage/rocksdb/
is based on the default clang format with a few minor changes. The file
storage/rocksdb/.clang-format describes conventions and can be integrated
with Vim or Emacs as described here:
http://releases.llvm.org/3.6.0/tools/clang/docs/ClangFormat.html#vim-integration
All code outside of storage/rocksdb/ should conform to the MySQL coding
conventions:
http://dev.mysql.com/doc/internals/en/coding-guidelines.html.
Several refinements:
0. There is an umbrella C++ namespace named "myrocks" for all MyRocks code.
1. We introduced "RDB" as the super-short abbreviation for "RocksDB". We will
use it as a name prefix, with different capitalization (see below), to ease
up code navigation with ctags and grep.
N.B. For ease of matching, we'll keep the variables and functions dealing
with sysvars as close as possible to the outside visible names of
sysvars, which start with "rocksdb_" prefix, the outward storage
engine name.
2. The names for classes, interfaces, and C++ structures (which act as
classes), start with prefix "Rdb_".
NB: For historical reasons, we'll keep the "ha_<storage_engine_name>" class
name for ha_rocksdb class, which is an exception to the rule.
3. The names for global objects and functions start with prefix "rdb_".
4. The names for macros and constants start with prefix "RDB_".
5. Regular class member names start with "m_".
6. Static class member names start with "s_".
7. Given the 80 character per line limit, we'll not always use full English
words in names, when a well known or easily recognizable abbreviation
exists (like "tx" for "transaction" or "param" for "parameter" etc).
8. When needing to disambiguate, we use different suffixes for that, like
"_arg" for a function argument/parameter, "_arr" for a C style array, and
"_vect" for a std::vector etc.
== Running Tests ==
To run tests from rocksdb, rocksdb_rpl or other rocksdb_* packages, use the
following parameters:
--default-storage-engine=rocksdb
--skip-innodb
--default-tmp-storage-engine=MyISAM
--rocksdb