ON DELETION ORDER
Problem:
When a InnoDB index page is under-filled, we will merge it with either
the left sibling node or the right sibling node. But this checking is
incorrect. When the left sibling node is available, even if merging
is not possible with left sibling node, we do not check for the
possibility of merging with the right sibling node.
Solution:
If left sibling node is available, and merging with left sibling node
is not possible, then check if merge with right sibling node is
possible.
rb#2506 approved by jimmy & ima.
btr_lift_page_up() writes wrong page number (different by -1) for upper than father page.
But in almost all of the cases, the father page should be root page, no upper
pages. It is very rare path.
In addition the leaf page should not be lifted unless the father page is root.
Because the branch pages should not become the leaf pages.
rb://1336 approved by Marko Makela.
btr_lift_page_up() writes wrong page number (different by -1) for upper than father page.
But in almost all of the cases, the father page should be root page, no upper
pages. It is very rare path.
In addition the leaf page should not be lifted unless the father page is root.
Because the branch pages should not become the leaf pages.
rb://1336 approved by Marko Makela.
Delete-mark change buffer records when resorting to a pessimistic
delete from the change buffer B-tree. Skip delete-marked records in
the change buffer merge and when estimating whether an operation can
be buffered. Without this fix, we could try to apply the same buffered
changes multiple times if the server was killed at the right moment.
In MySQL 5.5 and later: ibuf_get_volume_buffered_count_func(): Ignore
delete-marked (already processed) records.
ibuf_delete_rec(): Add a crash point before optimistic delete. If the
optimistic delete fails, flag the record processed before
mtr_commit().
ibuf_merge_or_delete_for_page(): Ignore delete-marked (already
processed) records.
Backport to 5.1: Rename btr_cur_del_unmark_for_ibuf() to
btr_cur_set_deleted_flag_for_ibuf() and add a parameter.
rb:1307 approved by Jimmy Yang
IN QUERIES
This bug was caused by an incorrect fix of
Bug#13807811 BTR_PCUR_RESTORE_POSITION() CAN SKIP A RECORD
There was nothing wrong with btr_pcur_restore_position(), but with the
use of it in the table scan during index creation.
rb:1206 approved by Jimmy Yang
Changes in the InnoDB codebase required to compile and
integrate the MEB codebase with MySQL 5.5.
@ storage/innobase/btr/btr0btr.c
Excluded buffer pool usage from MEB build.
buf_pool_from_bpage calls are in buf0buf.ic, and
the buffer pool functions from that file are
disabled in MEB.
@ storage/innobase/buf/buf0buf.c
Disabling more buffer pool functions unused in MEB.
@ storage/innobase/dict/dict0dict.c
Disabling dict_ind_free that is unused in MEB.
@ storage/innobase/dict/dict0mem.c
The include
#include "ha_prototypes.h"
Was causing conflicts with definitions in my_global.h
Linking C executable mysqlbackup
libinnodb.a(dict0mem.c.o): In function `dict_mem_foreign_table_name_lookup_set':
dict0mem.c:(.text+0x91c): undefined reference to `innobase_get_lower_case_table_names'
libinnodb.a(dict0mem.c.o): In function `dict_mem_referenced_table_name_lookup_set':
dict0mem.c:(.text+0x9fc): undefined reference to `innobase_get_lower_case_table_names'
libinnodb.a(dict0mem.c.o): In function `dict_mem_foreign_table_name_lookup_set':
dict0mem.c:(.text+0x96e): undefined reference to `innobase_casedn_str'
libinnodb.a(dict0mem.c.o): In function `dict_mem_referenced_table_name_lookup_set':
dict0mem.c:(.text+0xa4e): undefined reference to `innobase_casedn_str'
collect2: ld returned 1 exit status
make[2]: *** [mysqlbackup] Error 1
innobase_get_lower_case_table_names
innobase_casedn_str
are functions that are part of ha_innodb.cc that is not part of the build
dict_mem_foreign_table_name_lookup_set
function is not there in the current codebase, meaning we do not use it in MEB.
@ storage/innobase/fil/fil0fil.c
The srv_fast_shutdown variable is declared in
srv0srv.c that is not compiled in the
mysqlbackup codebase.
This throws an undeclared error.
From the Manual
---------------
innodb_fast_shutdown
--------------------
The InnoDB shutdown mode. The default value is 1
as of MySQL 3.23.50, which causes a “fast� shutdown
(the normal type of shutdown). If the value is 0,
InnoDB does a full purge and an insert buffer merge
before a shutdown. These operations can take minutes,
or even hours in extreme cases. If the value is 1,
InnoDB skips these operations at shutdown.
This ideally does not matter from mysqlbackup
@ storage/innobase/ha/ha0ha.c
In file included from /home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/ha/ha0ha.c:34:0:
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/include/btr0sea.h:286:17: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
make[2]: *** [CMakeFiles/innodb.dir/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/ha/ha0ha.c.o] Error 1
make[1]: *** [CMakeFiles/innodb.dir/all] Error 2
make: *** [all] Error 2
# include "sync0rw.h" is excluded from hotbackup compilation in dict0dict.h
This causes extern rw_lock_t* btr_search_latch_temp; to throw a failure because
the definition of rw_lock_t is not found.
@ storage/innobase/include/buf0buf.h
Excluding buffer pool functions that are unused from the
MEB codebase.
@ storage/innobase/include/buf0buf.ic
replicated the exclusion of
#include "buf0flu.h"
#include "buf0lru.h"
#include "buf0rea.h"
by looking at the current codebase in <meb-trunk>/src/innodb
@ storage/innobase/include/dict0dict.h
dict_table_x_lock_indexes, dict_table_x_unlock_indexes, dict_table_is_corrupted,
dict_index_is_corrupted, buf_block_buf_fix_inc_func are unused in MEB and was
leading to compilation errors and hence excluded.
@ storage/innobase/include/dict0dict.ic
dict_table_x_lock_indexes, dict_table_x_unlock_indexes, dict_table_is_corrupted,
dict_index_is_corrupted, buf_block_buf_fix_inc_func are unused in MEB and was
leading to compilation errors and hence excluded.
@ storage/innobase/include/log0log.h
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/include/log0log.h: At top level:
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/include/log0log.h:767:2: error: expected specifier-qualifier-list before â⠂¬Ëœmutex_t’
mutex_t definitions were excluded as seen from ambient code
hence excluding definition for log_flush_order_mutex also.
@ storage/innobase/include/os0file.h
Bug in InnoDB code, create_mode should have been create.
@ storage/innobase/include/srv0srv.h
In file included from /home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/buf/buf0buf.c:50:0:
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/include/srv0srv.h: At top level:
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/include/srv0srv.h:120:16: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘srv_use_native_aio’
srv_use_native_aio - we do not use native aio of the OS anyway from MEB. MEB does not compile
InnoDB with this option. Hence disabling it.
@ storage/innobase/include/trx0sys.h
[ 56%] Building C object CMakeFiles/innodb.dir/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/trx/trx0sys.c.o
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/trx/trx0sys.c: In function ‘trx_sys_read_file_format_id’:
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/trx/trx0sys.c:1499:20: error: ‘TRX_SYS_FILE_FORMAT_TAG_MAGIC_N’ undeclared (first use in this function)
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/trx/trx0sys.c:1499:20: note: each undeclared identifier is reported only once for each function it appears in
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/trx/trx0sys.c: At top level:
/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/include/buf0buf.h:607:1: warning: ‘buf_block_buf_fix_inc_func’ declared ‘static’ but never defined
make[2]: *** [CMakeFiles/innodb.dir/home/narayanan/mysql-server/mysql-5.5-meb-rel3.8-innodb-integration-1/storage/innobase/trx/trx0sys.c.o] Error 1
unused calls excluded to enable compilation
@ storage/innobase/mem/mem0dbg.c
excluding #include "ha_prototypes.h" that lead to definitions in ha_innodb.cc
@ storage/innobase/os/os0file.c
InnoDB not compiled with aio support from MEB anyway. Hence excluding this from
the compilation.
@ storage/innobase/page/page0zip.c
page0zip.c:(.text+0x4e9e): undefined reference to `buf_pool_from_block'
collect2: ld returned 1 exit status
buf_pool_from_block defined in buf0buf.ic, most of the file is excluded for compilation of MEB
@ storage/innobase/ut/ut0dbg.c
excluding #include "ha_prototypes.h" since it leads to definitions in ha_innodb.cc
innobase_basename(file) is defined in ha_innodb.cc. Hence excluding that also.
@ storage/innobase/ut/ut0ut.c
cal_tm unused from MEB, was leading to earnings, hence disabling for MEB.
BY A CONCURRENT TRANSACTIO
The member function QUICK_RANGE_SELECT::init_ror_merged_scan() performs
a table handler clone. Innodb does not provide a clone operation.
The ha_innobase::clone() is not there. The handler::clone() does not
take care of the ha_innobase->prebuilt->select_lock_type. Because of
this what happens is that for one index we do a locking read, and
for the other index we were doing a non-locking (consistent) read.
The patch introduces ha_innobase::clone() member function.
It is implemented similar to ha_myisam::clone(). It calls the
base class handler::clone() and then does any additional operation
required. I am setting the ha_innobase->prebuilt->select_lock_type
correctly.
rb://1060 approved by Marko
This bug has been there at least since MySQL 4.0.9. (Before 4.0.9, the
code probably was even more severely broken.)
btr_pcur_restore_position(): When cursor restoration fails, before
invoking btr_pcur_store_position() move to the previous or next record
unless cursor->rel_pos==BTR_PCUR_ON or the record was not a user
record.
This bug can cause skipped records when btr_pcur_store_position() is
called on the last record of a page. A symptom would be record count
mismatch in CHECK TABLE, or failure to find a record to delete-mark or
update or purge. The following operations should be affected by the
bug:
* row_search_for_mysql(): SELECT, UPDATE, REPLACE, CHECK TABLE,
(almost anything else than INSERT)
* foreign key CASCADE operations
* row_merge_read_clustered_index(): index creation (since MySQL 5.1
InnoDB Plugin)
* multi-threaded purge (after MySQL 5.5): not sure, but it might fail
to purge some records
Not all callers of btr_pcur_restore_position() should be affected.
Anything that asserts or checks that restoration succeeds is
unaffected. For example, cursor restoration on the change buffer tree
should always succeed, because access is being protected by additional
latches. Likewise, rollback, or any code accesses data dictionary
tables while holding dict_sys->mutex should be safe.
rb:967 approved by Jimmy Yang
print page dump
buf_page_print(): Remove the ut_ad(0) from the beginning. Add two flags
(enum buf_page_print_flags) that can be bitwise-ORed together:
BUF_PAGE_PRINT_NO_CRASH:
Do not crash debug builds at the end of buf_page_print().
BUF_PAGE_PRINT_NO_FULL:
Do not print the full page dump. This can be useful when adding
diagnostic printout to flushing or to the doublewrite buffer.
trx_sys_doublewrite_init_or_restore_page(): Replace exit(1) with ut_error,
so that we can get a core dump if this extraordinary condition happens.
rb:924 approved by Sunny Bains
This fix does not remove the underlying cause of the assertion
failure. It just works around the problem, allowing a corrupted
secondary index to be fixed by DROP INDEX and CREATE INDEX (or in the
worst case, by re-creating the table).
ibuf_delete(): If the record to be purged is the last one in the page
or it is not delete-marked, refuse to purge it. Instead, write an
error message to the error log and let a debug assertion fail.
ibuf_set_del_mark(): If the record to be delete-marked is not found,
display some more information in the error log and let a debug
assertion fail.
row_undo_mod_del_unmark_sec_and_undo_update(),
row_upd_sec_index_entry(): Let a debug assertion fail when the record
to be delete-marked is not found.
buf_page_print(): Add ut_ad(0) so that corruption will be more
prominent in stress testing with debug binaries. Add ut_ad(0) here and
there where corruption is noticed.
btr_corruption_report(): Display some data on page_is_comp() mismatch.
btr_assert_not_corrupted(): A wrapper around btr_corruption_report().
Assert that page_is_comp() agrees with the table flags.
rb:911 approved by Inaam Rana
Remove btr_cur_t::ibuf_cnt. The only dependence on cursor->ibuf_cnt
was ibuf_set_entry_counter(). That code path was removed in the
original bug fix (marko.makela@oracle.com-20111107072802-dgwagejlpub0rjkd).
rb:819 approved by Jimmy Yang
Bug#12612184 RACE CONDITION AFTER BTR_CUR_PESSIMISTIC_UPDATE()
The fix introduced potentially more severe crash recovery problems
than the bug causes. Revert the fix for now.
This was an attempt to address problems with the Bug#12612184 fix.
Even with this follow-up fix, crash recovery can be broken.
Let us fix the bug later.
btr_record_not_null_field_in_rec(): Remove the parameter rec.
Use rec_offs_nth_sql_null() instead of rec_get_nth_field().
rb:788 approved by Jimmy Yang
The fix of Bug#12612184 broke crash recovery. When a record that
contains off-page columns (BLOBs) is updated, we must first write redo
log about the BLOB page writes, and only after that write the redo log
about the B-tree changes. The buggy fix would log the B-tree changes
first, meaning that after recovery, we could end up having a record
that contains a null BLOB pointer.
Because we will be redo logging the writes off the off-page columns
before the B-tree changes, we must make sure that the pages chosen for
the off-page columns are free both before and after the B-tree
changes. In this way, the worst thing that can happen in crash
recovery is that the BLOBs are written to free pages, but the B-tree
changes are not applied. The BLOB pages would correctly remain free in
this case. To achieve this, we must allocate the BLOB pages in the
mini-transaction of the B-tree operation. A further quirk is that BLOB
pages are allocated from the same file segment as leaf pages. Because
of this, we must temporarily "hide" any leaf pages that were freed
during the B-tree operation by "fake allocating" them prior to writing
the BLOBs, and freeing them again before the mtr_commit() of the
B-tree operation, in btr_mark_freed_leaves().
btr_cur_mtr_commit_and_start(): Remove this faulty function that was
introduced in the Bug#12612184 fix. The problem that this function was
trying to address was that when we did mtr_commit() the BLOB writes
before the mtr_commit() of the update, the new BLOB pages could have
overwritten clustered index B-tree leaf pages that were freed during
the update. If recovery applied the redo log of the BLOB writes but
did not see the log of the record update, the index tree would be
corrupted. The correct solution is to make the freed clustered index
pages unavailable to the BLOB allocation. This function is also a
likely culprit of InnoDB hangs that were observed when testing the
Bug#12612184 fix.
btr_mark_freed_leaves(): Mark all freed clustered index leaf pages of
a mini-transaction allocated (nonfree=TRUE) before storing the BLOBs,
or freed (nonfree=FALSE) before committing the mini-transaction.
btr_freed_leaves_validate(): A debug function for checking that all
clustered index leaf pages that have been marked free in the
mini-transaction are consistent (have not been zeroed out).
btr_page_alloc_low(): Refactored from btr_page_alloc(). Return the
number of the allocated page, or FIL_NULL if out of space. Add the
parameter "mtr_t* init_mtr" for specifying the mini-transaction where
the page should be initialized, or if this is a "fake allocation"
(init_mtr=NULL) by btr_mark_freed_leaves(nonfree=TRUE).
btr_page_alloc(): Add the parameter init_mtr, allowing the page to be
initialized and X-latched in a different mini-transaction than the one
that is used for the allocation. Invoke btr_page_alloc_low(). If a
clustered index leaf page was previously freed in mtr, remove it from
the memo of previously freed pages.
btr_page_free(): Assert that the page is a B-tree page and it has been
X-latched by the mini-transaction. If the freed page was a leaf page
of a clustered index, link it by a MTR_MEMO_FREE_CLUST_LEAF marker to
the mini-transaction.
btr_store_big_rec_extern_fields_func(): Add the parameter alloc_mtr,
which is NULL (old behaviour in inserts) and the same as local_mtr in
updates. If alloc_mtr!=NULL, the BLOB pages will be allocated from it
instead of the mini-transaction that is used for writing the BLOBs.
fsp_alloc_from_free_frag(): Refactored from
fsp_alloc_free_page(). Allocate the specified page from a partially
free extent.
fseg_alloc_free_page_low(), fseg_alloc_free_page_general(): Add the
parameter "mtr_t* init_mtr" for specifying the mini-transaction where
the page should be initialized, or NULL if this is a "fake allocation"
that prevents the reuse of a previously freed B-tree page for BLOB
storage. If init_mtr==NULL, try harder to reallocate the specified page
and assert that it succeeded.
fsp_alloc_free_page(): Add the parameter "mtr_t* init_mtr" for
specifying the mini-transaction where the page should be initialized.
Do not allow init_mtr == NULL, because this function is never to be
used for "fake allocations".
mtr_t: Add the operation MTR_MEMO_FREE_CLUST_LEAF and the flag
mtr->freed_clust_leaf for quickly determining if any
MTR_MEMO_FREE_CLUST_LEAF operations have been posted.
row_ins_index_entry_low(): When columns are being made off-page in
insert-by-update, invoke btr_mark_freed_leaves(nonfree=TRUE) and pass
the mini-transaction as the alloc_mtr to
btr_store_big_rec_extern_fields(). Finally, invoke
btr_mark_freed_leaves(nonfree=FALSE) to avoid leaking pages.
row_build(): Correct a comment, and add a debug assertion that a
record that contains NULL BLOB pointers must be a fresh insert.
row_upd_clust_rec(): When columns are being moved off-page, invoke
btr_mark_freed_leaves(nonfree=TRUE) and pass the mini-transaction as
the alloc_mtr to btr_store_big_rec_extern_fields(). Finally, invoke
btr_mark_freed_leaves(nonfree=FALSE) to avoid leaking pages.
buf_reset_check_index_page_at_flush(): Remove. The function
fsp_init_file_page_low() already sets
bpage->check_index_page_at_flush=FALSE.
There is a known issue in tablespace extension. If the request to
allocate a BLOB page leads to the tablespace being extended, crash
recovery could see BLOB writes to pages that are off the tablespace
file bounds. This should trigger an assertion failure in fil_io() at
crash recovery. The safe thing would be to write redo log about the
tablespace extension to the mini-transaction of the BLOB write, not to
the mini-transaction of the record update. However, there is no redo
log record for file extension in the current redo log format.
rb:693 approved by Sunny Bains
GCC 4.6 has new -Wunused-but-set-variable flag, which is enabled
by -Wall, that causes GCC to emit a warning whenever a local variable
is assigned to, but otherwise unused (aside from its declaration).
Since the maintainer mode uses -Wall and -Werror, source code which
triggers these warnings will be rejected. That is, these warnings
become hard errors.
The solution is to fix the code which triggers these specific warnings.
In most of the cases, this is a welcome cleanup as code which triggers
this warning is probably dead anyway.
dbug/dbug.c:
Unused but set.
libmysqld/lib_sql.cc:
Length is not necessary as the converted error message is always
null-terminated.
sql/item_func.cc:
Make get_var_with_binlog private to this compilation unit.
If a error was raised, do not attempt to evaluate the user
variable as the statement execution will be interrupted
anyway.
sql/mysqld.cc:
Use a void expression to silence the warning. Avoids the use of
macros that would make the code more unreadable than it already is.
sql/protocol.cc:
Length is not necessary as the converted error message is always
null-terminated. Remove unnecessary casts and assignment.
sql/sql_class.h:
Function is only used in a single compilation unit.
sql/sql_load.cc:
Only use the variable outside of EMBEDDED_LIBRARY.
storage/innobase/btr/btr0cur.c:
Do not retrieve field, only the record length is being used.
storage/perfschema/pfs.cc:
Use a void expression to silence the warning.
tests/mysql_client_test.c:
Unused but set.
unittest/mysys/lf-t.c:
Unused but set.
Replace UNIV_BLOB_NULL_DEBUG with UNIV_DEBUG||UNIV_BLOB_LIGHT_DEBUG.
Fix known bogus failures.
btr_cur_optimistic_update(): If rec_offs_any_null_extern(), assert that
the current transaction is an incomplete transaction that is being
rolled back in crash recovery.
row_build(): If rec_offs_any_null_extern(), assert that the transaction
that last updated the record was recovered during crash recovery
(and will soon be rolled back).
btr_cur_compress_if_useful(), btr_compress(): Add the parameter ibool
adjust. If adjust=TRUE, adjust the cursor position after compressing
the page.
btr_lift_page_up(): Return a pointer to the father page.
BTR_KEEP_POS_FLAG: A new flag for btr_cur_pessimistic_update().
btr_cur_pessimistic_update(): If *big_rec != NULL and flags &
BTR_KEEP_POS_FLAG, keep the cursor positioned on the updated record.
Also, do not release the index tree x-lock if *big_rec != NULL.
btr_cur_mtr_commit_and_start(): Commits and restarts a
mini-transaction so that it will retain an x-lock on index->lock and
the page of the cursor. This is invoked when
btr_cur_pessimistic_update() returns *big_rec != NULL.
In all callers of btr_cur_pessimistic_update() that do not pass
BTR_KEEP_POS_FLAG, assert that *big_rec == NULL.
btr_cur_compress(): Unused function [in the built-in MySQL 5.1], remove.
page_rec_get_nth(): Return the nth record on the page (an inverse
function of page_rec_get_n_recs_before()). Refactored from
page_get_middle_rec().
page_get_middle_rec(): Invoke page_rec_get_nth().
page_cur_insert_rec_zip_reorg(): Make use of the page directory
shortcuts in page_rec_get_nth() instead of scanning the whole list of
records.
row_ins_clust_index_entry_by_modify(): Pass BTR_KEEP_POS_FLAG to
btr_cur_pessimistic_update().
row_ins_index_entry_low(): If row_ins_clust_index_entry_by_modify()
returns a big_rec, invoke btr_cur_mtr_commit_and_start() in order to
commit and start the mini-transaction without releasing the x-locks on
index->lock and the cursor page, and write the big_rec. Releasing the
page latch in mtr_commit() caused a race condition.
row_upd_clust_rec(): Pass BTR_KEEP_POS_FLAG to
btr_cur_pessimistic_update(). If it returns a big_rec, invoke
btr_cur_mtr_commit_and_start() in order to commit and start the
mini-transaction without releasing the x-locks on index->lock and the
cursor page, and write the big_rec. Releasing the page latch in
mtr_commit() caused a race condition.
sync_thread_add_level(): Add the parameter ibool relock. When TRUE,
bypass the latching order rules.
rw_lock_add_debug_info(): For nested X-lock requests, pass relock=TRUE
to sync_thread_add_level().
rb:678 approved by Jimmy Yang
Some ut_a(!rec_offs_any_null_extern()) assertion failures are indicating
genuine BLOB bugs, others are bogus failures when rolling back incomplete
transactions at crash recovery. This needs more work, and until I get a
chance to work on it, other testing must not be disrupted by this.
If UNIV_DEBUG or UNIV_BLOB_LIGHT_DEBUG is enabled, add
!rec_offs_any_null_extern() assertions, ensuring that records do not
contain null pointers to externally stored columns in inappropriate
places.
btr_cur_optimistic_update(): Assert !rec_offs_any_null_extern().
Incomplete records must never be updated or deleted. This assertion
will cover also the pessimistic route.
row_build(): Assert !rec_offs_any_null_extern(). Search tuples must
never be built from incomplete index entries.
row_rec_to_index_entry(): Assert !rec_offs_any_null_extern() unless
ROW_COPY_DATA is requested. ROW_COPY_DATA is used for
multi-versioning, and therefore it might be valid to copy the most
recent (uncommitted) version while it contains a null pointer to
off-page columns.
row_vers_build_for_consistent_read(),
row_vers_build_for_semi_consistent_read(): Assert !rec_offs_any_null_extern()
on all versions except the most recent one.
trx_undo_prev_version_build(): Assert !rec_offs_any_null_extern() on
the previous version.
rb:682 approved by Sunny Bains
